bluuebunny/crossref_metadata_2025_split huggingface dataset:
Tests of the Stability and Time-Step Sensitivity of Semi-Implicit Reservoir Stimulation Techniques
Authors: Nolen James S. , Berry D.W. 
Published: December 2007

Abstract
A reservoir simulation technique that employs semi-implicit approximations to relative permeabilities exhibits excellent stability and permeabilities exhibits excellent stability and convergence characteristics when applied to water- or gas-coning problems. Recent workers in this area have made a simplifying assumption in order to linearize the flow terms of the semi-implicit finite-difference equations. This paper describes a method of solving efficiently paper describes a method of solving efficiently the nonlinear form of the equations and demonstrates that time-step sensitivity is reduced by iterating on the nonlinear terms. In addition, it addresses the problem of allocating a well's production among multiple grid blocks. Example problems include both water-coning and gas-percolation applications.

Introduction
Multiphase reservoir simulators traditionally have employed finite-difference approximations in which relative permeabilities are evaluated explicitly at the beginning of each time step. Simulators of this type are capable of handling many reservoir studies in a perfectly satisfactory fashion, but they are incapable of solving economically problems characterized by high flow velocities. Included in this category are the studies of such phenomena as well coning and gas percolation. The difficulty in such problems is a stability limitation imposed by the use of explicit relative permeabilities. In an attempt to overcome this permeabilities. In an attempt to overcome this limitation, Blair and Weinaug developed a simulator that employed implicitly evaluated relative permeabilities. The increased stability of their permeabilities. The increased stability of their equations allowed the use of time steps much larger than previously possible, but this was counteracted by an increase in the computational work per time step and an increased difficulty in the iterative solution of the difference equations. While the net result was a significant advance in the solution of coning problems, improvements still were needed to increase the dependability and decrease the cost of obtaining solutions for such problems. More recently, two papers were published describing a method that employs semi-implicit relative permeabilities. This method is greatly superior to the fully implicit method, both in computational effort and maximum time-step size. In developing this method, the previous workers made a simplifying assumption to obtain linear finite-difference equations. We have developed a reservoir simulator based on the nonlinear form of the semi-implicit finite-difference equations. This paper describes the techniques used in the simulator and presents the results of some tests conducted with it. These include time-step sensitivity studies and tests of alternate production allocation methods. Some of these tests compare the nonlinear form of the semi-implicit method with the linear form.
SPEJ
P. 253
Fracture Initiation from Inclined Wellbores in Anisotropic Formations
Authors: Ong See Hong , Roegiers Jean-Claude 
Published: December 2007

ABSTRACT
This paper presents a wellbore stability design code that can be used to optimally drill, complete and stimulate inclined wells. The design code was developed for the most general case where the borehole, in-situ stress, and rock property coordinate frames are totally independent of each other. It essentially consists of a three-dimensional linear elastic stress analysis in anisotropic formations. Although this particular paper is only limited to tensile failure, based on the minimum normal stress theory, the numerical model is also able to consider shear failure by involving a generalized three-dimensional anisotropic yield criterion. The design code enables the selection of the most optimum borehole orientation and wellbore fluid gradient to avoid fracture initiation. It is also useful in conducting sensitivity studies, particularly when the data is scanty. A remarkable finding by exercising such code was that fracture initiation is strongly dependent on the formation anisotropy; a contradiction to the current industry thinking.
A Numerical Study of Diphasic Multicomponent Flow
Authors: Van-Quy N. , Simandoux P. , Corteville J. 
Published: December 2007

Abstract
This paper describes a general multicomponent two-phase flow model, taking into account convection, diffusion and thermodynamic exchange between phases. The main assumptions are: isothermal one-dimensional flow; two-phase flow (gas and liquid); each phase may be represented by a mixture of three components or groups of components. Actually, a great many recovery problems cannot be pictured by usual models because the oil and, in many cases, the injected fluid are not simple fluids and may bring about exchanges of components that considerably modify their characteristics. This is why efforts are now being made to develop "compositional" or "multicomponent" models capable of solving such situations. Generalization of the model to more complex systems can be considered. Cases treated may be any type of single- and two-phase flow, in particular any miscible process (e. g., high-pressure gas drive, condensing gas drive, slug displacement) and any diphasic processes with high mass exchange (e.g., displacement by carbon dioxide or flue gas). This model is working and has been successfully checked by experiments.

