bluuebunny/crossref_metadata_2025 huggingface dataset:
A Fully Implicit, Three-Dimensional, Three-Phase Simulator With Automatic History-Matching Capability
Authors: Tan T. B. , Kalogerakis N.
Published: December 2007

The reservoir simulator described in this paper has the capability of automatically determining parameter values of reservoir properties in specified zones that will best match observed data. The observed data can be grid cell pressures, water-oil ratios, gas-oil ratios and flowing well bottom hole pressures. A modified Gauss-Newton approach is used that significantly reduces the computational time in generating new parameter estimates. As a test problem, the Second SPE Comparative Problem which is a numerically difficult three phase coning problem, was chosen. The proposed algorithm was able to converge to the original values of permeability and porosity from a wide range of initial guesses and the computational effort was equivalent to performing a few typical simulator runs.
Estimating Relative Permeabilities by Automated History Matching Using Linear Modeling Techniques
Authors: Labban Z. S. , Horne R. N.
Published: December 2007

This paper presents a novel approach for estimating relative permeabilities through an automated history matching procedure which makes use of linear models. The new technique makes use of linear relationships which are found to exist between simulation runs for the same points in time.

Linear models relating phase relative permeabilities with reservoir fluid properties, pressure and production data are developed. The linear relationships are used in an iterative procedure to estimate relative permeability-saturation relationships for use in simulation models.

Several cases are presented to determine the validity of both the linear models as well as the new procedure.

A case is presented which shows the new method to have promising applications in scaling of rock relative permeabilities to coarse grid simulator interblock relative permeabilities directly from observed production and pressure data.
A New Parallel Iterative Linear Solution Method for Large-Scale Reservoir Simulation
Authors: Wallis J. R. , Foster J. A. , Kendall R. P.
Published: December 2007

Throughout the more than four decades of the existence of numerical reservoir simulation, computer hardware has been a strong driving force in the evolution of modeling capabilities. Advances in the architecture of computing platforms invariably stimulate advances in simulation technology. The principle underutilized hardware resource available today is the capability of many machines to perform concurrent or "parallel" processing. Within the family of algorithms comprising a reservoir simulator, numerical linear algebra is a long-standing bottleneck. Robust iterative linear solvers typically utilize recursive preconditioning methods and involve conjugate gradient-like computations such as dot products which are "fine" grained and are not ideally suited to the parallel processing environment.

This paper will describe a robust, high-performance linear solver formulated specifically for parallel computers with shared memory and a relatively small number of sophisticated processors (e.g. IBM 3090-400S, CRAY Y-MP). In particular, this paper will address the parallel iterative solution of the pressure equation although the method can be adapted to the fully implicit case. A new preconditioning based on the application of domain decomposition to a variant of Nested Factorization is described. A new variation of the Generalized Conjugate Residual (GCR) method better suited to parallel computation is also presented. Even for a "small" waterflood model with two layers and 8,164 active cells, a speedup of 3.9 was experienced on a four processor CRAY Y-MP; 3.3 on an IBM 3090-400S. Larger models exhibit almost ideal performance. Results are presented for up to eight processors (CRAY Y-MP). These results confirm our view that the performance potential of the parallel processing environment can be realized by reservoir simulation.
Towards a More Effective Parallel Reservoir Simulator
Authors: Meijerink J. A. , van Daalen D. T. , Hoogerbrugge P. J. , Zeestraten R. J. A.
Published: December 2007

In 1989 it has been reported how an operational black/volatile oil reservoir simulator of IMPEC type has been successfully parallelised for a medium-scale (10-100 processors) local memory MIMD

architecture1. The present paper reviews the principles underlying the parallelisation and describes the further development of the parallel simulator. Some attention is given to the linear solver which is of conjugate gradient type, with a local, block-wise preconditioner. A novel acceleration method, CGSTAB, for the solution of non-symmetric linear systems is described.

The parallel simulator is now being evaluated in an operational environment. It has been installed on a 90 processor, 5500,000 Meiko M40 that should support two simultaneous job streams, each running at one quarter to one half (depending on the input) of the speed of a 1 processor Cray-XMP.

So, at present, parallel computing leads to a substantial reduction of computing cost. In the very near future however, parallel computing machinery of the same family but based on the latest hardware, will beat traditional sequential computers on absolute performance too.
Field-Scale Simulation of Horizontal Wells with Hybrid Grids
Authors: Collins David A. , Nghiem Long X. , Sharma Ravi , Agarwal Rajeev K. , Jha Kamal N.
Published: December 2007

For an accurate simulation of horizontal-well performance, both flow in the wellbore and in the vicinity of the wellbore have to be modelled. This paper combines a novel technique for simulating horizontal wellbore hydraulics with an elliptic grid refinement around the wellbore to address both issues.

