bluuebunny/crossref_metadata_2025 huggingface dataset:
Petroleum Engineering Manpower Supply: Results of the 1986 Survey
Authors: Bourgoyne A. T.
Published: December 2007

The purpose of this article is to report on the results of the SPE manpower survey conducted annually by the SPE Manpower Committee. This yearly survey asks educators from all the schools listed in SPE's Petroleum Engineering and Technology Schools book to tel 1 how many petroleum engineering undergraduates they have, how many graduates they had last year, what their ability to get jobs were, and what they predict their graduates' ability to find jobs will be in the future. For those graduates reporting jobs, the sector of the industry in which the jobs were found is also reported.

This year, 20 of the 50 schools we solicited returned the surveys. Exactly half of the surveys went to U. S. schools; 12 of those were returned. In addition, one of five schools listing petroleum engineering options returned the survey. Other sources of information were used whenever possible to fill information gaps. SPE's annual Petroleum Engineering and Technology School s directory, based on surveys conducted by the Education and Accreditation Committee, is the best source of annual information on the size of the freshman, sophomore, junior, and senior classes.

This year's survey showed that the petroleum engineering job market was the worst it has been since the SPE Manpower Committee began collecting statistics in 1978. Only 29 percent of graduates seeking a job reported finding a job by the time of graduation. About 69 percent of the jobs found were with major oil companies. All other sectors of the petroleum industry showed a greatly reduced on-campus recruitment. Major oil companies also reduced on-campus recruitment significantly, but to a much lesser extent than the independent producers, pipeline companies, service companies, drilling contractors, government, consultants and financial institutions.
Computer Vision for Fundamental Studies in Porous Media: Part I–2-D Image Acquisition and Processing for Microscopic Distribution of Oil, Water, and Pore Space Networks
Authors: Yadav G. D. , Macdonald I. F. , Chatzis I. , Dullien F. A. L.
Published: December 2007

Microscopic studies of the distributions of oil and water and of their networks in the pore space, at various relative saturations, are of fundamental importance in understanding migration, distribution, entrainment and mobilization of oil in the context of a particular (enhanced) oil recovery method. There has been an upsurge of interest in quantitative image analysis of pore morphology from two-dimensional thin and polished sections; however, the subject of determining the three-dimensional geometry and topology of multifluid networks has not been dealt with at all.

We have developed novel techniques for studying the irregular, interconnected pore space network of reservoir rocks. An image acquisition and analysis system incorporating a micro-computer, video equipment and microscope has been built for these studies. We are in the process of extending the methodologies to study the separate wetting and nonwetting phase networks which exist during immiscible displacement processes. As a necessary first step, we have developed the interactive computer-based technique described here to extract individual phase images, e.g., water, oil, and rock, from images containing all these phases together. The two-dimensional serial section data are accumulated on video tapes in which, for a particular cross-section, images of wetting phase, non-wetting phase and all phases together are recorded and processed by the software developed by us. Image segmentation is done interactively with the aid of the operator. The criteria used in the image segmentation are discussed. The procedure and results are illustrated by analysing microscopic data collected for oil-water immiscible displacement in Berea sandstone during primary drainage. The processing of the two-dimensional images, including the methods of filtering, thresholding, edge-extraction, and combining images, is described.
Fracturing Treatment Quality Control: Results of a Three-Year Survey
Authors: Dees J. M. , Coulter G. R.
Published: December 2007

During 1983, 1984 and 1985, Sun Exploration and Production Company personnel surveyed on-site job performance on fracturing treatments throughout the USA.

The number of fracturing related problem jobs and the types of problems encountered are summarized in the survey results. Proppant samples were taken on many of the jobs included in the survey and analyzed as to mesh size specifications.

Specifically, more than 1000 frac jobs were evaluated in the survey. Problems occurred on approximately 20% of those jobs. The types of problems were analyzed and divided into service company related and non-service company related. From this analysis, the various service companies were evaluated as were the types of problems experienced. The non-service company related problems were also assessed.

Of 403 proppant samples, approximately 41% failed API mesh size specifications and 28% failed a less rigid mesh size specification set by Sun. The effect of this quality control problem is demonstrated with fracture flow capacity data.

From this survey, Sun has been able to identify and address fracturing quality control problems.
Threaded Connection Qualification Procedures Utilized for an Ultra-Deep, High-Pressure Gas Well
Authors: Minge J. C. , Pejac R. D. , Asbill W. T.
Published: December 2007

This paper describes the premium connection qualification program used to qualify three (3) different connections for the production tubular strings used in an ultra-deep, high pressure gas well. A total of eight (8) connection types were tested during the program. Four (4) connections failed to meet the program's acceptance criteria. Full-scale test procedures and the data acquisition system used to collect, store, reduce, and plot strain gauge data while testing are discussed.
Makeup Torques for API-Type Round Thread Casing Connections With Non-API Weights, Grades, and Coupling Diameters
Authors: Hainey M. F.
Published: December 2007

