bluuebunny/crossref_metadata_2025 huggingface dataset:
The Role of Subsea Systems as an Integral Part of Occidental’s North Sea Development Strategy
Authors: Azancot M. , Ward R. , Gibson S.
Published: December 2007

The paper provides an overview of subsea satellite developments in Occidental’s North Sea Operations. The logic and cost effectiveness of utilizing three subsea satellites to one platform are discussed. The overall impact on recoverable reserves and related extension of economic field life are quantified and additional potential developments are described.

Occidental’s increasing commitment to subsea development is discussed. A field history is presented from the first subsea installation in 1980 to the present. The installations have grown in complexity, keeping pace with the latest technology with optimum reserve recovery as the ultimate objective.

Development of the most recent field addition, Scapa, is discussed in detail. Particular attention is given to the installation and well completion procedures with emphasis on continued improvements that have been implemented.

Occidental’s North Sea experience is put in the context of international operations and it is the authors’ belief that the subsea systems described can be a major contributory factor in increasing the number of worldwide offshore developments.
Metocean Measurement Program for the Pearl River Basin Block 29/04 in the South China Sea
Authors: Sharma J. N. , Bole J. B. , Tryggestad S. , Bian Jiaxi
Published: December 2007

Amoco recently deployed a Metocean buoy, a directional waverider buoy, four Aandera current meters on a mooring and two upward-looking acoustic Doppler current profilers in the Pearl River Basin Block 29/04 in the South China Sea· This paper describes objectives of the measurement program, planning of instrumentation, deployment, and recovery operations, and oceanography features being investigated.

Measuring instruments were installed in August 1987 and good data were collected successfully during several typhoons. Samples of wind, waves, and current data are presented. Of particular interest are the current velocity profiles resulting from large scale oceanic circulation, a local eddy feature, monsoons, and typhoons. The data will be used to determine operational and extreme environmental loading criteria for offshore planning and design.
Selection of Paraffin Control Products and Applications
Authors: Thomas D. C.
Published: December 2007

Paraffin related problems in the oilfield continue to plague efficient production operations. Solutions to these problems vary with the cause of the problem, its location, severity, and economics. This paper presents the philosophy and methodology for investigating and recommending solutions to paraffin related field problems based on laboratory testing and its relationship to these field problems. Arriving at a solution to paraffin problems in the oilfield involves a systematic approach that evaluates laboratory test results and matches them to field needs. An important aspect of thi s approach includes combining information from the field, the correct mix of laboratory tests, and interpretation of the test results.
The Impact of New Tax Reforms on the Oil and Gas Industry: A Financial Analysis Approach
Authors: Yu J. P. , Yu T. C. , Neidermeyer A.
Published: December 2007

The Tax Reform Act of 1986 has made significant changes in the tax laws that affect U.S. industry. The new act lowers tax rates and makes major changes that will affect the ability of taxpayers to shelter income. Generally, profitable companies that for years have used various tax incentives to reduce their liabilities may incur higher taxes under the new act; however, the lower tax rate may reduce the overall tax liability. The objective of this paper is to study the impact of these tax changes on the oil and gas industry. A financial analysis approach is applied to the oil and gas industry in the Appalachian area.

This study also discusses the changes which directly and indirectly affect the oil and gas industry. Intangible drilling costs (IDC) treatment, excess IDC, percentage depletion, recapture on dispositions and depreciation are the oil and gas industry specific changes. The passive loas limitations, alternative minimum tax (AMT), and the capital recovery and investment tax credit affect the industry in general. How these non-industry specific changes impact on the oil and gas industry is also discussed. In addition, a cash flow approach is used to compare the financial situation of the oil and gas companies under the new and old law.

The cash flow analyses are done using Lotus 1-2-3 spreadsheets. The analyses are performed for both a small independent company that produces less than 1000 barrels of oil equivalent per day and an integrated company that is involved in upstream operations of refining and distribution. Under the new tax law, the independent company benefits because of a significant reduction in the tax rate and relatively few changes in the tax rules. However, the integrated company incurs a higher tax liability and AMT payment since the New Tax Reform Act eliminates tax shelters. The capital-intensive oil and gas industry will be less competitive than previously in attracting investment capital. Additional conclusions and recommendations are made to help the industry optimize overall tax costs.
Use of Microcomputer Graphics To Teach Waterflooding Concepts
Authors: Whitman D. L.
Published: December 2007

The use of microcomputers (and in particular their graphical capabilities) in classroom situations has been found to be a very effective teaching tool. With the main goal in mind to add visual content to the teaching of waterflooding concepts, three programs, using the graphical capabilities of the microcomputer, are developed to aid in this teaching. The first is a graphical demonstration of the layered Stiles’ model, the second is the linear Buckley-Leverett model which accounts for the effect of displacement efficiency, and the third is a Higgins and Leighton streamtube model which adds areal sweep effects.