The wellbore is represented by a row of cylindrical gridblocks where the well "permeability" and "relative permeabilities" are adjusted to yield the pressure drop and phase slippage predicted from multiphase flow correlations. With this method of coupling, the wellbore equations have the same primary variable set as the reservoir equations. This allows for a consistent application of the efficient solution techniques developed for reservoir simulation.

For a detailed simulation of flow around the wellbore, a system of fine elliptic and hyperbolic grids is used. It is shown how this grid system is constructed and coupled to the Cartesian coarse grids.

Simulation runs showing the importance of both wellbore hydraulics and flow in the vicinity of the wellbore are presented.
Seventh SPE Comparative Solution Project: Modelling of Horizontal Wells in Reservoir Simulation
Authors: Nghiem Long , Collins David A. , Sharma Ravi
Published: December 2007

This paper reports the results of comparisons of simulation runs performed by fourteen organizations on a problem involving production from a horizontal well in a reservoir where coning tendencies are important. The effect of well length and rates on the recovery is examined. In addition, the paper also reports the techniques used by the different participants to calculate the inflow into the horizontal well and the wellbore hydraulics.

A variety of methods was used by the participants to model the inflow into the horizontal wells ranging from the use of productivity indices to grid refinement. A multitude of techniques was also used to calculate wellbore hydraulics while a few participants selected to represent the wellbore by a constant-pressure line sink.

All participants consistently predict a decrease in the coning behavior with an increase in well length. However, variations in the predictions were observed. Although the modelling methods from different participants can be grouped into different categories, no trend in the predicted results, according to the methods used, could be observed.
An Automatic Ordering Method for Incomplete Factorization Iterative Solvers
Authors: D’Azevedo E. , Forsyth P. A. , Tang Wei-Pai
Published: December 2007

The minimum discarded fill (MDF) ordering strategy for incomplete factorization iterative solvers is developed. MDF ordering is demonstrated for several model non-symmetric problems, as well as a waterflooding simulation which uses an unstructured grid. The model problems show a three to five fold decrease in the number of iterations compared to natural orderings. Greater than twofold improvement was observed for the waterflooding simulation.
Characterization of Mixing Length Growth for Flow in Heterogeneous Porous Media
Authors: Furtado F. , Glimm J. , Lindquist W. B. , Pereira L. F.
Published: December 2007

The scale up problem concerns the prediction of field scale fluid flow properties from smaller scale (laboratory) data. It has been observed from field data that the mixing length for two phase flow has anomalous scaling behavior. Recent theoretical and computational developments have confirmed that anomalous scaling behavior results from multi-length scale heterogeneities not observable at laboratory length scales.

Two main results are presented here. One is a generalization of the fractal analysis of rock and fluid mixing properties, as a first step in moving from idealized self-similar reservoir properties to realistic geology. The other is a refinement of earlier computational results demonstrating anomalous diffusion for flow through reservoirs with weakly decaying fractal correlations.
A Global Optimization Approach to Grid Generation
Authors: Farmer C. L. , Heath D. E. , Moody R. O.
Published: December 2007

Simulation of heterogeneous reservoirs can require distorted grids to give an accurate model of the reservoir geology with a moderate number of grid cells. In this paper we study grid construction in which grid lines are encouraged to follow either the boundaries between different rock types or regions of different permeability. An algorithm is described which finds a global near-optimal solution, to such problems.

We find that, even with grid controls, good grids can depart from orthogonality. The final part of the paper therefore considers the problem of discretisation on near-orthogonal grids. We describe a mixed finite element approach which is a natural and compact generalisation of the standard block-centred finite difference method.
Simulating Naturally Fractured Reservoirs Using a Subdomain Method
Authors: Beckner B. L. , Chan H. M. , McDonald A. E. , Wooten S. O. , Jones T. A.
Published: December 2007

A subdomain formulation for modeling naturally fractured reservoirs is presented. "Representative Matrix Blocks" are subdivided into rectangular rings and layers to enhance pressure and saturation gradient resolution within the blocks. Improved description of matrix capillary and gravity forces can be achieved through this formulation. A three phase coupled implicit algorithm incorporates pressure dependent gas/oil capillary pressure，fracture permeability, and fracture porosity. Segregated and dispersed fracture fluid options are given, and field-scale simulations of primary depletion, water injection and gas injection are presented.

Naturally fractured simulations with matrix block discrefcizafcion can yield significantly different production forecasts from those without internal discretization. Quarter five-spot, low permeability waterfloods show differences in cumulative oil recovery as large as 35 percent. For small blocks, or moderate matrix permeability, differences in simulated oil rate are less than 10 percent.

The dependence of gas/oil capillary pressure on pressure is shown by example to have a large effect on oil production rate. Jones' relations17 between pressure and fracture porosity and permeability lead to modest changes in oil rate when compared with constant fracture properties. At early times fracture permeability reduction decreases oil rates, while fracture porosity variation leaves oil rates unaffected.

