bluuebunny/crossref_metadata_2025 huggingface dataset:
Some Practical Formulas To Predict Horizontal Well Behavior
Authors: Karcher B. J. , Giger F. M. , Combe J.
Published: December 2007

Horizontal and drainhole drilling have been used successfully to increase productivity of wells in the past years. Many formulae can be used to compute the productivity of horizontal or slanted wells compared to vertical ones. One objective of this work is to recall the proper way to use these formulae and to recall the assumptions made that may limit their use. The increase of productivity due to longer perforated interval increases as the logarithm of length and can reach values of two or three times the vertical well.

Also presented is a sample calculation of the influence of natural or artificial fractures on well productivity: a horizontal well may take advantage from an existing fracture network, much better than a vertical well would have. This is because the most permeable fractures are the open ones which have their planes parallel to the largest stress, and the largest stress is generally vertical because of rock weight. The productivity of a drainhole in a fractured medium can raise to 10 times the productivity of the drainhole alone.

Another improvement expected from horizontal wells is a larger flexibility regarding coning problems: it is possible to produce with an interface while keeping a good productivity and a high critical rate. The analytical means for critical rate computation are reviewed with their assumptions. Model computations give the examples of supercritical production in the bottom water drive case. The advantage of horizontal well is important at water breakthrough but does not increase much after and even decreases for favorable mobility ratios. Short drainholes may perform as well as horizontal wells if their distance allows a large interference of cones.

The third way of using horizontal wells is to increase areal sweep efficiency in regular pattern floods. The pattern showing the poorest efficiency is the direct line drive. Using horizontal wells drilled along the lines of producers can bring the areal sweep efficiency close to perfection. In that particular use, horizontal wells act like artificial fractures, with the advantage that their orientation can be controlled.
Determination of Fracture Height by Spectral Gamma Log Analysis
Authors: Anderson J. A. , Pearson C. M. , Abou-Sayed A. S. , Myers G. D.
Published: December 2007

Determining fracture height following hydraulic stimulation of a well is an important step in both evaluating the effectiveness of the treatment and estimating the subsequent production behavior of the well. Unfortunately, the temperature and gamma ray logs commonly used to assess fracture heights seldom yield unambiguous results. A new approach to the problem employs spectral gamma ray data to resolve some of these uncertainties. This paper outlines the method and presents data from a field study made using the new technique.
Material Selection and Welding Criteria for High Pressure Marine Risers Used in Tension Leg Platform Applications
Authors: Inglis Matthew R. , Kovach Paul J.
Published: December 2007

New materials have been developed for high pressure marine risers used in tension leg platform (TLP) applications. Modifications of standard AISI 8630 material provide low alloy steel grades which have good fracture toughness and excellent fatigue properties under high stress conditions, and are readily weldable.

Materials and welding procedures are reviewed in light of increased performance demands forTLP applications, and considering design criteria established by the relevant certifying authorities.

Work performed on the drilling and export risers for the industry's first (and to date, only) TLP installation is presented, with reference to monitoring and quality control activities involved in fabrication of those systems.
Examination of Field Data from a New Gas Sweetening Process
Authors: Bhatia Kishan , Brown Timothy M.
Published: December 2007

A new patented sour gas sweetening process was introduced to the gas processing industry in September 1984. This process consists of bubbling sour gas through a tower filled with a proprietary formulation, an alkaline aqueous solution of an anionic oxidizing agent. The toxic hydrogen sulfide is selectively removed from the sour gas and dissolved sulfides are converted to nonhazardous sulfur by the sweetening solution in the tower. The process is generally operated at ambient temperatures. The spent slurry from this batch process has been classified as a nonhazardous waste by the U.S. Environmental Protection Agency, fourteen state agencies, and the U.K. Department of Energy. The process was initially field tested at various locations in California in cooperation with major gas producers. More than 100 units are now operating in the United States and Canada. The hydrogen sulfide concentrations of sour gases treated with this process range from as low as 10 ppm to more than 20 percent; the operating pressures range between near atmospheric to greater than 1000 psig. The largest unit processes 16 MMscf/d sour gas using one tower at 1035 psig and the smallest unit handles 8 to 10 Mscf/d gas containing greater than 20 percent hydrogen sulfide. This paper presents: Detailed field data for over 100 operating unitsA description of the chemistry of the processComparative kinetic data on several hydrogen sulfide scavengers used in other batch processesDefines factors utilized in the design of improved towers used for this gas sweetening process based on the experience gained in the field.
Analysis of Pressure Tests Through the Use of Instantaneous Source Response Concepts
Authors: Cinco-Ley H. , Kuchuk F. , Ayoub J. , Samaniego-V. F. , Ayestaran L.
Published: December 2007

A general method of analysis for pressure transient tests is presented. This technique is based on the pressure response of an instantaneous source and it provides a mean to compute the first and second derivatives of the influence function (unit flow rate response) of the well-reservoir system. This information is basic in identifying the flow regimes occurring during the test. This method eliminates the effect of producing time on pressure buildup data.

