bluuebunny/crossref_metadata_2025 huggingface dataset:
Annular Pressure Predictions Throughout Foam Cement Operations
Authors: Garcia H. , Maidla E. E. , Onan D. L.
Published: December 2007

A joint effort was undertaken by an oil company, aresearch institute, and a service company to carry out field operations using foam cement This was achieved by understanding the fundamentals and technology involved, as they stand today.

The problem is presented and solved, considering both technical and managerial strategies. Learning was a key issue, together with the problem definition, the strategy involved, the management requirements, the technical procedures, the planning of the field operations, and the analysis of the final results.

The theory on pressure behavior during foam cement operations is covered and the complete formulation is presented in a way to allow the development of a numerical simulator. Concepts on the design of foam cement operations are covered, and field and foam cement requirements are addressed.

The type curve matching technique is presented for postanalysis and a complete field case study is covered that shows how to apply the method. The resulting uncertainties are addressed through statements of hypothesis that are then supported by the simulator results, other calculations, and field observations during the actual foam cementing job.

The results showed that the planning strategies were successful, as was the field case study diagnosis.
A New Model for Laminar, Transitional, and Turbulent Flow of Drilling Muds
Authors: Reed T. D. , Pilehvari A. A.
Published: December 2007

The concept of an "Effective" diameter is introduced for the flow of drilling muds through annuli. This new diameter accounts for both annular geometry and the effects of a non-Newtonian fluid. It provides the link between Newtonian pipe flow and non-Newtonian flow through concentric annuli. The method is valid in any flow regime and can be used to determine whether a non-Newtonian flow is laminar, transitional, or turbulent. An analytical procedure is developed for computing frictional pressure gradients in all three flow regimes. The analysis also quantifies how flow transition is delayed by increasing the yield stress of a fluid. In addition, it is shown that transition in an annulus is delayed to higher pump rates as the ratio of inner to outer diameter increases. Furthermore, the method accounts for wall roughness and its affects on transitional and turbulent pressure gradients for non-Newtonian flow through pipes and concentric annuli. Finally, the method runs on a 386 PC in only a few seconds.
High-Temperature, Borate-Crosslinked Fracturing Fluids: A Comparison of Delay Methodology
Authors: Ainley B. R. , Nimerick K. H. , Card R. J.
Published: December 2007

Borate crosslinked guar fracturing fluids have recently been re-engineered to allow use at higher temperatures in both fresh water and seawater. A key part of this work involves control of the crosslink delay time of the fluid.

This report presents an overview of the technology available to control delay time with an emphasis on the types of processes used in current commercial systems.

Control of delay time requires control of either the pH or the availability of borate ions or both. To date, control of pH can be effective in freshwater systems. Control of borate is effective in both fresh water and seawater. This may be accomplished by using low-solubility borate species or complexing the borate with a variety of organic species.
Advances in Flotation Unit Design for Produced Water Treatment
Authors: Casaday A. L.
Published: December 2007

Flotation units have been widely used for the treatment of produced water both onshore and offshore. They have, however, exhibited numerous operational and performance limitations. Over the past several years, new designs for the treatment of produced water by flotation have been developed. These have resulted from years of intensive research in both the laboratory and at oil production facilities. These new designs utilize features which improve the performance and reduce the operating problems associated with conventional designs.

The first design discussed is the pressurized IGF. This unit provides highly efficient removal of oil and suspended solids. It's operation improves safety because it eliminates any emission of volatile organic compounds, natural gas or hydrogen sulfide gas. The IGF resolves traditional flotation unit operating problems. These include the inability to operate under pressure, the production of large amounts of oily waste skimmings which require additional treatment, and the inability to operate on floating production facilities or tension leg platforms.

The recently developed and patented design includes several features which provide improved performance. These include the use of a cylindrical pressure vessel, the incorporation of floating skimmers for oil and suspended solids removal and a unique stator assembly for the dispersion of the gas into the liquid phase. Effluent from the IGF is suitable for discharge into surface waters or subsequent treatment prior to re-injection. The unit's design does not require motor driven skimmers. It's use can eliminate the need for additional pumps thereby decreasing the energy requirements of the water treatment equipment train.

A second new design which will be discussed is based on modification of an existing hydraulic induced gas flotation cell to operate as a dissolved gas flotation unit. The gas bubbles are formed by reducing the pressure of a gas saturated produced water stream. This produces a fine bubble dispersion which has been shown to remove smaller oil droplets than does conventional equipment. This patented process, called Hybrid Gas Flotation, allows for increased throughputs and improved effluent quality.
Production Analysis and Reservoir Simulation Identify Infill Drilling Potential in Previously Produced Basins
Authors: Syfan F. E. , Robinson B. M.
Published: December 2007

Over the last several years, intensive reservoir studies were performed on the Davis formation (known locally as the Pregnant Shale) in the Fort Worth Basin, and the Travis Peak formation in the East Texas Basin. These studies were part of the Gas Research Institute's Tight Gas Sands Program designed to improve the overall understanding of hydraulic fracturing processes and production performance in tight gas sand reservoirs.

