Reservoir Engineering

This research was funded by, and implemented within, a UK national research organisation, while the author was the KE and Impact Evaluation Manager responsible for assessing impact on a £15m UK government-funded research programme.

This work was also submitted as the authors MBA dissertation which was accepted and awarded in 2009.

ABSTRACT: A methodology and methods ‘toolbox’ is proposed for conducting impact research and assessment from within research programmes. The emphasis is upon how to clarify and assess the wider impacts from the early stages onwards.

The approach explicitly acknowledges, and attempts to address, the known issues and challenges of impact assessment while drawing upon the resources and opportunities available to research managers and researchers within such programmes.

The study has two triangulating foundations. Firstly, it examines the academic literature to help identify and design the pilot methodology and methods. Secondly it trials these in a real programme to both test and improve them.

The study was conducted over one year within one leading UK research organisation, where two research programmes (and around 60 research projects of £15m total value) were being assessed for their impacts. The study draws upon actual impact management experience and reflection, prospective (ex ante) and retrospective (ex post) assessments, participatory contributions from leading researchers undergoing assessment, and consultation with external users. The findings of this study outline the pilot and its first iteration. Recommendations are made for improvement to the methodology and methods.

A subsequent follow-on bid to UK government incorporating the impacts identified from implementing this methodology, successfully led to a further £15m of government funding.

It is expected the pilot methodology and methods will be applicable to other organisations, conducting and funding such research programmes, required to research and assess the wider research impacts.

Although primary focus of implemetation trials was upon research in physical sciences, technology, high-tech engineering, computing/IT, and environment, the wider literature study, the methodology design and justification, the methods proposed and used, and the resulting general recommendations and lessons are expected to apply more broadly to many other research areas, where the impact is to be found more widely in the society, economy, government or public sector or within organizations, policies, professions or the public.

Interest in this work is expected from research programme managers, impact managers and assessors, management consultants advising in this area, and government funding managers, all seeking to embed a developing approach to understand, capture, and enhance wider impact.

— Theory of Eight Palaces (八宫) or Eight Veins (八 脉) is useful in understanding economic disease. By using mathematical reasoning based on Yin Yang Wu Xing Theory in Traditional Chinese Economics (TCE), this paper demonstrates the treatment principle: ―Even if all changed, it is hard to change one's nature‖ (江山易改，本性难移). It means that for the economic society, there is the mathematical structure of Eight Palaces or Eight Veins as the second physiological system of a steady multilateral system. It can be used to determine the root-cause of the sick system by using the six indexes of comprehensive judgment as the Eight palaces or Eight veins. The six indexes are PPI (the Producer Price Index), AAF (the total output value of Agriculture forestry Animal husbandry and Fishery), CPI (the Consumer Price Index), GBR (the General Budget Revenue), GDP (the Gross Domestic Product), and GDP (the right of making money), simple namely PACGGF. The six indexes of PACGGF inflation rates which can be used as diagnostic subsystem of disease. The first or second transfer law of economic society energies of Eight Palaces or Eight Veins changes according to the different PACGGF inflation rates of an economic society whether in the normal range or not. Assume that the range of one of PACGGF inflation rates is divided into four parts from small to large. Both second and third are for a healthy economy. The treating works are the treatment directly for a root-cause and the prevention indirectly for a more serious relation economic disease as symptoms. Both the root-cause and symptoms come from the first transfer law of economic society energies. And both first and fourth are for an unhealthy economy. The treating works are the treatment directly for a root-cause or the prevention indirectly for a more serious relation economic disease as symptoms. Both the root-cause and symptoms come from the second transfer law of economic society energies. An economic disease treatment should protect and maintain the balance of two incompatibility relations: the loving relationship and the killing relationship.Economic disease treatment should protect and maintain the balance of two incompatibility relations: the loving relationship and the killing relationship. As an application, the Chinese GDP inflation rate can be used for the water subsystem how to do works based on to diagnose the root-cause of steady multilateral systems by using Eight palaces.

