Horizontal Wells

Naturally fractured reservoirs are the most significant
target for horizontal wells in the U. S. While most of the
horizontal wells drilled to exploit naturally fractured
reservoirs are not logged. substantial useful information
can be obtained by logging such wells. A previous
paper! contrasted various logging technologies including
acoustic televiewers. sonic logs, and oriented
microresistivity devices. Union Pacific Resources (UPRC)
has logged 42 of the 120 horizontal wells drilled to date;
38 of these wells have been logged with Schlumberger's
Formation MicroScanner (FMS), an oriented
microresistivity device. Extensive analysis of these logs
on UNIX-based workstations and correlation with
horizontal well performance has resulted in a correlation
between the horizontal well fracture index (RFI) and
horizontal well fluid Productivity Index (PI). Attempts to
correlate RFI with ultimate oil or oil and gas recoveries
have been unsuccessful; however. a correlation with
ultimate fluid (oil+water) recoveries has been developed.
These correlations have been used to integrate FMS
infonnation with artificial lift. stimulation, isolation, and
repair decisions as well. Example cases are used to
illustrate these decisions. Further. the quantified data
have been used in making development. exploitation, and
spacing decisions. Geostatistical techniques used in
reservoir characterization efforts have also incorporated
the spatial distribution and correlation of RFI density.

So called "water-fracs" have obtained excellent results in the Austin Chalk formation of Giddings field. This inexpensive treatment uses high volumes of water but no proppant. The reasons the treatment is successful include imbibition, gravity drainage, skin damage removal , and repressurization of the reservoir to enhance recovery. Union Pacific Resources Co. (UPRC) has treated about 2S0 vertical and ISO horizontal wells with very high economic success rates. Incremental recoveries from horizontal well water fracs alone exceed S million bbl of oil equivalent (6 Mcf = 1 bbl).

Nowadays, the bigger portion of produced oil and gas come from conventional resources all over the globe and these resources are being depleted in a severe manner. Over the past decade, the combination of horizontal drilling and hydraulic fracturing has allowed access to large volumes of shale gas that were previously uneconomical to produce. In recent years, they are seriously considered as supplementary to the conventional resources although these reservoirs cannot be produced at an economic rate or cannot produce economic volumes of oil and gas without assistance from massive stimulation treatments, special recovery processes or advanced technologies.
The vast increase in demand for petroleum and gas has encouraged the new technological development and implementation. With the directional drilling technology, it is possible to make use of highly deviated wellbores, extended reach drilling, horizontal wells, multilateral wells etc. Along with the technology itself simulation, reservoir characterization and the ability of future production prediction makes the development of unconventional resources a lot easier.
In this study, pressure and rate transient analysis techniques developed for hydraulically fractured reservoirs were applied for shale gas reservoirs to understand the applicability of those methods on unconventional systems. Pressure transient analysis is based on the analysis of the pressure which changes over time with variation of the fluid flow rate. For the particular analysis, fluid allowed to flow for a limited time, then well is closed and the pressure behavior is monitored and recorded in order to analyze the data. Rate transient analysis refers to production data analysis which utilizes similar concept to pressure transient analyses. It is similar to drawdown test where this drawdown period is equal to producing life of a particular field, where the flow periods are interrupted by shut-in periods, with less frequent data acquisition which is why the data quality for the analysis is not as good as for pressure transient analysis. Schlumberger Eclipse 300 simulation model was used to model the shale gas reservoir. Two commercial software tools – Saphire (Kappa) and F.A.S.T. (Fekete) that are used in petroleum engineering were applied to analyze the data. Advanced analytical models (F.A.S.T.) developed
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for horizontal multi-fractured reservoirs showed some good results; however it still doesn’t clear what are the actual flow regime conditions under different fracture stage and flowing conditions. In general those tools analyze the data to match either linear, bilinear or boundary dominated flow conditions. For that reason, in order to clearly understand flow regimes, rate normalized pressure derivative function was adopted along with the corrected pseudo-time function. As a result of this straight line analysis - flow regimes, fracture and reservoir permeabilities, fracture half length, fracture conductivity parameters were found under different fracture stage and flowing conditions. Under constant rate producing conditions, for single fracture case we obtained – fracture linear, elliptical, radial and late time effects, however for multi-fracture example, elliptical flow regime was masked due to close fracture spacing and additionally compound linear flow parallel to hydraulic fractures were exhibited. Under constant bottom-hole pressure producing conditions, for single fracture case we obtained pseudo-steady state flow showing pressure depletion in the stimulated reservoir region, radial flow, boundary dominated flow conditions, while for multi-fracture case we additionally observed compound linear flow regime.

