Skip to main content

Ahmed K Jaber

Universiti Teknologi PETRONAS, Petroleum Engineering, Graduate Student

Followers

17

Following

1

Co-author

1

Public Views

Specialist in Reservoir Engineering and Simulation. He holds BS and MS degrees in petroleum engineering from Baghdad University in 1996 and 1999 respectively. He holds the Ph.D. degree in Petroleum Engineering from Universiti Teknologi PETRONAS. Previously, he worked as a reservoir engineer during (2001-2006), Senior reservoir engineer (2006-2011) and as a chief assistant reservoir engineer during (2011-2013) in the Iraqi Ministry of Oil.
Supervisors: Chief Reservoir Engineer

less

Interests

Uploads

Papers by Ahmed K Jaber

Proxy modelling for rapid optimisation of miscible CO2-WAG injection in heterogeneous clastic reservoirs: a case study from Southern Iraqi oil fields

International Journal of Oil, Gas and Coal Technology, 2021

Multiple Linear Regression Approach for the Permeability Calculation from Well Logs: A Case Study in Nahr Umr Formation-Subba Oil Field, Iraq

The Subba oil field is a giant oil field located in south of Iraq about 110 km northwest Basra. N... more The Subba oil field is a giant oil field located in south of Iraq about 110 km northwest Basra. Nahr Umr reservoir in Subba oil field is a heterogeneous clastic reservoir. The calculation of the permeability was based on rock types delineation from well logs data. The methods that have been used for the rock types classification are; the rock-quality-index (RQI), flow-zone-indicator (FZI), and Discrete-rock-typing (DRT). It has been recognized that excellent permeability-porosity relationships were obtained after conventional core data are grouped according to their rock types. Conventional core data analysis were first used to define the rock types for the cored intervals, the data analysis from 7 plugs taken from 7 wells in Subba oil field were used for this purpose. The wireline log measurements at the cored depths were extracted, normalized, and subsequently analyzed together with the calculated rock types. The resulted mathematical model can be used to predict the rock type in ...

A review of proxy modeling applications in numerical reservoir simulation

Arabian Journal of Geosciences, 2019

The applications of numerical simulation modeling such as assisted history matching, production o... more The applications of numerical simulation modeling such as assisted history matching, production optimization, and reservoir performance forecasting usually lead to significant time, computer resources, and accordingly huge associated costs. To overcome these circumstances, proxy modeling is the suggested approach to deliver a cheap alternative and approximate nonlinear oil and gas reservoir responses such as recovery factor and reservoir operating parameters and characteristics. Proxy modeling is considered a powerful tool for optimization and uncertainty analysis alike. Conventionally, the reservoir simulation is solved by tuning selected uncertain reservoir parameters one at a time. While, the most important feature of proxy modeling is the ability to determine the combined effect of uncertain parameters at the same time. Petroleum engineering field usually requires a wide variety of parameter estimation problems, and proxy modeling can satisfy this demand. Proxy modeling can be developed based on different methods; the current paper presents a comprehensive review of the methods of developing of proxy modeling and their applications in reservoir simulation since proxy modeling is becoming more widely used as a simplify highly complex substitution to reservoir simulation with reasonable accuracy. This article reviews the methods used in recent years to develop proxy models as a successful replica of complex numerical flow simulation models. This will shed the light of different proxy models, their uses, and how to judge on their efficiencies.

A Data-Driven Model for Rapid Evaluation of Miscible CO-WAG Flooding in Heterogeneous Clastic Reservoirs

SPE Kuwait Oil & Gas Show and Conference, 2019

The compositional flow simulation model was frequently used to evaluate the miscible water altern... more The compositional flow simulation model was frequently used to evaluate the miscible water alternating CO2 flooding (CO2-WAG). The uncertainty and sensitivity analysis have to be conducted to examine the parameters mostly affecting the performance of the process. Accordingly, multiple simulation runs require to be constructed which is a time-consuming procedure and finally increase the computational cost. This paper presents a simplistic approach to assess the miscible CO2-WAG flooding in an Iraqi oilfield through developing a statistical proxy model. The Central Composite Design (CCD) was employed to build the proxy model to determine the incremental oil recovery (ΔFOE) as a function of seven reservoir and operating parameters (permeability, porosity, ratio of vertical to horizontal permeability, cyclic length, bottom hole pressure, ratio of CO2 slug size to water slug size, and CO2 slug size). In total, 81 compositional simulation runs were conducted at field-scale to establish th...

In-Depth Water Diversion Treatment by Coupling Preformed Particle Gel and Low Salinity Waterflooding in Fractured Carbonate Cores

SPE Kuwait Oil & Gas Show and Conference, 2019

The limitations of oil recovery from carbonate reservoirs are fractures and oil-wet conditions. T... more The limitations of oil recovery from carbonate reservoirs are fractures and oil-wet conditions. To overcome the reservoir heterogeneities and reduce fracture transmissibility, preformed particle gel was applied in injector wells. Experimentally, low salinity waterflooding was applied to change the core wettability from oil-wet to water wet for enhanced oil recovery. However, both processes have limitations that cannot be resolved using a single method. A non-uniform fracture width and uniform fracture width models were built using carbonate cores to evaluate the coupling low salinity waterflooding and preformed particle gel in fractured cores and how could be used to improve in-depth water diversion treatment. The results showed that low salinity waterflooding improved in-depth water diversion when injected after PPG directly while seawater showed less effect than low salinity waterflooding. Also, the uniformity of fracture had a significant effect on plugging efficiency oil recover...

A Simulation of Core Displacement Experiments for the Determination of the Relative Permeability

Journal of Engineering

Computations of the relative permeability curves were made through their representation by two fu... more Computations of the relative permeability curves were made through their representation by two functions for wetting and nonwetting phases. Each function contains one parameter that controls the shape of the relative permeability curves. The values of these parameters are chosen to minimize an objective function, that is represented as a weighted sum of the squared differences between experimentally measured data and the corresponding data calculated by a mathematical model simulating the experiment. These data comprise the pressure drop across core samples and the recovery response of the displacing phase. Two mathematical models are constructed in this study to simulate incompressible, one-dimensional, two-phase flow. The first model describes the imbibition process and the other describes the drainage process. The values of the relative permeability parameters are calculated by employing Rosenbrock optimization procedure. The reliability of this procedure has been confirmed by ap...

Petrophysical Properties of an Iraqi Carbonate Reservoir Using Well Log Evaluation

Iraqi Journal of Chemical and Petroleum Engineering, 2020

This research was aimed to determine the petrophysical properties (porosity, permeability and flu... more This research was aimed to determine the petrophysical properties (porosity, permeability and fluid saturation) of a reservoir. Petrophysical properties of the Shuiaba Formation at Y field are determined from the interpretation of open hole log data of six wells. Depending on these properties, it is possible to divide the Shuiaba Formation which has thickness of a proximately 180-195m, into three lithological units: A is upper unit (thickness about 8 to 15 m) involving of moderately dolomitized limestones; B is a middle unit (thickness about 52 to 56 m) which is composed of dolomitic limestone, and C is lower unit ( >110 m thick) which consists of shale-rich and dolomitic limestones. The results showed that the average formation water resistivity for the formation (Rw = 0.021), the average resistivity of the mud filtration (Rmf = 0.57), and the Archie parameters determined by the picket plot method, where m value equal to 1.94, n value equal to 2 and a value equal to 1. Porosity ...