Each program shows the results of the calculations involved in each model both with color graphics and a display of certain parameters. Each program also generates an output file and allows the user to generate a number of graphs of the results. Since the programs are written for a microcomputer, they are easily demonstrated in class and are available for student use outside of the classroom.
Scheduled Automation of Laboratory Displacement Experiments From a Computer Workstation
Authors: Nelson H. C. , Alameda G. K.
Published: December 2007

This paper describes a computer automation system which can control laboratory displacement experiments from a dedicated computer workstation. The dedicated computer is tied into a distributed network that supports remote access via asynchronous telephone communication. Thus, indirect control of displacement experiments can be extended to other workstations on the network or to a remote computer equipped with a telephone modem.

The automation system uses a computer to schedule and monitor displacement operations. Scheduled operations include data capture, pump control, valve switching, produced fluid sample collection, and analysis of produced gas by gas chromatography. The system provides continuous, real time screen data display and graphics data processing for immediate analysis of experimental results. The system also detects and responds to exceptional run conditions such as pressure set point violations or instrument hardware failures.

The displacement experiments are typically permeability measurements, slim tube measurements, or scaled core floods which may take weeks to complete. The computer automation system makes it possible to run displacement experiments continuously and safely over extended time periods with minimal operator intervention and no loss of data.
Reservoir Engineering Utilization of Microcomputers in a Technology Development Environment
Authors: Good P. A. , Rogers W. L. , Baxley P. T.
Published: December 2007

Microcomputers have assumed a pivotal support role in carrying out reservoir engineering research at Shell Development Company. Four specific application areas that have benefited from microcomputers are: Laboratory experimental control, data collection, first pass data manipulation and analysis, and graphical presentation of results using microcomputers have increased laboratory throughput while improving the quality of data obtained and the ease of understanding the implications of experimental results.Microcomputers are used extensively as smart terminals for coordinating access to the VAX, IBM, and CRAY computers used in carrying out simulation work.Over the past ten years, a comprehensive package of reservoir simulation workstation software has been developed on VAX minicomputers connected to dedicated graphics computers. With the advent of the 68000 based Amiga and 80286 and 80386 based PC "compatibles," it has become possible to emulate the necessary functionality of these dedicated workstations with an acceptable response time. This puts the power of a VAX 8800 based graphics workstation at each engineer's desk.Preparation of visual aids required for presentation of complex research results is facilitated by the powerful graphics programs available for DOS based microcomputers.

With ever more powerful microcomputers and peripherals becoming available at prices making it practical to put a high performance microcomputer system at each engineer's desk, we must continually review how to best integrate usage of the micro, mini, and mainframe computers available in our work environment.
Results of Remote Entry Units/Personal Computer Pilot Test
Authors: Glynn C. J.
Published: December 2007

Hand held remote entry units were tested in three non-automated oil fields. The units were used daily by gaugers to store routine operating information and then to upload that information to the corporate mainframe computer via a personal computer. The test resulted in reduced manpower requirements versus the traditional procedures.
Adaptive Local Grid Refinement
Authors: Ewing R. E. , Lazarov R. D.
Published: December 2007

In the multidimensional numerical simulation of certain multiphase fluid flow processes, many phenomena are sufficiently localized and transient that self-adaptive local grid refinement techniques are necessary to resolve the local physical behavior. For large-scale simulation problems, efficiency is the key to the choice of specific adaptive strategies. Several different types of grid refinement methods will be discussed and briefly compared. The differences in accuracy of the local finite difference stars, complexity of the data structure, and efficiency of the solution techniques will be explained. Concepts for incorporating these methods in existing large-scale simulators will be presented.

Many man-years have been invested in developing large-scale numerical simulators which do an excellent job of resolving most of the larger length-scale phenomena in our production processes. Although adaptive local refinement methods are crucial for many applications, most techniques which have been developed to date either cannot be incorporated in our codes or are so computationally complex that they destroy the efficiency of existing simulators. Recently new preconditioning techniques have been developed which allow grid refinement methods to be used efficiently in existing codes without disrupting the basic solution process. These techniques are also highly amenable to vectorization and parallelization of the algorithms. They are also a first step in allowing complex well models to be incorporated into large field-scale codes and applications.
Development and Application of Downhole Diagnostic Technology for Pumping Wells
Authors: Zhenying Lou , Yuandi Wang , Oing Zhu
Published: December 2007

The dynamic behavior of sucker rod is described by wave equation with viscous damping in dowmhole diagnostic technique for sucker rod pumping wells. Based on the polished rod load and its displacement measured on the surface, the load and displacement of the sucker rod string at an arbitrary depth in the wellbore can be calculated and the dynagraph card at that depth can also be drawn up. Thus the working condition of pumping system could be analysed accurately.