 Abstract— Theory of Eight Palaces (八宫) or Eight Veins (八 脉) is useful in understanding economic disease. By using mathematical reasoning based on Yin Yang Wu Xing Theory in Traditional Chinese Economics (TCE), this paper demonstrates the treatment principle: " Even if all changed, it is hard to change one's nature " (江山易改，本性难移). It means that for the economic society, there is the mathematical structure of Eight Palaces or Eight Veins as the second physiological system of a steady multilateral system. It can be used to determine the root-cause of the sick system by using the six indexes of comprehensive judgment as the Eight palaces or Eight veins. The six indexes are PPI (the Producer Price Index), AAF (the total output value of Agriculture forestry Animal husbandry and Fishery), CPI (the Consumer Price Index), GBR (the General Budget Revenue), GDP (the Gross Domestic Product), and GDP (the right of making money), simple namely PACGGF. The six indexes of PACGGF inflation rates which can be used as diagnostic subsystem of disease. The first or second transfer law of economic society energies of Eight Palaces or Eight Veins changes according to the different PACGGF inflation rates of an economic society whether in the normal range or not. Assume that the range of one of PACGGF inflation rates is divided into four parts from small to large. Both second and third are for a healthy economy. The treating works are the treatment directly for a root-cause and the prevention indirectly for a more serious relation economic disease as symptoms. Both the root-cause and symptoms come from the first transfer law of economic society energies. And both first and fourth are for an unhealthy economy. The treating works are the treatment directly for a root-cause or the prevention indirectly for a more serious relation economic disease as symptoms. Both the root-cause and symptoms come from the second transfer law of economic society energies. An economic disease treatment should protect and maintain the balance of two incompatibility relations: the loving relationship and the killing relationship.Economic disease treatment should protect and maintain the balance of two incompatibility relations: the loving relationship and the killing relationship. As an application, the Chinese Finance inflation rate can be used for the jun-fire subsystem how to do works based on to diagnose the root-cause of steady multilateral systems by using Eight palaces.

The diagram in represents a simple case in which the difference between oil-bearing and nonoil-bearing rock is clearly visible on the logs. This is not always the case, especially in carbonate reservoirs it is often very difficult to establish whether a certain interval will produce clean oil, or oil and water, or water only.

 Abstract— Theory of Sixty JiaZi (60 甲子) is useful in understanding economic disease. By using mathematical reasoning based on Yin Yang Wu Xing Theory in Traditional Chinese Economics (TCE) , this paper demonstrates the treatment principle: " seize the momentum of development， hasten lucky avoids disaster " (顺势而为,趋吉避凶). It means that for the economic society, there is the mathematical structure of Sixty JiaZi as the second physiological system of a steady multilateral system. It is used to predict the development of the corresponding subsystem based on 60 Jiazi numbers. People should be according to its momentum of development, hasten lucky avoids disaster. Theory of Eight palaces is to determine both the root-cause and symptoms of the sick system based on the six indexes of comprehensive judgment. It is the base of Six Jiazi. The six indexes are PPI (the Producer Price Index), AAF (The total output value of Agriculture forestry Animal husbandry and Fishery), CPI(the Consumer Price Index), GBR(the General Budget Revenue), GDP (the Gross Domestic Product), and Finance (the right of making money), simple namely PACGGF. The first or second transfer law of economic society energies of Sixty JiaZi changes according to the different PACGGF inflation rates of economic society whether in the normal range or not. Assume that the range of one of PACGGF inflation rates is divided into four parts from small to large. Both second and third are for a healthy economy. The treating works are the treatment directly for a root-cause and the prevention indirectly for a more serious relation economic disease as symptoms. Both the root-cause and symptoms come from the first transfer law of economic society energies. And both first and fourth are for an unhealthy economy. The treating works are the treatment directly for a root-cause or the prevention indirectly for a more serious relation economic disease as symptoms. Both the root-cause and symptoms come from the second transfer law of economic society energies. An economic disease treatment should protect and maintain the balance of two incompatibility relations: the loving relationship and the killing relationship.As an application, the Chinese GDP inflation rate can be used for the water subsystem how to do works based on to predict the root-cause of steady multilateral systems by using Sixty Jiazi.