Integrated Petrophysical Evaluation of a Heterogeneous Shaly-sand Reservoir: A Case Study in Nahr Umr Formation-subba Giant Oil Field, Iraq

Research Journal of Applied Sciences, Engineering and Technology, 2014

This study presents an integrated petrophysical evaluation for Nahr Umr reservoir by highlighting... more This study presents an integrated petrophysical evaluation for Nahr Umr reservoir by highlighting a practical trustworthy approach petrophysical model for Nahr Umr reservoir in Subba oil field depending on available data. The available data include core analysis conducted on seven core samples taken from seven wells in Subba oil field and well set logs which include gamma ray, static spontaneous, neutron, sonic, density and resistivity logs. Subba oil field is a giant oil field located in southern part of Iraq about 110 km Northwest Basra. Nahr Umr formation in Subba oil field is a heterogeneous clastic reservoir. It was considered one of the most important producing clastic reservoir in southern Iraqi oil fields. The conventional petrophysical models, by using neutrondensity cross-plot for lithology and porosity and Archie's equation for water saturation, can be adequate for evaluating clean sands. Usually the shaly sand formations are adhere to bad hole in shale section. Facies identification was achieved depending on core analysis data, core description data and wire line log measurements. The calculations of permeability was based on rock types identification and using available core data measurements. The generated permeability models can be used to calculate permeability for uncored intervals in all wells corresponding to each facies. Porosity was calculated using Neutron-density porosity model and Sonic model for bad hole section. Saturation model was built by utilizing the Indonesia Equation model, this model has proved its efficiency to be applied successfully for clastic Iraqi reservoirs. The petrophysical parameters were determined on a well-by-well basis. The formation resistivity factors (a, m) and water saturation exponent (n) have been derived from Pickett plot and formation water salinity. Reservoir quality calculations or net pay values are based on cutoffs values for porosity, saturation and shale volume.

Box-Behnken design for assessment proxy model of miscible CO 2 -WAG in heterogeneous clastic reservoir

Journal of Natural Gas Science and Engineering, 2017

Field-Scale Investigation of Miscible CO2 Injection in a Heterogeneous Shaly Sand Reservoir

ICIPEG 2016, 2017

Carbon dioxide flooding is considered one of the most commonly used miscible gas injection to imp... more Carbon dioxide flooding is considered one of the most commonly used miscible gas injection to improve oil recovery, and its applicability has grown significantly due to its availability, greenhouse effect, and easy achievement of miscibility relative to other gasses. Therefore, miscible CO2 injection is considered one of the most feasible methods worldwide. For long-term strategies in Iraq and the Middle East, most oil fields will need to improve oil recovery as oil reserves are falling. This paper presents a study of the effect of various miscible CO2 injection scenarios on the performance of the highly heterogeneous clastic reservoir in Iraq. An integrated field-scale reservoir simulation model of miscible CO2 flooding is accomplished. The compositional simulator, Eclipse-300, has been used to investigate the feasibility of miscible CO2 injection process. The process of the continuous CO2 injection was optimized to start in January 2056 as an improved oil recovery method after natural depletion and waterflooding processes have been performed, and it will continue until January 2063. The minimum miscibility pressure (MMP) for CO2 was determined using empirical correlation as a function of crude oil composition and its properties. Ten miscible CO2 injection options were undertaken to investigate the reservoir performance. These options included applying a wide range of the CO2 injection rates ranged between 1.25 and 50 MMScf/day. All development options were analyzed with respect to net present value (NPV) calculations to confirm the more feasible CO2 development strategy. The results showed that the application of CO2 injection option of a 20 MScf/day attained the highest recovery of 28% by January 2063 among the others. The recovery growth was so minor by increasing the CO2 injection rate above this level. Based on economic findings, the option of 20 MScf/day also attained the highest net present value. The results showed that after January 2063, the oil recovery attained by the different CO2 injection options are less than the one attained by the waterflooding process. Therefore, the miscible CO2 injection became unviable economically after January 2063.

Field-scale investigation of different miscible CO2-injection modes to improve oil recovery in a clastic highly heterogeneous reservoir

Journal of Petroleum Exploration and Production Technology, 2016

Optimal Field Development of Immature Clastic Heterogeneous Brownfield with Waterdrive: Subba Field, South Iraq Case Study

SPE North Africa Technical Conference and Exhibition, 2015

This paper presents an optimization analysis of different development options of Nahr Umr reservo... more This paper presents an optimization analysis of different development options of Nahr Umr reservoir in Subba oilfield. Nahr Umr reservoir is a highly heterogeneous clastic reservoir with moderate edge a bottom waterdrive and it has a short production history for six months. Many different development scenarios have been conducted in this study to test possible predictive scenarios to determine the most significant development option. The black oil commercial software simulator, Eclipse-100 was used to study fluid flow in the reservoir and to predict the future behavior of reservoir. The prediction scenarios considered in this study include, natural depletion through the existing wells, determine the optimal number of infill producers, and waterflooding option through conducting peripheral and five-spot patterns. The development plan assumed to commence at January 2017, then couple of runs using simulator flow model were conducted for ten years. The waterflood sceneries startedup on ...

Development of Heterogeneous Immature Brownfield with Waterdrive Using Dynamic Opportunity Index: A Case Study from Iraqi Oilfields

SPE North Africa Technical Conference and Exhibition, 2015

The developing of an immature brown oilfield through determining the optimal number and locations... more The developing of an immature brown oilfield through determining the optimal number and locations of infill wells pose extreme challenges due to high costs of drilling wells and uncertainty of geological and reservoir characteristic parameters. The improper well placement may lead to project failure. This paper presents a methodology to identify reservoir layers with high potential opportunities for optimal infill well placement in Nahr Umr reservoir of Subba oilfield. A full field numerical flow simulation model was constructed to assist in simulation the opportunity index and generate opportunity index (OI) which has been determined depending on static and dynamic properties. The generated OI maps for each layer in the reservoir assist in delineating the reservoir regions with favorable infill wells placement. This methodology was efficient, easy to apply and less time consuming as well as it reduce the uncertainty inherent to infill well placement. The presence of water aquifer drive and needing for waterflooding after few years of field life to maintain the field pressure, make the infill drilling with economic viability very crucial element in the field development plan. The performance of new wells, tested at different places of the field in the simulation model, had produced high watercut. It is very important to determine the reservoir opportunities zones in order to enhance sweeping efficiency and increase oil production rate from infill well. In this study a combination of extracted parameters from both static and dynamic models were used to generate opportunity index maps through writing codes into classic property calculator in the Eclipse-FloViZ commercial simulator software. In this case study of Nahr Umr reservoir in Subba oilfield the results showed distinct identification reservoir potential regions for each layer at the reservoir at last time step of history match. These regions showed high OI values that reflected the actually mapped oil in each layer at that time. Intorduction The process of identifying the infill wells locations in immature brownfield with waterdrive requires a level of precision and scrutiny. A case study considered in this study is Nahr Umr reservoir in Subba oilfield. This field described as brownfield and located in Southeast Iraq, 110 km Northwest of Basra, and 325 km Southeast of Baghdad. Nahr Umr reservoir in this field is a heterogeneous clastic reservoir. As the average value of heterogeneity index for different core samples of Nahr Umr reservoir was found equal to 0.814,

Evaluation of Miscible CO<sub>2</sub>-Flooding to Improve Oil Recovery in a Clastic Heterogeneous Reservoir