The mathematical method and main functions of the downhole diagnostic technique are discussed in this paper. The method of torque calculation and parameter optimization required by field practices are also expounded. Finally the application of this set of techniques in Henan oilfield has been demonstrated also.
Geological Charateristics Of A Low Permeable Sandstone Reservoir And Its Stimulation In Xiangxi Formation Of Bajiaochang Gas Field
Authors: Shaochun Zou , Xianyu Xia , Yuchua Li
Published: December 2007

The gas reservoirs of the upper Triassic Xiangxi group in the Sichuan basin are typically tight, low-permeable Sandstones. The gas comes from the coal seams of the same group. The Bajiaochang gasfleld is one of the large gasfields originated from coal in the Sichuan basin.

The authigemic clay minerals such as illite and chlorite form the inner coating in the pore space of the reservoirs, which not only leads to the extreme low permeability of the gas reservoir, but also is the main cause damaging the reservoir. The productivity of the gas well is low, very hard to get it into commercial production.

The reservoirs are very sensitive to water and acid, so general acidizing does not restore and improve their permeability.

The fracturing experiments with sand as proppant have been carried out in recent years, demonstrating that the reservoir can easily be fractured and proppantpacked, and hence should be stimulated. To treat this kind of low-permeable reservoir with both preventing damage and fracturing treatment should get economical benefit.
A Method For Evaluating Shale Stability And Its Application In The Field
Authors: Rutang Wang , Tianyun Jiang
Published: December 2007

Muddy shale is a name given to those compacted clay deposits. Deposits become sedimentary rocks through the courses of compaction, dehydration, recrystallization and ion exchange. Being affected by the buried depth, geological age, temperature and ion circumstances etc. during its compaction and dehydration, clay minerals will change their pattern. Usually, shallow formations are younger, liable to swell and disperse. Deeper formations are relatively dense and hard, and is poorly swelling and dispersive. According to the complicated borehole problems which occured during drilling operation, shale is divided into sloughing shale, collapsing shale, mud creation shale, swelling shale and plastic shale. Moreover, gas bearing shale and abnormally high-pressured shale are also the important factors responsible for the complexity of the borehole problems.
Reduction Of Surfactant Retention With Polyphosphates In Surfactant Flooding Process
Authors: Chengzhi Yang , Bazin B. , Labrid T. , Yanli Liu
Published: December 2007

Reduetion of surfactant retention by using polyphosphates as chelating agent in micellar flooding is discussed in this paper.

Laboratory flooding tests have been performed in simulated sandpacks which consisted of kaolinte and quartz, with petroleum sulfonate TRS 10 - 80 dissolved in brines with different sodium (or calcium) concentrations. Micellar slug flooding with or without polyphosphate preflush was compared. Other experiments concerning the influences of polyphosphates on surfactant solubility in calcium brines,the exchangeable cations on clay surface, etc. were also performed.

The main conclusions are: 1)in a calcium brine environment, the loss of surfactant can be reduced significantly by the addition of polyphosphates to both preflush and micellar slug,but in a sodium brine environment, its effectiveness is somewhat poor; and 2) polyphosphates improve the surfactant solubility in calcium brine and enhance the exchange of cations between solid and liquid. These behaviors can be explained by the chelation of polyphosphate with calcium and its effect on the surface potential of clay particles. Based on the experimental results, it is concluded that polyphosphates are potential additives in surfactant flooding.
Composite Characteristics of Complex Salt Formation and Its Drilling Technology
Authors: Genminc Li
Published: December 2007

This paper presents the distribution and characteristics of the complex salt formation and its drilling technology in north area of Duns Pu Depression in Zhonsyuan oilfield. The author summarizes the drilling experiences of complex salt formation since 1976, considers the drilling technology of complex salt formation in Zhongyuan oilfield has been developed through three stages. Since entering into the third development stage in 1987, mud technology and drilling engineering for salt formation is becoming perfect, penetration rate is increased and sticking problem is eliminated.
Evaluation of Polymer Flooding in Daqing Oil Field and Analysis of its Favourable Conditions
Authors: Zhiwu Wang , Jingcun Zhang , Yanli Jiang
Published: December 2007

Based on the results of sharp decline in water cut, increase in the oil production rate, and a 5% increase in the recovery factor obtained in a polymer flooding pilot test in a reservoir with positive rhythm in Daqing Oil Field, this paper discusses the favorable conditions for polymer flooding in this oil field, including low reservoir temperature, low salinity and low content of high valence ions both in the formation and injection water, and relatively high oil saturation left in the reservoir after water flooding… etc.; and gives both theoretic and practical basis for a possible extensive application of polymer flooding in Daqing Oil field.
The Development of a Deflocculated Polymer Mud for HTHP Drilling
Authors: Abdon J. C. , Jackson B. L. , McClelland G. S.
Published: December 2007

A High Solids Deflocculated Polymer (HSDP) drilling fluid has been developed and field proven at densities as great as 2 0.9 ppg (156 pcf) and sustained BHST's above 3 00 degrees Fahrenheit. The approach used to develop the HSDP mud had the primary goal of reducing complexity: a minimum number of additives were incorporated into the mud, and each additive was selected on the basis of its performance and limited functionality. Products with more than one primary function or with a strong secondary function were determined to be unsuitable.