Retrograde gas condensate systems are complex systems as a result of the unique compositional changes that when the reservoir pressure is decreased. Correct selection of Equation of State (EOS) is necessary for proper fluid characterization so that the PVT behavior in the simulation model is a good representation of the reservoir fluid. High quality and accurate PVT data can reduce uncertainty in reservoir fluid properties and set the stage for reservoir engineering modeling whilst improving the technical work on which investment decisions are made.

Drill stem testing follows the basic principles of mechanics, hydromechanics, common sense and practicability. This seminar paper will present methods for the quantitative analysis of drill stem test. The drill-stem test operation is divided for discussion into three phases: planning the test, performing the test, and interpretation. This seminar paper, provides a thorough review of the technical and practical aspects of drill stem testing.

 Abstract— Student course registration is a fundamental process within most educational institutions enabling students to interactively ascertain courses to be registered for seasonally. The adoption of software based registration system has eliminated the fundamentals issues associated with previous based registration systems. The restrictiveness of UTAUT was a fundamental purpose for extending it in addressing course registration using two additional construct of UTUAT: ease of use and system availability. Eighteen (18) anonymous system users cutting across six universities with experience ranging between 1 – 12 years of system usage and aging ranging between 18 – 30 years were employed for this research. All system users were employed on a voluntary basis using the construct of UTAUT: performance expectancy, effort expectancy, and social influence, ease of use, system availability and facilitating condition. The performance of the Extended UTUAT (E-UTUAT) was portrayed using six graphs depicting UTAUT constructs with results ranging for 83%, 39%, 56%, 72%, 72% and 67% for Yes respectively.

 Abstract— Theory of both Zangxiang (藏象) and Jingluo (经 络) is useful in understanding economic disease. By using mathematical reasoning based on Yin Yang Wu Xing Theory in Traditional Chinese Economics (TCE), this paper demonstrates the treatment principle: " Searching for the primary cause of disease in treatment, treat both symptoms and the root-cause at the same time " (治病求本,标本兼治). It means that for the economic society, there is the mathematical structure of both Zangxiang and Jingluo as the second physiological system of steady multilateral systems. It can be used to determine both the root-cause and symptoms of the sick subsystem by using both Zangxiang and Jingluo. The first or second transfer law of economic society energies of both Zangxiang and Jingluo changes according to the different Finance (Producer Price Index) inflation rate of economic society whether in the normal range or not. In general, for the Finance inflation rate, the normal range of theory is [2.9515%,6.1002%] nearly to [3%,6%] and the center is 4.2359% nearly to 4%. Assume that the range of a Finance inflation rate is divided into four parts from small to large. Both second and third are for a healthy economy. The treating works are the treatment directly for a root-cause and the prevention indirectly for a more serious relation economic disease as symptoms. Both the root-cause and symptoms come from the first transfer law of economic society energies. And both first and fourth are for an unhealthy economy. The treating works are the treatment directly for a root-cause or the prevention indirectly for a more serious relation economic disease as symptoms. Both the root-cause and symptoms come from the second transfer law of economic society energies. Economic disease treatment should protect and maintain the balance of two incompatibility relations: the loving relationship and the killing relationship.As an application, the Chinese Finance inflation rate can be used for the jun-fire subsystem how to do works based on to determine both the root-cause and symptoms of the sick subsystem of steady multilateral systems. Index Terms— Traditional Chinese Economics (TCE), Yin Yang Wu Xing Theory, steady multilateral systems, incompatibility relations, side effects, medical and drug resistance problem

Wellbore instability is one of the key problems that engineers encounter during drilling. Often, field instances of instability are a result of a combination of both chemical and mechanical factors, the former resulting from the failure of the rock around the hole due to high stresses, low rock strength, or inappropriate drilling practice and the latter arising from damaging interactions between the rock, generally shale, and the drilling fluid. The increasing demand for wellbore stability analyses during the planning stage of a field arise from economic considerations and the increasing use of deviated, extended reach and horizontal wells, all of which are highly susceptible to the problem. This paper presents a review of the causes, symptoms, prevention, associated consequences, types and respective problems and the principle behind the problem of wellbore instability in oil well drilling.