Introduction
Many investigations, broth experimental and theoretical, have been made on the recovery of oil from reservoirs. With regard to mathematical models, most of those conceived up to now have dealt with oil recovery by the injection of a fluid that is miscible or immiscible with the oil. For miscible drives, single-phase flow with a binary mixture and miscibility in all proportions is involved. In such an ideal situation oil recovery is theoretically total. For immiscible displacements flow is diphasic. Capillary pressure and relative permeability play a preponderant role. Since irreducible oil saturation preponderant role. Since irreducible oil saturation is inevitable, oil recovery can never be total. Actually, a great many recovery problems cannot be pictured by such models because the oil and, in many cases, the injected fluid are not simple fluids and may bring about exchanges of components that considerably modify their characteristics. This is why efforts are now being made to develop "compositional" or "multicomponent" models capable of solving such situations. Such a model is described here. It is designed to handle the most general case of the displacement of one fluid by another. This model offers the following possibilities.
A General Pressure Buildup Theory for a Well in a Closed Drainage Area (includes associated paper 6563 )
Authors: Ramey H.J. , Cobb William M. 
Published: December 2007

Pressure buildup analysis, when properly done, yields the same results nomatter which of the conventional methods is used. As illustrated here with aclosed square, general interpretation equations may be derived that are correctfor closed drainage regions of any shape.

Introduction
In 1935, Theis1 showed that buildup pressures in a shut-in waterwell should be a linear function of the logarithm of the time ratio(t+?t)/?t, and that the slope of the line is inverselyproportional to the mean formation effective permeability. Muskat discussedpressure buildup in oil wells in 1937, and proposed determination of staticpressure by a semilog trial-and-error plot that has been found to be applicableto a variety of buildup cases. In the late 1940's, van Everdingen presented aseries of lectures on well test analysis in the U.S. that related to aclassical study of unsteady flow by van Everdingen and Hurst.3 In1951, Horner4 presented a study of pressure buildup that appears tohave summarized fundamental efforts of a number of pioneering researchers inthe Shell companies. Horner also recommended a semilog buildup curve identicalwith the Theis curve, and presented a method for extrapolation to fully builtup static pressure for a closed circular reservoir. This sort of semilogpressure buildup plot is often referred to in the oil industry as a Hornerplot. About the same time, Miller-Dyes-Hutchinson5 presented ananalysis for buildup when the well had been produced long enough to reachpseudosteady, or true steady state prior to shut-in. Their work indicated thatbuildup pressures should plot as a linear function of the logarithm of shut-intime. As in the Horner plot, the slope of the straight line was shown to beinversely proportional to the permeability to the flowing fluid. It isinteresting that about the same time Jacob6 presented a similarapproach to determine aquifer transmissibility for a water well productiontest. Miller-Dyes-Hutchinson presented several important extensions of builduptheory. One was an initial attempt to apply buildup theory to multiphase flow. This problem was later resolved by Perrine.7 More important to thisstudy, an approach to extrapolation to fully built-up static pressure waspresented for outer boundary conditions of either no flow (closed), or constantpressure (water drive).
Thus, by the early 1950's, both Horner and Miller-Dyes-Hutchinson hadpresented methods for determining permeability and static pressure from buildupdata. Although there were similaries - both involved semilog plotting - therewere confusing differences between the methods. Perrine7 presented an excellentreview of this theory in 1956 that clearly indicates the state of understandingat that time. He stated that Horner-type plot (which he referred to as the vanEverdingen-Hurst method) was valid for a new well in a large reservoir, butthat the Miller-Dyes-Hutchinson approach was best for older wells in fullydeveloped fields. The latter is a widely held misconception.
A Coupled Rod and Fluid Dynamic Model for Predicting the Behavior of Sucker-Rod Pumping Systems—Part 2: Parametric Study and Demonstration of Model Capabilities
Authors: Lekia S. D. , Evans R. D. 
Published: December 2007

Summary
Equations for predicting the behavior of sucker-rod pumping systems including the coupled dynamic effects of rod and fluid motion and kinematics of the surface pumping unit which were presented in Part I of this two-part paper series. These equations are used together with complementary sucker-rod system predictive formulas for parametric studies in this paper. Example problems are used to investigate the effects of well and fluid parameters on sucker-rod design parameters and the results are compared against calculations using the API Bulletin 11L3.
Building an Internet World Wide Web Server
Authors: Barnett A. A. , Bates F. G. , Russell J. E. 
Published: December 2007