The reservoir studies consisted of production data analysis using analytical models and reservoir simulators. In addition, pre-fracture and post-fracture pressure buildup tests were analyzed using both conventional transient analysis techniques and reservoir simulators. This approach allowed us to evaluate various reservoir conditions ranging from simple single-phase, single-layer models to multiphase, three-dimensional models. As such, the analyses provided a more thorough description of the reservoir parameters that control well performance, one of which is the effective drainage area or recovery efficiency.

This paper summarizes the results of the reservoir studies conducted on the Davis formation and the Travis Peak formation and demonstrates the importance of proper reservoir characterization to maximize per well recovery and drainage pattern efficiency.
Inflow Performance Relationships With Inertial Effects in the Reservoir
Authors: Camacho-Velazquez Rodolfo , Padilla-Sixto Roberto , Vasquez-Cruz Mario
Published: December 2007

This work presents results on inflow performance relationships (IPR) under the presence of inertial effects in the reservoir. Both, slightly compressible liquid flow and solution gas-drive systems are considered. Up to date, most of the studies on this area have been directed toward dry gas reservoirs. However, as it is shown in this paper, the presence of non-Darcy flow has a sound effect on inflow performance for reservoirs containing other fluids. Thus, the shape of the IPR curve for a liquid flow system may present a parabolic behavior, similar to the shape of the multiphase IPR curves.

For the case of multiphase flow it is illustrated that the value of the exponent "n" in Fetkovich's equation1, is smaller than one when non-Darcy flow effects are important. This observation agrees with Fetkovich1 conclusion based on field data. It is also verified that a cartesian plot, as suggested by Jones, Blount and Glaze2, is useful to detect and evaluate the presence of non-laminar flow.

The behavior of the integrand of the deliverability equation suggested by Fetkovich1 is explored under multiphase non-Darcy flow and a new deliverability equation is presented.

Synthetic examples obtained with a finite difference black-oil simulator are presented. The numerical model considers a variable bubblepoint formulation, which has important consequences under non-laminar flow, especially on the repressurization effects which influences the rate-pressure behavior. Also, field examples are presented.

Different procedures proposed in the literature to predict oil rates are examined under non-laminar flow conditions.
Stimulating Weak Formations Using New Hydraulic Fracturing and Sand Control Approaches
Authors: Abass H. H. , Wilson J. M. , Venditto J. J. , Voss R. E.
Published: December 2007

This paper discusses particular aspects critical to designing a successful fracturing treatment for higher permeability reservoirs with the objectives of stimulation and/or sand control. The process entails creating a short and wide fracture and packing it with multiple layers of proppant, possibly incorporating a resin-coated proppant.

Use of a reservoir simulator to predict or history match a pressure drop profile throughout a given drainage area will be presented. A fracture length can be determined from the pressure drop profile so that a near wellbore damaged area is bypassed and formation failure conditions are not reached. Types of failure mechanisms responsible for solids production formation are discussed. Pressure analysis during fracture packing is presented.

A new technique to orient the perforations relative to the in-situ stress field for optimum fracturing treatment and sand control is presented. A comprehensive treatment design and operational recommendations are given. This paper includes the use of a three-dimensional fracture design model, proppant choice and scheduling, of carrier fluid and additives.
A New Method for the Relief of Annular Heat-Up Pressures
Authors: Leach C. P. , Adams A. J.
Published: December 2007

Annulus fluid heat-up during production often causes high burst/collapse stresses, particularly in subsea wells where the annuli may be sealed. Various means have been tried to overcome the problem, but all suffer from problems of either high cost, potential unreliability or operational restrictions. This paper describes a new method for annular pressure relief, using a crushable foam wrap enclosing the top few joints of the inner string of the sealed annulus. The method is cheap, practical and effective in all cases.
Generalized Performance of Hydraulic Fractures With Complex Geometry Intersecting Horizontal Wells
Authors: Deimbacher F. X. , Economides M. J. , Jensen O. K.
Published: December 2007

Hydraulic fracturing of horizontal wells is a relatively novel stimulation treatment. For most depths of petroleum interest fractures away from the well are vertical and normal to the minimum horizontal stress direction. If a horizontal well is drilled at a trajectory other than the expected fracture direction a complicated fracture-to-well connection is likely to occur. Past literature has suggested a longitudinal fracture initiation followed by a tortuous turning path towards the final fracture direction, or multiple fractures.