Segregated fluid flow in the fractures leads to smaller matrix/fracture fluid transfer rates, and hence lower oil recovery. A dispersed water phase in the fracture is exposed to larger matrix surface area, creating additional opportunity to exchange itself with oil contained within the matrix block.
Quick Determination of Pressures in Well-Spacing Patterns
Authors: Higgins R.V. , Leighton A.J.
Published: December 2007

American Institute of Mining, Metallurgical and Petroleum Engineers Inc.

A quick method to determine the pressure distribution between wells for various well patterns is presented. In the determinations, patterns is presented. In the determinations, the effect of well diameter may be included. Comparison of the results with potentiometric models presented in the literature showed excellent agreement. By the method presented, it would be easy to obtain quickly the pressure distribution in an entire reservoir.

The computer program uses the flowing well pressures at bottom of wells to calculate the pressures at bottom of wells to calculate the pressure distribution throughout the entire pressure distribution throughout the entire reservoir. The program is relatively short and uses the grid method for solution. It uses the point successive over relaxation technique point successive over relaxation technique [Liebmann accelerator] and has an open subroutine to increase the size of the accelerator if the progress of the computation so requires.

Use of the program saves construction of a potentiometric model. The printed pressure potentiometric model. The printed pressure distribution can be obtained quickly. Another advantage is that the effect of any change in the location of wells or pressures about the wells can be ascertained quickly—average computer time was less than 2 minutes.

Introduction

The literature mentions that a series of steady-state flow equations may be used to mathematically represent unsteady-state flow after the initial withdraw of a small quantity of fluid. As a result, pattern efficiency in reservoirs can be investigated reasonably accurately by assuming steady-state flow during the period of interest. The advantage of steady-state flow is the reduction in time needed to obtain a solution. The results presented in this report are steady-state presented in this report are steady-state solutions except in one instance where an unsteady-state calculation for a slightly compressible liquid was used to obtain well pressures for subsequent steady-state solution of the pressure distribution throughout the reservoir. pressure distribution throughout the reservoir. Streamlines may be drawn on plots of the pressure distributions obtained using this pressure distributions obtained using this method. The shape factors and areas of the cells formed by the resulting flow nets may be calculated and the resulting data used in the prediction of fluid injection performance. However, obtaining the streamlines performance. However, obtaining the streamlines and shape factors are not included in this paper. paper.

THEORY

The solution by finite differences [numerical methods] of the Laplace equation to determine the potential distribution in two dimensions has been reported in the literature.
Recent Case Histories of New Well Applications for Horizontal Drilling
Authors: Bitto R. , Henderson A. B. , Broussard L.
Published: December 2007

In the tradition of other papers that have reviewed horizontal technology and experience (1,2,3), this paper will present a relatively current summary of the status of horizontal drilling. The result of an extensive review of the published literature, careful study of numerous post-well reports, and personal conversations with drilling engineers and directional drilling supervisors who have conducted horizontal drilling operations, the following brief discussions of case histories describe a variety of drilling methods which were used in oilfields in various parts of the world.

It will be evident that in the past few years great strides have been made to advance horizontal drilling in three main disciplines. These are: Well planningDrilling mechanics, andRig site operations
Injection System for Microfrac or Step-Rate Testing
Authors: Hamid S. , Jackson B. M. , Legenza J. E.
Published: December 2007

Constant rate injection of a fluid into a well for microfrac and step rate testing is accomplished through the use of an injection system. The system provides accurate flow rate control (within 2% of the desired rate) during injection, which results in superior quality of data such as the fracture extension pressure, etc. for formation analysis. The injection system eliminates discontinuities in flow rate which may be present when using an engine-driven pump with a manual transmission. The inherent flow rate fluctuations present in the positive displacement pump flow rate are also minimized by the injection system. The system permits use of a large fracturing pump for low flow rate injections, thereby increasing the rangeability of the service equipment, which results in lowering the costs.

Laboratory test data and numerically generated results of a computer model are presented in this paper, along with case histories of two jobs.
Rock Matrix Properties of the Ratcliffe Interval (Madison Limestone) Flat Lake Field, Montana
Authors: White E.J. , Marchant L.C. , Roberts D.K.
Published: December 2007

American Institute of Mining, Metallurgical and Petroleum Engineers Inc.

Because fundamental reservoir information is frequently lacking in complex carbonate formations,, sound interpretive methods cannot be applied. This report presents the results of numerous laboratory tests of core samples from 20 wells in the Ratcliffe interval of the Madison limestone in the Flat Lake field in northeastern Montana.

Correlations between porosity, permeability, saturation characteristics, mineral permeability, saturation characteristics, mineral constituency and pore geometry inferred from mercury injection measurements are discussed. The heterogeneity of the matrix and its influence on fluid flow, saturation and wettability characteristics of the reservoir are considered.