The system is composed of a polymer viscosifier, a polymer deflocculant, and a polymer fluid loss agent. Barite is added as needed to develop density, and is the only solid intentionally added to the HSDP system. Viscosity and fluid loss are not developed with clay: this drilling fluid functions best when the MBT is as low as possible. Alkalinity is controlled with sodium hydroxide.

The resulting HSDP fluid is manageable at densities exceeding 20 ppg (150 pcf). System rheology is stable at temperatures as high as 350 degrees F. A ten minute gel strength as low as 10 can be maintained if required. The API LTLP filtration rate can be held below 4 cc, and HTHP filtration rate, as defined in this paper, can be kept below 12 cc economically.

Field application has demonstrated this mud to be very tolerant to contamination with monovalent and divalent cations (Na+, Mg++, Ca++), carbonates (CO3−−, HCO3−), water, oil, and various gases. It is reasonably tolerant to the presence of drilled solids.
A Proposed Technique for Evaluating Multirig Drilling Operations
Authors: Khalaf F.
Published: December 2007

This paper proposes an evaluation technique based on operational efficiencies to evaluate development drilling performance. Three time-based efficiency definitions are proposed. These definitions can be used to evaluate rig controlled operations, other operations not controlled by the drilling contractor, and overall drilling performance. Data compiled from 101 wells (drilled in two offshore fields between 1982 and 1988) are used to give examples of actual field applications. The performance in the same field may not be uniform with depth and could vary with the contractor and the type of operation.

Also, a concept based on the top drilling-performance per field (record well) has been advanced in this paper. It provides a depth-rate correlation between fields with different total well depths. This concept can be used to identify low drilling performance. The results obtained from the efficiency and record-well concepts help determine the best combination of services and techniques to achieve potential improvements in low- performance areas.
Design Parameters for Offshore Well Casing Cathodic Protection
Authors: Seubert M. K.
Published: December 2007

To provide protection from external corrosion to a number of Saudi Aramco offshore oil wells in the Arabian Gulf, a test program was undertaken to develop design parameters for protection utilizing impressed current. Casing potential profile logs showed that 50 amperes per well was required for full protection of the well casing through the corrosive formation. The location of the anodes should also be no less than 400 ft. from the well platform for optimum current distribution. Because of the lack of reliable performance of offshore impressed current cathodic protection systems, this paper also covers the design of the system utilizing anodes with high power output and high resistance to chemicals. The offshore well casing cathodic protection program follows a highly successful onshore program which has been in operation for a number of years.
Procedures for Initializing Reservoir Simulation Models
Authors: Fawakhiri A. Y. , Hassan I. M. , Abed A. F. A. R.
Published: December 2007

The simulation models of large heterogeneous reservoirs require both detail and consistency in the input data. This paper presents the initialization procedures that have been tailored to meet such requirements. The main topics include the construction of the areal and vertical grid systems, the definition of fluid contacts, SCAL and PVT data analyses, and standard measures aimed at securing a representative initialization of the problem to be simulated. The presented procedures are being applied successfully in conducting routine simulation studies for this type of reservoirs.
A Reservoir/Wellbore Model for Multiphase Injection and Pressure Transient Analysis
Authors: Almehaideb R. A. , Aziz K. , Pedrosa O. A.
Published: December 2007

Phase injectivities for multiphase injection processes are studied using an isothermal black-oil numerical model that properly treats wellbore/reservoir interaction. A fully implicit technique for the coupling of wellbore and reservoir flow equations is described. The effect of gravity segregation in the wellbore is taken into account to simulate cocurrent water and gas injection. It is shown that the current techniques used in reservoir simulation for assigning phase injectivities yield inconsistent results when wellbore phase redistribution takes place.

The effect of multiphase flow in the well and in the reservoir during well testing is also investigated. The fully coupled wellbore /reservoir model is employed to study the effect of wellbore phase segregation on buildup pressure response.
Characterization of Carbonate Porosity Using Petrophysical Properties and Image Analysis
Authors: Funk J. J. , Choinski M. C. , Saxman B. B. , Callender C. A.
Published: December 2007

Three techniques for describing pore size distributions were investigated to explain large differences in Klinkenberg b factors for heterogeneous, high permeability, carbonate core samples. Gas expansion permeametry was used to determine gas permeability and Klinkenberg-corrected permeability on a select group of Middle East carbonate cores. Samples with similar high permeabilities (600 - 900 md) showed a factor of 20 variation (0.6-12.8) in Klinkenberg b factors. Mercury injection derived pore size distributions were compared with petrographic image analysis (PIA) and scanning electron microscopy (SEM) analysis results to identify a basis for the range in b factor values.