This phenomenon happens within a distance that is a few times the well diameter. The consequences are increased treatment pressures and a potentially severe fracture width reduction at the turning point. Posttreatment production performance is likely to be affected substantially. Reservoir simulation studies were carried out demonstrating the dependence of production rate on the angle between the horizontal well and the final fracture trajectory, the length of the perforated interval and the dimensionless fracture conductivity, under an assumption of a choke effect at the turning point. An angle threshold was identified beyond which the well production decreases significantly.
A New Method for Obtaining Injection Profiles and Fracture Apertures Using Radioactive Tracers
Authors: Reis J. C.
Published: December 2007

A new method for interpreting radioactive tracer injection profiles has been developed for use after the tracer has entered the formation. Equations for obtaining fluid injection rates for radial flow and for obtaining in-situ fracture apertures for linear flow are presented. From a Monte Carlo study of gamma ray transport, it was found that the wellbore gamma ray intensity decayed exponentially with radioactive tracer distance into the formation. The attenuation of gamma rays reaching a centralized detector is independent of wellbore diameter. An equation for the dependence of the attenuation on formation bulk density and initial gamma ray energy was developed.
Steady and Unsteady-State Lifting Performance of Gas Wells Unloading Produced or Accumulated Liquids
Authors: Tek M.R. , Gould T.L. , Katz D.L.
Published: December 2007

Steady and unsteady state performance of wells subject to two-phase flow performance of wells subject to two-phase flow are considered. A new concept called "the lifting potential" is introduced. The concept explains stability phenomena observed in loading, unloading, heading and dying of gas wells. It is also shown to be a useful tool in designing well bore or gas lift equipment for optimum performance.

Introduction

Problems connected with design, engineering and performance analysis of wells subject to two-phase flow have been of continuing interest to the industry for some time. Oil wells producing volatile crude during primary producing volatile crude during primary recovery, majority of oil production during secondary recovery, condensate wells subject to retrograde phenomena in the well bore, and gas wells subject to marginal water production are typical of areas where multiphase flow problems are encountered.

In vertical two-phase flow systems the main problem of practical engineering import may be specifically stated as follows:

Knowing the geometry of conduit, physical properties of the two-phase flow physical properties of the two-phase flow system, and conditions prevailing at well head, predict pressure profiles down the flow string.

Contributions to various aspects of two-phase flow problems have been numerous in the literature.

Through the years a number of investigators choose to correlate both slippage and friction losses by a unique and single energy loss factor. Their efforts, now considered by many as first order engineering approximations, fell short of their desired goal because these correlations did not include the effects of all pertinent variables, and more importantly, they did not reflect the effect of various flow regimes.

Another school of thought is represented by other investigators who choose to define, measure and predict slip or "hold-up" as intermediate parameters leading to the calculations of pressure drops.
A Review of Well Injectivity Performance in Saudi Arabia's Ghawar Field Seawater Injection Program
Authors: Bayona H. J.
Published: December 2007

In the late 1970’s, it became necessary to convert to seawater as the source of injection water in the pressure support program of the North Uthmaniyah section of the Ghawar Field in Saudi Arabia. This peripheral waterflood had been initiated by Saudi Aramco in 1966 to maximize recovery of oil from the Arab ’D’ limestone reservoir in this unique field, the largest in the world.

This paper will provide a brief introduction to the seawater processing facilities which includes over 400 kilometers of pipeline and can supply 4.2 MMBD of treated seawater.

The paper will also discuss Saudi Aramco efforts to study and mitigate declining well injectivities. Experience in water quality control, well stimulation efforts to improve injectivity, and analysis of well plugging characteristics/profiles and their relation to reservoir permeability will be covered. An empirical relationship between the injectivity index and the cumulative water injected has been published and is now being evaluated as a means of monitoring well plugging and, indirectly, to monitor water quality. Efforts made to minimize well plugging by improving seawater quality and by internally coating the seawater piping system are also discussed.

Finally, using solar powered flow computers to measure water injection rates and run pressure fall-off surveys will be compared to the previously used analog flow meters and subsurface pressure fall-off bombs.
Breathing New Life Into a Thin Oil Column by Horizontal Drilling
Authors: Al Zarafi Ahmed
Published: December 2007

The Shuaiba reservoir is one of a stacked system of reservoirs in the Saih Rawl field in Central Oman. Relative to other reservoirs in the field, development of the tight Shuaiba limestone has been unattractive because of rapid water breakthrough in vertical wells completed in the thin oil column.

The production performance of a trial horizontal well, drilled in 1991, has been very encouraging. A three-fold increase in oil productivity has been observed, indicating that encroachment of water to horizontal wells is significantly less of a problem than coning to vertical wells. Simulation models have been constructed and used to history match the performance of vertical wells and predict the performance of full field development by horizontal drilling. Optimum well spacing has been identified for various values of oil column height while sensitivities to other identified key variables, such as reservoir quality have been evaluated.