The matrix permeability is preponderantly related to a relatively small fraction of the pore volume having pore entry radii larger than pore volume having pore entry radii larger than about 0.5 microns, while the porosity is mainly attributable to smaller pores. Pore geometry determined by mercury injection measurements may be correlated with permeability but not with porosity. Although a favorable water-oil mobility ratio for the matrix is inferred from the laboratory data, the very low effective permeability to water indicates that injection permeability to water indicates that injection rates will be low.

Background

In general there is less fundamental knowledge about the physical properties and performance characteristics of carbonate performance characteristics of carbonate [limestone and dolomite] reservoir rocks than of sandstones, because of the usually more complex depositional environment and post depositional processes that affect carbonates. In many processes that affect carbonates. In many fields these factors result in frequent vertical and lateral changes in lithology that make meaningful correlations very difficult. When basic reservoir information is lacking, fundamental engineering principles and sound interpretive procedures cannot be applied, and more or less intuitive procedures become accepted practice. practice. The petroleum industry has recognized for some time the need for greater emphasis on carbonate reservoir research and in recent years has supported a much greater research effort in this area.
Use of the Low-Volume Flowmeter in Devonian Shale Wells of the Appalachian Basin
Authors: Walbe K. , Collart D. , Young F. , Beal J.
Published: December 2007

Locating and measuring low volume gas entries is a critical problem in many Devonian Shale wells in the Appalachian Basin, since many of the small gas entries are below the resolution of conventional geophysical logging tools.

The Low Volume Flowmeter (LVFM) is an extremely sensitive flow measurement tool that consists of three basic parts. The lowest part of the tool contains the sensor section which is comprised of a pressure transducer and a tracer gas reservoir positioned below a tracer gas detector; the upper part of the tool which contains the casing collar locator for cased hole referencing; and the central section which contains the gamma ray detector for lithology correlation in both open and cased holes.

Flowrate is determined by injecting a tracer gas into the gas flow. The dilution of the tracer gas is then measured at a downstream detector. Mass flow is therefore determined by this method rather than the velocity of the gas in the wellbore as measured by conventional production logging spinner surveys. Therefore, the LVFM can measure a full spectrum of flow rates independent of variables which may affect other conventional production logging equipment including gas composition, inclination of the wellbore, temperature, size of tool, irregular borehole diameters and large variations in gas flow rates from different pay zones in the well.

The LVFM is capable of being stacked with other geophysical tools for both open and cased hole operations in vertical and horizontal wells.
A Portable Device for Analyzing Cements Under Simulated Pumping Conditions
Authors: Surjaatmadja J. B. , Lee C. L.
Published: December 2007

A recently developed, portable cement laboratory instrument has been used to test cement consistency under actual downhole conditions. Control variables include pressure, temperature, and shear experienced by a cement slurry in the test. During a simulated temporary suspension of pumping, the device can perform static gel strength evaluations to help predict pumpability of the cement. In addition, the device can also perform static gel strength tests after the job to allow further cement quality evaluations.

When a computer is used with the instrument, the user simulates actual conditions of the lead, tail, or intermediate cement slurry. The computer uses this information to control pressure, temperature, and shear rate during simulation. Accurate simulation of job parameters can provide closer predictions of cement performance.

Portability of the instrument gives an additional option for the user as to where the instrument is used. In the laboratory, the cement testing instrument is used as an aid in slurry design to better meet job requirements. On location, such as on an offshore rig, the cement testing device can be used with well instrumentation and a microprocessor to acquire information about a cement job. The computer can calculate proper job parameters to be used to test the slurry. Slurry samples to be tested can be taken from the lead or tail cement. A closer prediction of the cement on-job performance is provided.
Theory and Empirical Data on Production and Reserves Affected by Compressors, Clinton Wells
Authors: Fox W. F. , West M.
Published: December 2007

This paper presents the results of the implementation of compression to increase the deliverability of Clinton sandstone natural gas wells by lowering the effective line pressure against which the wells must produce. Graphs in this paper display the historical producing rates with time, both before the compression was implemented and after the compression was implemented.

The wells studied are producing natural gas through the tubing, through valves that open and close intermittently with duration of flow time and shut-in time controlled by clocks. Some of the wells have controls located at the wellhead and some are controlled at the separator.

Comparisons are made between estimated reserves that would have been produced and accompanying economics without compression versus estimated reserves to be produced and accompanying economics with compression. The estimated incremental reserves and revenue are compared to the initial cost to install the compression.

Duration of intermittent flow times and shut-in times and the accompanying pressures before compression are compared to those subsequent to implementation of compression.