Make-up torque calculation procedures are presented for API-type round thread casing connections with non-API weights, grades, and coupling dimensions--connections which are commonly used in the industry but for which there is not an industry-published reference on make-up procedures. Included are a simplified version of the API procedure for calculating optimum make-up torques that may be used for non-API weights and grades of casing, a procedure for adjusting make-up torques for connections with oversize or special clearance couplings, and a procedure for calculating make-up torques for connections used in sour service.
A New Nozzle System To Achieve High ROP Drilling
Authors: Chia R. , Smith R.
Published: December 2007

Given the various controllable drilling parameters, hydraulic power is perhaps the most versatile, and yet least understood effect. The primary usage of hydraulic energy and the drilling fluid as applied by rock bits is to clean the wellbore bottom and the teeth of the bit. For decades, hydraulic energy had been determined according to first order approximations of jet effects, such as impact force and/or hydraulic horsepower. These factors were useful to the drilling personnel but did not provide enough information for the engineer to intentionally design the hydraulic system to clean the bit and wellbore. In order to achieve the cleaning objectives, one needed to know not only the jet velocity but also its interaction with the bit body and the rock formation. The challenge to find the stagnation zones, the erosion rate on the different parts of the bit, and the movement of the rock chips became apparent.

The paper discusses a computer simulation study of the fluid characteristics at each point of importance on the bit, which has been utilized to design a new nozzle system. This study consists of mini-extended nozzles, stabilizer pads, and a center nozzle. The means of designing an optimized hydraulic system, including laboratory work and the statistical analysis of field run data for correlation between theory and practice is presented. This integrated nozzle configuration increased the overall rate of penetration an average of 18 percent based upon 134 mini-extended nozzle bit runs. The drilling costs were cut inherently due to the penetration rate increase.
Relating Gulf Coast Sand/Shale Statistics to Petrophysical Properties as Seen by Seismic
Authors: Burns C. S.
Published: December 2007

Over 1250 wells on the Cenozoic continental shelves of Texas and Louisiana have been digitized and entered into a log-analysis program. The velocity-density functions of sand and shale have been statistically cataloged both vertically (via geopressure) and regionally. The major criteria for defining the lateral extent of the trend boundaries were based on shale analyses and velocity-density maps. The Plio-Pleistocene depocenters statistics from this trend illustrate the majority of the classification schemes. The velocity and density contribution to the total reflection coefficient varies dramaticly from Miocene to Pleistocene. The exclusion of density, or its approximation from velocity, results in reflection coefficients which are unreliable for seismic interpretation. By incorporating geologic age, shale percentage, geopressure, and depth of burial, with an approximate expression for the reflection amplitude as a function of incident angle, the ability to predict lithology from seismic data is greatly enhanced.

Provided the P-wave velocity and density are known, the incident-angle dependent amplitude variation becomes a function of the difference in the two Poisson's ratios at a formation boundary. Thus seismic estimates of Poisson's ratio can be obtained, which can aid in the determination of fracture pressure and lithologie characterization of reservoirs.
Geologic Controls on Producibility at Clear Creek Field, Uinta County, Wyoming
Authors: Alexander W. G.
Published: December 2007

Production from the eolian Nugget formation at Clear Creek field in the southwest Wyoming thrust belt is controlled in large part by permeability anisotropy emplaced at the time of deposition and subsequent reorientation of the formation as a result of folding. Maximum permeability in this eolian system occurs in and parallel to dune slip-face bedding planes. Vertical permeability across less porous interdunal deposits ranges from two to three orders of magnitude less than the maximum permeability in the dune deposits. At the time of Nugget deposition the dune orientation was predominantly northwest-southeast with the slipfaces dipping to the southwest, giving a northwest-southeast orientation to the axis of maximum permeability (Kmax axis). This Kmax axis was curved or bent during subsequent folding of the sediments, giving it various orientations depending on structural position. Higher gas oil ratios are observed at Clear Creek where the separation of oil zone perfs from the gas cap along the Kmax axis is smaller. These higher gas oil ratios result as gas is preferentially "channeled" along the slipface bedding planes to the oil zone perfs. In situations as at Clear Creek, where the oil zone is thin and a gas cap is present, oil zone completions must be located where the Kmax axis is near horizontal, thus maximizing the separation of perfs from the gas cap. This reduces the "channeling" of gas along the Kmax axis and maximizes oil zone recoveries. Another parameter affecting producibility is rock deformation due to faulting. Faulting in the Nugget results in the development of intense gouge zones along and adjacent to fault planes. These gouge zones represent potential barriers to flow.
Friction Losses in Vertical Tubing as Related to Hydraulic Pumps
Authors: Brown F. Barton , Coberly C.J.
Published: December 2007

In a previous paper, the authors showed that the viscosity of the fluid in a well varies in an exponential manner with well depth due to the temperature and pressure gradients of the well. A viscosity gradient, , was introduced as a means to integrate the friction loss in the tubing string of a well.