An explicit and stable procedure is discussed to compute both the derivatives of the influence function and the initial reservoir pressure. This technique is suitable for DST and Repeat Formation Tests as well as for pressure buildup and fall off tests with long shut in period; variable flow rate before shut in can be taken into account. Examples of application are presented.
Microscopic Aspects of Capillary Imbibition
Authors: Rose Walter , Channapragada Rao
Published: December 2007

As a general rule, the action of capillary forces cannot be ignored in treating capillary imbibition (where one fluid is displaced by another replacing fluid). This circumstance requires that the capillary driving force term be identified and cast in a form which will serve the needs of analysis and throw some light on the details of the displacement process.

Given a saturation gradient defining the flood-front profile at a particular instant, the corresponding capillary pressure gradient is found to have only qualitative meaning as a measure of the capillary driving force acting to project flood-front forward. This viewpoint is contrary to common opinion; hence, it is necessary to re-examine the microscopic aspects of capillary imbibition so that a quantitatively meaningful capillary driving force term can be derived which has a macroscopic importance.

The microscopic analysis leads to some interesting conclusions. Of major importance is the idea that a Darcy Law analog cannot be written as the macroscopic law of force descriptive of the unsteady states of multiphase-flow systems. This means, for example, that published solutions of the Buckley-Leverett problem are in error, as are other analyses which depend on use of the conventional relative permeability concept. A second conclusion which can be drawn is that the capillary forces are the major factor determining microscopic displacement efficiency, even for cases when the injection rates are high (e.g., there is a large imposed gradient in pressure energy). It is found, moreover, that the capillary driving force and, hence, the displacement efficiency are rate-dependent in ways usually overlooked.

In this paper, the Buckley-Leverett problem is discussed at length as a device to show the importance of taking the microscopic viewpoint before attempting to deduce how capillary imbibition and displacement can be characterized in the macroscopic sense. Attention is thus focused on the need to derive a valid law of force for the unsteady states of multiphase flow, if valid equations of motion are to be written. Although this paper does not suggest a law of force to replace the rejected Darcy Law analog, at least the capillary driving force term is given in unambigious form.

It is concluded that, for a while at least, capillary imbibition of a wetting fluid into and through porous media cannot be cast in an analytically or numerically integrable form; hence, experimental procedures (scaled-model experiments) are proposed as an appropriate way to investigate fluid-fluid displacement. To be noted is the fact that these experimental procedures are no more difficult to undertake than the relative permeability and capillary pressure experiments required to give the basic data needed for conventional Buckley-Leverett calculations.
Hydraulic Fracturing of a Moderate Permeability Reservoir, Kuparuk River Unit
Authors: Niemeyer B. L. , Reinart M. R.
Published: December 2007

Sixty-five percent of the proven reserves in one of the United States' largest oil fields, the Kuparuk River Unit, are contained in the lower of two producing horizons. This zone, commonly referred to as the "A" sand, has a permeability of between 30 and 100 md. Unfortunately this interval is easily damaged during drilling and completion operations. Low initial flow efficiencies have been confirmed by numerous pressure transient tests. A program of hydraulic fracturing was initiated in March 1984 to overcome near wellbore damage and provide stimulation to more efficiently tap "A" sand reserves.

More than 300 fracture stimulations have been completed to date in the arctic setting of the Kuparuk River Unit. These jobs have used a variety of fluids, proppants, and pumping schedules. The current hydraulic fracture design was evolved by continual interpretation of field results and related data from these previous stimulations. Success of the overall program has been impressive. Average post-fracture flow efficiency has been in excess of 100%. Post-fracture rate increase has averaged approximately 300%, accounting for a total rate increase of over 125,000 BOPD (19,900 m3/d). Based on these results, fracturing will continue to play an important part in future field development.

This paper is the first review of the Kuparuk River Unit fracture program. It provides a case history of the development of a standard fracture design. In addition, the findings of this study would be applicable to reservoirs elsewhere with similar characteristics.
A Post-Audit of Fracture Stimulations in the Vicksburg Formation of South Texas
Authors: Brim H. B.
Published: December 2007

Many South Texas low permeability Vicksburg gas completions have been made economical through hydraulic fracturing. Between 1981 and 1984, 36 Vicksburg completions by Sun Exploration and Production Company were evaluated and subsequently fraced based on the results of pre-frac testing and frac optimization studies. These completions are located in 14 gas fields in Jim Wells, Brooks, Starr, and Hidalgo Counties of South Texas at depths ranging from 4,500' to 12,200' (1,372 m to 3,719 m).