Comments are included concerning the use of the "decline curve" to estimate natural gas reserves.
Fracturing Study of the Elk Sands of Southwestern Pennsylvania
Authors: Reese R. R. , Poulsen D. K.
Published: December 2007

The Elk Sands in Clearfield and Cambria Counties of Southwestern Pennsylvania have been difficult to successfully fracture stimulate. Treatments successfully applied to the upper Devonian Sands resulted in screenouts andlittle productivity increase when applied to the Elks. This paper discussesvarious studies that have been conducted, including net pressure analysis and threedimensional modeling, to understand the fracturing behavior of these formations. Recommendations are made for improving future treatments of these formations.
Electronic Controller for the Optimization of Plunger-Lift Wells
Authors: Crow R. W.
Published: December 2007

New developments in controller design that simplify plunger lift operations and obtain maximum production are always needed. Many plunger lift wells are currently operated by electronic controllers which utilize either time and/or pressure to regulate production. Some monitor casing, tubing, and sales line pressures and are designed to respond to predetermined conditions. Even though these controllers automate the plunger lift operation, maximizing is still a trial and error process. As the well conditions change, the programmed values used by these controllers do not change, requiring continuous operator adjustment for optimization.

Now, using an electronic microprocessor programmed to interface with a sensor installed at the well head, a controller can constantly monitor plunger arrivals and automatically adjust plunger operation to maximize production. This paper will describe the controller's logic and function in plunger lift operation and present typical case histories.
Geotechnical Evaluations for Siting Horizontal Wells in Devonian Shale Reservoirs
Authors: Mroz T. H. , Schuller W. A.
Published: December 2007

Geologic mapping techniques are used to define the orientation and production potential of fractured fairways in the Devonian shales. Two directional well site evaluations show the rationale behind selection of the sites and determination of well design geometry. Three-dimensional models are developed for each site. The threedimensional model is shown to be an economical tool for defining and developing a producing reservoir.
Rigless Acid Fracturing Through Dual Completions: An Offshore Experience in the Upper Zakum Field
Authors: Al Tamimi Y. K.
Published: December 2007

Well Stimulation by Fracturing (Acid & Hydraulic) was quickly accepted by the Oil Industry since its introduction in the late 40's (first ever hydraulic Fracturing job was conducted in Kansas, U.S.A. in July, 1947), still, its applicability to Abu Dhabi fields and reservoirs did not gain momentum until the 80's. This late arrival can be attributed to the fact that poor Permeability Reservoirs were not considered for development before then, or because, even when the development of these "tight" Reservoirs was undertaken (as is true for the Upper Zakum), too many constraints were imposed (Geological, Reservoir and type of Completion). Such constraints made fracturing difficult to carry out.

Also, major advancement in Fracturing design and techniques took place in the 80's. Such techniques made it possible to reexamine the applicability of fracturing in the poor potential wells of the Upper Zakum.

This paper presents a review of the steps taken to ensure the success of Acid Fracturing in poor Permeability wells, and how constraints / limitations imposed by well completion and reservoir conditions were accounted for. . The exercise was successfully carried out in the multilayered heterogeneous reservoir of Thamama II in the Upper Zakum field, offshore Abu Dhabi.

The uniqueness of the exercise is that in all cases presented, Acid Fracturing treatment was conducted through one tubing string in dually completed wells, yet on rigless basis. Good post treatment productivity was achieved at optimum cost and therefore minimum pay back time.
Through Tubing Gas Saturation Monitoring
Authors: Watfa M. , Pollock D.
Published: December 2007

Quantitative gas saturation monitoring have always been a desired target for fluid monitoring in hydrocarbon bearing reservoirs. Over the years many techniques were attempted for monitoring gas saturations which involved the use of both open hole and cased hole logs. None of these techniques gave a reliable measure of gas saturation, and their results were considered at best qualitative. In many reservoirs in the Middle East, the need for an accurate technique of gas saturation monitoring became more acute because of gas cap expansion or the formation of secondary gas caps, which are on the whole the product of reservoir depletion. Moreover, high production rates in permeable reservoirs resulted in gas coning and the production of free gas.

With the introduction of the Dual-Burst Thermal Decay Time (TDT-P) Tool, accurate through tubing measurements are now available that have opened new horizons for gas saturation monitoring. Such data was used successfully to monitor quantitatively gas saturations in various reservoirs in the Middle East. The technique involves the use of the two measurements from the TDT-P: capture cross-section (∑) and porosity (øtdt). These two measurements were combined with results from open hole log evaluations, such as lithology, porosity and clay volume, to solve for values of water, oil and gas saturations. This technique was tried on a large number of wells, and the accuracy of the results, for most of the reservoirs under study (porosity >15 pu), is of the order of 10 saturation units.
Carbon Dioxide Corrosion in Oil Wells
Authors: Gunaltun Y.
Published: December 2007

After detection of severe corrosion in Umm-Al-Dalkh oil wells, well production and fluid characteristics, metallurgy of tubing material, downhole operations were reviewed in order to define the main reasons of corrosion. Some of the wells were Caliper surveyed. Worked over tubing and X-mas trees were inspected.

Inspection results were correlated with different parameters which may influence CO2 corrosion in oil wells.
The Design & Implementation of a Digital Control System on an Operating Plant
Authors: El Komy O. F. , Shukri T.
Published: December 2007

The LNG plant on Das Island, Abu Dhabi, has been in operation since 1976. Its control system has been modernized from conventional analogue to a distributed control system (DCS) utilizing a Honeywell TDC3000 system. The Plant control was changed over from the old system to the new system on a loop by loop basis whilst the units remained in operation.