This paper presents the accepted relations for friction loss in circular sections in a form suitable for oilfield use.

Hydraulically operated pumps may also involve the flow in an annulus between a large and small-diameter tubing or between a tubing and casing. Where annular flow is involved, the inner tube usually will be eccentric to the outer tube or casing. The available literature was reviewed on this subject, and correction factors proposed by several different writers were combined in the friction loss relations for both laminar and turbulent flow.

To simplify calculations in annular sections, equivalent diameters are introduced that take into consideration these factors. These diameter may then be used in the normal friction loss relations for circular section. They are tabulated for the more common combinations of tubing and casing sizes.

Charts and nomographs are presented. Together with the nomographs of the previous paper, they enable the petroleum engineer to quickly estimate tubing sizes and to determine the friction losses in a given system.

Introduction

In an ordinary hydraulic system, the conduit is normally circular in cross section, the viscosity of the fluid and the specific gravity are constant and the static head probably is small. In a hydraulically operated oil-well pumping system, the conduit may be either circular or annular. Also the fluid is subjected to a high static head and large temperature gradient and, as a result, viscosity and specific gravity will vary with well depth. Because of this large variation of viscosity, the flow in the tubing strings may be both turbulent and laminar. Therefore, the calculation of friction losses in hydraulic pumping installations poses a number of problems not encountered in ordinary hydraulic systems.
Tax Regime and the Development of the Petroleum Industry in Australia
Authors: Robson R. J. , Widmer G. R.
Published: December 2007

Australia is a Federation of States with responsibility for the development of mineral resources being vested in the sovereign States, except in offshore regions where the Commonwealth has jurisdiction. Thus, different taxation regimes may apply in different geographical regions. The paper will outline the development of the tax regimes applying in Australia from the onset of large scale petroleum production in 1969 to the present day.

The paper will briefly trace the "boom and bust" syndrome and deal with the benefits of providing a stable pricing and fiscal environment for the exploitation of hydrocarbons. The paper will also describe the income taxes, production levies, and royalties which are found in the oil and gas sector and make up the Government's taxation receipts. It will also indicate how changes in the fiscal mix will effect the future course of petroleum exploration in Australia.

To demonstrate the variability of different taxation regimes that exist, economic models have been constructed to show the taxation effects on the prospectivity of different regions and the profitability of different sized oil fields. These will be evaluated in relation to the cost of development and remoteness from infrastructure and markets, and the results presented in graphical form. Conclusions as to the appropriate form of regime will be drawn.

Australia's 70% self-sufficiency in light crude oil is expected to decline to 30% in the 1990's in the absence of further large discoveries. Continuation of stable taxation and pricing policies is seen to be necessary if this decline in self-sufficiency is to be arrested.
Specific Mixing Energy: A Key Factor for Cement Slurry Quality
Authors: Orban J. A. , Parcevaux P. A. , Guillot D. J.
Published: December 2007

In this paper, the relationships between cement mixing and cement slurry quality are investigated. Laboratory mixing conditions, using a high shear mixer, are compared to field mixing conditions, including conventional jet mixer, recirculating type mixer and batch mixer.

All the mixing conditions can be reduced according to a single parameter, the specific mixing energy, that allows the comparison of laboratory and field mixing with confidence.

Typical cement slurry properties, like rheology, free water, fluid loss, thickening time and compressive strength, are measured as a function of the specific mixing energy. All these properties improve when the specific mixing energy increases. The efficiency of cement additives, like dispersants and fluid-loss agents, is also found to vary significantly with the energy. A tentative explanation is proposed through a mechanism of particle deflocculation and dissolution, leading to an increase in the available specific surface area.

Optimal slurry properties are obtained at specific energies close to that imparted by a laboratory mixing following the API Specification 10. The specific mixing energy parameter has been quantified for different pieces of typical field equipment and conditions, from mixers to centrifugal and high pressure positive displacement pumps, and pumping through orifices. Current standard field practices can represent as low as 10 %, of the specific energy imparted by the API procedure. Comparative measurements in the field have shown that the cement slurries mixed then in these conditions have considerably poorer properties than the same ones mixed in the laboratory.

As a consequence it is recommended to increase the field specific mixing energy to a value as close as possible to the API one. This provides optimum slurry quality and good similarity between laboratory and field conditions.
Nitrogen Management at the East Binger Unit Using an Integrated Cryogenic Process
Authors: Emmons Fred R. , Hudspeth Lon D. , Clancy James P. , Zornes David R. , Philcox John E.
Published: December 2007

The East Binger Field located in Caddo County, Oklahoma had an expected primary recovery of only 10.7%. After extensive reservoir, laboratory, and model studies, a plan of unitization was approved and an inert gas miscible displacement project was initiated in 1977. Unanticipated operational problems, such as leaks in casings, tubing and packers, plugging of low permeability sand, and other problems were analyzed and solved. Oil and gas production to date is consistent with the predictive models. An anticipated problem of inert gas breakthrough has been handled to date by planned interim methods.