Gas condensate reservoirs in Niger Delta and around the world are becoming increasingly important as a result of additional liquid recovery and increasing demand for light oil and natural gas. During reservoir depletion liquid condense out of the gas as pressure drop below dew point pressure. Most of the condensed liquid is lost to the reservoir. Recovery of lost condensate from gas condensate reservoir requires careful reservoir analysis and technology with which to exploit this great resource. In this study, horizontal wells have been found useful in reducing pressure decline in reservoir. Pressure decline results to dropout of condensate in gas condensate reservoir. This work intends to use horizontal well technology to improve production from gas condensate wells. It will also compare the use of gas injection in alleviating condensate bank in both vertical and horizontal well with depletion scenario in both types of wells. In the study, several simulations were run. The results from the simulations showed that production increased with the presence of an injector for both horizontal and vertical well as compare to the absence of an injector. Under the sensitivities runs, the optimum rate of injection was seen to be the lower injection rate of 920Mscf/day, as it had the higher Net Present Value.

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.

Horizontal wells have been applied in many types of
reservoir conditions with a variety of applications. The
most successful of these has been exploiting the very
large horizontal permeability anisotropies associated with
naturally fractured reservoirs. Log analysis has always
been difficult in naturally fractured reservoirs; very little
has been published regarding horizontal well logs. This
paper summarizes Union Pacific Resources (UPRC)
experience logging dozens of horizontal wells in several
different naturally fractured reservoirs, summarizes the
improved information resulting from this experience,
contrasts various well logs applicable in such areas, and
describes a method for categorizing fracture apertures
used to quantify the total horizontal well fracture index
(RFI).

A horizontal well with a non-linear trajectory is fundamentally an intricate system, and determination of its inflow productivity index using numerical simulation is computationally challenging. This work presents an approach that is more efficient than numerical simulation. The methodology involves dividing the reservoir into different sections, with each section treated as a closed-box model. A constant pressure is assumed for the two sides of the sections, which are parallel to the plane of the trajectory, and end flow is eliminated so that each section of the well is fully penetrating. A simplified isobaric geometry and a flow path were developed using the numerical simulation of flow in a fully penetrating well in a box model; an analytical index equation was then developed from the simplified geometry. The results of the numerical simulation were used to generate an empirical correlation for the shape factor to bring the result of the productivity index equation close to simulation and line source solutions, thus converting the analytical index equation into a semianalytical equation. The application of the semi-analytical equation to a horizontal well, undulating in a vertical plane, to predict its productivity was demonstrated using an example. This model is the first productivity index equation with the capability to handle a horizontal well with a non-linear trajectory.

With the advent of the improvised technologies in the world of Oil and Gas, the drilling and mining activities could reach the extent of High Pressure High Temperature Wells which are flowing under undue high pressure and temperature. HPHT wells. HPHT wells are characterized basically with high bottom hole temperature and pressure and demands high maintanence throughout the life cycle of the well. In the context of the drilling activities carried out in such type of wells the conventional drilling fluid could not ascertain a good productivity in the development phase and henceforth the need of the hour calls for the use of specially designed drilling fluids to mitigate the problem. In line with the advancements, the sector of Nanotechnology has gained utmost importance in due course of time. In the domain of Petroleum Exploration, the use of nanocomposite and nanotubes can pave the way forward to replace conventional equipments and accessories so address the concerns of the unpredictable sub-surface phenomena. This paper showcases the work to generate a Multi Walled Carbon Nanotube based Non Damaging Drilling Fluid (NDDF) system specially to be designed for HPHT wells. The paper work involves a plethora of laboratory assignments and review to analyse the rheological properties and draw a comparative study of conventional and MWCNT based drilling fluid for HPHT wells.