IADC/SPE Asia Pacific Drilling Technology Conference, 2016

Carbon dioxide flooding is considered one of the most commonly used miscible gas injection to imp... more Carbon dioxide flooding is considered one of the most commonly used miscible gas injection to improve oil recovery and its applicability has grown significantly due to its availability, greenhouse effect and easy achievement of miscibility relative to other gasses. Therefore, miscible CO2-injection is considered one of the most feasible methods worldwide. For long term strategies in Iraq and the Middle East, most oil fields will need to improve oil recovery as oil reserves are falling. This paper presents a study of the effect of various miscible CO2-injection scenarios on the performance of the highly heterogeneous clastic reservoir in Iraq. An integrated field-scale reservoir simulation model of miscible CO2-flooding is accomplished. The compositional simulator, Eclipse-300 has been used to investigate the feasibility of miscible CO2-injection process. The process of the continuous CO2-injection was optimized to start in January 2056 as an improved oil recovery method after natural depletion and water flooding processes have been performed, and it will continue until January 2063. The minimum miscibility pressure (MMP) for CO2 was determined using empirical correlation as a function of crude oil composition and its properties. Ten miscible CO2-injection options were undertaken to investigate the reservoir performance. These options included applying a wide range of the CO2-injection rates ranged between 1.25 to 50 MMScf/day. All development options were analyzed with respect to net present value (NPV) calculations to confirm the more feasible CO2 development strategy. The results showed that the application of CO2-injection option of a 20 MScf/day attained the highest recovery of 28% by January 2063 among the others. The recovery growth was so minor by the increasing the CO2-injection rate above this level. Based on economic findings the option of 20 MScf/day also attained the highest net present value (NPV). The results showed that after January 2063, the oil recovery attained by the different CO2-injection options are less than the one attained by the waterflooding process. Therefore, the miscible CO2-injection became unviable economically after January 2063.

Integrated Petrophysical Evaluation of a Heterogeneous Shaly-sand Reservoir: A Case Study in Nahr Umr Formation-subba Giant Oil Field, Iraq

This study presents an integrated petrophysical evaluation for Nahr Umr reservoir by highlighting... more This study presents an integrated petrophysical evaluation for Nahr Umr reservoir by highlighting a practical trustworthy approach petrophysical model for Nahr Umr reservoir in Subba oil field depending on available data. The available data include core analysis conducted on seven core samples taken from seven wells in Subba oil field and well set logs which include gamma ray, static spontaneous, neutron, sonic, density and resistivity logs. Subba oil field is a giant oil field located in southern part of Iraq about 110 km Northwest Basra. Nahr Umr formation in Subba oil field is a heterogeneous clastic reservoir. It was considered one of the most important producing clastic reservoir in southern Iraqi oil fields. The conventional petrophysical models, by using neutron-density cross-plot for lithology and porosity and Archie's equation for water saturation, can be adequate for evaluating clean sands. Usually the shaly sand formations are adhere to bad hole in shale section. Facies identification was achieved depending on core analysis data, core description data and wire line log measurements. The calculations of permeability was based on rock types identification and using available core data measurements. The generated permeability models can be used to calculate permeability for uncored intervals in all wells corresponding to each facies. Porosity was calculated using Neutron-density porosity model and Sonic model for bad hole section. Saturation model was built by utilizing the Indonesia Equation model, this model has proved its efficiency to be applied successfully for clastic Iraqi reservoirs. The petrophysical parameters were determined on a well-by-well basis. The formation resistivity factors (a, m) and water saturation exponent (n) have been derived from Pickett plot and formation water salinity. Reservoir quality calculations or net pay values are based on cutoffs values for porosity, saturation and shale volume.

Optimal Field Development of Immature Clastic Heterogeneous Brownfield with Waterdrive: Subba Field, South Iraq Case Study

This paper presents an optimization analysis of different development options of Nahr Umr reservo... more This paper presents an optimization analysis of different development options of Nahr Umr reservoir in Subba oilfield. Nahr Umr reservoir is a highly heterogeneous clastic reservoir with moderate edge a bottom waterdrive and it has a short production history for six months. Many different development scenarios have been conducted in this study to test possible predictive scenarios to determine the most significant development option. The black oil commercial software simulator, Eclipse-100 was used to study fluid flow in the reservoir and to predict the future behavior of reservoir. The prediction scenarios considered in this study include, natural depletion through the existing wells, determine the optimal number of infill producers, and waterflooding option through conducting peripheral and five-spot patterns. The development plan assumed to commence at January 2017, then couple of runs using simulator flow model were conducted for ten years. The waterflood sceneries startedup on January 2023 and January 2027 for inverted five-spot and peripheral patterns respectively with 58 producers and 66 injectors for peripheral pattern and 102 producers and 77 injectors for inverted five-spot pattern. The results are analyzed based on economic criteria to optimize the number of infill drilling. The optimization of development options was achieved based on net present values analysis. Introduction Reservoir simulation models mostly used to describe the physical phenomenon of the fluid flow in the porous media. Therefore, in the recent years reservoir modeling has become an integral part of reservoir characterization and development plan optimization. The robust development studies usually constructed through integrating the petrophysical analysis, geological properties distributed by the geological model, optimal locations of infill drilling, and production strategies on reservoir simulation and finally evaluating their response on the economic criteria. The integration process is complicated, and the analyses results will be more reliable if they coupled with economic criteria. Reservoir studies usually require to conduct many simulation runs to evaluate the production strategies and reservoir performance. In this study, several simulations runs were performed to examine the reservoir performance relative to net present value calculations. Black oil simulator (Eclipse-100) was used to conduct the simulation runs. The reservoir under study is Nahr Umr reservoir in Subba oilfield, which is described as heterogeneous clastic reservoir. The heterogeneity index was determined based on Lorenz coefficient calculations which based on the flow capacity distribution to measure the contrast in permeability relative to homogeneous

Multiple Linear Regression Approach for the Permeability Calculation from Well Logs: A Case Study in Nahr Umr Formation -Subba Oil Field, Iraq

The Subba oil field is a giant oil field located in south of Iraq about 110 km northwest Basra. N... more The Subba oil field is a giant oil field located in south of Iraq about 110 km northwest Basra. Nahr Umr reservoir in Subba oil field is a heterogeneous clastic reservoir. The calculation of the permeability was based on rock types delineation from well logs data. The methods that have been used for the rock types classification are; the rock-quality-index (RQI), flow-zone-indicator (FZI), and Discrete-rock-typing (DRT). It has been recognized that excellent permeability-porosity relationships were obtained after conventional core data are grouped according to their rock types. Conventional core data analysis were first used to define the rock types for the cored intervals, the data analysis from 7 plugs taken from 7 wells in Subba oil field were used for this purpose. The wireline log measurements at the cored depths were extracted, normalized, and subsequently analyzed together with the calculated rock types. The resulted mathematical model can be used to predict the rock type in cored intervals and in uncored wells through (DRT) prediction. This allows the generation of a synthetic rock type log for all wells. The permeability model is constructed as a function of a number of wire line measurement–logs data (sonic, gamma ray, neutron porosity, deep indication, spontaneous potential, bulk density, porosity, and shale volume). The wells that chosen to apply this procedure that contains core data, and logs-data together. These wells cover a wide range area of the Subba field. The permeability function contains 9-parameters; the values of these parameters are calculated by employing multiple linear regressions for each rock type. High correlation coefficients were obtained for all resulted equations used for calculated permeability compared to the core permeability; the resulted equations enable to calculate permeability in non-cored intervals in all wells for each rock type.