In 1984, as a result of engineering and economic studies of several viable alternatives, a decision was made by the East Binger Unit (EBU) to switch to a nitrogen management concept. Under construction, with a late 1986 startup date, is a nitrogen management facility which will replace the existing inert gas supply system as well as replace the interim method of handling produced gas. The facility which is integrated to reduce capital, energy and other operating costs, will provide cryogenically-produced nitrogen from both nitrogen rejection and air separation, 985 Btu/SCF [3.48 × 104 MJ/m3] residue gas, pipeline quality natural gas liquids and 18,000 MSCFD (thousand standard cubic feet per day) [5.1 × 105 m3/D] of 5,000 psig [3.45 mPa] nitrogen. With nitrogen management, higher hydrocarbon recoveries and lower lifting costs are expected.
Simulation of Unstable Miscible Displacements by Finite Element Method
Authors: Peters E. J. , Kasap E.
Published: December 2007

A modified finite element method was developed to simulate unstable miscible displacements in heterogeneous porous media. The modification was to evaluate the transport properties at the center of the elements, instead of at the numerous gauss points. This averaging procedure reduced the computational time by as much as thirty percent compared to the standard finite element method while still retaining the fingering behavior of the unstable displacements. Further, the modified method showed less grid orientation effect and resulted in a more robust numerical model than the standard finite element method.
Studies of Gas Injection Into Oil Reservoirs by a Cell-to-Cell Simulation Model
Authors: Pederson K. S. , Fjellerup J. , Thomassen P. , Fredenslund A.
Published: December 2007

Injection of various gases into two different North Sea reservoir oils has been simulated using a cell to cell model. It is shown that ternary diagrams are insufficient to represent the mixing processes which take place in a petroleum reservoir into which gas is being injected. New criteria for evaluating the results of a cell to cell calculation are suggested. The highest recoveries are obtained when a miscible drive is established. However, also in cases where miscibility is not achieved, a marked enhancement of the oil recovery may be possible.
An Artificial Intelligence Approach to Lithostratigraphic Correlation Using Geophysical Well Logs
Authors: Olea R. A. , Davis J. C.
Published: December 2007

Computer programs for lithostratigraphic correlation of well logs have achieved limited success. Their algorithms are based on an oversimplified view of the manual process used by analysts to establish geologically correct correlations. The programs experience difficulties if the correlated rocks deviate from an ideal geometry of perfectly homogeneous, parallel layers of infinite extent.

Artificial intelligence provides a conceptual basis for formulating the task of lithostratigraphic correlation, leading to more realistic procedures. A prototype system using the "production rule" approach of expert systems successfully correlates well logs in areas of stratigraphic complexity. Two digitized logs are used per well, one for curve matching and the other for lithologic comparison. The software has been successfully used to correlate more than 100,000 ft [30 480 m] of section, through clastic sequences in Louisiana and through carbonate sequences in Kansas. Correlations have been achieved even in the presence of faults, unconformities, facies changes, and lateral variations in bed thickness.
A Study of Stress in Devonian Shale: Part I—3D Stress Mapping Using a Wireline Microfrac System
Authors: Evans K. F. , Engelder J. T.
Published: December 2007

We describe an experiment to characterize in detail variations in the state of stress within a horizontally-bedded sandstone/shale limestone sequence in western New York. The measurements were made using a new wireline-based "microfrac" system which, by its nature, permits frequent sampling of stress. Three wells, 1 km or so apart featured in the study. In one well, 43 intervals were tested to 1 km depth. The measured stress-profiles in all three wells show an identical pattern of stress variations. Two stratigraphic regimes of markedly different stress ratio are recognized which are separated by a transition zone. Within this zone variations in stress are clearly correlated with lithology.
Friction Pressure of Foamed Stimulation Fluids Evaluated With an On-Site Computer
Authors: Mack D. J. , Baumgartner S. A.
Published: December 2007

Computerized monitoring of hydraulic fracturing treatments has been an accepted practice for several years. Not only can a continuous record of the treatment parameters be made, but the real-time bottomhole treating pressure can be determined without the use of a reference string or bottomhole pressure tool. However, to calculate the bottomhole treating pressure, the friction pressure of the fluid or slurry must be determined. For conventional, incompressible oil and water-based fluids friction pressure is a straightforward calculation since rate and proppant concentration are the main considerations. The friction pressure for foam fracturing fluids requires a more complex solution.