With the growth of oil and gas resource demand, the hydro-oscillator is widely used to enhance the Rate of penetration (ROP) and improve the efficacy in drilling various wells. The vibration model is the key issue of dynamics analysis and optimization of downhole tools. For the vibration analysis of the new drill string system with hydro-oscillator in the horizontal well, based on the design of the new hy-dro-oscillator and its operation conditions, the kinematics expressions are presented. Combined with the vibration force calculation results of the hydro-oscillator, the dynamics model of the new drill string system is established. Furthermore, the important features of vibration frequency, displacement, velocity and acceleration are discussed in the numerical example calculation results. By comparing the results of the calculation and experiment test, we can verify the correctness of the analysis model. With the hydro-oscillator vibration effect, the static friction between the drill string and wellbore is changed to the dynamic friction, so it can result in a significant increase in run length. At the same time, the ROP can be enhanced with the vibration effect. Moreover, with the parameters' adjustment according to the operation conditions, the analysis method and model can also provide references to the study of similar downhole tools dynamics or mechanical properties.

La conificación de agua puede ser prevenida mediante la implementación de pozos horizontales, que en diferencia de los pozos verticales, ocasionan una menor caída de presión en el yacimiento al aumentar el área disponible al flujo del medio poroso hacia la tubería.

Water coning is a serious issue for the oil and gas industry. This poses a big
concern regarding the costs that to be incurred for separation and equipment
capacity. Coning is the production of an unwanted phase with a desired phase. Over
the years, many techniques and control methods has been birthed, however, the issue
of coning can only be mitigated and not completely discharged. Reservoir and
production engineers need to understand the basic framework; the parameters that
greatly influence coning and how effective manipulation of it can deal with it. With the
introduction of horizontal wells, the production rate is two to four times that of
vertical wells, and coning is reduced and the breakthrough time is increased.
Numerous papers has been written regarding to coning and vertical wells, only a few
emphasize on horizontal wells and simultaneous water coning and gas coning. The
objective of this research is to study the post breakthrough performance in
simultaneous coning and a black oil simulator was use for the research. Sensitivity
analysis was carried out on: the production rate of oil (qt), horizontal permeability,
vertical permeability, perforation length, the height above perforation, extent of
reservoir area and the formation porosity. A generalized correlation was developed
for predicting coning behavior using non-linear analysis

TX 75083-3836, U.S.A., fax 01-972-952-9435. Abstract The application of horizontal wells has increased tremendously with significant and positive results in the United States over the past decade. The pace of horizontal drilling (for oil) has remained high at about 600 to 1000 wells per year since 1990. Most of these wells have been drilled in three (3) formations: the Austin Chalk (79%) in Texas, the Bakken Shale in North Dakota (5%), and the Niobrara (2%) in Colorado and Wyoming. Wells in other formations constitute about 14%. The Department of Energy National Petroleum Technology Office (DOE/NPTO), working closely with industry, has developed a unique analytical system (including models and database) to asses the potential for the wider application of technology to the balance of the remaining domestic oil resources across a variety of formations. The findings of the DOE effort are the primary scope of this paper.

Wells are excavations into the earth for developing groundwater, oil, brine, gas, and engineering geology operations. Water wells are dug, driven, bored, or drilled into the saturated zone of water-bearing formations (aquifers) to extract groundwater for drinking and irrigation.
Shallow water wells are excavated into lose and soft rocks by hand, or mechanically, mainly in unconfined aquifers. They are rarely deeper than 50–60 m, normally with a circular section of 1–3.5 m in diameter. One supports their walls with masonry or a precast concrete ring lining to prevent collapsing. The lining often extends above the ground to prevent people from falling into the well and to reduce contamination.
In dug wells, if the water table lowers below their bottom, one can use the existing well as the fore shafts of new wells drilled down below the new water level. In the ancient past, water was brought to the...

Mineral deeds present a list of perennial interpretative problems, which create uncertainty about ownership rights in mineral estates and the proceeds from the sale of oil and gas production.  Consequently, the following issues arise: (1) deeds with conflicting fractions; (2) the “mineral or royalty” question; (3) the application of the common law “rule against perpetuities” to non-participating royalties, a common interest in the oil patch; (4) the meaning of “minerals”—does it include oil and gas?; (5) the executive’s duty to lease; and (6) deed interpretation versus “reformation.”