Box-Behnken design for assessment proxy model of miscible CO 2 - WAG in heterogeneous clastic reservoir

Most giant clastic reservoirs in Iraq will need to apply enhanced oil recovery in the near future... more Most giant clastic reservoirs in Iraq will need to apply enhanced oil recovery in the near future, as these reservoirs go to maturity. The need to develop a rapid and cheap assessment of the enhanced oil recovery methods has become a hot topic in petroleum engineering. Different field-scale heterogeneous geological models were built based on the Nahr Umr reservoir in the Subba oilfield to perform compositional reservoir simulations. The BoxeBehnken experimental design was employed to build and verify the proxy assessment model of miscible CO 2-WAG flooding. Four operational parameters of the miscible CO 2-WAG process were considered, including CO 2 slug size, ratio of CO 2 slug size to water slug size, cyclic length and bottom hole pressure. Using the proxy model, significant first order interactions were sorted out and different operating parameter interactions were established and analyzed for the evaluation of the miscible CO 2-WAG process. In similar oil reservoirs with similar geological conditions and fluid properties to the Nahr Umr reservoir, the proxy model can be applied to roughly predict the incremental oil recovery over the miscible CO 2-WAG flooding process at different levels of operating parameters. The approach could serve as screening criteria and a guide for the application of CO 2-WAG projects.

Field-scale investigation of different miscible CO 2 -injection modes to improve oil recovery in a clastic highly heterogeneous reservoir

Carbon dioxide flooding is considered one of the most commonly used miscible gas injections to im... more Carbon dioxide flooding is considered one of the most commonly used miscible gas injections to improve oil recovery, and its applicability has grown significantly due to its availability, greenhouse effect and easy achievement of miscibility relative to other gases. Therefore, miscible CO 2-injection is considered one of the most feasible methods worldwide. For long-term strategies in Iraq and the Middle East, most oilfields will need to improve oil recovery as oil reserves are falling. This paper presents a study of the effect of various CO 2-injection modes on miscible flood performance of the highly heterogeneous clastic reservoir. An integrated field-scale reservoir simulation model of miscible flooding is accomplished for this purpose. The compositional simulator, Eclipse composi-tional, has been used to investigate the feasibility of applying different miscible CO 2-injection modes. The process of the CO 2-injection was optimized to start in January 2056 as an improved oil recovery method after natural depletion and waterflooding processes have been performed, and it will continue to January 2072. The minimum miscibility pressure was determined using empirical correlations as a function of reservoir crude oil composition and its properties. Four miscible CO 2-injection modes were undertaken to investigate the reservoir performance. These modes were, namely the continuous CO 2-injection (CCO 2), water-alternating-CO 2-injection (CO 2-WAG), hybrid CO 2-WAG injection, and simultaneous water and CO 2-injection (CO 2-SWAG) processes. All injection modes were analyzed in respect to the net present value (NPV) and net present value index (NPVI) calculations to confirm the more feasible CO 2 development strategy. The results indicated that the application of CO 2-SWAG injection mode of 2:1 SWAG ratio attained the highest oil recovery, NPV and NPVI, among the other modes. The achieved incremental oil recovery by this process was 9.174 %, that is 189 MM STB of the oil produced higher than the waterflooding case, 1.113 % (23 MMSTB of oil) in comparison with the CCO 2-flooding case, 1.176 % (24.3 MMSTB of oil) in comparison with the hybrid CO 2-WAG case and almost 0.987 % (204 MMSTB of oil) when compared with the CO 2-WAG case. The results indicated that the application of CO 2-WAG injection mode of 1.5:1 WAG ratio attained the highest oil recovery after the SWAG process.

A Simulation of Core Displacement Experiments for the Determination of the Relative Permeability ‫أﺳﺘﺨﺪام‬ ‫ﺗﺠﺎرب‬ ‫ﻧﻤﺬﺟﺔ‬ ‫اﻟﻨﺴﺒﻴﺔ‬ ‫اﻟﻨﻔﺎذﻳﺔ‬ ‫ﻟﺤﺴﺎب‬ ‫اﻟﻤﻜﻤﻨﻴﺔ‬ ‫اﻟﻨﻤﺎذج‬ ‫ﺧﻼل‬ ‫اﺣﺔ‬ ‫اﻻز‬ ‫ﺟﺎﺑﺮ‬ ‫ﺧﻠﻴﻞ‬ ‫أﺣﻤﺪ

ABCTRACT Computations of the relative permeability curves were made through their representation ... more ABCTRACT Computations of the relative permeability curves were made through their representation by two functions for wetting and nonwetting phases. Each function contains one parameter that controls the shape of the relative permeability curves. The values of these parameters are chosen to minimize an objective function, that is represented as a weighted sum of the squared differences between experimentally measured data and the corresponding data calculated by a mathematical model simulating the experiment. These data comprise the pressure drop across core samples and the recovery response of the displacing phase. Two mathematical models are constructed in this study to simulate incompressible, one-dimensional, two-phase flow. The first model describes the imbibition process and the other describes the drainage process. The values of the relative permeability parameters are calculated by employing Rosenbrock optimization procedure. The reliability of this procedure has been confirmed by applying it to four displacement cases. The optimum values of the relative permeability parameters, which reflect the final shape of the relative permeability curves, are achieved at the minimum value of the objective function. All the above processes are be embodied in relative permeability package RPP which is constructed in this study using FORTRAN language.

Proxy modelling for rapid optimisation of miscible CO2-WAG injection in heterogeneous clastic reservoirs: a case study from Southern Iraqi oil fields

International Journal of Oil, Gas and Coal Technology, 2021

Multiple Linear Regression Approach for the Permeability Calculation from Well Logs: A Case Study in Nahr Umr Formation-Subba Oil Field, Iraq

The Subba oil field is a giant oil field located in south of Iraq about 110 km northwest Basra. N... more The Subba oil field is a giant oil field located in south of Iraq about 110 km northwest Basra. Nahr Umr reservoir in Subba oil field is a heterogeneous clastic reservoir. The calculation of the permeability was based on rock types delineation from well logs data. The methods that have been used for the rock types classification are; the rock-quality-index (RQI), flow-zone-indicator (FZI), and Discrete-rock-typing (DRT). It has been recognized that excellent permeability-porosity relationships were obtained after conventional core data are grouped according to their rock types. Conventional core data analysis were first used to define the rock types for the cored intervals, the data analysis from 7 plugs taken from 7 wells in Subba oil field were used for this purpose. The wireline log measurements at the cored depths were extracted, normalized, and subsequently analyzed together with the calculated rock types. The resulted mathematical model can be used to predict the rock type in ...

A review of proxy modeling applications in numerical reservoir simulation

Arabian Journal of Geosciences, 2019

The applications of numerical simulation modeling such as assisted history matching, production o... more The applications of numerical simulation modeling such as assisted history matching, production optimization, and reservoir performance forecasting usually lead to significant time, computer resources, and accordingly huge associated costs. To overcome these circumstances, proxy modeling is the suggested approach to deliver a cheap alternative and approximate nonlinear oil and gas reservoir responses such as recovery factor and reservoir operating parameters and characteristics. Proxy modeling is considered a powerful tool for optimization and uncertainty analysis alike. Conventionally, the reservoir simulation is solved by tuning selected uncertain reservoir parameters one at a time. While, the most important feature of proxy modeling is the ability to determine the combined effect of uncertain parameters at the same time. Petroleum engineering field usually requires a wide variety of parameter estimation problems, and proxy modeling can satisfy this demand. Proxy modeling can be developed based on different methods; the current paper presents a comprehensive review of the methods of developing of proxy modeling and their applications in reservoir simulation since proxy modeling is becoming more widely used as a simplify highly complex substitution to reservoir simulation with reasonable accuracy. This article reviews the methods used in recent years to develop proxy models as a successful replica of complex numerical flow simulation models. This will shed the light of different proxy models, their uses, and how to judge on their efficiencies.