Waterflooding helps in the recovery of great amount of oil that would have otherwise been abandoned in the reservoir that is depleted. A reservoir in the Niger Delta, Reservoir OB-63 has been used to illustrate this. Reservoir OB-63 had oil initially in place as 9.6346 MMSTB and was produced for some time with the reservoir natural energy. The remaining oil in the reservoir as at the time that the natural energy of the reservoir was no more sufficient to produce oil was 3.88MMSTB. The reservoir has been left as depleted reservoir with the remaining oil in it. But from the analysis conducted in this work it is seen that if secondary oil recovery project by waterflooding is embarked on the reservoir, part of the remaining abandoned oil would be recovered. With the specifications given, about 1.59MMSTB of the 3.88MMSTB of oil in reservoir OB-63 would be produced as at the breakthrough time of 760 days. Moreover, considering the economic aspect of the project, reservoir OB-63 and is good to be invested in. From the NPV calculations performed, it is seen that the NPV of reservoir OB-63 at discount rate of 10% is $5.30 million. Since the NPV at the time of breakthrough is greater than zero, it is worth investing in.
Keywords: waterflooding, secondary oil recovery, factor, production, injection, water, fractional flow, efficiency, displacement, areal sweep, vertical sweep.

Penentuan cadangan minyak bumi dilakukan untuk memperkirakan jumlah cadangan yang dapat diproduksikan ke permukaan. Umumnya penentuan cadangan dengan menggunakan metode decline curve dilakukan saat berlangsung proses produksi untuk dapat memperkirakan life-time dari sumur.

 Abstract— Theory of both Zangxiang (藏象) and Jingluo (经 络) is useful in understanding economic disease. By using mathematical reasoning based on Yin Yang Wu Xing Theory in Traditional Chinese Economics (TCE), this paper demonstrates the treatment principle: " Searching for the primary cause of disease in treatment, treat both symptoms and the root-cause at the same time " (治病求本,标本兼治). It means that for the economic society, there is the mathematical structure of both Zangxiang and Jingluo as the second physiological system of steady multilateral systems. It can be used to determine both the root-cause and symptoms of the sick subsystem by using both Zangxiang and Jingluo. The first or second transfer law of economic society energies of both Zangxiang and Jingluo changes according to the different GDP (Gross Domestic Product) inflation rate of economic society whether in the normal range or not. In general, for the GDP inflation rate, the normal range of theory is [5.8114%,16.359%] nearly to [6%,16%] and the center is 10.208% nearly to 10%. Assume that the range of a GDP inflation rate is divided into four parts from small to large. Both second and third are for a healthy economy. The treating works are the treatment directly for a root-cause and the prevention indirectly for a more serious relation economic disease as symptoms. Both the root-cause and symptoms come from the first transfer law of economic society energies. And both first and fourth are for an unhealthy economy. The treating works are the treatment directly for a root-cause or the prevention indirectly for a more serious relation economic disease as symptoms. Both the root-cause and symptoms come from the second transfer law of economic society energies. An economic disease treatment should protect and maintain the balance of two incompatibility relations: the loving relationship and the killing relationship.As an application, the Chinese GDP inflation rate can be used for the water subsystem how to do works based on to determine both the root-cause and symptoms of the sick subsystem of steady multilateral systems. Index Terms— Traditional Chinese Economics (TCE), Yin Yang Wu Xing Theory, steady multilateral systems, incompatibility relations, side effects, medical and drug resistance problem

This paper aims to review some of the widely used conventional and other contemporary Inflow & Productivity models that exist for Horizontal wells, and comment on their limitations by drawing on the experiences of other author's critiques on these IPR models.