The ultimate recovery from the Saih Rawl Shuaiba reservoir can be significantly increased via development by horizontal drilling, at an appreciably lower unit cost than development with vertical wells, thus confirming the potential for a sizeable development project.
Seismic Modeling Study of Subsalt-Imaging Problems in the Gulf of Suez
Authors: Ruckgaber G. M.
Published: December 2007

Seismic waves used to image pre-Miocene reservoirs in the Gulf of Suez are often severely hampered by distortion and noise that arise in the shallower South Gharib Salt and Zeit formations, respectively. A sequence of seismic forward models was computed for a structure in the B-Trend area of the southern Gulf to isolate the causes of this distortion and noise and investigate their significance for seismic imaging.

Processing and analysis of the resulting model data indicate that current seismic processing methods followed by depth migration can adequately image pre-Miocene structure in the B-Trend and, hence, in most of the Gulf of Suez. Seismic energy traversing the thin, cyclic layers of the Zeit formation experiences frequency-dependent delay, but low-pass filtering minimizes the dispersive effect of this frequency-dependent delay and yields a seismic wavelet only negligibly attenuated.

The major problem for seismic imaging is caused by long-period multiples between the air-water interface and the many high-reflectivity interfaces of the Zeit. These multiples are poorly attenuated by CMP stacking-particularly at the bottoms of synclines flanking the salt swells. The resulting high-amplitude events are smeared laterally upward by migration, severely masking images of structure beneath the adjacent salt swells.
Application of Reprocessed Seismic Sections from Petroleum Exploration Surveys for Groundwater Studies, Eastern Abu Dhabi, UAE
Authors: Woodward D. G. , Al-Jeelani A. H.
Published: December 2007

Field tapes from a deep seismic survey for petroleum exploration were reprocessed in order to extract seismic information on shallow reflectors for use in ground-water exploration. A potable aquifer in eastern Abu Dhabi occurs at depths less than 150 m. Field methods, acquisition parameters, and section processing were originally designed to enhance reflectors expected at depths up to 6,000 m. Seismic data collected from depths of about 110-330 m were muted from the original sections, so that all seismic data concerning the aquifer were deleted from these sections. Reprocessing efforts concentrated on restoring information for the first second of seismic data.

A unique sequence of reprocessing parameters was established based on results from many experimental trials. Major enhancements to the resolution of shallow reflectors resulted from: (1) application of a 20-hertz, low-cut filter; (2) recomputation of static corrections to a datum nearer the land surface; (3) intensive velocity analyses; and (4) near-trace muting analyses. The number, resolution, and continuity of shallow reflectors were greatly enhanced on the reprocessed sections, as was the delineation of major faults and folds. The 33 reprocessed sections were instrumental in preparing a map of the major structural features which affect the shallow aquifer system.

Results from this study show that seismic field tapes collected for deep petroleum exploration can also be reprocessed to explore for shallow ground water.
Hole Stability in Nile Delta Area: Abu Madi, Nidoco, and El-Qara Wells
Authors: Hussein N. K. , Taha A. L. A. E.
Published: December 2007

Hole instability in Nile Delta area, specially in the Middle and East leases is one of the main drilling problems encountered in most of the wells drilled either by Petrobel or Nidoco. Shale swelling, caving, tight holes, and consequently loss of circulation problems were experienced and overcame using several techniques.

This paper is focused on the analysis of the main drilling hazards related to shale instability including analysis of pore pressure data obtained from sonic, sigma, and RFT logs and prediction of pore pressure expected in the forecasted wells.

It discusses the different mechanisms of Nile Delta shale instability, Field observations and results of X-Ray diffraction analysis of shale samples collected from the area wells led to a significant improvement in shale stability by using potassium polymer mud instead of sodium chloride lignosulphonate mud. Also tight hole and differential pipe sticking possibilities while drilling through low pressure porous sands were reduced by using ultra fine cellulosic materials.

Conclusion and recommendations for drilling performance optimization are included in this paper.
Solar-Powered Air Compressor: An Economical and Ecological Power Source for Remote Locations
Authors: Soules T. R. , Tran P. V.
Published: December 2007

Many, wellheads that require safety systems are located in remote areas where conventional power sources are not available. These safety systems require power in the form of hydraulic or pneumatic pressure to operate various sensors and wellhead equipment. Until now, remote locations have been limited to three sources of power: (1) bottled nitrogen, (2) Diesel/gasoline-powered systems, and (3) the use of gas off the well. Now, however, there is another option.

A state-of-the-art, solar-powered air compressor has been developed that has the capability to provide the required power for the safety systems located in remote locations.

In addition to offering an economical and ecological solution to the need for a safe and reliable power source, the solar-powered air compressor can provide a more cost-efficient option to the above alternatives. The solar-powered air compressor is inexpensive to maintain since primary service (battery replacement) is only necessary every 2 to 5 years, and the units can be transported easily as they are designed on 4-foot [1.22 meter] skids that fit into a standard pick-up truck.