No method provided a direct correlation with Klinkenberg b values. All methods indicated that samples with high permeability and high b values also had an increase in the distribution of larger pores. PIA results indicated statistically a linear relationship between the number of throats and b factor.
Well Test Design and Final Interpretation Improved by Integrated Well Testing and Geological Efforts
Authors: Ayestaran L. C. , Nurmi R. D. , Shehab G. A. K. , El Sisi W. S.
Published: December 2007

In the last decade, well testing has undergone significant technological changes - evolving from an approach mainly involving the determination of a well's producibility to a sophisticated discipline capable of detecting reservoir heterogeneities in the area around a well. Some of reservoir heterogeneities which have been encountered and analyzed are included in this paper: patches of non-reservoir fades, fault boundaries, and thin shale barriers. Although these examples are from Egypt, the Arabian Peninsula, and Pakistan, the same types of heterogeneities are found in many other reservoirs around the world.

A commonly occurring anomaly in transient pressure tests has been found to be caused by patches of non-reservoir, or impermeable rock within a reservoir zone away from the well. Numerical modelling has provided insight into the pressure effects of different types of heterogeneities and their variations in size, permeability characteristics, and distances from the test well. The areal extent of thin barriers within a Middle Eastern braided stream sandstone reservoir was determined using pressure transient testing. Other field examples show how geological and geophysical data are integrated for a more thorough analysis of faults and other heterogeneities. With appropriately designed well tests, the presence and attributes of various barriers have been defined, such as the distance from the well, and sometimes even the angle between two faults. The geological efforts concentrated on the identification of the type of heterogeneity and its probable direction from the well in addition to the orientation of any barriers detected. Walkaway VSP data provided additional faulting information which could not be determined using well testing. Only an integration of disciplines provided a realistic characterization of the reservoir around the well.
Reservoir Sweep Improvement With Cross-Linked Polymer Treatments
Authors: Mody B. G. , Dabbous M. K.
Published: December 2007

Poor reservoir volumetric sweep efficiency results in bypassing, trapping of such of the in-place hydrocarbons, and in the early production of large volumes of water.

This paper discusses technology and field results of treating wells in reservoirs with natural water drive as well as reservoirs under waterfloods with polymer solutions containing delayed cross-linkers to improve reservoir sweep efficiency.

The continuais monitoring and analysis technique has been applied successfully to selectively treat water saturated zones and to preserve the integrity of oil production. The uniqueness of the profile control system application is the continuous monitoring during the treatment which allows assessment of formation response and provides a valuable tool for treatment design refinement and optimization of injected slug volume.

A large number of wells have been treated utilizing delayed cross-linked polymer systems specially tailored for the specific reservoirs. Continuous reservoir monitoring and analysis of data on-site during the polymer application has resulted in better than an 85 percent success ratio.

Wells treated were cased as well as openhole completions, long to very short pay sections, naturally fractured, and hydraulically fractured. The reservoirs treated were bottom water drive and waterfloods, as well as reservoirs under gas injection. The treatments were performed successfully in sandstone and limestone, as well as dolomitic formations.

Cross-linked polymer treatments have resulted in a significant reduction in water production, and, as a result, many temporarily abandoned wells have been put back on production due to savings in operating costs and enhancement of oil inflow into the wellbore.
Appraisal of Techniques Applied To Stimulate the Deep Khuff Gas Wells
Authors: Abdalla M. Seham
Published: December 2007

The design of stimulation job for deep, tight, sour gas bearing formations at high pressure (7000-8000 psi) and bottom hole temperature in the range of 320°F is always difficult, particularly when an expensive special alloy tubing string and fittings are used.

Factors such as, amount of acid to stimulate a long section of tight dolomitic limestone and the operational constraints (tubing capacity, contact time and tubing susceptibility to corrosion by acid, coiled tubing utilization) dictated a rather critical procedure to be implemented.

A compromise between the large volume of acid required and the expected long time needed to spot with coiled tubing made it necessary to carry out the job in two stages. Accordingly, a small acid wash was spotted at bottom applying enough back pressure to stop gas influx. Then the required volume for matrix acidising was bullheaded within the contact time limit (stimulation rate up to 7.7 BPM at 3900 psi WHIP was achieved). The well was back flowed before bullheading the main acid volume, this played a big role in improving the injectivity

The completion string and coiled tubing were protected by circulating a special inhibitor coat ahead of the acid in addition to the normal inhibitor added to the acid.

Proper spotting of acid across the perforated intervals and the high rate achieved at high pressure while bullheading the matrix acidization volume eliminated the need for costly mechanical or chemical diverters.

The stimulation programme was implemented on four Khuff gas wells. The wells performance following the acid wash and the matrix acidization jobs proved that the acid wash is almost enough to achieve the required potential for such tight formations.
Design of Surface Facilities for a High-Pressure Miscible Gas Injection Pilot Scheme
Authors: Saadawi H.
Published: December 2007

A high pressure miscible gas injection pilot project has been recently implemented in Bu Hasa field, Abu Dhabi. The objective of this pilot scheme is to evaluate pattern miscible gas injection as a potential enhanced recovery mechanism in Bu Hasa North Shuaiba Formation.