Nowadays various recovery mechanisms are used in the petroleum industry to increase hydrocarbon production as much as possible in a given oil and gas field. Water flooding being the main technology used, it recovers 10 to 40 percent of the oil in place. Many factors are causes of this low recovery percentage that can be the fingering effect etc. The remaining oil in the reservoir can be divided into two categories that are: the remaining oil beyond water flooding process and bypassed oil.
The purpose of this research is to examine the efficiency of polymer flooding compared to water flooding, examine the effect of oil viscosity change due to change in reservoir pressure and temperature, and make a proper choice of polymer concentration for better oil recovery for the Tambaredjo oil field by doing simulation on the black oil reservoir model.
Firstly, water flooding was simulated, and various cases were investigated such as water injection rate and well pattern. The five spots well pattern has given a higher recovery compared to two spots and nine spots well patterns. And the water injection rate of 22,000Stb/Day has given better recovery compared to 11,000Stb/Day, 15,000Stb/Day, 20,000Stb/Day and 22,000Stb/Day. Thus, the five spots well pattern and 22,000Stb/Day were used in the second step which is polymer flooding.
Secondly, polymer flooding was simulated and various values of polymer concentration were set. The better polymer concentration was 22lb/bbl because it has given a better oil recovery compared to 2lb/bbl, 6lb/bbl, 10lb/bbl,14lb/bbl and 18lb/bbl.
Thirdly, an examination of oil viscosity change was done by varying the reservoir oil viscosities in the oil PVT table. This case helped to understand the effect of reservoir pressure and temperature change that affect reservoir oil viscosity and thus affect also the oil recovery.
The oil recovery increased from 16% (case of water flooding) to 24.5% (case of polymer flooding). This allows us to conclude that with the reservoir model on which the study was done, polymer flooding is not favorable for the Tambaredjo oil field. But this last sentence would be validated after performing one of the stimulations methods to see if there will be an increase in the oil recovery from this field. A study would be undertaken to examine either one of the stimulation methods would improve the oil recovery from the Tambaredjo oil field.

This paper is the second part of a two-part article (part one published April 1997). Waterflood management is critical, particularly for poor quality or geologically complex reservoirs. In part one, we examined oil production response to a waterflood. In the second part, we investigate gas and water production response as well as injection analysis and reservoir pressure response.

The growing global campaign and awareness on global warming and climate change and ways of reducing the greenhouse gas emissions into the atmosphere has raised a lot of concern towards ways of possibly reducing the amount of carbon dioxide (CO2) which is a major contributor to global warming within the environment. Over the past few decades, the injection and trapping of carbon dioxide (CO2) gas into petroleum reservoirs like sandstones, shale and carbonates have become a globally accepted enhanced oil recovery technique and an efficient carbon storage process.
Carbonate reservoirs have been studied to contain most of the world’s oil and gas, with the Middle East as one of the major zones dominated by carbonate formations. With carbonate reservoirs understood to have large volumes of oil, there still exist some challenges regarding the recovery of these oil from carbonate reservoirs due to their heterogeneous nature. Some of the challenges identified included early gas breakthrough due to viscous fingering effect of CO2, acid effect of carbonates when in contact with CO2 and reservoir brine, oil recovery challenges due to the effects of CO2 on the reservoir permeability, CO2 injection rates on oil recovery, injection effect of CO2 on oil viscosity and CO2 injection effect on the relative permeability of oil.
This research has been carried out using a typical carbonate reservoir data from a Middle East field. A carbonate reservoir model was developed using Eclipse reservoir simulator software and based on some of the available field data, so as to investigate some of the challenging scenarios experienced in carbonate formations during CO2 injection and their effects on oil recovery factor from the reservoir. The developed eclipse model was set to run on a time-step of 10 years so as to predict the performance of the reservoir over time. Sensitivity studies on oil recovery factor was carried out to examine how changes in CO2 injection rate, CO2 density and reservoir oil density can affect the oil recovery from carbonate reservoirs and to know the most critical effect regarding oil recovery during CO2 flooding. The result shows that CO2 density has the most significant oil recovery at 17.05% followed by the CO2 injection rate with a recovery factor of 16.5% after 10years of production while the oil density has no influence on oil recovery during CO2 injection.

— The stress of reinforced material soil based Caragana under compression and bending deformation is observed through experiments. The finite element numerical simulation of these two properties is carried out through ABAQUS software, obtaining the stress and strain fields of the material under two basic deformation. Compared with the results of the test and ABAQUS numerical simulation, the error is very small, which shows that the ABAQUS modeling can simulate the stress and deformation process of the materials well.