This paper details a post-audit of well performance for these 36 Vicksburg completions, introduced by a review of Vicksburg reservoir characteristics and Sun's pre-frac evaluation methods. An example of the frac optimization and selection process is presented. The post-audit reviews predicted/actual initial deliverability, ultimate gas recovery, and frac length. An economic post-audit is also presented to illustrate the profitability of Sun's Vicksburg fracturing program. Finally, the conclusions of the post-audit as they relate to future Vicksburg frac candidates are presented and discussed.

The results of the post-audit generally indicate that the accuracy of post-frac initial deliverability projections provides a good correlation to the accuracy of projected ultimate recovery and the accuracy of frac length calculations. Also, the average ratio of predicted/actual initial deliverability provides a good overall indicator of a confidence factor that can be applied to Sun's reservoir simulator's projections of fractured well performance. Finally, statistical data infers that there is an evolution of skill in projections of post-frac well performance.
Offshore Safety - Drilling Operations
Authors: Dawson James A.
Published: December 2007

This paper was prepared for the 41st Annual Fall Meeting of the Society of Petroleum Engineers of AIME, to be held in Dallas, Tex., Oct. 2–5, 1966. Permission to copy is restricted to an abstract of not more than 300 words. Illustrations may not be copied. The abstract should contain conspicuous acknowledgment of where and by whom the paper is presented. Publication elsewhere after publication in the JOURNAL OF PETROLEUM TECHNOLOGY or the SOCIETY OF PETROLEUM ENGINEERS JOURNAL is usually granted upon request to the Editor of the appropriate journal provided agreement to give proper credit is made.

Discussion of this paper is invited. Three copies of any discussion should be sent to the Society of Petroleum Engineers office. Such discussion may be presented at the above meeting and, with the paper, may be considered for publication in one of the two SPE magazines.

This paper presents the safety practices as applied by Gulf Oil Corporation to simultaneous drilling and producing operations in the Gulf of Mexico.

Safety rules and regulations, both company and Coast Guard, are set forth and some detailed instructions are given as to the procedures to follow in particular situations.

Personnel safety equipment and training, safety devices, safety practices and Hurricane Action Plans are explained.

The use of special systems for control of small fires and the procedures for cheeking and maintaining this equipment has increased the confidence of the personnel engaged in offshore operations. Routine testing of equipment and daily practice drills have reduced the time to close a drilling well in from the 5 to 10 minutes required 10 years ago to an average of less than 1-1/2 minutes today.

Another result of the safety practices employed has been the maintenance of near normal production rates while a drilling rig is in the process of drilling and completing a particular platform.

The over-all result of the application of these safety practices has been the establishment and maintenance of high morale among all personnel involved in the exploitation of petroleum resources in the Gulf of Mexico.

Introduction

The application of good safety practices has been recognized for many years by operators and drilling contractors. The benefits derived from an effective safety program are large in terms of tangibles and intangible. The greatest intangible reward is better morale which is the most important single incentive that will keep a man returning to his job and performing to the best of his ability.

Since the advent of large scale offshore operations in the late 1950's, one of the basic problems confronting a major company operating in the Gulf of Mexico has been the development of proper habits and training of men to safely drill wells while producing from the same platform.
An Integrated Approach to Refining Reservoir Description Through Monitoring Fluid Movements in the Prudhoe Bay Reservoir
Authors: Bradley M. E. , Mayson H. J. , Wilkins K. L.
Published: December 2007

Accurate reservoir description significantly enhances the ability to assess reservoir performance and to predict future performance from simulation and analytical techniques. These predictions impact infill drilling, waterflood area selection and operation, production offtake strategies, well completions, and workover philosophy. An integrated approach that uses available production and surveillance data has been employed to refine reservoir description. The available data includes: open and cased hole log data, reservoir pressure and transient analysis interpretations, RFT pressure data, and individual well production histories.

Downdip production from beneath continuous shale complexes has resulted in lateral movement of gas from the original gas cap at Prudhoe Bay. This and other physical evidence of barriers to vertical flow have been used to calibrate and enhance confidence in geologic shale maps based on well to well correlations. In areas where vertical gas cap expansion has occurred, tracking reservoir fluid movements has provided a method to identify the occurrence and observe the drainage of oil lenses from discontinuous shales. In addition, the data has allowed the computation of volumetric sweep efficiencies to improve reserve estimates, and delineate areas where recoveries can be increased by adjustments to offtake strategy, or application of future improved oil recovery techniques.
Evaluation of Oil-Soluble Resin as an Acid-Diverting Agent
Authors: Houchin L. R. , Dunlap D. D. , Hudson L. M. , Begnaud P. C.
Published: December 2007