The pilot project facilities were designed to inject up to 14 MMscf/D [400 × 103 std m3/d] of gas at a wellhead injection pressure of 5200 psi [35.8 MPa]. The injection pattern is an inverted 5 spot with one injection well, four producing wells and two observation wells.

Designing the facilities for such a project requires the collective efforts of many engineering disciplines. This paper describes the surface facilities and presents the basic philosophy adopted in optimising and designing these facilities for the Bu Hasa Pilot Gas Injection Project.
A Relative Distance Indicator from Gamma Ray Spectroscopy Measurements with Radioactive Tracers
Authors: Gadeken L. L. , Smith H. D.
Published: December 2007

The effectiveness of downhole operations is increasingly being evaluated using gamma ray spectroscopy tools in conjunction with one or more radioactive tracers. The materials placed in the well are selectively tagged with tracer isotopes. The spectroscopy measurements are typically used to distinguish the vertical distributions of two or more tracers which have distinct gamma ray energy signatures. In addition, it is possible to use the characteristic shape of the Compton scattered portion of the gamma ray spectrum to determine qualitatively how far each tracer is located from the tool, to within the depth of investigation of the measurement.

A series of calibration experiments was performed to establish the response of three gamma ray spectroscopy tools to six common tracer isotopes. Two artificial formations were constructed to simulate a typical cased hole environment. In order to investigate radial distribution effects, one test formation was subdivided so the formation region consisted of three annuli. The principal purpose was to determine tool sensitivities to different isotopes so that a weighted-least-squares algorithm could be implemented to process multi-tracer logs. The shapes of the tracer spectra were also evaluated for Compton scattering and photoelectric absorption effects.

The results of this study were combined with extensive field experience to show that, in addition to measuring the relative distribution of the tracer isotopes as a function of depth, it is also possible to make a qualitative determination of the average radial distance from the spectroscopy tool for each tracer. A log example illustrates the utility of this analysis.
Latest Experience in Seawater Injection Operations
Authors: Heraiba F. A. , Allam M. I.
Published: December 2007

This paper describes ZADCO water injection system, basis of selecting major equipment and the philosophy of water treatment. The paper covers the operating problems met during the early stages of start up and the experience gained by which similar problems can be avoided in future projects.

The bacterial growth problems in water injection flow lines is presented along with ZADCO measures for cleaning the lines and maintaining good quality of water at the injection wells.

The paper discusses the water quality monitoring methods, reliability of each and the interpretation of its values.
Impact of Super Permeability on Completion and Production Strategies
Authors: Moore D. M.
Published: December 2007

Unpredictable flood front movement, abnormal well production characteristics, and unique geologic occurrences coupled with an integrated field data collection effort eventually merged to identify and confirm localized as well as areally extensive, interconnected zones of super-permeability in a carbonate reservoir. Super-permeability has been identified in fractures, skeletal-oolitic grain-stones and stromatoporoid-red algae-coral. The preponderance of super-permeability examples, however, point to a coral-like organism, referred to as cladocoropsis, which was dolomitized and subsequently leached out leaving pencil-sized vugs yielding horizontal permeabilities in the darcy range.

The abnormal properties of super-permeability dictated an investigation which would focus on predictive techniques and would also address conformance issues. To accomplish these objectives, geologic, production, workover, logging, geochemical and available historical data was screened. Additionally, two wells, drilled in a known super-permeability area, were logged and cored. Selective perforation completions were performed oh one of the new producers as well as a workover candidate with the objective of minimizing the detrimental effect of the super-permeable zone on overall well productivity.

This paper serves to present general observations on super-permeability and its effect on vertical and horizontal flood performance. Also included is a case study covering a 100 square kilometer portion of a field in Saudi Arabia.
An Evaluatio'n of Various Logging Methods for the Determination of Remaining Oil Saturation in a Mixed Salinity Environment
Authors: Freeman D. W. , Fenn C. J.
Published: December 2007

This paper describes several known log analysis methods and calculation techniques used on a number of wells for determining remaining oil saturation in a mixed or unknown water salinity environment. The results obtained from these various methods are compared with remaining oil saturations obtained from coring with sponge core. In zones where the porosity is greater than fifteen percent and the zone is well swept, the remaining oil determined from the carbon-oxygen ratio agrees very well with results obtained from sponge cores. Due to the shallow depth of investigation of the carbon-oxygen tool, care must be taken to insure that the reservoir zone of interest is free of filtrate.
Reservoir Evaluation of the Permian Gharif Formation, Sultanate of Oman
Authors: Focke J. W. , van Popta J.
Published: December 2007