A Data-Driven Model for Rapid Evaluation of Miscible CO-WAG Flooding in Heterogeneous Clastic Reservoirs

SPE Kuwait Oil & Gas Show and Conference, 2019

The compositional flow simulation model was frequently used to evaluate the miscible water altern... more The compositional flow simulation model was frequently used to evaluate the miscible water alternating CO2 flooding (CO2-WAG). The uncertainty and sensitivity analysis have to be conducted to examine the parameters mostly affecting the performance of the process. Accordingly, multiple simulation runs require to be constructed which is a time-consuming procedure and finally increase the computational cost. This paper presents a simplistic approach to assess the miscible CO2-WAG flooding in an Iraqi oilfield through developing a statistical proxy model. The Central Composite Design (CCD) was employed to build the proxy model to determine the incremental oil recovery (ΔFOE) as a function of seven reservoir and operating parameters (permeability, porosity, ratio of vertical to horizontal permeability, cyclic length, bottom hole pressure, ratio of CO2 slug size to water slug size, and CO2 slug size). In total, 81 compositional simulation runs were conducted at field-scale to establish th...

In-Depth Water Diversion Treatment by Coupling Preformed Particle Gel and Low Salinity Waterflooding in Fractured Carbonate Cores

SPE Kuwait Oil & Gas Show and Conference, 2019

The limitations of oil recovery from carbonate reservoirs are fractures and oil-wet conditions. T... more The limitations of oil recovery from carbonate reservoirs are fractures and oil-wet conditions. To overcome the reservoir heterogeneities and reduce fracture transmissibility, preformed particle gel was applied in injector wells. Experimentally, low salinity waterflooding was applied to change the core wettability from oil-wet to water wet for enhanced oil recovery. However, both processes have limitations that cannot be resolved using a single method. A non-uniform fracture width and uniform fracture width models were built using carbonate cores to evaluate the coupling low salinity waterflooding and preformed particle gel in fractured cores and how could be used to improve in-depth water diversion treatment. The results showed that low salinity waterflooding improved in-depth water diversion when injected after PPG directly while seawater showed less effect than low salinity waterflooding. Also, the uniformity of fracture had a significant effect on plugging efficiency oil recover...

A Simulation of Core Displacement Experiments for the Determination of the Relative Permeability

Journal of Engineering

Computations of the relative permeability curves were made through their representation by two fu... more Computations of the relative permeability curves were made through their representation by two functions for wetting and nonwetting phases. Each function contains one parameter that controls the shape of the relative permeability curves. The values of these parameters are chosen to minimize an objective function, that is represented as a weighted sum of the squared differences between experimentally measured data and the corresponding data calculated by a mathematical model simulating the experiment. These data comprise the pressure drop across core samples and the recovery response of the displacing phase. Two mathematical models are constructed in this study to simulate incompressible, one-dimensional, two-phase flow. The first model describes the imbibition process and the other describes the drainage process. The values of the relative permeability parameters are calculated by employing Rosenbrock optimization procedure. The reliability of this procedure has been confirmed by ap...

Petrophysical Properties of an Iraqi Carbonate Reservoir Using Well Log Evaluation

Iraqi Journal of Chemical and Petroleum Engineering, 2020

This research was aimed to determine the petrophysical properties (porosity, permeability and flu... more This research was aimed to determine the petrophysical properties (porosity, permeability and fluid saturation) of a reservoir. Petrophysical properties of the Shuiaba Formation at Y field are determined from the interpretation of open hole log data of six wells. Depending on these properties, it is possible to divide the Shuiaba Formation which has thickness of a proximately 180-195m, into three lithological units: A is upper unit (thickness about 8 to 15 m) involving of moderately dolomitized limestones; B is a middle unit (thickness about 52 to 56 m) which is composed of dolomitic limestone, and C is lower unit ( >110 m thick) which consists of shale-rich and dolomitic limestones. The results showed that the average formation water resistivity for the formation (Rw = 0.021), the average resistivity of the mud filtration (Rmf = 0.57), and the Archie parameters determined by the picket plot method, where m value equal to 1.94, n value equal to 2 and a value equal to 1. Porosity ...

Integrated Petrophysical Evaluation of a Heterogeneous Shaly-sand Reservoir: A Case Study in Nahr Umr Formation-subba Giant Oil Field, Iraq

Research Journal of Applied Sciences, Engineering and Technology, 2014

This study presents an integrated petrophysical evaluation for Nahr Umr reservoir by highlighting... more This study presents an integrated petrophysical evaluation for Nahr Umr reservoir by highlighting a practical trustworthy approach petrophysical model for Nahr Umr reservoir in Subba oil field depending on available data. The available data include core analysis conducted on seven core samples taken from seven wells in Subba oil field and well set logs which include gamma ray, static spontaneous, neutron, sonic, density and resistivity logs. Subba oil field is a giant oil field located in southern part of Iraq about 110 km Northwest Basra. Nahr Umr formation in Subba oil field is a heterogeneous clastic reservoir. It was considered one of the most important producing clastic reservoir in southern Iraqi oil fields. The conventional petrophysical models, by using neutrondensity cross-plot for lithology and porosity and Archie's equation for water saturation, can be adequate for evaluating clean sands. Usually the shaly sand formations are adhere to bad hole in shale section. Facies identification was achieved depending on core analysis data, core description data and wire line log measurements. The calculations of permeability was based on rock types identification and using available core data measurements. The generated permeability models can be used to calculate permeability for uncored intervals in all wells corresponding to each facies. Porosity was calculated using Neutron-density porosity model and Sonic model for bad hole section. Saturation model was built by utilizing the Indonesia Equation model, this model has proved its efficiency to be applied successfully for clastic Iraqi reservoirs. The petrophysical parameters were determined on a well-by-well basis. The formation resistivity factors (a, m) and water saturation exponent (n) have been derived from Pickett plot and formation water salinity. Reservoir quality calculations or net pay values are based on cutoffs values for porosity, saturation and shale volume.

Box-Behnken design for assessment proxy model of miscible CO 2 -WAG in heterogeneous clastic reservoir

Journal of Natural Gas Science and Engineering, 2017

Field-Scale Investigation of Miscible CO2 Injection in a Heterogeneous Shaly Sand Reservoir

ICIPEG 2016, 2017

Carbon dioxide flooding is considered one of the most commonly used miscible gas injection to imp... more Carbon dioxide flooding is considered one of the most commonly used miscible gas injection to improve oil recovery, and its applicability has grown significantly due to its availability, greenhouse effect, and easy achievement of miscibility relative to other gasses. Therefore, miscible CO2 injection is considered one of the most feasible methods worldwide. For long-term strategies in Iraq and the Middle East, most oil fields will need to improve oil recovery as oil reserves are falling. This paper presents a study of the effect of various miscible CO2 injection scenarios on the performance of the highly heterogeneous clastic reservoir in Iraq. An integrated field-scale reservoir simulation model of miscible CO2 flooding is accomplished. The compositional simulator, Eclipse-300, has been used to investigate the feasibility of miscible CO2 injection process. The process of the continuous CO2 injection was optimized to start in January 2056 as an improved oil recovery method after natural depletion and waterflooding processes have been performed, and it will continue until January 2063. The minimum miscibility pressure (MMP) for CO2 was determined using empirical correlation as a function of crude oil composition and its properties. Ten miscible CO2 injection options were undertaken to investigate the reservoir performance. These options included applying a wide range of the CO2 injection rates ranged between 1.25 and 50 MMScf/day. All development options were analyzed with respect to net present value (NPV) calculations to confirm the more feasible CO2 development strategy. The results showed that the application of CO2 injection option of a 20 MScf/day attained the highest recovery of 28% by January 2063 among the others. The recovery growth was so minor by increasing the CO2 injection rate above this level. Based on economic findings, the option of 20 MScf/day also attained the highest net present value. The results showed that after January 2063, the oil recovery attained by the different CO2 injection options are less than the one attained by the waterflooding process. Therefore, the miscible CO2 injection became unviable economically after January 2063.