        States with long histories of production and case law have grappled with several of these issues, providing answers for some and confusion regarding others.  To promote consistency, courts should adopt rules that embrace the goal of ensuring title stability by rejecting rules that require scrutiny of extraneous evidence and that motivate strained interpretations.  In addition to providing guidance to courts, certain cases provide valuable drafting lessons about perennial issues in oil, gas and mineral deeds.

Unconventional resources are defined to include coal-bed methane (CBM), tight gas and source rock-(often shale) based reservoirs. Tight gas and CBM have not been " unconventional " in the United States and Canada for more than a decade and are being developed in many countries as more or less conventional plays. Source rock-based plays (shale oil, shale gas) in North America have become widely commercialized and contribute substantially to both gas and hydrocarbon liquid production. Vast quantities of shale resources outside of the United States and Canada have been identified but generally remain at early stages of development. Although large numbers of horizontal, multi-stage hydraulically fractured shale wells have been drilled commercially, such plays remain unconventional for a variety of reasons. Shale plays differ from tight gas, CBM and historically conventional plays for the same reasons. Unlike the other plays whose characteristics that result in success are well known, shale plays only have indicators pointing to success. The reasons for variability in individual well performance for shale plays are poorly known. Methodologies to " derisk " potential plays vary. Mathematical models to predict performance for shale plays are less rigorous and operators often rely on overly simplified approaches. Highly competitive North American markets with scores of well-funded competitors and relatively easy access to land and technology have resulted in rapid evaluation of many shale plays at the cost of a substantial number of underperforming wells. In the study, several plays are presented, showing how quickly derisking occurs, what factors contribute to them and how they impact long-term efficiency. A consistent method for gathering data (seismic, test wells, cores, logs, geomechanical information) is proposed to minimize excess costs and maximize NPV. The approaches to optimize development are applied to shale plays with synthetic properties established on observed heterogeneities but reservoir characteristics for some international shale prospects. The economics are tested with various strategies to illustrate the differences in value obtained.

SPE 22704 Horizontal wells have been applied in many types of
reservoir conditions with a variety of applications. The
most successful of these has been exploiting the very
large horizontal permeability anisotropies associated with
naturally fractured reservoirs. Log analysis has always
been difficult in naturally fractured reservoirs; very little
has been published regarding horizontal well logs. This
paper summarizes Union Pacific Resources (UPRC)
experience logging dozens of horizontal wells in several
different naturally fractured reservoirs, summarizes the
improved information resulting from this experience,
contrasts various well logs applicable in such areas, and
describes a method for categorizing fracture apertures
used to quantify the total horizontal well fracture index
(RFI).

With the growth of oil and gas resource demand, the hydro-oscillator is widely used to enhance the Rate of penetration (ROP) and improve the efficacy in drilling various wells. The vibration model is the key issue of dynamics analysis and optimization of downhole tools. For the vibration analysis of the new drill string system with hydro-oscillator in the horizontal well, based on the design of the new hydro-oscillator and its operation conditions, the kinematics expressions are presented. Combined with the vibration force calculation results of the hydro-oscillator, the dynamics model of the new drill string system is established. Furthermore, the important features of vibration frequency, displacement, velocity and acceleration are discussed in the numerical example calculation results. By comparing the results of the calculation and experiment test, we can verify the correctness of the analysis model. With the hydro-oscillator vibration effect, the static friction between the drill string and wellbore is changed to the dynamic friction, so it can result in a significant increase in run length. At the same time, the ROP can be enhanced with the vibration effect. Moreover, with the parameters' adjustment according to the operation conditions, the analysis method and model can also provide references to the study of similar downhole tools dynamics or mechanical properties.

The demand of multistory Building is increases day by day. The residential plus commercial building predominantly used for the need of large span. The large span is needed for Flat slab, Waffle slabs & ribbed slab stands as an excellent option for architects when larger spans in a building has to be covered with the least possible number of columns. The use of different types slabs are evolving as a new trend and are becoming a big challenge for structural engineers. Therefore it is necessary to study about its structural behavior. The paper is review the behavior of different types slab for large span type of building. Final aim to gets the suitable type of slab for large span for effective manner. It is found that very less work is taken setback building with large span, it is required to analysis on the setback building with large span.