bluuebunny/crossref_metadata_2025_split huggingface dataset:
The Comparable Efficiency of Mathematical Techniques Used in Reservoir Simulation
Authors: Traylor C. , Sheffield M. 
Published: December 2007

Abstract
The results of this work compare the computing efficiency of several mathematical methods which can be used in solving the equations governing reservoir fluid flow. Two-dimensional, water-oil movement in a vertical cross-section and in two areal reservoirs are considered as examples. The fluids used are slightly compressible and both gravitational and viscous forces are considered. The mathematical techniques considered are successive line overrelaxation; block Jacobi, semi-iterative; iterative and noniterative alternating direction implicit; the strongly implicit procedure; symmetric successive line overrelaxation, semi-iterative, and line Saul'Ev.
A new method is presented for comparing "equal quality" results. Basically, this involves the determination of a correlation of quality in a material balance-type term vs quality in solving the equations, the L2 norm. The conclusions of this work disagree with reports in the literature in some respects. These differences are attributed to the fact that a compressible fluid system was considered in this work. Results indicate that geometry and fluid properties affect the convergence rates of iterative techniques. Furthermore, noniterative techniques require extremely small time steps to produce the same quality solutions as iterative techniques produce.

Introduction
The use of reservoir simulators to predict field performance has become widely accepted by the petroleum industry in the past decade. Engineers use both iterative and noniterative techniques to obtain approximate solutions of linear equations which described fluid flow. Variational methods are presently being investigated. With the increased used of reservoir simulators, means of reducing the computer time required to make field studies are needed. Indeed, the amount of computer time required to solve a particular field problem may vary tenfold, depending only on the mathematical method used.
This investigation is concerned with comparing the computational efficiency of solution techniques of finite difference approximations to the equations describing reservoir fluid flow. Iterative methods are discussed in detail and noniterative methods are briefly considered. Iterative procedures usually require a set of parameters to speed convergence to an acceptable parameters to speed convergence to an acceptable answer. These methods are of little value to the engineer unless a reliable procedure for choosing effective parameters is known. Where possible, this investigation makes use of possible, this investigation makes use of programmed algorithms to compute parameters programmed algorithms to compute parameters internally in the reservoir simulator.
Formation Evaluation by Linear Programming In the Presence of Errors and Uncertainty
Authors: Ramsey Terry L. , Helander Donald P. 
Published: December 2007

Abstract
A proposed solution is presented for the evaluation of formation lithology, saturations and heterogeneities in the presence of errors. A general linear model was constructed capable of using all the available information. This model is indeterminate and requires a formalized decision-making process to evaluate the most likely formation properties. The indeterminate problem is solved by maximizing an index which problem is solved by maximizing an index which gives appropriate weight to experience and minimizes errors.
After a solution has been achieved, further analysis is possible for the investigation of the stability of the solution, for an indication of the quality of the data, and for a definitive evaluation of the influence experience has upon the final solution.
Examples of the solution are given for both mineral and petroleum evaluation.

Introduction
As a result of a series of analyses of the interpretative process necessary for the determination of formation properties, a number of techniques, usually computer implemented, have been published. However, because of major simplifying assumptions and a failure to recognize the requirements of the decision-making process which must consider experience, none of the solutions was entirely satisfactory. Experience is the quality which makes one solution more acceptable than others under otherwise identical qualifications.
In the early development of analytical models for formation evaluation, a simple lithology was considered which could be described by linear equations in a fully determined system. These models were extended to allow the inclusion of geological information and an arbitrary number of logs to evaluate more complex lithology. These solutions were useful; but, for cases of limited information or for complex lithology, the problem was indeterminate and could not be problem was indeterminate and could not be solved. Recognition of the indeterminate problem forced the examination of the solution problem forced the examination of the solution criteria and the objectives of log analysis. These problems were further accentuated by the recognition of possible errors in the log measurements.
The problem considered is determination of the most likely representation of the formation properties as described by well logs. The properties as described by well logs. The approach to the problem was to set up a mode that considered the physical characteristics within the limitations of the errors associated with the measurements. Any information expressed as an equality or as a limit was utilized.
The Effect Of Temperature And Pressure On Wave Velocities In Porous Rocks
Authors: Mobarak S.A. , Somerton W.H. 
Published: December 2007

Abstract
The interpretation of sonic logs from deep, high temperature reservoirs is complicated by lack of data on the effects of temperature and pressure on sonic velocity and the relation of these effects to pore properties. In the present work, dilatational wave velocities were measured for several sandstones and were found to decrease by as much as ten percent when temperatures were raised from 68F to 392F. This could result in over-estimation of porosity by nearly one-third. A temperature and pressure correction chart for interpretation of sonic velocity data is proposed.