A computer van was used to monitor carbon dioxide and nitrogen foam treatments incorporating a reference string or bottomhole pressure tool. The foam friction pressure was determined from the continuous knowledge of foam composition and treatment parameters. The treatment data were used to develop a technique to predict foam friction pressures for bottomhole treating pressure calculations. This paper presents a foam friction pressure technique which allows the bottomhole treating pressure to be calculated without the use of a reference string or bottomhole pressure tool. The calculation of bottomhole treating pressure for a foam treatment incorporates a technique to correct the hydrostatic head pressure of carbon dioxide and nitrogen foams. In addition, the different effects of proppant addition on friction pressure between nitrogen and carbon dioxide generated foams are discussed.
Evaluation of Calcium Carbonate Scale Inhibitors for Prudhoe Bay, Alaska
Authors: Underdown D. R. , Newhouse D. P.
Published: December 2007

The formation of calcium carbonate scale in the perforations and near well bore formation sandstone is one of the major factors affecting production in the Prudhoe Bay field. Previous work (1–11) has shown that squeeze treatments using certain phosphonate scale inhibitors help to control the formation of calcium carbonate scale in low water-cut wells. However, the desorption rate of the phosphonate from the formation may cause the effectiveness of the treatment to be decreased dramatically as the water-cut in the wells increases.

It has been observed that scale inhibitor squeeze treatments employing polymer-phosphonate blends appear to last longer in high water-cut wells than those treated only with phosphonate. This study evaluated the effect of various polymers on the desorption rate and inhibitive character of the phosphonate determined by Meyers (1) to be the most effective in inhibiting calcium carbonate scale in Prudhoe Bay.

Standard NACE scale inhibitor tests were conducted to evaluate the effectiveness in preventing scale for the various systems. Flow tests in formation cores were run to determine the feedback rate of the phosphonate from various systems. The core studies were monitored for the amount of phosphonate desorbed as a function of water-cut and total pore volumes of brine flowed through the core. Results showed that a high molecular weight maleic copolymer to be the most effective in decreasing the desorption rate of the phosphonate.
Two New Density Correlations
Authors: Chien M. C. H. , Monroy M. R.
Published: December 2007

The Liquid density predicted by the Peng-Robinson (P-R) equation of state is often off by 10% or more at temperature and pressure conditions encountered in most reservoirs. To improve the density predictions, two new density correlations have been developed. The first correlation is based on the chain-of-rotators (COR) equation of state and the second is based on the three-parameter Peng-Robinson (PR3) equation of state. The COR correlation is applicable to wider pressure and temperature ranges, but is computationally expensive. It is suited for interpreting fluid-analysis data, where no extensive phase-behavior calculations are needed. On the other hand, the PR3 correlation is more limited in its application range, but is computationally more efficient. It is particularly suited for compositional reservoir simulation where many density calculations are repeatedly carried out.

In general, both correlations are comparable to the Standing-Katz correlation for liquid-density calculation and comparable to the P-R equation of state for vapor-density calculation. However, they are superior to the Standing-Katz correlation for liquid mixtures near critical points or liquid mixtures at high pressures. Overall, the COR equation of state gives an average prediction error of 1.9% for liquid densities and 2.7% for vapor densities, and the PR3 gives an average prediction error of less than 2% for both liquid and vapor densities. The required inputs are any two of the following properties for each pseudocomponent: molecular weight, specific gravity, and normal boiling point. This easy input requirement makes the correlations very attractive for engineering uses.
Phase Equilibria in Natural Gas Systems: Data for Two Helium-Bearing Natural Gases
Authors: Brandt L. Warren , Stroud Lowell , Miller John E.
Published: December 2007

A windowed phase equilibrium apparatus was used to obtain equilibrium vapor and liquid-phase samples of two helium-bearing natural gases at experimental conditions ranging from approximately -50 to -275 F at pressures from 100 to 500 psia. Helium contents of the gases studied are 2.5 and 0.75 per cent. The equilibrium samples were analyzed by means of a mass spectrometer and special helium analysis apparatus.

Loss of helium by solution in the condensed natural gas is a major concern in achieving high over-all efficiency in the separation of helium from natural gas by low-temperature methods. Data relating to helium solubility in condensed liquid phases and the condensation characteristics of the gases are presented and discussed. Equilibrium vaporization coefficients for methane, nitrogen and helium, obtained from experimental phase equilibrium data, also are given.

A sharp increase in demand for helium the last few years, urgently required in the United States' atomic energy and space programs, resulted in a helium shortage early in 1958. A recently completed plant at Keyes, Okla. has alleviated this condition temporarily, but it is expected that in a few years demand again will exceed supply. As a step toward meeting the nation's helium needs in future years, the U.S. Bureau of Mines Helium Activity of the Dept of the Interior-the only producer of helium in this country-announced in recent press releases a policy for conservation of this gas. Brief discussions of this policy have appeared. Long-range plans call for the construction of additional plants to remove helium from natural gas streams not going to fuel markets and to store the helium underground. It is possible that private industry will be interested in building and operating these "conservation" plants. "Crude" helium produced at these plants would be sold to the Government for storage.