Laboratory tests were conducted to study the effects of using finely ground oil soluble resin as a diverting agent in hydrochloric-hydrofluoric acid treatments. The evaluation was conducted using a wellbore model which simulates varying permeability. These test results indicate that even though an even vertical distribution of fluids occurred when oil soluble resin was added continuously to all fluids, an inadequate ratio of HCl to HCl-HF acid was evident in the high permeability sections. This problem limits the effectiveness of a mixed acid system and may create acid induced inorganic precipitates. Based on results of the continuous diverting tests, a series of staged diverting evaluations were conducted. These results indicate that oil soluble resin may be effectively used in stages between acid stages to divert injected fluids.
Obtaining and Verifying Quality Cement Blends
Authors: Kunze K. R.
Published: December 2007

A blending study showed that air agitation and transfer methods perform best when cement solids volume is kept below 30% of blend bottle volume. Above this volume the blend quality markedly declines. In the air agitation method, additional agitation longer than the customary ten minutes provides no benefit. In the transfer method, additional transfers beyond three do not improve blend uniformity. There is evidence that the admix bottle blending method is less adversely affected by blend size. However, the consistent uniformity of small blends suggests that the 30% maximum volume guidelines should be applied without exception.
Huntsman and West Engelland Fields, Cheyenne County, Nebraska: A Case History of Technical Lessons from a Legal Conflict
Authors: Tek M. R. , Coleman D. D. , Parker J. M.
Published: December 2007

During the years 1982-85, a lengthy litigation took place between KN Energy and Marathon Oil Corp. The case involved performance of two fields on structures adjacent to a common saddle and suspected migration of storage gas into the gas cap of a producing oil field. After some 3 years of extensive study, discovery proceedings and preparations, the case came to trial in U.S. District Court in Lincoln, Nebraska, 8 Duly 1985. After nearly a month in court, agreement was reached between the parties to settle the case on 6 August 1985. The purpose of this paper is not to redress and reargue the legal controversy. Rather, it is to share in the technical forum of gas technology, the lessons learned from the synergistic study leading to a forensic conclusion.

The case history is unique and significant because it relates to extensive data from 2 fields and provides insight helpful to understanding major geological and operational factors affecting migration, exchange and mixing of mobile fluids underground.

The paper, written from the perspectives of applied reservoir engineering, geology and geochemistry, includes methodologies applicable to other similar situations – often suspected but not sufficiently investigated.

Application and calculations involving inventory verification methods, production-pressure trends, study of well records, gas-water, gas-oil contacts, computer simulation by finite element method, and identification of resident gas by isotope chemistry are among areas highlighted by specific examples.
Simultaneous Determination of Residual Saturation and Capillary Pressure Curves Utilizing the Ultracentrifuge
Authors: King M. J. , Falzone A. J. , Cook W. R. , Jennings J. W. , Mills W. H.
Published: December 2007

Residual saturation and capillary pressure curves are important for modelling reservoir and laboratory processes. Knowledge of the residual saturation curve is necessary to determine the ultimate production from a tertiary recovery process Capillary pressure is required to interpret laboratory core floods and to describe multi-phase reservoir fluid flow.

The ultracentrifuge provides a rapid means of determining capillary pressure and residual saturation relationships. It is non-destructive, uses small samples, and is capable of attaining both high capillary pressures and extremely low residual saturations.

The effects of variation in residual saturation with Bond number are not included in the traditional Hassler-Brunner analysis for capillary pressure. Such desaturation effects can explain the anomalous experimental saturation distributions reported at high rotation rates [1,2]. The current work generalizes the Hassler-Brunner analysis to include desaturation and also to include the variation in centripetal acceleration through the core. The analysis also provides for the determination of residual saturation as a function of Bond number (kΔρg/σ).

Laboratory ultracentrifuge data is analyzed and both capillary pressure and Bond number residual saturation curves are obtained. The conversion of Bond number residual saturation curves to capillary number (µv/σ) curves may be performed by comparison with residual saturation curves obtained from core floods. In general, the ultracentrifuge residual saturation curves greatly extend those measured during conventional, non-destructive core floods; close to 100% oil recovery has been observed with the ultracentrifuge.
Mechanisms of Oil Displacement by Microorganisms
Authors: Kianipey S. A. , Donaldson E. C.
Published: December 2007

Mechanisms of oil displacement at the oil-brine-sand interfaces by bacteria were investigated by microscopic observations and capillary pressure changes using unconsolidated, thin, reservoir flow cells. Three genera of bacteria, Bacillus, Pseudomonas. and Clostridium. were injected into water-wet and oil-wet cells of unconsolidated sand, saturated with brine and crude oil. The flow cells were placed under a microscope for visual and photographic observations. The flow cells were connected to a manometer to examine the complete capillary pressure hysteresis loop before and after introduction of bacteria.

The thin reservoir flow cells were first saturated with brine, and then displaced to irreducible water saturation with crude oil. Oil and brine displacements were then made to determine the complete capillary pressure relationship. Next, the bacteria and nutrients were introduced and incubated in the flow cell for 24-48 hours. Microscopic observations were recorded photographically. After incubation, oil and brine displacements were again made to determine the capillary pressure hysteresis loop.