This paper will describe the operating principles and design considerations which led to the development of a new solar-powered system, four of which are currently in use in Gabon.
Modified SSSV for Oil Wells With Sanding Tendency
Authors: Gazaq N. M. , Hedjazi A -K. G. , Hilts R. L.
Published: December 2007

Many of Saudi Aramco’s wells have been experiencing a substantial increase in sand production resulting from increased drawdown and water production. As a result, sand has accumulated in the internal mechanism of many subsurface safety valves, rendering the valve’s internal mechanism inoperative.

A design change that was proposed by the manufacturer to eliminate the possibility of sand accumulation in the valves was approved by Saudi Aramco for installation on a trial basis. The design modification incorporated technology typically used in tubing retrievable subsurface safety valves.

The modified valves were installed and tested in sand-producing wells. Based on field results, other valves have been modified and installed. Their performance and ability to maintain the safety control required is presently being monitored, and the results to date have been encouraging.
Will Parallel Computing Ever Be Practical?
Authors: Killough John E.
Published: December 2007

Recently the lure of scalable distributed memory parallel computing with hundreds or even thousands of inexpensive, but powerful, RISC-based processors has resulted in a significant effort in the development of software for petroleum engineering and seismic applications. Unfortunately, few if any applications have found their way into a production environment from the reservoir engineering perspective. Several hurdles remain to be overcome if parallel computing is to become commonplace as a tool for applications. This article addresses three areas of concern for a major area of petroleum engineering - reservoir simulation: load balancing, data structures, and linear equation solutions. Examples from real reservoir simulations and possible solutions for several situations are discussed.
Evaluation of Pipeline Integrity by On-Line Inspection
Authors: Heraiba F. A.
Published: December 2007

Advanced On-line inspection tools coupled with reliable interpretation of inspection data and adequate reporting formats are required to evaluate the structural integrity of the pipeline. This evaluation is a vital requirement for pipeline operators in order to define necessary preventive measures and repairs required to avoid line rupture or leakage.

ZADCQ is operating a large pipeline network transferring crude oil, gas and injection water under a wide range of operating conditions.

In order to evaluate the integrity of this network, ZADCO had conducted several surveys using different types of inspection tools.

This paper presents an operator's point of view about the capabilities and limitations of the different tools and the reporting formats submitted from inspection contractors.

The paper provides recommendation about methodology for selecting the most appropriate tool for a specific job.
Prediction of Carbonate and Sulfate Scales in Oilfields
Authors: Yeboah Y. D. , Samuah S. K. , Saeed M. R.
Published: December 2007

This paper presents a new and reliable scale prediction model. The available models for scale prediction are based only on thermodynamics and limited solubility data. The new model is based on thermodynamics, kinetics and hydrodynamics of the system. The model uses experimental solubility data in single and mixed-salts as well as natural oilfield brines to accurately predict scaling potentials. Once the potential has been established to exist, the model uses the flow characteristics and experimental kinetic data to predict the scale deposition profile as a function of position and time.

Critical saturation indices beyond which scaling occurs with near certainty have been established for the common scales SrSO4, CaSO4.2H2O, BaSO4 and CaCO3. The results of the model prediction in actual oilfields and test wells are presented. The model has been developed in a menu-driven, user-friendly format with options for tabular and graphic presentation of results. This paper presents details of the computational approach used to predict the saturation index or scaling potential.
Nimr Horizontal Drilling: A Case History
Authors: Al-Rawahi S. M. , Small G. P. , Glendinning D. R.
Published: December 2007

The recent technological advances in horizontal drilling techniques and design optimization have enabled Petroleum Development Oman (PDO) to develop a number of its fields by horizontal drain holes. More than 70 horizontal wells have been drilled and completed in the different fields within the PDO concession area (table-1). About 40% of the horizontal wells to date have been drilled in the Nimr oil field, in the Eastern Flank (Fig.1), where drilling a horizontal well today is cheaper and faster than drilling a vertical well less than three years ago.

Cost effective casing design, drilling fluid optimization and the application of improved deviation and cementing techniques have resulted in significant drilling and completion cost reduction and more efficient performance.

The increased recovery of the heavy and viscous oil, delayed water breakthrough, improved PIF (Productivity Improvement Factor), and reduced skin damage are some of the more immediate benefits. While in the long run, it is planned to replace vertical drain holes by horizontals at a ratio of more than two to one resulting in accelerated oil production and reduced surface facilities congestion. Moreover, reservoir studies have showed a potential increase in the recovery factor that should generate wider applications for horizontal wells.

This paper reviews the different steps of the horizontal well design improvement, the milestones that have been achieved in both drilling and completion techniques, the future development drilling plans of the field and the potential applications for other fields with similar geological and reservoir characteristics. It also highlights the problems that had been encountered in both the drilling and the production phases and the techniques used to overcome them.