Introduction
Improvement in drilling techniques and the consequent drilling of more deep wells have given rise to problems associated with the high pressures and high temperatures encountered in deep wells. Temperatures approaching 400F and pressures exceeding 10,000 psi are becoming common, leading to problems with drilling fluids and with the running of logs. In addition, the behavior of subsurface formations becomes more complex at these extreme conditions. For correct interpretation of logs run under these conditions, knowledge is needed of the effect of temperature and pressure on the property being deduced from the log data. An example with which this paper deals is the effect of high pressures and temperatures on elastic wave velocities in rocks and the relation of these effects to sonic log interpretation. The literature contains theoretical analyses and test results which indicate that elastic wave velocities increase with increasing pressure. Test results show that the rate of increase in wave velocities is higher at lower pressures than at higher pressures. This increase is attributed to closing of microcracks within the rock and to increase in grain-to-grain contact area with pressure.
Application of Recent Advances in the Mechanics of Sand Consolidation
Authors: Harrisberger W.H. , Coulter A.W. , Gurley D.G. 
Published: December 2007

Abstract
A complete shut-off of sand flow in producing wells can be attained and high success producing wells can be attained and high success ratios are possible. Successful sand control using sand consolidation plastics depends on complete coverage of the zone with a resin that will leave the formation well consolidated with the highest retained permeability. In addition, the consolidated formation must retain its strength for many years. The materials and techniques to accomplish these objectives are available.
Sand consolidation plastics have been in use since the early 1940's with varying degrees of success. Over the years there have been many improvements in the materials used, but these improved materials have not significantly changed the success ratios. It is now recognized that well completion and workover methods and job performance are probably more important than the performance are probably more important than the type or quality of resin used. In the past few years, many added improvements have been made in methods, materials and techniques. This paper will point out these improvements.
The completion techniques that will be covered are selection of perforated interval and perforation density. The job performance techniques covered will be cleaning of perforations, clean fluids, clean tubular goods, injection rates and pressures and zone isolation. Of prime importance are the considerations for prime importance are the considerations for consolidating dirty formations.
Some of the improvements in plastic systems that will be discussed include special pre-flushes, high-resin-content plastics, coupling agents, and diverting agents.
The overall purpose of the paper is to put together in usable form all the factors that must be considered in planning and performing sand consolidating plastic treatments and to establish guidelines that will lead to higher success ratios in these treatments.

Introduction
The degree of success with sand consolidation plastics is very difficult to measure because of plastics is very difficult to measure because of the wide variation of definition of success. However, a survey conducted by the API Southern District Study Committee on sand control indicated that the overall success ratio for sand consolidation plastics on old and new wells was 76 per cent. This plastics on old and new wells was 76 per cent. This same survey showed that the success ratio for gravel packs with liners was 72 per cent. Success here is packs with liners was 72 per cent. Success here is defined as either producing sand-free or at tolerable sand production.
Simulation of In-Situ Combustion in a Two-Dimensional System
Authors: Smith James T. , Ali S.M. Farouq 
Published: December 2007

Abstract
A two-dimensional mathematical model of the forward combustion process was developed and used for studying the effects of fuel content and air injection rate on the sweep efficiency attained in in-situ combustion. The model incorporates the effects of single-phase gas flow, heat generation by a combustion front, change of permeability in the burned zone, heat transfer by conduction and convection within the reservoir, and heat loss by conduction to the adjacent formations. A numerical scheme was developed to solve the system of partial differential equations constituting the model.
The model was used to investigate combustion in a quadrant of a five-spot pattern. It was found that as the fuel content of the reservoir increases (0.5 to 2.0 lb/cu ft), the sweep efficiency at combustion front breakthrough increases (68 to 84 percent) and tends to reach a plateau. The advantage of a high sweep may be offset, however, by a corresponding increase in heat loss and total air requirement. Sweep efficiency did not show a consistent trend with variation in the air injection rate for a given fuel content.
For a constant air injection rate, the percent heat loss from the reservoir increases percent heat loss from the reservoir increases linearly with the fuel content. Also, for a constant fuel content, the heat loss decreases with increasing injection rate. Feedback of heat from the adjacent formations into the reservoir was observed in the vicinity of the injection wellbore. Based upon the cumulative heat loss, however, this effect was negligible.
Breakthrough time for the combustion front increases rapidly as the fuel content increases. Accordingly, the cumulative air requirement for a project also increases with increasing fuel content.
For a constant injection. rate the peak temperature along the combustion front increases as the fuel content is increased. The temperature at any given point on the front varies in response to the existing fuel content, the magnitude of air flux, and the heat loss rate at that point. For a constant fuel content, the air flux is the factor which determines whether portions of the combustion front will be extinguished, resulting in poor reservoir sweep, high air-oil ratios, and economic failure.