During incubation, some emulsification of the oil at the oil-brine-sand interfaces were observed. Biogenic gas production caused pressure increases in the flow cells. Final measurements of the capillary pressure hysteresis loop showed decreases in residual oil saturation of 9-24% and changes in wettability to more water-wet systems.

This work shows the potential of microbial enhanced oil recovery, and investigates some of the mechanisms of oil displacement by three genera of bacteria. These considerations are important with regard to the technical feasibility of microbial enhancement of oil recovery.
A Fully-Implicit Model for Electrically Enhanced Oil Recovery
Authors: Killough J. E. , Gonzalez J. A.
Published: December 2007

A fully-implicit, three-dimensional reservoir simulator has been developed to model the electrically-enhanced oil recovery process (EEOR). The EEOR process is based orí the concept that by passing an electrical current through a conductive oil bearing formation, resistive heating of the oil will occur with corresponding reduction in oil viscosity. Over the past decade several attempts have been made to model this process with limited success because of simplifying assumptions in either the numerical formulation or the physics of the process. The formulation presented here rigorously models the physical phenomena important to the process with the additional feature of a fully-implicit treatment for added stability. Features of the model include the following: Rigorous treatment of formation resistivity as a function of temperature, water resistivity, and salinityAbility to simulate DC or multiphase AC electrical powerCapability of handling vaporization of connate water with resultant effects on resistance and power levelsCurvilinear, radial, or cartesian grid systemsCapability for horizontal electrodes and conductive fractures

Solution of the multiphase alternating current

case is accomplished by solving for both the real and imaginary portions of the complex electrical potential field. Through the use of the complex field it is necessary to solve only two equations for the electrical potential regardless of the number of phase differences in the power source. Since the model is based on the combustion formulation of Coats9, it includes many of the general features of that formulation.

Examples include a validation of the simulator using both laboratory data available in the literature and an analytical model. Grid orientation effects for the EEOR process are shown to be somewhat less than those for a conventional waterflood of a viscous oil. The importance of detailed modeling of nearwell phenomena is demonstrated. A unique feature of the model is demonstrated with a simulation involving the vaporization of connate water. Application of the EEOR process to a forty acre five spot waterflood shows the rate acceleration effect that is available with the process. Hypothetical simulations of novel electrode configurations involving horizontal electrodes and conductive well fractures show the advantages of these completion/electrode schemes. Finally, a comparison of direct current and three phase alternating current indicates an advantage for three phase power in a nine-spot pattern.
Development of Slickline Logging Tools for Very High-Temperature Applications
Authors: Carson C. C. , Wolfenbarger F. M.
Published: December 2007

Five logging tools were developed for collecting data in the DOE-sponsored Salton Sea Scientific Drilling Project (SSSDP) well. The tools were designed to function at temperatures up to 400°C (752°F) and were successfully operated in the well at temperatures of 360°C (680°F). All of the tools—mechanical units for measuring and recording temperature, pressure, and flow rate; an electronic memory tool for measuring and recording temperature and pressure; and a special purpose battery pack for powering a downhole fluid sampler—are designed for slickline operation. In each, selected critical components are placed inside a dewar that provides thermal protection for a limited time. This paper discusses the tools, their development and operation, the results from their use in the SSSDP well, and potential extensions to geothermal and gas well applications.
Pulse Testing Reveals Poor Lateral and Vertical Continuity in a Reservoir Consisting of Distributary-Channel Sands
Authors: Roest J. A. , Jolly D. C. , Rodriguez R. A.
Published: December 2007

Pulse testing revealed that free gas had accumulated against an unexpected permeability barrier in a watered-out sandstone reservoir. It also suggested vertical permeabilities to be poor. This interpretation, which was confirmed by production tests and build-up surveys, led to a refinement of the geological reservoir model.

Furthermore, valuable insight was obtained into the interpretation of pulse tests in areally heterogeneous reservoirs.
Sata Log
Authors: Thurber C.H. , Gay B.J.
Published: December 2007

A new logging technique known as the Sata log is now being routinely run which exhibits two curves of the acoustic family. One curve is the transmission amplitude of the received signal, the other curve is the attenuation of the acoustic signal as shown by the difference in amplitude between two receivers. The log has shown that gas, oil and water may be distinguished on a qualitative basis in both high-and low-porosity media. The basis principles of the two curves are discussed which covers the consideration of the coefficient of coupling of the fluid to the formation and, also, the coefficient of coupling with respect to formation to formation in a vertical sense and the relative relationship of the transmission of the acoustic signal within the formation as an independent entity bearing little influence from the mud to formation effect. Examples of logs are shown which illustrate the effects of fresh-water sands on other logs, as compared to its effect on the Sata log. Wet or dry sands are illustrated, and comparisons of gas and wet formations are illustrated.