Summary
The World Wide Web (WWW) is the fastest growing client/server environment on the Internet. This environment consists of a group of software products and a set of protocols and conventions. The WWW environment, based on hypertext and hypermedia technology, allows intuitive, seamless, "point and click" access to and interaction with information distributed across the Internet. Many think of the WWW as solely responsible for transforming the way the Internet is accessed and used by millions of users worldwide.
Although the use of WWW "clients" is intuitive and seamless, the building and deploying of WWW "servers" is more complex and time-consuming. Both commercial and shareware/freeware WWW server software is available for most hardware and operating system configurations. Choosing the right server depends on your objectives. A Windows/DOS server is sufficient for providing access to small amounts of information to a small number of users. A commercial server with user authentication and encryption capability is required to provide wide area access to mission critical information residing in distributed databases.
This paper discusses WWW technology and describes how to choose and obtain a WWW server. We include many references to online resources and documentation, and we also discuss authoring tools.
An Experimental Investigation of the S.P. and Resistivity Phenomena in Dirty Sands
Authors: Wyllie M.R.J. , Southwick P.F. 
Published: December 2007

Abstract
The importance of the so-called "dirty sand" or "conductive solids" problem in electric log interpretation was first stressed in a paper presented in 1949. Since that time the problem has been generally recognized as a most serious one. Several research papers bearing on the theory of the effects of clay contaminants on reservoir rock resistivities have appeared. These papers, while contributing to the theory of the problem, have not offered any practical solution.
In the present paper an experimental investigation has been made of the effects of ion-exchange materials on the electrical properties of natural and synthetic porous media. The method used to make synthetic dirty sands is entirely novel and has proved a valuable guide to a better understanding of the properties of dirty sands generally. The effects of ion-exchange materials on both the resistivity and self potential (S.P.) logs have been examined. From the data obtained it has been possible to formulate a simple, practical method whereby electrical logs of dirty sands can be qualitatively interpreted. The method is in all essentials identical to that presently in use for interpreting clean sands. New light has also been thrown on the significance of the term formation factor when it is applied to dirty sands.

Introduction
In 1949 a paper was presented which showed that the presence of so-called "conductive solids" introduced considerable complexities into the analysis of the resistivities of dirty sands, i.e., permeable formations containing clay. The reduction of the self potential (S.P.) resulting from the presence of interlaminated shale or interstitial clay in permeable formations has been discussed by Doll.
Noteworthy papers which dilate further upon the effects of shale and clay on the resistivity of permeable formations are those of deWitte, Berg, Wyllie, and most recently, Winsauer and McCardell. The last authors have endeavored to elucidate the chemistry of the resistivity phenomena in dirty sands in terms of an adsorption hypothesis. Specifically, they attribute the electrolytic conductivity of shales and clays within a permeable formation to an ionic double-layer effect and, for this reason, regard the term "conductive solids" as a misleading one.
Some consideration has been given to the effect of dirty sands on the S.P. by Wyllie and by McCardell, Winsauer and Williams.
Leveraging Software Investment: Designing and Building Quality Software Products
Authors: Meikle D. E. , Campkin Michael , Grimley Brendan 
Published: December 2007

Summary
Software investments represent a significant, if not dominant, proportion of the information technology cost within an oil and gas operating company. Technical software costs are particularly high because companies value specialized applications that have high development costs. Training and support for these applications drive up costs even more, especially if an application has not had rigorous quality control applied during its development process. Oil and gas operators then must dedicate additional internal resources for product support, which increases the product's real cost even further.
This paper shows the rigorous methods of quality control and assurance techniques involved in software development and testing and the benefits of these methods to the oil and gas technical applications’ investor. Our paper also illustrates how technical applications’ support cost may be reduced by designing quality and stability into the software through the application of quality control techniques during the specification, design, implementation, documentation, and testing phases. Lastly, we discuss the metrics we used to measure the quality of the software's performance.
Implementation of a World Wide Web Server for the Oil and Gas Industry
Authors: Blaylock R. E. , Martin F. D. , Emery Robert 
Published: December 2007

Summary
The Gas and Oil Technology Exchange and Communication Highway (GO-TECH) provides an electronic information system for the petroleum community for exchanging ideas, data, and technology The PC-based system fosters communication and discussion by linking the oil and gas producers with resource centers, government agencies, consulting firms, service companies, national laboratories, academic research groups, and universities throughout the world. The oil and gas producers can access the GO-TECH World Wide Web (WWW) home page through modem links, as well as through the Internet. Future GO-TECH applications will include the establishment of "virtual corporations" consisting of consortia of small companies, consultants, and service companies linked by electronic information systems. These virtual corporations will have the resources and expertise previously found only in major corporations.
Comparison of Carbon Dioxide and Methane as Additives at Steamflood Conditions
Authors: Freitag N. P. , Kristoff B. J. 
Published: December 2007