Introduction
In-situ combustion is a highly promising oil recovery technique that has been tested under a wide variety of conditions. Up to now, however, a complete mathematical model of this complex process is lacking.
Pulse-Testing Method for Measuring Thermal Properties of Solids
Authors: Fairchild J.W. , Woods E.G. 
Published: December 2007

Abstract
This paper describes a new technique, thermal pulse testing, for the measurement of thermal conductivity, volumetric heat capacity, and thermal diffusivity of solids. Thermal pulse testing is a transient technique which is pulse testing is a transient technique which is analogous to the present technique of pressure pulse testing, a method of obtaining fluid flow pulse testing, a method of obtaining fluid flow properties between two or more wells. properties between two or more wells. Thermal pulse testing is superior in two major ways to other methods of obtaining thermal conductivities, heat capacities and thermal diffusivities. First, several simultaneous measurements of all three properties of a sample are obtained with one test. Secondly, an appropriate method of analysis eliminates any effect of linear temperature changes in the system during the measurement period, and it tends to reduce any nonlinear trends. One such method is described. Also, a measure of precision is obtained from tests made under precision is obtained from tests made under essentially identical conditions.
The method uses a small heater along the axis of a cylindrical sample and an accurate temperature sensor on the midplane of the cylinder at a known radial distance between the heater and outer boundary. Power is input, at a constant rate, to the heater with an alternating on/off pulse, while the resulting temperature response out in the sample is detected with the temperature sensor. The thermal properties are then determined from interpretation charts based on the exponential integral (Ei) solution of the diffusion equation, which assumes that the system is homogeneous with infinite outer boundaries and zero inner radius. Data from nonradial or finite-acting systems can be interpreted with other analytic solutions of the diffusion equation or by numerical regression techniques.
Experiments have been conducted to test the thermal pulse-test technique. The effects of changing pulse length and distance to the temperature probe were considered. Results obtained from a thermal pulse test of a known sample were compared with published values and with results obtained from the same sample by the thermal conductivity probe technique. The results obtained from this new technique compared well with both the published values and the probe technique.
The work described in this paper has shown that thermal pulse testing as a method of obtaining thermal properties is useful and practical.
Modeling High Angle Wells in Laminated Pay Reservoirs
Authors: Fair P.S. , Kikani Jitendra , White C.D. 
Published: December 2007

Introduction
Productivity improvement and acceleration projects have gained substantially from the success of horizontal well drilling technology. The successful placement of near-horizontal wells in difficult reservoir configurations has become routine. However, not all reservoir situations are amenable to horizontal drilling. Specifically, laminated reservoirs, such as thinly bedded turbidites in the Gulf of Mexico (GOM), have been perceived as poor targets. Potentially large reserves are locked in these reservoirs. These laminated turbidite systems have zero vertical permeability at the Bouma sequence scale and extremely small kv/kh ratios (kv/kh 0) at the full field, reservoir simulation grid block scale.
In general, a small well count is essential to help minimize development costs. To achieve requirements of both high productivity and small well count, highly deviated wells (80 &lt;90) cutting the entire sand package are desirable. Such well configurations have been known to improve productivity of these wells. However, the deviated well model given by Cinco fails to predict any improvement in well productivity. This apparent paradox is reconciled in this paper.
Bed thickness, well diameter, and well angle control the productivity of these thin-bedded sequences. For wells that are nearly horizontal, a simple technique to calculate the productivity improvement factor (PIF) is derived. The range of validity of this approximation was determined by comparison with fine-grid simulations.
These inflow relationships have been used to construct the well models for simulations of GOM reservoirs. An example application is presented along with specific guidelines to determine the correct well kh as validated by a grid sensitivity study.