Field-scale investigation of different miscible CO2-injection modes to improve oil recovery in a clastic highly heterogeneous reservoir

Journal of Petroleum Exploration and Production Technology, 2016

Optimal Field Development of Immature Clastic Heterogeneous Brownfield with Waterdrive: Subba Field, South Iraq Case Study

SPE North Africa Technical Conference and Exhibition, 2015

This paper presents an optimization analysis of different development options of Nahr Umr reservo... more This paper presents an optimization analysis of different development options of Nahr Umr reservoir in Subba oilfield. Nahr Umr reservoir is a highly heterogeneous clastic reservoir with moderate edge a bottom waterdrive and it has a short production history for six months. Many different development scenarios have been conducted in this study to test possible predictive scenarios to determine the most significant development option. The black oil commercial software simulator, Eclipse-100 was used to study fluid flow in the reservoir and to predict the future behavior of reservoir. The prediction scenarios considered in this study include, natural depletion through the existing wells, determine the optimal number of infill producers, and waterflooding option through conducting peripheral and five-spot patterns. The development plan assumed to commence at January 2017, then couple of runs using simulator flow model were conducted for ten years. The waterflood sceneries startedup on ...

Development of Heterogeneous Immature Brownfield with Waterdrive Using Dynamic Opportunity Index: A Case Study from Iraqi Oilfields

SPE North Africa Technical Conference and Exhibition, 2015

The developing of an immature brown oilfield through determining the optimal number and locations... more The developing of an immature brown oilfield through determining the optimal number and locations of infill wells pose extreme challenges due to high costs of drilling wells and uncertainty of geological and reservoir characteristic parameters. The improper well placement may lead to project failure. This paper presents a methodology to identify reservoir layers with high potential opportunities for optimal infill well placement in Nahr Umr reservoir of Subba oilfield. A full field numerical flow simulation model was constructed to assist in simulation the opportunity index and generate opportunity index (OI) which has been determined depending on static and dynamic properties. The generated OI maps for each layer in the reservoir assist in delineating the reservoir regions with favorable infill wells placement. This methodology was efficient, easy to apply and less time consuming as well as it reduce the uncertainty inherent to infill well placement. The presence of water aquifer drive and needing for waterflooding after few years of field life to maintain the field pressure, make the infill drilling with economic viability very crucial element in the field development plan. The performance of new wells, tested at different places of the field in the simulation model, had produced high watercut. It is very important to determine the reservoir opportunities zones in order to enhance sweeping efficiency and increase oil production rate from infill well. In this study a combination of extracted parameters from both static and dynamic models were used to generate opportunity index maps through writing codes into classic property calculator in the Eclipse-FloViZ commercial simulator software. In this case study of Nahr Umr reservoir in Subba oilfield the results showed distinct identification reservoir potential regions for each layer at the reservoir at last time step of history match. These regions showed high OI values that reflected the actually mapped oil in each layer at that time. Intorduction The process of identifying the infill wells locations in immature brownfield with waterdrive requires a level of precision and scrutiny. A case study considered in this study is Nahr Umr reservoir in Subba oilfield. This field described as brownfield and located in Southeast Iraq, 110 km Northwest of Basra, and 325 km Southeast of Baghdad. Nahr Umr reservoir in this field is a heterogeneous clastic reservoir. As the average value of heterogeneity index for different core samples of Nahr Umr reservoir was found equal to 0.814,

Evaluation of Miscible CO<sub>2</sub>-Flooding to Improve Oil Recovery in a Clastic Heterogeneous Reservoir

IADC/SPE Asia Pacific Drilling Technology Conference, 2016

Carbon dioxide flooding is considered one of the most commonly used miscible gas injection to imp... more Carbon dioxide flooding is considered one of the most commonly used miscible gas injection to improve oil recovery and its applicability has grown significantly due to its availability, greenhouse effect and easy achievement of miscibility relative to other gasses. Therefore, miscible CO2-injection is considered one of the most feasible methods worldwide. For long term strategies in Iraq and the Middle East, most oil fields will need to improve oil recovery as oil reserves are falling. This paper presents a study of the effect of various miscible CO2-injection scenarios on the performance of the highly heterogeneous clastic reservoir in Iraq. An integrated field-scale reservoir simulation model of miscible CO2-flooding is accomplished. The compositional simulator, Eclipse-300 has been used to investigate the feasibility of miscible CO2-injection process. The process of the continuous CO2-injection was optimized to start in January 2056 as an improved oil recovery method after natural depletion and water flooding processes have been performed, and it will continue until January 2063. The minimum miscibility pressure (MMP) for CO2 was determined using empirical correlation as a function of crude oil composition and its properties. Ten miscible CO2-injection options were undertaken to investigate the reservoir performance. These options included applying a wide range of the CO2-injection rates ranged between 1.25 to 50 MMScf/day. All development options were analyzed with respect to net present value (NPV) calculations to confirm the more feasible CO2 development strategy. The results showed that the application of CO2-injection option of a 20 MScf/day attained the highest recovery of 28% by January 2063 among the others. The recovery growth was so minor by the increasing the CO2-injection rate above this level. Based on economic findings the option of 20 MScf/day also attained the highest net present value (NPV). The results showed that after January 2063, the oil recovery attained by the different CO2-injection options are less than the one attained by the waterflooding process. Therefore, the miscible CO2-injection became unviable economically after January 2063.

Integrated Petrophysical Evaluation of a Heterogeneous Shaly-sand Reservoir: A Case Study in Nahr Umr Formation-subba Giant Oil Field, Iraq

This study presents an integrated petrophysical evaluation for Nahr Umr reservoir by highlighting... more This study presents an integrated petrophysical evaluation for Nahr Umr reservoir by highlighting a practical trustworthy approach petrophysical model for Nahr Umr reservoir in Subba oil field depending on available data. The available data include core analysis conducted on seven core samples taken from seven wells in Subba oil field and well set logs which include gamma ray, static spontaneous, neutron, sonic, density and resistivity logs. Subba oil field is a giant oil field located in southern part of Iraq about 110 km Northwest Basra. Nahr Umr formation in Subba oil field is a heterogeneous clastic reservoir. It was considered one of the most important producing clastic reservoir in southern Iraqi oil fields. The conventional petrophysical models, by using neutron-density cross-plot for lithology and porosity and Archie's equation for water saturation, can be adequate for evaluating clean sands. Usually the shaly sand formations are adhere to bad hole in shale section. Facies identification was achieved depending on core analysis data, core description data and wire line log measurements. The calculations of permeability was based on rock types identification and using available core data measurements. The generated permeability models can be used to calculate permeability for uncored intervals in all wells corresponding to each facies. Porosity was calculated using Neutron-density porosity model and Sonic model for bad hole section. Saturation model was built by utilizing the Indonesia Equation model, this model has proved its efficiency to be applied successfully for clastic Iraqi reservoirs. The petrophysical parameters were determined on a well-by-well basis. The formation resistivity factors (a, m) and water saturation exponent (n) have been derived from Pickett plot and formation water salinity. Reservoir quality calculations or net pay values are based on cutoffs values for porosity, saturation and shale volume.