To assist industry in evaluating their desired extent of participation in the program, the Bureau of Mines Helium Activity recently placed on open file a report presenting computed phase equilibrium data for the helium-bearing natural gas supplying the Amarillo, Tex., helium plant and experimental phase data for the gas supplying the Keyes, Okla., plant. Helium contents of these gases are 1.8 per cent at Amarillo and 2.1 per cent at Keyes. A later open-file report presented experimental-phase data for a natural gas containing 0.7 per cent helium and is of interest because this helium content is expected to be representative of natural gases to be processed for helium in the conservation program.
Effect of Tarmat on Reservoir Behavior: Reservoir Simulation Case Studies
Authors: Acharya U. B.
Published: December 2007

It is fairly common to find tarmat or heavy oil at the base of hydrocarbon column in many reservoirs in the Middle East. Reservoir simulation field study of one such reservoir, namely Reservoir "A" of a field in this region is described in this paper. Another example of such a reservoir (Reservoir "B") is also briefly discussed.

The tarmat which is present at the base of the hydrocarbon column controls the degree of intercommunication between the aquifer and the oil column. In the study of Reservoir "A", the approach for simulating the tarmat behaviour was mainly to modify the interblock transmissibility whereas in the study of Reservoir "B", the approach was to modify the relative permeability.

Both the approaches gave good results and clearly indicated that in both the reservoirs, initially, the tarmat acted as a permeability barrier and hence the reservoirs behaved as depletion drive reservoirs. Afterwards, with continued production, the pressure differential between the aquifer and the oil zone was substantial enough to breakdown the tarmat layer. Several prediction schemes were made on both reservoirs with the status of tarmat as of the end of the history match. The optimum production scheme for both reservoirs is water injection above the tarmat. For Reservoir "B", pilot water injection has already commenced.
Laboratory Miscible Displacement Study in Arabian Carbonate Cores
Authors: Asar H. K. , Satman A. , Saner S.
Published: December 2007

Determining the applicability and type of the EOR method to maximize oil recovery from carbonate reservoir containing Arabain heavy crude is the subject of this study. Various EOR displacement experiments including waterflooding, CO2 flooding, enriched gas injection and LPG injection were carried out. Results of laboratory theoretical and experimental studies indicated that hydrocarbon miscible flooding could maximize oil recovery.

Following necessary preliminary studies, a systematic series of miscible flood displacements of the Arabian heavy oil using a slim tube apparatus and a natural core displacement apparatus was performed.

In this paper, findings from a variety of laboratory slim tube and natural core flooding experiments are Discussed and analyzed. Factors influencing the mechanism of miscible displacement, as a secondary process replacing conventional water flooding and as a tertiary process recovering waterflooding residual are elucidated.
Abu Dhabi Offshore Khuff Gas Completions Using Exotic Metallurgy
Authors: Ray D. R.
Published: December 2007

The use of exotic metallurgy for the completion of deep, hot, sour gas wells is growing. The design of such completions must consider alloy selection, equipment specification, quality assurance, acidizing procedures and packer fluids. These aspects are discussed in relation to a recent Khuff gas project in Abu Dhabi.
Infill Drilling Enhances Oil Recovery in Egypt's First Waterflood Field
Authors: Mahmoud M. L.
Published: December 2007

This paper presents both the primary and secondary historical performance during the first 20 years for the Kareem zone, the major producing Horizon of the giant Egyptian oil field El Morgan. The justifications and qualifications pertaining to the initiation of major peripheral waterflood project for the first time in Egypt are reviewed.

The paper emphasizes the results of a recent comprehensive geoiogical/engineering study where an extensive multidevelopment plan including 35 new wells was recommended to improve both areal and vertical sweep. Results available todate demonstrate that infill drilling in a mature waterflood can enhance oil recovery both in terms of accelarating production and adding new reserves.
Variation of a Natural Sandstone Reservoir Element: An Objective Analysis of Core Measurements
Authors: Greenkorn R.A. , Johnson C.R.
Published: December 2007

Samples from 39 complete cores of a natural sandstone reservoir 150-ft square and about 8-ft thick were analyzed for variation and change in variation or gross reservoir thickness, permeability and porosity. For objective analysis, the gross reservoir thickness is defined as that entire interval in which flow is confined, regardless or the permeability or porosity or the included rock strata. This thickness is measured directly from cores. Ten randomly spaced and oriented horizontal plugs were cut from each core. Each plug was saturated with reservoir water and permeability was measured with a constant-head discharging apparatus. Porosity of three or each suite of plugs was determined by the liquid saturation method.

Mean squares, measures of variation, show the natural variation of the thickness, permeability and porosity for different groups or the data. Comparison of the mean squares of these groups demonstrates the change of variation. This application or data control methods shows these properties to have a large variation, and change or variation, in a natural reservoir.

Introduction

To interpret and predict fluid flow in a natural rock system, it is necessary to know not only the correct average values of thickness, permeability and porosity, but also the natural variation of these properties. Of equal concern is the change of variation in the reservoir. That is, are the heterogeneities heterogeneously distributed? Unfortunately, the degree of variation of thickness, permeability and porosity of most oil fields or any other natural reservoir is unknown.