The Permian Gharif Formation consists of predominantly fluvial and coastal clastic sediments, with one major marine incursion in the Lower Gharif represented by the Haushi Limestone. It overlies the glacio-genic Al Khlata Formation with which it forms the Haushi Group, a stratigraphic unit of regional significance. Both Formations form significant reservoirs in Central and South Oman. They are in turn overlain by the redbeds and carbonates of the Permo-Triassic Khuff Formation. The Gharif elastics are very heterogeneous on scales from 100 km down to microscopic. Oil accumulations occur as single or stacked reservoirs depending on the lateral extent of claystone intervals and a complex hydrocarbon migration and structural history. Single accumulations are often further divided into zones which behave as separate reservoirs during production, depending on the geometry (connectedness) and properties of the sand bodies. Oil properties also vary widely with API values ranging from 12 to 53 and in-situ viscosities ranging from 10000 to less than 1 mPa.s. Combination of very variable reservoir and oil properties hampers prospect evaluation, in spite of the great number of Gharif penetrating wells (over 400) drilled to date in the area. In producing fields, individual wells produce at widely different rates, and also vary in decline rates, and water, gas, and sand production.

The large number of uncertainties make it difficult to optimise development, particularly since the relatively large number of small, marginally economic accumulations do not justify major investments in appraisal drilling, coring, or manpower intensive studies.

However, the desert environment of interior Oman allows a flexible and stepwise development often commencing with temporary facilities, which are gradually-replaced with more permanent facilities as the size and production potential of an accumulation is confirmed by several years of production history from an adequate number of producers. Such early production data also provide valuable information on the reservoir architecture. Newly drilled wells may show preferential pressure depletion or water encroachment which helps in assessing lateral and vertical reservoir continuity. As more fields are brought on stream, the integrated data base emerges on the basis of which production performance in this complex Formation can be better predicted.
Problems Associated with Dual Completion in Sip Wells: A Case History
Authors: El Hanbouly H. S. , Saqqa M. R. , Constantini N. M.
Published: December 2007

The standard dual well completions in ADCO Fields comprise two tubing strings, one single packer to isolate the upper from the lower pseudo reservoir, and one dual hydraulic packer above the top perforations to isolate the tubing/casing annulus from the injected or produced fluids.

The following three main problem areas were encountered with the standard dual completion. Pressure build up in the tubing/casing annulus.Obstructions to wireline tools.Communication between the two strings.

Operational and statistical analysis with regard to the sources of these problems; led to the following conclusions: Damage or unseating of the dual hydraulic packer, the presence of a snap latch in the secondary string and damage to the elastomer seals by the corrosion inhibitor in the packer fluids are the main reasons for the presence of annulus pressure.The 2.3/8″ tubing and associated completion equipment are the highest potential problem components of the well completion. The restricted inside diameter of the 2.3/8″ tubing and its susceptibility to bending/buckling result in obstructing the wireline operations.The presence of a sliding door in the primary string, between the single and the dual packers, and damage to the primary string between the two packers proved to be the main reasons for the communication between the two strings.

Some modifications to the completion design and running procedure were made in order to solve the associated problems.

These modifications proved to be highly beneficial in improving the integrity and durability of the downhole completion.
Producing Geisum Offshore Field Through Floating Production Storage and Offloading (FPSO) Facilities
Authors: Motaal A. A. Abdel , El Kholy Y. A.
Published: December 2007

Geisum Field is a small offshore oil field discovered in the Gulf of Suez- EGYPT. Success to develop the field depends largely on the utilization of FPSO facilities. This paper presents the design of optimum development plan for this marginal oil field. It presents the project operations conducted through a short time of fourteen months to install both field production and FPSO facilities. Also it includes the technical data about both field operations and facilities that are related to the success achieved to produce Geisum heavy and extreemly viscous crude oil.
Gas Injection in a Saturated Oil Reservoir
Authors: Murty C. R. K. , Al-Khayat S. A.
Published: December 2007

This is a follow-up to an earlier paper (SPE 11491)1 presented at the Third Middle East Oil Conference in March 1983 wherein crestal gas injection into the gas cap of Arab ‘D’ zone followed by gas cycling was recommended. The main objective of this injection is to avoid gas cap shrinkage which would result in lost oil reserves if the oil band is allowed to migrate and resaturate the gas cap.

Lean Khuff gas is being injected into the gas cap via a crestal well since February 1986. The injection mainly offsets the associated gas production. The results thus far have been encouraging: (a)The reservoir pressure has gone up by 35 Psig (241.3 kPa).(b)The gas cap shrinkage appears to have been halted.(c)The water cut in the affected wells is decreasing.(d)The daily oil production rate from the zone has been stabilized.(e)No injected gas breakthrough is observed in any of the producing wells.

The production performance further points out that injeotion response is only felt in North area wells whereas water invasion from South continues. To counter the water movement and balance the voidage created by fluid withdrawals, an increase in the gas injection is recommended.