Optimal Field Development of Immature Clastic Heterogeneous Brownfield with Waterdrive: Subba Field, South Iraq Case Study

This paper presents an optimization analysis of different development options of Nahr Umr reservo... more This paper presents an optimization analysis of different development options of Nahr Umr reservoir in Subba oilfield. Nahr Umr reservoir is a highly heterogeneous clastic reservoir with moderate edge a bottom waterdrive and it has a short production history for six months. Many different development scenarios have been conducted in this study to test possible predictive scenarios to determine the most significant development option. The black oil commercial software simulator, Eclipse-100 was used to study fluid flow in the reservoir and to predict the future behavior of reservoir. The prediction scenarios considered in this study include, natural depletion through the existing wells, determine the optimal number of infill producers, and waterflooding option through conducting peripheral and five-spot patterns. The development plan assumed to commence at January 2017, then couple of runs using simulator flow model were conducted for ten years. The waterflood sceneries startedup on January 2023 and January 2027 for inverted five-spot and peripheral patterns respectively with 58 producers and 66 injectors for peripheral pattern and 102 producers and 77 injectors for inverted five-spot pattern. The results are analyzed based on economic criteria to optimize the number of infill drilling. The optimization of development options was achieved based on net present values analysis. Introduction Reservoir simulation models mostly used to describe the physical phenomenon of the fluid flow in the porous media. Therefore, in the recent years reservoir modeling has become an integral part of reservoir characterization and development plan optimization. The robust development studies usually constructed through integrating the petrophysical analysis, geological properties distributed by the geological model, optimal locations of infill drilling, and production strategies on reservoir simulation and finally evaluating their response on the economic criteria. The integration process is complicated, and the analyses results will be more reliable if they coupled with economic criteria. Reservoir studies usually require to conduct many simulation runs to evaluate the production strategies and reservoir performance. In this study, several simulations runs were performed to examine the reservoir performance relative to net present value calculations. Black oil simulator (Eclipse-100) was used to conduct the simulation runs. The reservoir under study is Nahr Umr reservoir in Subba oilfield, which is described as heterogeneous clastic reservoir. The heterogeneity index was determined based on Lorenz coefficient calculations which based on the flow capacity distribution to measure the contrast in permeability relative to homogeneous

Multiple Linear Regression Approach for the Permeability Calculation from Well Logs: A Case Study in Nahr Umr Formation -Subba Oil Field, Iraq

The Subba oil field is a giant oil field located in south of Iraq about 110 km northwest Basra. N... more The Subba oil field is a giant oil field located in south of Iraq about 110 km northwest Basra. Nahr Umr reservoir in Subba oil field is a heterogeneous clastic reservoir. The calculation of the permeability was based on rock types delineation from well logs data. The methods that have been used for the rock types classification are; the rock-quality-index (RQI), flow-zone-indicator (FZI), and Discrete-rock-typing (DRT). It has been recognized that excellent permeability-porosity relationships were obtained after conventional core data are grouped according to their rock types. Conventional core data analysis were first used to define the rock types for the cored intervals, the data analysis from 7 plugs taken from 7 wells in Subba oil field were used for this purpose. The wireline log measurements at the cored depths were extracted, normalized, and subsequently analyzed together with the calculated rock types. The resulted mathematical model can be used to predict the rock type in cored intervals and in uncored wells through (DRT) prediction. This allows the generation of a synthetic rock type log for all wells. The permeability model is constructed as a function of a number of wire line measurement–logs data (sonic, gamma ray, neutron porosity, deep indication, spontaneous potential, bulk density, porosity, and shale volume). The wells that chosen to apply this procedure that contains core data, and logs-data together. These wells cover a wide range area of the Subba field. The permeability function contains 9-parameters; the values of these parameters are calculated by employing multiple linear regressions for each rock type. High correlation coefficients were obtained for all resulted equations used for calculated permeability compared to the core permeability; the resulted equations enable to calculate permeability in non-cored intervals in all wells for each rock type.

Box-Behnken design for assessment proxy model of miscible CO 2 - WAG in heterogeneous clastic reservoir

Most giant clastic reservoirs in Iraq will need to apply enhanced oil recovery in the near future... more Most giant clastic reservoirs in Iraq will need to apply enhanced oil recovery in the near future, as these reservoirs go to maturity. The need to develop a rapid and cheap assessment of the enhanced oil recovery methods has become a hot topic in petroleum engineering. Different field-scale heterogeneous geological models were built based on the Nahr Umr reservoir in the Subba oilfield to perform compositional reservoir simulations. The BoxeBehnken experimental design was employed to build and verify the proxy assessment model of miscible CO 2-WAG flooding. Four operational parameters of the miscible CO 2-WAG process were considered, including CO 2 slug size, ratio of CO 2 slug size to water slug size, cyclic length and bottom hole pressure. Using the proxy model, significant first order interactions were sorted out and different operating parameter interactions were established and analyzed for the evaluation of the miscible CO 2-WAG process. In similar oil reservoirs with similar geological conditions and fluid properties to the Nahr Umr reservoir, the proxy model can be applied to roughly predict the incremental oil recovery over the miscible CO 2-WAG flooding process at different levels of operating parameters. The approach could serve as screening criteria and a guide for the application of CO 2-WAG projects.

Field-scale investigation of different miscible CO 2 -injection modes to improve oil recovery in a clastic highly heterogeneous reservoir

Carbon dioxide flooding is considered one of the most commonly used miscible gas injections to im... more Carbon dioxide flooding is considered one of the most commonly used miscible gas injections to improve oil recovery, and its applicability has grown significantly due to its availability, greenhouse effect and easy achievement of miscibility relative to other gases. Therefore, miscible CO 2-injection is considered one of the most feasible methods worldwide. For long-term strategies in Iraq and the Middle East, most oilfields will need to improve oil recovery as oil reserves are falling. This paper presents a study of the effect of various CO 2-injection modes on miscible flood performance of the highly heterogeneous clastic reservoir. An integrated field-scale reservoir simulation model of miscible flooding is accomplished for this purpose. The compositional simulator, Eclipse composi-tional, has been used to investigate the feasibility of applying different miscible CO 2-injection modes. The process of the CO 2-injection was optimized to start in January 2056 as an improved oil recovery method after natural depletion and waterflooding processes have been performed, and it will continue to January 2072. The minimum miscibility pressure was determined using empirical correlations as a function of reservoir crude oil composition and its properties. Four miscible CO 2-injection modes were undertaken to investigate the reservoir performance. These modes were, namely the continuous CO 2-injection (CCO 2), water-alternating-CO 2-injection (CO 2-WAG), hybrid CO 2-WAG injection, and simultaneous water and CO 2-injection (CO 2-SWAG) processes. All injection modes were analyzed in respect to the net present value (NPV) and net present value index (NPVI) calculations to confirm the more feasible CO 2 development strategy. The results indicated that the application of CO 2-SWAG injection mode of 2:1 SWAG ratio attained the highest oil recovery, NPV and NPVI, among the other modes. The achieved incremental oil recovery by this process was 9.174 %, that is 189 MM STB of the oil produced higher than the waterflooding case, 1.113 % (23 MMSTB of oil) in comparison with the CCO 2-flooding case, 1.176 % (24.3 MMSTB of oil) in comparison with the hybrid CO 2-WAG case and almost 0.987 % (204 MMSTB of oil) when compared with the CO 2-WAG case. The results indicated that the application of CO 2-WAG injection mode of 1.5:1 WAG ratio attained the highest oil recovery after the SWAG process.