The first objective of this study, then, is to ascertain the variation of thickness, permeability and porosity within a small segment of a natural reservoir sandstone. The data were obtained from a brine-saturated upper Pennsylvanian sandstone which is 250-ft deep. Thickness and permeability were measured from 39 complete cores from a 150-ft square of this sandstone, and porosity from 31 of these. The average thickness is about 8 ft, the average permeability is 0.4 darcy and the average porosity is about 24 per cent. Location of the core holes, numbered in the order they were drilled, is shown in Fig. 1.

The second objective of this study is to analyze the variation of thickness, permeability and porosity to establish the magnitude of the changes of variation.
Effects of Reservoir Heterogeneity on Performance
Authors: Hopkinson J.L. , Natanson S.G. , Temple A.P.
Published: December 2007

The paper deals with the application of several idealized models in the diagnosis and description or the effects attending flow in a heterogeneous reservoir. The types of heterogeneity considered are restricted to discontinuous vertical and horizontal change in flow parameters and, to some extent, the occurrence of fracturing.

The models are described and the characteristic behavior of each model discussed. The results of the mathematical analyses of the models are then applied to two field cases.

First, the pressure behavior of a single well in an undeveloped reservoir is analyzed to illustrate the degree to which the application of idealized models can detect the type and extent of heterogeneity present.

Secondly, the model results are applied in the study of a vertically heterogeneous field.

Finally, conclusions are presented which summarize the possible applications of the model theories to field behavior.

Introduction

The investigation into the effects of various types of reservoir heterogeneity arose from the study of a particular sandstone field. The reservoir formation, some 340-ft thick, consists of sandstone, siltstone and shale; the variation in permeability is much more pronounced vertically than horizontally. The structure is a shallow anticline; the aquifer is of considerable extent on one flank but is believed to shale out rapidly on the other. Up to the present, flow has been single-phase. A structure map of this field and a typical vertical cross section are shown in Figs. 1 and 2, respectively.

A general investigation was carried out to assess the effect which the different types of heterogeneity observed in the reservoir would have on the field's performance. This investigation is the subject of the present paper.

DEVELOPMENT OF MODELS

Preliminary Considerations

The first approach to the problem of flow in heterogeneous media consisted of simulating a 2-layer radial system in single-phase flow by a capacitance-resistance network. The analogue was two-dimensional and consisted of 8 × 13 mesh points. The radial extent of the physical system simulated was approximately 100 times the well radius, and the thickness of each layer was 18 times the well radius. The two layers had the same expansibility and a permeability ratio of 1:10. Cross flow between layers was allowed.
The Construction of Curvilinear Co-ordinate Grid Systems for Reservoir Simulation
Authors: Ferguson W. I. , Wadsley A. W.
Published: December 2007

The construction of optimally orthogonal grid systems has, in the past, been a somewhat ad-hoc procedure. In this paper, several new methods of deriving grid systems for full field and symmetry (production) element, curvilinear models are described. The basis of the approach to constructing full field curvilinear models assumes that the engineer has identified those aspects of the reservoir geometry to which the simulation grid will correlate or conform. The "primary" and "secondary" grid lines to the orthogonal grid typically should conform to various geological features such as faults, reservoir boundries, formation top and/or bottom depth contours and fluid contacts.

The methods described to construct full field grids include: contour-to-grid interpolation and grid-to-contour construction procedures which define a global (conforming) potential field in the reservoir from which the global orthogonal grid is constructed;the use of the Boundary Element Method to calculate a global potential field to likewise construct a globally orthogonal grid;the use of geometric construction procedures, including dot-product minimization and rubber banding to construct primary and secondary line sets from engineer defined correlating lines.

The use of the BEM in constructing curvilinear grids for production elements based upon isopotential and streamline definition is also described in detail.
Evaluation of Single-Layer Transients in a Multilayered System
Authors: Ehlig-Economides C. , Joseph J. , Erba M. , Vik S. A.
Published: December 2007

Recent developments in well testing have focused on obtaining the properties of each layer in a multi-layered reservoir. Quantification of the dynamic reservoir description includes determination of the layer permeabilities and skins, effective drainage boundaries, and zone average pressures. The subject of this paper is a new well test procedure for acquiring the transient flowrate and pressure response of any single layer in a commingled system. Convolution of the bottom hole flowing pressure with the layer flowrate produces a response function equivalent to the pressure transient that would be measured if the layer were packed off in the well.

A major advantage of this test is that wellbore effects on the transients are minimized, thus enabling reservoir characterisation in the vicinity of the wellbore that is not possible by any previously reported means. Hence, the early time response affords the possibility of quantifying partial penetration skin or the radial extent of an altered zone.