This paper outlines:

– The various phases of the DCS retrofit project. – Change over planning and implementation. – Benefits gained from applying the modern control technology to the plant – Experience gained by ADGAS.
Controlling Water Flood Advance in Asab Thamama B Reservoir
Authors: Hassan A. , Youssef Fahd , Ayoub M.
Published: December 2007

After fifteen years of production/injection history from Asab Thamama B reservoir, a detailed experience has been gained in controlling and monitoring the waterflood advance. This can be considered as a field example which is illustrative of the various carbonate reservoirs of the Thamama group, in ADCO concession (Fig. 1).

Further to a detailed geological model which was obtained after the drilling of some 200 wells, a simulation study was performed to evaluate several water flooding scenarios. Peripheral water injection was selected with an optimised distribution of water per area and per pseudo-reservoir.

Monitoring of the water advance has been achieved through open hole logs, cased hole logs, water cut measurements and wet well performance. Results have been used to establish water front advance per layer and to evaluate displacement efficiency by water.
Detection of Gas and Water Fronts by Pressure Buildup Surveys
Authors: Khalaf A. A. W.
Published: December 2007

Umm Shaif is a field where the oil bearing zone is trapped between a massive gas cap at the crest and a peripheral aquifer supported by peripheral water injectors. In this field, pressure build up surveys managed to distinguish between gas and water fronts and to determine the distance to either of these fronts long before the fronts reach the wellbore. The gas front behaved as a constant pressure boundary, while water acted as a pressure support boundary.
Simulation of Artificially Fractured Wells with Single-Well Models
Authors: Haddad S. H. , Sonrexa K.
Published: December 2007

This paper presents a new approach to forecast the behaviour of an acid-fractured well by numerical simulation. Unlike the known conventional methods, the present technique applies the "Dual-Porosity System" theory.

Several wells were individually modeled successfully using their production history and all the pre-fracture and post-fracture pressure buildup tests in a single continuous run.

The forecasted pressures and oil rates were in good agreement with their actual values. Also, the fracture lengths imposed to match the post-frac history showed good agreement with the values derived from test analyses. This method, thus, provides a viable predictive tool and a means to support the well test interpretation results by respecting more precisely, as we believe, the flow pattern in the vicinity of the wellbore and within the fractured medium.
Drilling Simulation for the Design of Horizontal Wells
Authors: Burnham M. P. , Boulter D.
Published: December 2007

Drilling engineering design tools have been used to investigate torque/drag behaviour, tubular buckling in highly inclined and horizontal wells and casing wear susceptibility. Used in concert or separately, these drilling simulators are useful tools for the design of extended reach and horizontal wells. Work to date has proven the use of these computer programs in the field. This paper addresses the application of these drilling engineering tools for horizontal wells. Their application and effectiveness is illustrated in the planning of the the North Sea's first horizontal well drilled from a floating vessel. Furthermore, their use in the pre-planning of developments is discussed, with emphasis placed on developing a strategy to identify the mechanical limitations of horizontal drilling.
East Zeit Field Reservoir Management
Authors: Johnson J. D. , Mohamed H. B.
Published: December 2007

The effective reservoir development and surveillance of East Zeit field has achieved resource delineation and improved profitability, despite significant technical difficulties caused by the very complex geology (intensive faulting, facies changes) and lack of interpretable seismic (variable salt layers). Results of two successful development drilling programs, reservoir performance, and model studies are discussed. New techniques for interpreting seismic data which show potential for significant advances in the ability to map East Zeit field are also presented.

Material balance studies identified significant reserve potential at East Zeit. This potential was assessed with a reservoir model developed in Houston and confirmed with a PC-based simulator in Cairo. Less than four years after initiating production, proved reserves were increased by over 100% to nearly 80 MBbl (12.7 Mm3) based on results of consolidated engineering and geological studies. A well workover and additional drilling program has increased well production capacity to 25-30 kBbl/d (4.0-4.8 km3/d). The second phase of development drilling has shown that potential exists for additional reserves in the field.
The Hydrotreatment Of Coal-Derived Oil
Authors: White Paul J. , Jones J.F. , Eddinger R.T.
Published: December 2007