No quantitative claims for this logging technique are being made. The Sata log also has the unique ability to log in casing, showing conditions behind the casing which lead to the location of cement tops. Formations may be logged through the casing when the formations are in contact with the casing.

Introduction

A new type of log called the Sata log, which appears to give direct indications of water, oil and gas content of porous media in a borehole, is being made available to the oil industry.

The name "Sata" comes from the identifying letters applied to the two curves represented by this logging technique. SA is the abbreviation for signal attenuation; TA is the abbreviation for transmission amplitude. These two curves are part of the family of acoustic parameters - velocity, wave length, frequency, amplitude, attenuation, acoustic impedance and others.

Theory

The Sata log differs from acoustic velocity logging by logging the amplitude and attenuation of the signal rather than the travel time. Signal character has been described in literature previously.

Fig. 1 shows an idealized-received logging signal as seen on the monitoring scope. The horizontal sweep is in time and the vertical displacement is in amplitude. Only the first peak of the negatively going signal is measured since this cycle is probably the result of the bulk modulus wave. Isolation of the measurement of this cycle is made to prevent the questionable influence of the water, shear, tube and reflected waves which follow.
Two-Phase Flow through Chokes
Authors: Sachdeva R. , Schmidt Z. , Brill J. P. , Blais R. M.
Published: December 2007

Two-phase flow through wellhead chokes, including both critical and subcritical flow and the boundary between them, was studied. Data were gathered for air-water and air-kerosene flows through five choke diameters from 1/4 in. (6.35 mm) to 1/2 in. (12.7 mm), and results were compared to published correlations. A new theoretical model for predicting flow rates and the critical-subcritical flow boundary was tested against these data, as well as data from two published studies. The new model substantially improves the existing methods for predicting choke behavior in two-phase flow.
The Analysis of Amplitude vs. Offset To Detect Hydrocarbon Contacts in Saudi Arabia
Authors: Chiburis E. F.
Published: December 2007

Analyses of seismic amplitude vs offset (source to receiver distance), AVO, can yield information regarding the physical properties of the reflecting horizons. Specifically, changes in formation fluid content are theoretically discernible in the behavioral changes in AVO, due principally to changes in the Poisson's ratio of the rock units. An AVO analysis of five seismic lines across an oil field in Saudi Arabia was conducted in an attempt to detect the spatial position of the oil/water contacts. The results indicate that the AVO patterns are directly correlative with the known fluid contacts in the area.
Offshore Storm Design Criteria Improvements by Hindcasting and Joint-Probability Analysis of Results in the Arabian Gulf
Authors: Shabib H. M.
Published: December 2007

This paper describes the methodology and results of a hindcasting study used to predict offshore storm design criteria in the Arabian Gulf for 1,10 and 100 year return periods. The paper further describes the benefit of applying joint probability concept to the hindcast results in estimating design forces. The result for the structure described herein is a reduction of the 100 year design force by 31 percent.

A recent storm hindcast study in the Arabian Gulf involved a review of the offshore storm design criteria and an extreme event analysis for major Saudi Arabian fields. The results of the study were a set of design criteria for winds, waves, currents and surge levels for return periods of 1, 10, and 100 years.

The outcome of the study was a significant improvement on the design parameters previously used. Conservatism was reduced by the use of state-of-the-art numerical hindcast models that had been validated with measured data. The study considered directionality of wind and currents and accounted for refraction of waves in the shallow fields.
Viscosity Correlations for Saudi Arabian Crude Oils
Authors: Khan S. A. , Al-Marhoun M. A. , Duffuaa S. O. , Abu-Khamsin S. A.
Published: December 2007

Empirical equations for estimating viscosity: above, at, and below the bubble point pressure were developed based on data from Saudi Arabian crude oils. Both statistical and graphical techniques have been employed to evaluate these equations as compared to other published crude oil viscosity correlations using the same data. It is shown that the developed correlations provide more accurate estimates of viscosity in all three regimes of pressure.
An Overview of Gas Production, Distribution, and Conservation Policies in the Sultanate of Oman
Authors: Al-Hinai K. B. M. , Al-Balushi S. B. S. , Madhava N.
Published: December 2007

Natural gas is assuming greater importance in Oman with increasing demands for power generation, oil field usage and other industrial uses. The steps being taken by the Ministry of Petroleum arid Minerals are described within, which comprise of exploration and evaluation programs; construction of a gas distributionnet work and expansion plans; gas conservation and utilization operations.

This paper describes the various phases involved and the associated milti-disciplinary interactions/coordination that is required to anticipate and ensure proper action. Based on long term gas demand some of the efforts that are being made to generate adequate gas resources are outlined.