The identification of fluid contacts (gas–water contact—GWC, oil–water contact—OWC and gas–oil contact—GOC) is essential for field reserve estimates and field development and, also, for detailed formation evaluation. For the accurate calculation of some petrophysical parameters, such as porosity, the reservoir interval has to be zoned by fluid type, to account for differences in fluid saturations and fluid properties (e.g., hydrogen index, density, sonic transit time) in the various intervals: gas cap, oil column and aquifer zone. The fluid contacts may vary over a reservoir either because of faults, semipermeable barriers, rock quality variations / reservoir heterogeneity, hydrocarbon-filling history or a hydrodynamic activity. Horizontal contacts are typically taken into consideration, although irregular or tilted contacts occur in some reservoirs. The methods used for determining the fluid contacts include fluid sampling, water and hydrocarbons saturation estimation from geophysical well logs, analyses of conventional or sidewall cores, and formation pressure measurements. The pressure profiles obtained with various formation testing tools over reservoir intervals are, frequently, the primary source of data for defining the fluid contacts. When good quality pressure data can be collected, the fluid contacts can be determined by identifying the depths at which the pressure gradients (pressure versus depth trends) change. This study addresses some issues related to the identification of GWC for two gas fields of Early Pliocene age (Dacian stage), belonging to the biogenic hydrocarbon system of western Black Sea basin-Romanian continental shelf. We show that the identification of these contacts based exclusively on pressure gradients analysis is uncertain or may be inaccurate. The pressure gradients approach should be checked against the results of the conventional interpretation of geophysical well logs (e.g. changes in the computed fluid saturations as a function of depth) and, if available, the results of nuclear magnetic resonance (NMR) log investigations, which are able to indicate the intervals with clay-bound water, capillary-bound water and movable fluids.

Geo-pressured gas reservoirs are reservoirs with high pressure gradient of about (0.5-1.0) psi/ft. The increase in pressures has been proposed by some authors to be caused by inability of excess fluids to leak-off after major tectonic events of compressional folding or rapid deposition of thick sediments in young sedimentary rocks. The limitation of the conventional method in estimating original gas in place (OGIP) in a geo-pressured gas reservoir is that the solution gas in connate water is habitually neglected in estimating the OGIP. As a result, its contribution of the total gas production is omitted in the MBE. This leads to an inaccurate estimation of OGIP and gas reserve. To eliminate this error, a new form of MBE is presented by this study. It includes the contribution of solution gas in connate water to the total gas production. A comprehensive compressibility term that includes the rock compressibility (Cf), water compressibility (Cw) and the gas solubility in water (Rsw) are introduced into the material balance equation and P/Z plots are formulated. The result of the formulation indicates a 5 -12% increase in the estimation of the OGIP as compared to some existing methods. This tells the importance of the solubility of gas in brine in the estimation of the OGIP and the importance of its inclusion in the Material Balance Equation.

Up to now, there has not been one specific correlation published to directly estimate the bubble-point pressure in the absence of pressure-volume-temperature (PVT) analysis. Presently, there is just one published correlation available to estimate the bubble-point oil formation volume factor (FVF) directly in the absence of PVT analysis. Multiple regression analysis technique is applied to develop two novel correlations to estimate the bubble-point pressure and the bubble-point oil FVF. The developed correlations can be applied in a straightforward manner by using direct field measurement data. Separator gas oil ratio, separator pressure, stock-tank oil gravity, and reservoir temperature are the only key parameters required to predict bubble-point pressure and bubble-point oil FVF.