The successful application of horizontal well technology in the Nimr field has only been possible through the multi-disciplinary efforts of Drilling Engineering, Production Chemistry and Petroleum Engineering staff.
Horizontal Drilling in Saudi Arabian Oil Fields: Case Histories
Authors: Al-Buraik K. A. , Pasnak J. M.
Published: December 2007

A total of thirteen wells have been drilled in the carbonate reservoirs and eight wells in the sandstone reservoirs. Currently there are eight wells in progress.

These wells represent the first horizontal wells drilled in Saudi Arabia. This paper will present generalized case histories for both carbonate and sandstone horizontal wells. It will also discuss well plans, drilling fluids, casing, cementing liner, coring, logging, and completions. In addition, problems encountered during drilling will be discussed.
Application of Short-Radius Horizontal Hole Drilling
Authors: El-Sadek A. S.
Published: December 2007

The short radius horizontal hole drilling technique is used in ADCO operations to turn the uell bore from vertical to horizontal within the target reservoir in less than 44 ft of vertical hole.

Experience gained from the drilled wells have been used to improve the drilling programme and drilling tools and which has continuously resulted in increasing the length of the horizontal hole at a reduced unit cost.
Sea Level Changes in the Aptian and Barremian (Upper Thamama) of Offshore Abu Dhabi, UAE
Authors: Azer S. R. , Toland Christopher
Published: December 2007

The sequence stratigraphy of the Early Cretaceous (Aptian and Barremian) Upper Thamama Shuaiba and Kharaib Formations is studied using cores and logs from three key wells in Offshore Abu Dhabi. Three regressive transgressive cycles are readily recognised in the Shuaiba and Kharaib Formations. Two unconformities are fairly well documented at the top Shuaiba and at the base Kharaib. Emphasis is given to three sequences within the Shuaiba and Kharaib Formations.

Shallowing or deepening upwards cycles are determined and the relative sea level curves constructed.An attempt to correlate the produced sea level curves with the global Vail/Haq curves is carried out to verify whether these apply to the area or that there are different sea level curves pertaining specifically to Offshore Abu Dhabi.

The transgressive and highstand systems tracts, maximum flooding surfaces and sequence boundaries are determined. Chronostratigraphic zonation and correlation of the Shuaiba and Kharaib Formations are carried out to determine whether straight line layer cake stratigraphy applies, as is currently believed or whether the lithostratigraphic units are in fact diachronous. Distribution charts for major fossil groups are produced. Ammonite data for age calibration are introduced. The unconformities within the Upper Thamama are defined and confirmed.

The main objective of this project is to erect a provisional sequence stratigraphic framework for the Upper Thamama in the Offshore Abu Dhabi area.

This framework forms a template for further reservoir description and sequence stratigraphic studies.
3-D Electrofacies Model, Safaniya Reservoir, Safaniya Field, Saudi Arabia
Authors: Al-Sabti H. M. , Al-Bassam K. A.
Published: December 2007

The Safaniya reservoir is the main producing reservoir in the Safaniya Field, the largest offshore oil field in the world. It lies within the Wasia Formation of Middle Cretaceous Albian age, and was deposited in a fluvial dominated deltaic environment. The southern part of the field is dominantly thick, massive sands, while the northern part is more heterogeneous, with all types of sub-deltaic environments; distributary channels, mouth bars, crevasse splays and interdistributary bay shales, prodelta shales, and shallow marine shales and sands. The complex heterogeneity of the reservoir provides a challenge in characterizing reservoir behavior. To better understand fluid movement; lateral water encroachment, and water fingering in the reservoir architecture context, a 3-D electrofacies model (Abbott, 1982) was constructed for the Safaniya reservoir. It is based upon a detailed 11-layer geologic description, used an electrofacies database of 573 of the 624 total wells in the field, and was built using a 3-D geocellular modeling program.

The model has an area of 3900 sq. km. The modeled vertical interval from top Mauddud to Base Dair marker averages 540 feet in thickness. Cell dimensions of the model are 250m X 250m areally and 1 foot vertically. Reservoir thickness is several hundred feet which yields a total 3-D model of 45.5 million cells.

This electrofacies model is available to generate various maps and cross sections to help in reservoir management decision making and to provide 3-D geologic input for multi-layer reservoir simulation models.
Gas Gravity Drainage Under Secondary and Tertiary Conditions in Fractured Reservoirs
Authors: Saidi A. M. , Sakthikumar S.
Published: December 2007

Variety of gases can be used for injection into reservoirs under conditions varying from immiscibility to full miscibility. Also gas injection has found applications in both secondary and tertiary conditions. The advantage and disadvantage of different combinations of each of the above will depend on the particular context. The reported laboratory work and subsequent simulation work has been done in clarifying the influence of the parameters controling the efficiency of the different processes under gravity drainage conditions.