The Office of Coal Research, Department of the Interior, sponsors research and development to encourage and stimulate the production and conservation of coal in the United States. ARCO Chemical Company, a Division of the Atlantic Richfield Company, and FMC Corporation have been carrying out research and development under Project Seacoke and Project COED, respectively. One of the products from the COED process is a coal-derived oil intended to be asynthetic crude oil. The Seacoke process would also produce a similar material. ARCO, as part of their job, was charged with advancing knowledge in the field of hydrotreating materials such as would be derived from these two processes. Accordingly, the following work was carried out by ARCO under their OCR-sponsored project utilizing oil produced by the COED process. As produced, the coal-derived oil has a low hydrogen content and a high concentration of heteroatoms, making it unsuitable for use in many existing refining processes. Hydrotreating of the oil is required to alleviate these shortcomings. Treating was carried out in a continuous downflow system employing a recycle hydrogenstream. Throughout the program, a single catalyst, HDS-3A, manufactured by American Cyanamid, was used. It is a 1/16-inch extrudate containing 3.0% NiO and 15.0% MoO3 on alumina.
The Role of 3D Seismic on the Future Development of the Idd el Shargi Field, Offshore Qatar
Authors: Jubralla A. F. , Hamam K. A.
Published: December 2007

This paper discusses the results of the 3D Seismic Survey acquired in 1987 in the Idd el Shargi North Dome with the objectives of defining the detailed structural picture of the Shuaiba reservoir.

Initially pattern waterflood was the preferred development option as the field appeared simple and sparsely faulted based on old 2D seismic. 3D interpretation has shown two main fault systems, one of which had not been recognised before. The crest is intensively faulted whereas the flanks are either unfaulted, or have only one fault system. The crestal area will now be developed by gas/oil gravity drainage process. Other areas of the field are still under study.
Microbial Corrosion and Biologically Induced New Products Example from a Seawater Injection System, Umm Shaif Field, U.A.E.
Authors: Lapointe P. A. , Muhsin M. A. , Maurin A. F.
Published: December 2007

The detrimental role of sulphate reducing bacteria (SRB) and their generation of the highly corrosive hydrogen sulphide gas is well established. There is evidence of the presence of carbonate generating bacteria (CGB) in association with SRB in the water injection system of Umm Shaif field offshore Abu Dhabi.

These bacteria tend to produce solid calcium, magnesium and iron carbonates which constitute a significant amount of debris forming part of the protective media for SRB growth and plug the formation if it is dislodged from the pipe wall and transported to the injectors.

The evidence for CGB existence together with other bacterial activity is obtained from chemical analysis, X-ray diffractogram, microprobe analysis and scanning electron microscope examination.
Monitoring Sweep in Peripheral Waterflood: A Case History
Authors: Rouser B. J. , Al-Askar Y. A. , Hassoun T. H.
Published: December 2007

This paper examines the techniques used and the results obtained in monitoring the water advance in a peripheral waterflood of a carbonate reservoir. The peripheral pattern used in the subject reservoir gives a water advance similar to that obtained in a water drive reservoir. However, monitoring this particular reservoir is complicated by the use of a low salinity brine for flooding and the areal shape of the reservoir.

The use of pulsed neutron capture logging in conjunction with production logging has been effective in differentiating between oil and water in porous zones in existing producers. The use of the two logs has been successful despite the problems normally encountered when logging open hole completions in a reservoir being flooded with a low salinity brine. Results have been confirmed and enhanced by open hole logs of new wells being drilled in the water invaded areas.

The paper highlights difficulties encountered, such as acid effect on the pulsed neutron capture log response and the effect of lower salinity flood water as the reservoir becomes better swept. The techniques used to overcome these problems is discussed. A number of examples are shown and a remaining oil map prepared from these surveillance techniques is examined.
Tectonics, Stratigraphy, and Hydrocarbon Exploration in the Strait of Hormuz
Authors: Pauken R. J. , Hemer D. O.
Published: December 2007

The objective of this study was to describe the little-known structure and stratigraphy of the Strait of Hormuz in terms of the better known stratigraphy and tectonic history of the Oman region. Four structural provinces surround the Strait of Hormuz: (1) the Zagros fold belt to the northwest (2) the Arabian Platform to the southwest, (3) the Makran Basin to the east and (4) the Oman Mountains to the south. The development of these structural provinces, over 260 Ha of geologic time, influenced the stratigraphy and structure of the Strait. This was the result of rifting and sea-floor spreading (opening of Neo-Tethys) in the late Paleozoic and early Mesozoic and a variety of tectonic events associated with the closure of Neo-Tethys and the northward motion of the Arabian Plate, from mid Cretaceous to Recent.

The stratigraphic section encountered in the Strait ranges in age from Infracambrian to Recent and is composed of four depositional sequences bounded by prominent regional unconformities. These include; Permian-Triassic rift sequence deposited during the opening of Neo-Tethys, a Jurassic-mid Cretaceous carbonate shelf sequence, a late Cretaceous orogenic sequence and Tertiary-Recent orogenic and post-orogenic deposits.

The most dramatic regional tectonic event was the closing of the Tethyan seaway during the late Cretaceous, illustrated by thrusting of the Hawasina nappes and obduction of the Semail ophiolites along the eastern Oman margin, south of the Dibba Zone. Structural development associated with this event is not easily recognized in the Strait. This is because of the overpowering structural effects of the younger Miocene compressional episode, the most important tectonic event recorded in the Strait.