Summary
Heavy-oil production from a steamdrive may be improved by adding gases to reduce the steam requirement, to swell the oil, and to reduce oil viscosity. To help compare carbon dioxide (CO2) and methane (CH4), two of the most reasonable choices of gaseous additives, we measured the viscosity and density of a Lloydminster- type heavy oil when saturated with each gas at a single pressure at 25°, 80°, and 150°C. Our measurements were repeated in the presence of a water phase to address the lingering questions about the effect of water on this equilibrium, especially at 150°C.
In addition to confirming trends identified by previous authors, the results showed that the benefit of dissolved CH4 diminishes much less rapidly with rising temperature than for CO2. By 150°C the differences in benefit are small, which indicates that CH4 could be a more economical choice than CO2 as a steam additive in many reservoirs. In addition, no effect of equilibrium water was detected.
Field Experiments on Hydraulic Fracturing
Authors: von Schonfeldt Hilmar , Fairhurst C. 
Published: December 2007

Abstract
Hydraulic fracturing experiments at two underground and one near-surface location in igneous and shale formations were described. The tests were designed to study the feasibility of hydraulic fracturing as a method of determining in-situ stresses. The tests were carried out in open holes of 2-3/8-in. diameter. Fracturing tests on two 5-ft diameter cores were also reported. The test results revealed an increase in the magnitude of the stress as the face of an opening was approached from inside a rock mass. Horizontal fractures also were observed in areas of reportedly high lateral stress, providing some evidence for the validity of the providing some evidence for the validity of the principle of least resistance. The results also principle of least resistance. The results also indicate that caution must be used in using the shut-in pressure as a measure of the least compressive stress.

Introduction
Hydraulic fracturing is best known as a well stimulation method. There are other important applications, however, for which the process shows great potential. One of these is in the area of in-situ stress determination as suggested by Scheidegger Kehle and Fairhurst. The mechanics of the fracturing process is the same in any application, and improvement of the method may therefore be expected through a mutual exchange of experience in each of these areas.
The theory of the hydraulic fracturing technique relates measurable quantities such as the breakdown pressure and the instantaneous shut-in pressure to pressure and the instantaneous shut-in pressure to the tectonic stresses and certain physical rock properties. properties. Assuming negligible pore pressure and fluid penetration, the break-down pressure (pC) at the penetration, the break-down pressure (pC) at the instant of fracture initiation is given by the following expressions....................(1)
when the fracture extends in a "radial" direction (in a plane parallel to the axis of the borehole). And...................(2)
when the fracture extends in a direction normal to the borehole axis.
Corresponding expressions that include the effect of pore pressure and fluid penetration are given in the literature Because our work was done in dry and impermeable formations, Eqs. 1 and 2 are considered adequate. These formulae are based on the assumption that the borehole is drilled parallel to 3 and that the rock behaves as a linearly elastic isotropic material; it also assumes that the fracture is initiated in a direction perpendicular to the least compressive stress, i.e., 2 or 3, respectively, in accordance with the principle of least resistance.
The terms "radial" and "normal" fractures are introduced in place of the commonly used terms "vertical" and "horizontal" fractures in order to avoid possible confusion in the event a borehole is drilled in a direction other than the vertical.
Design, Execution, and Evaluation of Acid Treatments of Naturally Fractured Carbonate, Oil Reservoirs of the North Sea
Authors: Lietard Olivier , Bellarby Jonathan , Holcomb David 
Published: December 2007

SummaryThis paper discusses damage removal in naturally fractured carbonate, oil reservoirs of the central North Sea, located in the vicinity of salt domes. The reservoir rock is the well-known Tor chalk, the mechanical properties of which have been greatly modified by the proximity of diapirs. The matrix rock is much harder (similar to a limestone) and extensively fissured. Wells drilled through these reservoirs suffer from very severe damage as a result of the invasion of the natural fractures by large amounts of drilling mud. Productivity is restored by high-rate damage-removal treatments alternating stages of crosslinked gel, customized acid formulations, and ball sealers. Pre- and postjob well performances demonstrate huge productivity-index increases as a result of the cleanup of the natural fissures. This paper emphasizes mud-loss survey during drilling and perforation strategies; candidate selection, i.e., pre- and postjob productivity based on both rock (matrix and fissures) and damage properties; treatment execution (as per actual North Sea jobs); and treatment evaluation and diversion efficiency.