This paper addresses the problem of oil recovery by gas injection under primary condition and of water flooded reservoirs with particular emphasis on the use of lean hydrocarbons gas. A systematic investigation was carried out to highlight the parameters controling such processes. The work comprised of analysing reported laboratory experiments under reservoir conditions and interpretation of these experiments using a compositional simulator. Laboratory experiments included both centrifuge tests and core floods under reservoir conditions. The core displacement was designed to help determine the 3- phase oil relative permeability at low oil saturation.

The investigation confirms that tertiary lean gas injection is capable of mobilizing Waterflood residual oil and thus reducing the residual oil saturation. The work also helps to identify the role of 3- phase relative permeability. In addition the role of gas-oil diffusion under tertiary condition is discussed. Moreover, simulations were made to clarify the effect of block boundaries in block-to-block interaction.
Application and Optimization of Continuous Flow Gas-Lift Wells for Zeit Bay and Ras Budran Wells
Authors: El Massry Y. A. W. , Abdel Hamid A. H. , Abu El Yazid M. M.
Published: December 2007

Gas lift installation in the Ras Budran and Zeit Bay fields have been tailoredto fit the widely differing both reservoir conditions encountered. The accuracy of multi-phase flow calculations combined with well test information and their usein simulating well performance has played an important role in efforts to improvegas lift efficiency in both fields.

Using these well performance simulatedmodels, an analytical procedure has been introduced to determine the optimum distribution of gas to wells in a continuous flow gas lift system by which wells can belifted over a range of producing conditions by regulating the injected gas volumesat surface.This procedure has been utilized in the assessment of the requirement for future gas lift gas compression and non-associated gas supply wells.

It is demonstrated throughout this paper that potential exists in many areas for increasing production by the optimization of lift gas resources through application of sound engineering and operating principles.
Development and Use of a Finely Gridded Window Model for a Reservoir Containing Super Permeable Channels
Authors: Valle Antonio , Pham Anthony , Hsueh P. T. , Faulhaber John
Published: December 2007

This paper discusses the development and use of a finely-gridded 3-D window model (1/3 km by 1/3 km by 15 layers) for a highly heterogeneous producing area of a large carbonate reservoir. The reservoir portion being modeled contains a vast area of hardened dolomite rock interbedded with a leached Cladocoroosis facies. This leached Cladocoropsis facies forms inter- connected linear vugs in the rock yielding horizontal permeabilities in the tens of darcies. The vertical permeability across the dolomite, however, is in the microdarcy range.

Special consideration was given to model layer selection, horizontal and vertical permeability distribution, grid size, and relative permeability assignments in order to accurately model the observed field performance. The results of this finely-gridded window model compare well to observed historical field data and are superior to results of previous coarser models. The model is being used to identify areas of poor oil displacement for possible exploitation and increased oil recovery.
Drilling Templates for Drilling Before Offshore Installation
Authors: Ghany M. M. Abdel , El Ahmady H. M.
Published: December 2007

Drilling template is a simple plane steel structure fabricated using heavy wall pipes and beam elements. It acts as a guide frame for designated drilling wells and as a guide for the installation of jacket positioning by the docking piles. Templates could be set either on the sea-bed or around an existing well by using hanging clamps.

Drilling templates have been widely used in offshore activities when drilling operation is preceeding platforms installation. Such case usually exists in new development plans where drilling new wells and construction of production facilities are interfering with each other. Templates, then could be used for drilling wells while project is proceeding its normal schedule.

In many other cases templates are used to drill and evaluate the wells first and based on the results, proper sizing for production equipment and facilities will be followed.

AGIBA had successfully constructed and installed three drilling templates for the developing project of its ASH- RAFI Lease. ASHRAFI DEVELOPMENT LEASE was awarded to AGIBA in Sep., 90. The development plan of this new offshore concession placed the drilling campaign in between the whole project schedule. In order to execute the work of both Drilling & Project Departments without waiting each other, the idea of drilling template was implemented to avoid any conflict between the execution dates.