Notwithstanding the uncertainties associated 1 with the projected gas demands and the international market prices for natural gas the paper assesses the current problems and prospects.
Energy Conservation in Oil Fields
Authors: Ansari M. A. , Eissa A. M.
Published: December 2007

Kuwait Oil Company confronted with shortage of gas at low oil production rates in 1983 conducted an energy audit in oil fields in South East Kuwait. Production history of 1981-82 was studied for production rates, GORs, selection of gathering centres and operational practices. Testing of production facilities followed to record process parameters, fluid analysis, energy consumption, machinery performance and gas losses. Computer simulation models were developed to generate case studies at optimum conditions. Economies in energy through changes in operational modes and equipment modification were evaluated at US $ 4.18 million/year minimum to 21.62 million/year maximum with 3.75 years payout period.
The Effect of Overburden Pressure on Relative Permeability
Authors: Ali H. S. , Al-Marhoun M. A. , Abu-Khamsin S. A. , Celik M. S.
Published: December 2007

In routine core analysis, porosity and permeability, both relative and absolute, are measured on rock samples which are not under net overburden (confining) pressure. Using these data to predict reservoir performance or estimate reserves can lead to serious errors since all reservoirs are under net overburden pressure.

Data collected from constant rate, dynamic displacement experiments were utilized to study the effect of net overburden pressure on porosity and absolute and relative permeabilities. These experiments were conducted on small, consolidated rock samples under net overburden pressures up to 41.37 MPa (6000 psi) and room temperature. The pore pressure was maintained atmospheric.

Examination of the data shows a decrease in porosity and permeability with increase in overburden pressure. A correlation between porosity and overburden pressure and also between permeability and overburden pressure has been developed using linear regression analysis. Both correlations are found to be logarithmic. The irreducible water saturation and residual oil saturation increase with increased overburden pressure levels. While the relative permeability to oil decreases with increasing overburden pressure, a corresponding negligible decrease in water relative permeability is observed.
An Improved Technique for Estimating Permeability in Carbonates
Authors: Watfa M. , Youssef F. Z.
Published: December 2007

The permeability of a reservoir is a function of fluid type, pore size and distribution, facies type, sha-liness and heterogeneities such as non-connecting vugs and fractures. Many equations and statistical techniques have been proposed to predict permeabilities using logs or log-derived results such as porosity and irreducible water saturation. However, none of the proposed techniques can be used universally since a particular relationship in one field or for a particular facies cannot be extended to other fields or facies. The standard procedure at present is to experiment with functions on a trial and error basis to establish correlations between core-derived permeabilities and log measurements. In carbonate formations, where structural heterogeneities and textural changes are common, the applications of these techniques are very limited.

A new technique has been developed to improve permeability estimates in carbonates. The technique aims to quantify both the field-wide variations and local variations in a reservoir. A theoretical model has been developed which defines the permeability of a porous medium as flow path length and pore radius change. The effects of heterogeneities, such as vugs and fractures, are also considered in the modelling. Correlations are established between the important geometrical factors that were determined in the model, and log-derived results such as the Archie factor m, the total porosity and the secondary porosity. The paper discusses in detail the principle and mathematical deriviations of this model and presents examples which demonstrate the improved accuracy of the permeability estimates as compared with proposed techniques for estimating permeability.
An Overview of the Formation Evaluation of Recent Discoveries in the Thamama, Arab, and Araej Reservoirs, Offshore Abu Dhabi
Authors: Azer S. R. , Borai A. M.
Published: December 2007

The Lower Cretaceous Thamama group, the Upper Jurassic Arab Formation and the Middle Jurassic Araej Formation are potential reservoirs and carry the bulk of the hydrocarbons-in-place in offshore Abu Dhabi.

Testing of these reservoirs in some areas revealed that drastic discrepancies existed when comparing test results with computer processed interpretations (CPIs) for well logs.

Reservoirs which tested water free hydrocarbons were indicated to be water bearing on well logs.

Several anomalous examples from the above mentioned reservoirs were studied.

The integration of all pertinent data is of utmost importance for proper formation evaluation.

The geological factors of different formations, which affect log measurements are the products of depositional and diagenetic processes.

Petrophysically, the cementation factor, thin bedding and deep invasion are critical when computing water saturation. A new log interpretation model is developed to decipher this formation evaluation problem, which resulted in more realistic water saturation calculations.
Diagenetic Effects on Reservoir Properties of the Permian Khuff Formation in Eastern Saudi Arabia
Authors: Al-Jallal I. A.
Published: December 2007

The Permian Khuff Formation represents the earliest major transgressive carbonates deposited on a shallow continental shelf in eastern Saudi Arabia. A detailed study was made of slabbed cores and thin sections from various wells recently drilled into this rock unit. The Khuff Formation was deposited in tidal flat environments including subtidal, intertidal and sabkha (supratidal). These depositional environments represent four major cycles. Each cycle starts with a transgressive grainstone facies which makes up the Khuff reservoirs and ends with regressive, muddy and anhydritic facies which make up the non-reservoir units.