Implications of Existing Deviated Well Solutions
Thin-bedded turbidite reservoirs in the deep water Gulf of Mexico are currently being considered for development. These fields contain reservoirs which have bed thicknesses that are on the order of 0.25 inch thick and are separated by very low permeability shales. These reservoirs can be modeled as having no vertical permeability (kv=0). Based on Cinco's deviated well solution, one would not expect high angle wells to perform any better than a vertical well for this situation. This comes directly from the form of Cinco's pseudoskin (S):
(1)
where
(2)
and
(3)
After some further consideration, we have concluded that the line source approximation for the wellbore which Cinco applied, may be the reason that his solution indicates no improvement in thinly bedded reservoirs. We offer an alternative limiting solution.
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A New Tool for Core Recovery of Soft, Unconsolidated Formations
Authors: Lindsey H.E. , Courter Clay N. , Lebourg Maurice P. 
Published: December 2007

Abstract
This paper describes a new core barrel device for cutting and retrieving subterranean cores, particularly from soft or unconsolidated formations; it utilizes a fluid-pressure collapsible sleeve above the core bit to receive and hold the cored material and permit its retrieval in its original subterranean condition. Pressure responsive valves maintain a fluid pressure behind the collapsible sleeve to retain it in the collapsed position until the core is received in the sleeve and also permit fluid behind the sleeve to exhaust as the core enters the sleeve while the sleeve continues to offer lateral support for the core and also remains collapsed above the core. When the core barrel is withdrawn, a small amount of soft core material may fall from the lower portion of the core barrel and the lower portion of the sleeve collapses to retain the remainder of the core in the core barrel.
This paper describes the operation of the new core barrel and full results obtained in very soft uranium ores in South Texas. Some of these cores were previously unobtainable by former conventional methods. The operation of this tool is quite simple and it can be furnished in small or larger sizes and in varying lengths, permitting its use in areas and fields offshore or land, small or large rigs, shallow or deep, and can be used for the recovery of mineral ores or petroleum sands. Drawings illustrating its potential use in ocean floor sampling are shown.

Introduction
The recovery of soft unconsolidated formation core samples has always been a difficult problem. In the past, conventional coring equipment has been modified by the use of "finger" catchers, traps and other devices to facilitate recovery of such formations. However, there is a need for a simple tool that will not only retain the core when it is retrieved but will support it and prevent its bridging as it is being cored. This new tool should be simple to operate and should be available in different lengths and sizes. It should be adaptable to large and small drilling rigs and operate successfully at any depth on land or water.
The Role Of Oil Mud In Controlling Differential-Pressure Sticking Of Drill Pipe
Authors: Simpson Jay P. 
Published: December 2007

Simpson, Jay P., Member AIME
Publication Rights Reserved
This paper is to be presented at the Upper Gulf Coast Drilling and Production Conference of the Society of Petroleum Engineers or AIME in Beaumont, April 5–6, 1962 and is considered the property of the Society of Petroleum Engineers. Permission to publish is hereby restricted to an abstract of not more than 300 words, with no illustrations, unless the paper is specifically released to the press by the Editor of the Journal of Petroleum Technology or the Executive Secretary. Such abstract should contain conspicuous acknowledgment of where and by whom the paper is presented. Publication elsewhere after publication in Journal of Petroleum Technology or Society of Petroleum Engineers Journal is granted on request, providing proper credit is given that publication and the original presentation or the paper.
Discussion of this paper is invited. Three copies of any discussion should be sent to the Society of Petroleum Engineers office. Such discussion may be presented at the above meeting and considered for publication in one of the two SPE magazines with the paper.

Abstract
Published studies of differential-pressure sticking of drill pipe have presented methods of testing mud for tendency to cause wall sticking. One such method has been extended to permit simulation of downhole temperature and mud circulation, and data have been obtained for both water and oil muds typical of those currently in use. The laboratory data indicate an oil mud with good rheology, suspension, and filtration properties (as tested under downhole conditions of temperature and differential pressure) to be a very effective means of combatting differential-pressure sticking.
During the past year oil muds have been used on the Louisiana and Texas Gulf Coast to replace water muds in drilling and completion operations where differential-pressure sticking was a problem. Mud densities have varied from 12.5 to 18.8 ppg, formation temperatures have been as high as 300 F, and well depths have been as great as 16,500 feet. Using adequately conditioned non-asphaltic oil muds, these operations have been conducted with no further difficulty from differential-pressure sticking.
For areas in which differential-pressure sticking has been the primary problem and expense, the use of oil mud has become accepted field practice. Total well costs have been greatly reduced by the elimination of fishing operations and reducing time spent on the well.