Miocene structuring resulted in the formation of anticlinal and horst features associated with thrust faulting, resulting in a SSW-NNE structural grain paralleling the Oman Peninsula. These structural highs were subsequently eroded, producing a prominent angular unconformity which is easily identified on seismic sections. Some of the structuring was locally enhanced by diapirism of the underlying Hormuz Salt. Above this unconformity is a relatively flat-lying post-orogenic sequence of Miocene limestones, shales and sandstones which would constitute a potential seal for any hydrocarbon accumulations reservoired in the underlying structures.

Potential reservoir facies include fractured Middle Cretaceous to Lower Tertiary limestones present under the Miocene unconformity and thick, eastward-thickening, turbidite deposits of the same age. Numerous wells drilled in the Southern Arabian Gulf Basin, west of the Strait have encountered both oil and gas. The occurrence of oil and gas wells, along with numerous shows and undrilled structures indicate that this area should be given careful consideration for future exploration.
Horizontal Well Technology: Performance Evaluation and Technoeconomic Assessment
Authors: Singh R. S.
Published: December 2007

Horizontal wells could turn out to be one. of the. most Important technological developments of the decade. What was considered an exotic way of drilling in early eighties, and mote ox less an extension of deviated drilling, now appears as a significant production technique.

The paper computes the productivity indices, Pls for both horizontal and veitical wells, the ratio of Pls E the replacement factors. Three variants have been cons-idered, viz drilling of vertical, short-radius and long radius horizontal wells in a fractured basement reservoir. Performance prediction and technoeconomic evaluation has been made for future.

Extensive literature review has been carried out and computations made. It is concluded that even though horizontal option appears to be beneficial, obviously there are cases when it not so. For the examples considered herein, long-radius horizontal well completions are found bettet than both vertical and short-radius horizontal well completions, but vertical welis seem to have an edge over the short-radius horizontal wells.
The Application of Local Grid Refinement to Simulate a Large Hydrocarbon Reservoir as an Alternative to a Two-Model Approach
Authors: Al-Towailib H. S. , Liu J. S.
Published: December 2007

Simulation of a large hydrocarbon reservoir that interacts with other producing reservoirs through a common aquifer with a single regular fine-grid model can be very difficult if not entirely impossible. Such a model will require a very large number of cells in order to account for all interactions among the producing reservoirs and still provide enough resolution in the window area being studied. Due to the limitations in computer hardware that can handle the enormous resources required by the model and the solution algorithm, this task is found to be impractical.

A two-model approach has been used to overcome this difficulty. In this approach, a coarse-grid, areal model of all reservoirs and the aquifer and a fine-grid, three-dimensional model of the window area of interest are used. The two models are run alternately to feed each other with reservoir rates and boundary conditions while the convergence of boundary conditions is maintained. This approach is found to be resource intensive and requires excessive human effort.

This paper discusses the application of the local grid refinement approach as an alternative to the two-model approach to simulate a large hydrocarbon reservoir. The local grid refinement approach involves use of only one model of the reservoir and its associated aquifer system. It allows a finely gridded multi-layer model of the reservoir of interest to be imbedded into a coarsely gridded, single-layer areal model of its associated aquifer system. Consequently, the number of cells is reduced significantly and it becomes practical to simulate the large hydrocarbon reservoir and its associated aquifer system in one model.

For this purpose, therefore, a locally refined grid model was constructed and initialized using data from the already existing models used in the two-model approach. History match runs were made successfully. If compared with the two-model approach, the LRG model history match results are favorable.

The LRG model approach is found to be more advantageous than the two-model approach in terms of eliminating the inaccuracies, the excessive resources, and the intensive human efforts associated with the two-model approach. The simulation results has proved that this approach is feasible and more efficient than the two-model approach. Therefore, the use of this approach will greatly simplify the simulation of the large hydrocarbon reservoir and its associated aquifer system.
Geology and Hydrocarbon Potential of the Tihama Basin, Republic of Yemen
Authors: Doornenbal J. C. , DeGroot P. F. L. , Saif S. M. , Schroot B. M.
Published: December 2007

The Tihama basin at the west coast of Yemen was studied to gain a thorough understanding of its geology and hydrocarbon potential. Literature, field data, ten deep exploration wells, five shallow stratigraphic tests and a selection of seismic data were studied, resulting in stratigraphic correlation profiles and structural sections. The study comprises a compilation of exploration data gathered by different companies since the early 1950's. A gross structural and sedimentological model for the area was the result of the study. The Miocene to Recent sedimentary suite can be divide into three units: the Pre-Evaporite, the Evaporite and the Post-Evaporite Groups. The area can be divide in six different structural elements according to the location relevant to the spreading axis of the Red Sea and to the central part of the Miocene salt basin. Potential traps abound in the Pre-Evaporite and the Evaporite Group. In the Post-Evaporite Group the hydrocarbon potential is questionable because of lack of seal. Throughout the study area the quality and degree of maturation of the source rocks appear to be highly variable.