The paper presents a brief review of the production performance, discusses the results of gas injection and examines the future requirements.
Miscible Gas Injection: Surface Tension Effect in Case of a Separator Gas
Authors: Thiebot B. M.
Published: December 2007

One of the most attractive recovery process, either in secondary or in tertiary conditions, is the gas injection under dynamic miscibility conditions. Under high reservoir pressure, a lean gas will develop a frontal dynamic miscibility process while a rich gas will develop a rear dynamic miscibility process under lower reservoir pressure.

It is shown from the experimental measurements of surface tensions and phases densities that, on the opposite of what is expected according to numerical simulation results, the process corresponding to the development of a miscible front with a rich separator gas as injection gas is intermediate between conventional high pressure and condensing gas drive miscibilities.

This was the case for a Middle East field, for which a lean gas and a rich separator gas were studied.

Slim tube experiments were conducted to determine dynamic minimum miscibility pressures while surface tensions and phase densities were determined during a multiple contact test study simulating the basic rear miscibility process at the trailing edge of the displacement front.

The surface tensions measurements put into evidence that: –In case of a rich separator gas, the dynamic miscibility process developed was neither rear, as predicted by the numerical simulation, nor frontal, but rather intermediate.–A better fit of the Parachor computation is obtained if the experimental determination of the molecular weight of the heavier fraction (Undecanes-plus) is performed during a multiple contact test study simulating the dynamic miscibility process of a gas injection.
Geohistory Analysis: A Key for Reservoir Fluid Distribution, Abu Dhabi, U.A.E.
Authors: Marzouk I. M.
Published: December 2007

Hydrocarbons were discovered in Abu Dhabi in Permo-Carboniferous, Permian, Triassic, Jurassic, Cretaceous and Tertiary reservoirs.

Reservoir fluids encountered vary from non-hydrocarbon gas, dry gas, wet gas/high condensate yield gas, light oil, medium gravity oil, heavy oil, bitumen and formation water.

Reservoir fluid distribution varies in space from one field to the other and in geologic time from one reservoir to the other and even varies within one and the same reservoir.

Unique fluid distribution patterns were reported from different fields in Abu Dhabi. These patterns have raised questions which need explanation.

Geohistory analysis, mainly burial and thermal history, maturity profiles, paleo-structures and migration mechanism have explained the process of reservoir fluid distribution in most of the hydrocarbon reservoirs in Abu Dhabi.

A fluid distribution model was constructed for each geologic age. These models will help in future exploration for hydrocarbons by developing exploration concepts and predicting reservoir fluid types in undrilled prospects.
The Lower and Middle Jurassic in Offshore Abu Dhabi: Stratigraphy and Hydrocarbon Occurrence
Authors: Hassan T. H.
Published: December 2007

The Lower and Middle Jurassic of Offshore Abu Dhabi is represented by a thick (1100–1700 ft.) sequence composed dominantly of limestone with minor dolomite and shale and is bounded at the top and at the base by major regional unconformities. The sequence consists of two formations: the Izhara Formation which is overlain by the Araej Formation. The Hamlah Formation which underlies the Izhara is customarily dated as of Early Jurassic age but in this article it is assigned to the Triassic. The Izhara and Araej were deposited in an extensive, shallow epicontinental sea. Reservoir development in the Izhara is generally poor but a number of reservoir units occur in the Araej particularly in the Uweinat and the Upper Araej. Porosity is generally less than 20 percent.

Hydrocarbons are present in the Izhara in only one structure but are known to occur in the Araej in at least fifteen structures in the Area. Geochemical analysis indicates three possible sources for the Araej hydrocarbons: the Upper Jurassic Diyab Formation, the Hamlah/Izhara and the Triassic Gulailah Formation. Geothermal modelling indicates that oil generation may have been initiated from the Gulailah in the Late Jurassic and from the other source rocks later in the Cretaceous. Gas generation from the Gulailah commenced in the Early Tertiary and later from the Hamlah/Izhara and the Diyab. The major migration directions of the hydrocarbons were mainly to the north and northeast.
Field Measurement of Borehole Closure Across Salt Formation: Implementation to Well Cementing
Authors: Kim C. M.
Published: December 2007

Deformation of a borehole across a salt bed in the U.S. Gulf Coast was monitored in support of a well cementing design. The well was drilled using a drilling mud of 13.3 lb/gal density through a salt-anhydrite section situated at depths of 17560 to 17870 feet. With the mud in place, caliper runs were made to measure the change in borehole diameter with time. The mud density in the borehole was then increased subsequently and caliper runs repeated until no noticeable change in borehole diameter within a 30-hour duration was recorded. When the mud density was 17.3 lb/gal, the borehole finally stabilized. Induced stress around the borehole was calculated. A relationship between induced stress (or mud density) and change in borehole diameter was established. Optimum density of cement slurry for the well was obtained. Results of the caliper measurements, along with the field measurement procedures are presented.