In the city of Constantia (Salamis), Cyprus, stands a grand Byzantine reservoir known as the Loutron. Its final form dates it to the early seventh century. Supported by 36 piers which formed 52 bays, the Constantia reservoir would be the largest vaulted structure on the island.  It was intended to be a showpiece; built conspicuously above ground to serve as a pendant, facing across the agora towards the famous Temple of Zeus (which had been converted to a church). As such it would have resembled the well-known nymphaea of Anatolia.  In investigating the structure, wider questions have arisen regarding the development of Byzantine cisterns compared to earlier Roman designs. In Italy and North Africa, the Romans achieved a high-level of sophistication in their monumental waterworks; they covered their cisterns with long continuous barrel-vaults. In contrast, beginning in the fifth century, the eastern Roman provinces broke from this tradition by incorporating domical or groin-vaults. Recent surveys and excavations of Byzantine and Umayyad cisterns and reservoirs in Palestine, as well as new architectural studies in Alexandria (Egypt), indicate that the driving motivation for this redesign was use of modular units based upon the quadratus; that is, “square schematism” seems to be the underlying principle. Such techniques may have influenced the design of Byzantine and Umayyad religious structures in the seventh and eight centuries.

From the publication here:

http://www.sas.upenn.edu/ancient/publications.html

Fossil fuels account for more than 90% of the world total energy consumption. The emission of CO 2 to the atmosphere can be reduced by the development and implementation of carbon capture and storage technologies. The geological formations considered for CO 2 storage are saline aquifers, depleted and semidepleted hydrocarbon reservoirs, and unminable coal seams. The efficient short-term injection and the stable long-term geological storage of carbon dioxide are affected by complex hydro-chemo-mechanical interactions that take place in the formation, including water acidification, mineral dissolution, and stress and volume changes. Positive feedback mechanisms may lead to runaway effects. These hydro-chemo-mechanical coupled processes and emergent phenomena may hinder the storativity of injected carbon dioxide. Technological developments such as adequate geophysical tools for injection and reservoir monitoring, are needed for the safe geo-storage of CO 2 .

Rahayu field was discovered in 1973 and it is a three-way closure anticline bounded by thrust fault bearing NW-SE at the west. The hanging wall is the only oil productive block with area coverage of 5x3 km and consists of 129 producers and 24 peripheral
injectors.

The main oil production comes from the Sierra group formation that consists of 3 main reservoirs, A, B and C. The A reservoir is subdivided into A1950 sand, A2020 sand, and A2050 sand. The B reservoir is subdivided into B2250 sand. The C reservoir is subdivided into C2420R, C2420S, C2420T, and C2420U. Those reservoirs are deposited in the Early Miocene age in an estuary environment setting. The reservoir depth ranges from 1900-2800 feet. Since 1997 enhanced waterflood method was started to improve oil recovery by converting producer well at the flank structure into injector wells. Those peripheral injectors surround the Rahayu field, even near the main thrust fault, in order to maintain reservoir pressure and also fluid displacement.

Rahayu field is considered as a matured waterflood field and it needs alignment between peripheral injector-to-producer to make sure that the water is injected to the right reservoir. The main concern for this study is for all injectors that located along the thrust fault boundary. The main focus of this study was to make a robust interpretation for thrust fault outline and the subsurface location of injector and producer well trajectory along the fault surface.

In order to reduce the permeability to water or brine, there is a possibility of polymer injection into the reservoir. In the present work, special focus has been paid in polymer [partially hydrolyzed polyacrylamide (PHPA)] injection as a part of chemical method. Tests were conducted in the laboratory at the ambient temperature to examine the reduction in permeability to water or brine in the well-prepared sand packed after the polymer injection. The experiments were performed to study the effect of polymer adsorption on permeability reduction by analyzing residual resistance factor values with different concentrations of polymer solutions. The rheological behavior of the polymer has also been examined. The experimental results also indicate that the adsorption behavior of polymer is strongly affected by salinity, solution pH, and polymer concentration. To investigate the effect of polymer adsorption and mobility control on additional oil recovery, polymer flooding experiments were conducted with different polymer concentrations. It has been obtained that with the increase in polymer concentrations, oil recovery increases.