A Simulation of Core Displacement Experiments for the Determination of the Relative Permeability ‫أﺳﺘﺨﺪام‬ ‫ﺗﺠﺎرب‬ ‫ﻧﻤﺬﺟﺔ‬ ‫اﻟﻨﺴﺒﻴﺔ‬ ‫اﻟﻨﻔﺎذﻳﺔ‬ ‫ﻟﺤﺴﺎب‬ ‫اﻟﻤﻜﻤﻨﻴﺔ‬ ‫اﻟﻨﻤﺎذج‬ ‫ﺧﻼل‬ ‫اﺣﺔ‬ ‫اﻻز‬ ‫ﺟﺎﺑﺮ‬ ‫ﺧﻠﻴﻞ‬ ‫أﺣﻤﺪ

ABCTRACT Computations of the relative permeability curves were made through their representation ... more ABCTRACT Computations of the relative permeability curves were made through their representation by two functions for wetting and nonwetting phases. Each function contains one parameter that controls the shape of the relative permeability curves. The values of these parameters are chosen to minimize an objective function, that is represented as a weighted sum of the squared differences between experimentally measured data and the corresponding data calculated by a mathematical model simulating the experiment. These data comprise the pressure drop across core samples and the recovery response of the displacing phase. Two mathematical models are constructed in this study to simulate incompressible, one-dimensional, two-phase flow. The first model describes the imbibition process and the other describes the drainage process. The values of the relative permeability parameters are calculated by employing Rosenbrock optimization procedure. The reliability of this procedure has been confirmed by applying it to four displacement cases. The optimum values of the relative permeability parameters, which reflect the final shape of the relative permeability curves, are achieved at the minimum value of the objective function. All the above processes are be embodied in relative permeability package RPP which is constructed in this study using FORTRAN language.

Development of Heterogeneous Immature Brownfield with Waterdrive Using Dynamic Opportunity Index: A Case Study from Iraqi Oilfields

The developing of an immature brown oilfield through determining the optimal number and locations... more The developing of an immature brown oilfield through determining the optimal number and locations of infill wells pose extreme challenges due to high costs of drilling wells and uncertainty of geological and reservoir characteristic parameters. The improper well placement may lead to project failure. This paper presents a methodology to identify reservoir layers with high potential opportunities for optimal infill well placement in Nahr Umr reservoir of Subba oilfield. A full field numerical flow simulation model was constructed to assist in simulation the opportunity index and generate opportunity index (OI) which has been determined depending on static and dynamic properties. The generated OI maps for each layer in the reservoir assist in delineating the reservoir regions with favorable infill wells placement. This methodology was efficient, easy to apply and less time consuming as well as it reduce the uncertainty inherent to infill well placement. The presence of water aquifer drive and needing for waterflooding after few years of field life to maintain the field pressure, make the infill drilling with economic viability very crucial element in the field development plan. The performance of new wells, tested at different places of the field in the simulation model, had produced high watercut. It is very important to determine the reservoir opportunities zones in order to enhance sweeping efficiency and increase oil production rate from infill well. In this study a combination of extracted parameters from both static and dynamic models were used to generate opportunity index maps through writing codes into classic property calculator in the Eclipse-FloViZ commercial simulator software. In this case study of Nahr Umr reservoir in Subba oilfield the results showed distinct identification reservoir potential regions for each layer at the reservoir at last time step of history match. These regions showed high OI values that reflected the actually mapped oil in each layer at that time. Intorduction The process of identifying the infill wells locations in immature brownfield with waterdrive requires a level of precision and scrutiny. A case study considered in this study is Nahr Umr reservoir in Subba oilfield. This field described as brownfield and located in Southeast Iraq, 110 km Northwest of Basra, and 325 km Southeast of Baghdad. Nahr Umr reservoir in this field is a heterogeneous clastic reservoir. As the average value of heterogeneity index for different core samples of Nahr Umr reservoir was found equal to 0.814,

Evaluation of Miscible CO2-Flooding to Improve Oil Recovery in a Clastic Heterogeneous Reservoir

Carbon dioxide flooding is considered one of the most commonly used miscible gas injection to imp... more Carbon dioxide flooding is considered one of the most commonly used miscible gas injection to improve oil recovery and its applicability has grown significantly due to its availability, greenhouse effect and easy achievement of miscibility relative to other gasses. Therefore, miscible CO2-injection is considered one of the most feasible methods worldwide. For long term strategies in Iraq and the Middle East, most oil fields will need to improve oil recovery as oil reserves are falling. This paper presents a study of the effect of various miscible CO2-injection scenarios on the performance of the highly heterogeneous clastic reservoir in Iraq. An integrated field-scale reservoir simulation model of miscible CO2-flooding is accomplished. The compositional simulator, Eclipse-300 has been used to investigate the feasibility of miscible CO2-injection process. The process of the continuous CO2-injection was optimized to start in January 2056 as an improved oil recovery method after natural depletion and water flooding processes have been performed, and it will continue until January 2063. The minimum miscibility pressure (MMP) for CO2 was determined using empirical correlation as a function of crude oil composition and its properties. Ten miscible CO2-injection options were undertaken to investigate the reservoir performance. These options included applying a wide range of the CO2-injection rates ranged between 1.25 to 50 MMScf/day. All development options were analyzed with respect to net present value (NPV) calculations to confirm the more feasible CO2 development strategy. The results showed that the application of CO2-injection option of a 20 MScf/day attained the highest recovery of 28% by January 2063 among the others. The recovery growth was so minor by the increasing the CO2-injection rate above this level. Based on economic findings the option of 20 MScf/day also attained the highest net present value (NPV). The results showed that after January 2063, the oil recovery attained by the different CO2-injection options are less than the one attained by the waterflooding process. Therefore, the miscible CO2-injection became unviable economically after January 2063.

Field-Scale Investigation of Miscible CO 2 Injection in a Heterogeneous Shaly Sand Reservoir

Carbon dioxide flooding is considered one of the most commonly used miscible gas injection to imp... more Carbon dioxide flooding is considered one of the most commonly used miscible gas injection to improve oil recovery, and its applicability has grown signicantly due to its availability, greenhouse effect, and easy achievement of miscibility relative to other gasses. Therefore, miscible CO 2 injection is considered one of the most feasible methods worldwide. For long-term strategies in Iraq and the Middle East, most oil elds will need to improve oil recovery as oil reserves are falling. This paper presents a study of the effect of various miscible CO 2 injection scenarios on the performance of the highly heterogeneous clastic reservoir in Iraq. An integrated eld-scale reservoir simulation model of miscible CO 2 flooding is accomplished. The compositional simulator, Eclipse-300, has been used to investigate the feasibility of miscible CO 2 injection process. The process of the continuous CO 2 injection was optimized to start in January 2056 as an improved oil recovery method after natural depletion and waterflooding processes have been performed, and it will continue until January 2063. The minimum miscibility pressure (MMP) for CO 2 was determined using empirical correlation as a function of crude oil composition and its properties. Ten miscible CO 2 injection options were undertaken to investigate the reservoir performance. These options included applying a wide range of the CO 2 injection rates ranged between 1.25 and 50 MMScf/day. All development options were analyzed with respect to net present value (NPV) calculations to conrm the more feasible CO 2 development strategy.