This paper will discuss AGIBA's experience in the installation of its three templates in ASH- RAFI. Planning for the job, preparation of the existing wells, installation, positioning and orientation. We believe these procedures will positively assist in future similar jobs in offshore operations.
Applications of Projection Onto Convex Sets to Stochastic Inversion
Authors: Malinverno Alberto , Rossi D. J.
Published: December 2007

Obtaining a map of the spatial distribution of some physical property in a reservoir from sparse data is a fundamental problem in reservoir characterization. This problem can be stated in terms of an inverse problem as the search for a map that satisfies certain constraints. The constraints are a set of measurements and information on the spatial statistics of the property. A common practice is to construct nonunique "conditional simulations," i.e., maps that are consistent with point measurements (typically obtained at wellbores) and with the spatial statistics of the property being mapped. We introduce a method (Projection onto Convex Sets, or POCS) that lets us perform a "stochastic inversion," i.e., obtain nonunique simulations that are constrained not only by spatial statistics and point measurements, but also by low-resolution measurements obtained away from the wellbores (e.g., seismic traveltime data). Numerical experiments show that incorporating data from the region away from wellbores allows us to better locate large-scale heterogeneities in the reservoir volume. Locating heterogeneities may be important for accurate modeling of fluid flow within the reservoir.
MWD Rock Mechanical Properties to Avoid Drilling Related Problems
Authors: Ahmed U. , Bordelon D. , Allen D.
Published: December 2007

Borehole instability, wellbore sloughing and lost circulation are some of the drilling-related problems that can be avoided with real-time access to mechanical properties of the rock and certain failure geometry. Typically, mechanical properties of the rock are available after the completion of drilling or from a nearby well. Neither cases allow one to make real-time drilling changes to the current well to avoid any of the above drilling-related problems. Derivation of rock mechanical properties and failure geometry from MWD (measurement while drilling) have been the subject of research in recent past; however, the complex nature of the problem continues to elude the industry.

In this paper we document two recent developments in calculating rock mechanical properties and failure geometry through use of MWD tool responses. First, we discuss the combined use of drilling weight-on-bit (DWOB), torque (TOR) and rate of penetration (ROP) to establish rock failure characteristics of the wellbore wall. We follow this with a note on the integration of MWD data with LWD (logging while drilling) data such as gamma ray and dual resistivity to identity rock via lithology and strength parameters and to determine the susceptibility of the rock to failure. Second, we illustrate the integration of MWD caliper measurements with wireline measurements to establish criteria for failure geometry prediction and calculation on a real-time basis. Several field examples are presented to illustrate the developments and findings reported.
Casing System Risk Analysis Using Structural Reliability
Authors: Adams A. J. , Parfitt S. H. L. , Reeves T. B. , Thorogood J. L.
Published: December 2007

This paper describes a method for quantitative risk analysis (QRA) of casing/tubing systems, using a structural reliability approach. The technique was used to calculate risk-calibrated design factors for exploration and development wells, taking into account the nature and consequences of failure for each string, stress check type and load case. The methodology and results are a significant advance on previous work.
The Aftermath of the Kuwaiti Oil Fires
Authors: Bou-Yabes A. A. , Akbar S. H.
Published: December 2007

Although the last oil well fire was announced dead officially on 6th November 1992, the oil wells were far away from being ready to be put back on stream for oil production which is the main source of income for a war-torn country. This paper presents more accurate statistics of the Fire Fighting Stage and discusses in detail the efforts, techniques, equipment, procedures and steps taken to restore the production from the explosions and fire damaged wells. Figure 1 shows a pie chart for the condition of the wells controlled by the major fire fighting teams, while figure 2 shows the pie charts for the methods used by these teams in controlling the oil wells. The operations executed under the Post Capping Operations, although does not seem as dangerous as the initial Capping of the wells, it is equally as hard and demanding as the initial Capping Operational is almost equivalent to capping the gushing wells. It was not important as to how you cap the well during the fire stage. However, during post capping operations you have to stick to the laid out procedure using the required available equipment to achieve a set goal of having the wells ready to be taken for the rig workover. To achieve this ultimate goal of installing a new wellhead and X-mas tree instead of the Damaged remains of the wellhead, the following steps were developed in what is known as the Post Capping Operation:-

Cutting off the damaged wellhead and securing the well with full bore ball valves. Fishing the tubing string to allow for working space. Securing the well with inflatable packers. Installing a new wellhead.

The above work is not as simple as it may seem, as most of the wells were full of bad surprises.
Strategic Background and Economic Analysis in the Development of a Project for Coiled Tubing Drilling
Authors: Cameron Gerald , Ozzola Vito , Schenato Adelmo
Published: December 2007

As operating costs escalate and the oil price remaining stubbornly low, now more than at any time in the history of the oil industry the economics of every phase of business must be minutely examined from the exploration and appraisal through to production. In addition to this, another problem arises when dealing with a project such as coiled tubing drilling, as whilst this technology will provide a similar end product to conventional drilling practices it is such a departure from conventional drilling practices as to create scepticism.

This paper describes some of the ground work involved as part of a feasibility study carried out for coiled tubing drilling for a situation of drilling from top hole to total depth and sets out a system whereby the financial implications of investment into a new technology can be assessed by comparing three strategies. The best scenario for return on investment and increased profitability can then be chosen.

The study deals with the economic analysis, risk analysis and the methodology used in achieving the final results. These results compare the three strategies on the basis of numerical values of drilling operational costs and production.