The productivity of most gas condensate wells is reduced significantly due to condensate banking when the bottomhole pressure falls below the dew point.
The liquid drop-out in these very high rate gas wells may lead to low recovery problems. The most important parameter for determining condensate well productivity is the effective gas permeability in the near wellbore region. An understanding of relative permeability data is necessary for accurate forecast of well productivity. This work also gives an accurate method for modeling the deliverability of gas condensate reservoir. Well deliverability is calculated using a modified form of the Evinger-Muskat pseudopressure (originally proposed for solution gas drive oil wells).
In order to fulfill this objective Çalişgan’s experimental procedure and Fevang’s experiment were reviewed and relative permeability were determined by using binary fluid as test fluid under reservoir conditions. As a fluid system, the model of methanol/n-hexane system was used as a binary model that exhibits a critical point at ambient conditions. Condensate relative volume was also determined as a function of relative permeability ratio and viscosity of both gas and condensate phase.
The laboratory results show a clear view of the relative permeability during condensation. As the temperature increases the wetting phase saturation increases and the wetting phase saturation remain the same for different flow rate but different temperatures. Condensate relative volume increases as the relative permeability ratio decreases and vice versa.
A simple FORTRAN program was written to calculate relative permeability from a mathematical expression relating it with fluid viscosity and condensate relative volume at different temperature.

Keywords: Gas Condensate, Relative Permeability, Binary Fluid, Wetting Phase Saturation, Condensate Relative Volume

A la edad de 45 años, Eduardo Juan Couture Etcheverry, el gran jurista uruguayo, impartió una conferencia en el Colegio de Abogados de Buenos Aires, reproducida en el Boletín del mismo de 1949. Tiene como génesis un esbozo publicado en la Revista de Derecho Procesal de 1948, de donde nace una pequeña obra jurídica de enorme contenido ético, quizá de los más famosos textos de la literatura en la materia, Los mandamientos del abogado, mejor conocido como El decálogo del abogado.

In the oil province of southern Iran like other hydrocarbon zones, thorough understanding and risk management resulting from the rock mass deformation, can be of great help in executing operational processes such as the stabilization of the borehole wall, controlling the sand production in the borehole and hydraulic fracture. In oil well excavation operations, determining maximum and minimum horizontal stresses helps in designing the excavation route in the minimum stress direction so that collapsing of the borehole wall and drilling tube blockage against the rocks is avoided. The aim of this study was removing the main excavation problems especially of the diversion wells through exact geomechanical calculations in the Darian lime formation depth range in the understudy field. In order to develop the geomechanical model, first the bulk, the shear and the Young's modules, the Poisson coefficient and Vp/Vs ratio were calculated using the visual log data integrated with the geomechanical parameters , and the strength parameters like uniaxial compressive strength, internal friction coefficient and tensile strengths and static modulus of elasticity were determined and then the determination of direction and min/max horizontal stresses alongside the formation thickness were studied. In the end by the assessment of the geome-chanical model and calculating the mud weight during drilling of the understudy well, and using the STAB View software output, the mud weight window of 80-120 PCF and the drilling Azimuth range of 30°-45° was recommended for the prevention of borehole wall collapse for Darian formation.

Permeability determination in Carbonate reservoir is a complex problem, due to their capability to be tight and heterogeneous, also core samples are usually only available for few wells therefore predicting permeability with low cost and reliable accuracy is an important issue, for this reason permeability predictive models become very desirable. This paper will try to develop the permeability predictive model for one of Iraqi carbonate reservoir from core and well log data using the principle of Hydraulic Flow Units (HFUs). HFU is a function of Flow Zone Indicator (FZI) which is a good parameter to determine (HFUs). Histogram analysis, probability analysis and Log-Log plot of Reservoir Quality Index (RQI) versus normalized porosity (ø z) are presented to identify optimal hydraulic flow units. Four HFUs were distinguished in this study area with good correlation coefficient for each HFU (R 2 =0.99), therefore permeability can be predicted from porosity accurately if rock type is known. Conventional core analysis and well log data were obtained in well 1 and 2 in one of carbonate Iraqi oil field. The relationship between core and well log data was determined by Artificial Neural Network (ANN) in cored wells to develop the predictive model and then was used to develop the flow units prediction to un-cored wells. Finally permeability can be calculated in each HFU using effective porosity and mean FZI in these HFUs. Validation of the models evaluated in a separate cored well (Blind-Test) which exists in the same formation. The results showed that permeability prediction from ANN and HFU matched well with the measured permeability from core data with R 2 =0.94 and ARE= 1.04%.