Development of reservoir quality appears to be complexly controlled by lateral continuity or discontinuity of depositional facies and, more effectively, by diagenesis. Because of these lateral changes, Khuff reservoir development does not exactly follow present structural position. Some wells located on present structural highs are in non-reservoir facies, while other structurally lower wells are very porous.

Diagenesis has both increased and/or decreased reservoir quality. In places, dolomitization and leaching have enhanced the reservoir porosity and permeability. In other places, dolomitization and/ or cementation have seriously decreased the porosity and permeability.

Good porosity and permeability are related to the preservation of primary interparticle pores in totally dolomitized grainstones or leaching of remaining calcite in dolomitized mudstones. The later process produces secondary intercrystalline pores. Good porosity and poor permeability probably reflect an early exposure to fresh water leaching in grainstones, producing unconnected or poorly connected moldic pores. Poor porosity and permeability are caused by one or more of the diagenetic effects of cementation, dolomitization, or absence of leaching in all facies types.

Current studies show that Khuff reservoir changes can be described by a combination of depositional and diagenetic models. However, prediction of reservoir continuity is possible only for short distances from existing wells.
Camurlu Field Immiscibie CO2 Huff and Puff Pilot Project
Authors: Gondiken S.
Published: December 2007

A pilot project of enhanced oil recovery by CO2 injection has been carried out in Camurlu field for the first time in Turkey. CO2 gas was injected without using a compressor into selected C-11 and C-22 wells for three consequtive cycles during two years. Five or six fold increases in daily oil production rates of the wells especially within the first few weeks of last cycles have been observed. Field-wide application was decided since it has been understood that better working conditions and better selection of equipment and materials could yield much better results.
Design Factors and their Influence on Profile Modification Treatments for Waterfloods
Authors: Avery M. R. , Gruenenfelder M. A. , Tarlton J. M.
Published: December 2007

In the past 5 years, chemical profile modification for water injection wells has evolved from the experimental stage to a routine procedure. Chemical profile modification can be used under a wide range of reservoir conditions to treat a variety of reservoir heterogeneities known as thief zones. This paper presents a discussion of the typical thief zone problems, how they are diagnosed and the design process necessary for a successful profile modification treatment.
Case Study: Enhanced Oil Recovery Potential for the Garzan Field, Turkey
Authors: Warren G. M. , Memioglu E. , Bakiler C. S.
Published: December 2007

The Garzan B and C Pools, located in southeast-central Turkey (Figure 1), were studied for enhanced oil recovery (EOR) potential. A review of this study is presented in this paper.

The study consisted of a review of geological and reservoir engineering data followed by black oil reservoir simulation history matching of primary and waterflood depletion phases over a 27 year period. Selected pattern elements were then subjected to various EOR processes using compositional and thermal simulation models. The optimal EOR process, selected on the basis of technical and economic criteria, was extrapolated to full field scale and compared to optimized waterflood simulation predictions.

The study predicts that immiscible Dodan gas (mainly CO2) injection on 54 acre [21.9 ha] inverted 9-spot patterns will provide enough recovery and economic benefits over optimized waterflooding to warrant proceeding with a pilot gas injection scheme.
Case History of an Immiscible Gas Injection Pilot in a Massive Carbonate Reservoir with Water Drive
Authors: Welch V. S.
Published: December 2007

This paper describes a case history of an immiscible gas injection pilot which was carried out in a massive, carbonate reservoir in the Middle East. The reservoir contains an undersaturated, intermediate gravity oil, and recovery was less than five percent after 40 years natural depletion by intermediate to strong edge-water drive. Immiscible gas injection was recognized as a potentially economic recovery process and a gas injection pilot was initiated in 1983. A cross-sectional model study has provided the basis for evaluating and confirming the success of the gas injection pilot. A numerical simulator was used to match the 40 years of natural depletion followed by two years of immiscible gas injection. Performance was then predicted for two future operating plans. Reservoir analysis data collected during the injection shut-in and during an additional six months of gas injection, following the shut-in period, show that the reservoir mechanisms predicted by simulation to improve performance and recovery are operative. This paper discusses the description of the reservoir and its history, the model description and application, history match and 20-year predictions, and one year post-operative performance following the history match period.
Exploitation of Sui Main Limestone Reservoir at Sui: The Prolific Gas Producer of Pakistan
Authors: Schail H. M. , Sadiq F.
Published: December 2007

Sui Main Limestone (SML) is the most prolific reservoir accounting for 90% of all production from Sui Gas Field. Work carried out for obtaining estimates of reserves, future production potential and ultimate recovery from the SML reservoir is discussed. The paper presents results of well coning and reservoir simulation studies conducted. Work carried out in determining the reservoir's future compression requirements (over 75,000 HP) and debottlenecking of wells and gas gathering system is also highlighted.

The paper highlights the monitoring/ control of production operations for SML. Casing/tubing corrosion, failure and resulting fluid seepages are discussed. Problems related to formation water production and its monitoring/removal are presented.