A second advantage is the possibility for long duration testing of the single layer with little interuption in the well production. If the interval tested by this method is not communicating vertically with adjacent layers in the reservoir, the recorded transients can be evaluated for reservoir heterogeneities such as dual porosity behavior.
Improved Reservoir Description through the Integration of Seismic, VSP, and Well Logs
Authors: Roberts D. E. , Winchester A. J.
Published: December 2007

A Reservoir Modelling workstation that allows fast access to, and integrated interpretation of data from the disciplines of Geophysics, Geology and Reservoir Engineering is being developed. Currently, from an initial overall reservoir 3-D geometry description (derived from seismic & log data), the model is elaborated to include more geological detail through the extension of single well geology diagnostic to the entire reservoir. A longer term objective is to integrate pressure and flow information with this static description to produce a 3-D dynamic reservoir model. Some of the techniques that have evolved during development of the static model have been applied to a North Sea oil field. Data used in this study included 3-D surface seismic, VSP surveys from 12 wells, and well log information from 28 wells.
Numerical Simulation of the North Sea Fulmar Oil Field: Evaluating Reservoir Depletion Strategies
Authors: Valenti N. P. , Buckles R. S.
Published: December 2007

The Fulmar field, located in the Central North Sea, began production in 1982. This thick reservoir covering an area of only 10 sq. km has an 0IP of approximately 850 MB0 (135 × 106 m3). Initial reservoir pressure was 5700 psi (39,300 kPa) (3900 psi above saturation pressure, 2200 psi above hydrocarbon gas-oil minimum miscibility pressure, and, 1000 psi above hydrostatic pressure). During the first two years of operation, the field pressure dropped more than 1000 psi (6,900 kPa), a secondary gas cap developed because of gas injection, and the oil-water contact advanced up to 100 ft (30 m). A 3-D, 3-phase, black-oil numerical model of the field was developed in 1984 based on 27 months of production data to project future performance with alternative development and depletion strategies.

Interesting features of the simulation include: miscible gas injection into an undersaturated oil reservoir, pressure communication between fault blocks with different original oil-water contacts, the modeling of gas and water coning at wells located near the dome shaped crest of the structure, and compliance with facility, drilling and recompletion constraints, as maintained by rate and well management routines in the simulator.

A description of the 5000 block numerical model is provided along with the history match and results of simulation predictions. Conclusions drawn from this work include the following: (1) A production plateau of at least 135 kBD (894 m3/h) can be maintained until 1987 without additional drilling; (2) this plateau can be extended an additional three years through further drilling, recompletions, and re-distribution of water injection; and (3) improved oil recovery from the Clyde sand unit can not be achieved simply by modifying the production-injection strategy for that zone.
Compaction Behavior of Ekofisk Chalk as a Function of Stress
Authors: Johnson J. P. , Rhett D. W.
Published: December 2007

Reservoir management of the Ekofisk field requires accurate predictions of reservoir compaction that will occur during the production lifetime of the field. Laboratory measurements must provide realistic values of strain as a function of effective stress or predictive models will not give reliable estimates of compaction and surface subsidence.

The compaction behavior of Ekofisk chalk as a function of effective applied stress has been studied in the laboratory. The objective of this study was to obtain data which can be used to predict reservoir resulting from increased stress on the chalk due to reduction in reservoir pressure with production of the field. Compaction data for uniaxial strain conditions and for ultimate strain at a given applied stress are required as input for the predictive model. It was found that results obtained under hydrostatic test conditions are very similar to those obtained in uniaxial tests when the hydrostatic test results are converted by a standard formula to uniaxial conditions in the elastic region of the compaction curve and applied directly in the plastic (pore collapse) region. This observation for this particular material is valuable in providing a means of utilizing more easily obtainable hydrostatic data for many studies, and also is interesting with regard to understanding what is happening to the chalk in the pore collapse region.

Laboratory studies clearly show that strain in chalk is time-dependent. Ideally, compressibility tests should be of sufficient duration to observe all potential strain that would occur during the life of the field. This is clearly not feasible, however, and the analyst must obtain data from tests conducted on a time frame of days or weeks. To deal with this dilemma, a numerical technique was developed that predicts the ultimate compaction chalk will undergo when subjected to a given stress for infinite time. The technique has been applied to a large number of chalk compressibility tests. Correlation coefficients indicate the numerical technique does very well predicting chalk compaction in extended laboratory tests. The numerical technique allows real-time evaluation of strain equilibration during compressibility tests, it allows shorter tests, and it provides predictions of ultimate compaction of the reservoir.
Subsea Well Servicing: A New and Economical System—The SWIMS
Authors: Le Bouteiller D. , Berthler O.
Published: December 2007

Presently, most of the subsea wells wire line interventions are performed from a drilling semi-submersible using a completion/work over riser, a heavy equipment for a relatively simple operation.

The paper presents a new concept of riser, specifically designed for that purpose. It permits a very significant cost reduction, it is diver less, guideline less and can be operated from a medium sized DP monomull.

Its design includes many original technical solutions in matters such as riser re-entry, safety and riser handling.