bluuebunny/crossref_metadata_2025_split huggingface dataset:
Tarmat Behavior Under Water Injection in a Reservoir With Two Intersecting Faults
Authors: Osman Mohammed E. 
Published: December 2007

Summary
Tarmat problems, which are present in many oil reservoirs, were investigated in a series of papers. Tarmat behavior under water injection by an injector away from faults was presented in the first study, and the second study treated the case of a water injection under tarmat by an injector near a single fault. This paper investigates the case where an injector near two intersecting faults is used and resulted in a technique that can be used, both analytically and graphically, to predict the behavior of tarmat anywhere in the reservoir. It was found that the effect of both faults lessens and becomes more linear with increasing distance of the injector from the two faults. Also, a set of equations is presented to predict the response time (after tarmat breakdown) at any observation well in the reservoir.
Detailed Validation of an Empirical Model for Viscous Fingering With Gravity Effects
Authors: Fayers F. John , Newley Trevor M. J. 
Published: December 2007

Summary
This paper extends to two-dimensional (2D) flows the derivation and validation of an empirical model for viscous fingering previously developed. Fine-scale numerical simulations are used to provide basic data for validating the approximations, and these fingering results are also checked against a range of experiments. The flow rate dependence of gravity segregation in vertical section experiments conducted by van der Poel is examined, where the broadly acceptable agreement of the empirical model is limited by some identified additional features.
An Adaptive-Implicit Switching Criterion Based on Numerical Stability Analysis
Authors: Fung Larry S-K. , Collins David A. , Nghiem Long X. 
Published: December 2007

Summary
A new switching criterion for adaptive-implicit reservoir simulation, based on the numerical stability of the local amplification matrix, is discussed. Adaptive-implicit methods can be used to achieve substantial savings in computing time and storage. The success of their application, however, depends critically on an appropriate switching criterion. The standard criterion discussed in the literature is the application of threshold changes in the primary variables, which are usually determined by some preliminary testing and chosen conservatively because of their empirical nature. Further, backward switching (implicit to explicit) is not normally feasible. With the switching criterion discussed in this paper, these disadvantages are eliminated. The method has been applied to a variety of black-oil reservoir simulation problems, including the first and second SPE Comparative Solution Projects and a water-injection problem. In all cases tested, the new criterion is shown to perform satisfactorily. For the waterflood problem in particular, the new criterion with backward switching was found to decrease computing time and storage significantly compared with the standard switching criterion. This criterion can easily be extended to other types of reservoir simulators.
High-Resolution Simulation of Unstable Flows in Porous Media
Authors: Christie M. A. 
Published: December 2007

Summary
This paper describes accurate numerical methods used to solve equations governing two-phase, three-component flow on a fine grid to obtain predictions of fingering behavior for both miscible and immiscible flows. The reasons for the choice of finite-difference scheme are discussed. Results are presented that show almost complete stabilization of fingering for illustrative line-drive and quarter five-spot configurations when water and solvent are injected simultaneously at the optimum water-alternating-gas (WAG) ratio.
Discontinuous and Mixed Finite Elements for Two-Phase Incompressible Flow
Authors: Chavent Guy , Cohen Gary , Jaffré Jérôme , Eymard Robert , Guérillot Dominique R. , Weill Luce 
Published: December 2007

Summary
The simulation of multiphase flow presents several difficulties, including (1) the occurrence of sharp moving fronts when convection is dominating, (2) the need for a good approximation of velocities to calculate the convective terms of the equation, and (3) flow singularities around wells. To handle the first difficulty, we propose a Godunov-type higher-order scheme based on a piecewise linear approximation of the saturation associated with a multidimensional slope limiter. With respect to the second, the pressure equation is approximated by means of a mixed-hybrid formulation equivalent to the classic mixed formulation but yielding a positive-definite linear system. To solve the third difficulty, we introduce macroelements around wells. Numerical experiments illustrate the capabilities of the method.
Implementation of an Improved Adaptive-Implicit Method in a Thermal Compositional Simulator
Authors: Tan T. B. 
Published: December 2007

Summary
A multicomponent thermal simulator with an adaptive-implicit-method (AIM) formulation/inexact-adaptive-Newton (IAN) method is presented. The final coefficient matrix retains the original banded structure so that conventional iterative methods can be used. Various methods for selection of the eliminated unknowns are tested. AIM/IAN method has a lower work count per Newtonian iteration than fully implicit methods, but a wrong choice of unknowns will result in excessive Newtonian iterations.
For the problems tested, the residual-error method described in the paper for selecting implicit unknowns, together with the IAN method, had an improvement of up to 28% of the CPU time over the fully implicit method.
Simulation off Fluid Flow in Hydraulic Fracturing: Implications for 3D Propagation
Authors: Ben Naceur Kamel , Thiercelin Marc , Touboul Eric 
Published: December 2007

SummaryA formulation for simulating arbitrarily shaped 3D fractures is presented. The technique extends previous variational techniques and provides a stable solution with a minimum number of elements. The model is used to assess the applicability of simplified height-growth models. Issues related to the treatment of 2D convection fields, associated with the fluid-flow equations, are also addressed.
Stability of Highly Inclined Boreholes
Authors: Aadnoy B. S. , Chenevert M. E. 
Published: December 2007

Summary
Hole inclination produces alterations in the stress state around the borehole and in the physical properties of the rock. Depending on specific conditions, such effects may lead to collapse of the borehole or a reduction in the fracture-initiation pressure. This paper shows how to determine such effects through the application of stress analysis and rock mechanics.
Ultrasonic Inspection of Rotary-Shouldered Connections
Authors: Chapman Paul W. 
Published: December 2007

Summary
This paper presents the results of a research project that combined laboratory investigation and field data to identify the parameters that affect the sensitivity and reliability of an ultrasonic system of inspection for rotary-shouldered connections. Variations of the parameters were introduced in a controlled environment so that the type and magnitude of their effect could be determined and quantified.
Drillstring Fatigue Performance
Authors: Chen Wen-Ching 
Published: December 2007

Summary
The life-prediction technique of a whole-life fatigue model was applied to drillstring components. Good agreement existed between the life predictions and the experimental data of drill collars. These life predictions were then used to study the effects of material properties and commonly used thread profiles on the fatigue life of drillstring components. Results of the study indicate that the newly developed microalloying technology and thermomechanical-processing technology in steel metallurgy can significantly benefit the fatigue life of drillstring components. The sensitivity studies on the effect of thread profile on fatigue performance of drillstring components indicate that fatigue life could be enhanced by an improved thread-profile design.
Surface-Casing Strain Capacity for North Slope Operations
Authors: Hirshberg A. J. , Moyer M. C. , Rickenbach R. M. 
Published: December 2007

Summary
Thaw subsidence during the production life of wells drilled through the permafrost can transfer very high axial compressive loads to the surface casing. Improved techniques were required to define the compressive strain capacity of surface casing for North Slope operations. These techniques were used to identify cost-effective surface-casing designs capable of withstanding the axial compressive strains imposed by permafrost thaw.
Plans to drill North Slope development wells on closer surface spacing resulted in predicted permafrost thaw loads on the surface casing that exceed current operating practices. In addition, development of lower-productivity wells has resulted in completions with smaller-diameter tubulars. Both of these considerations have led to a reassessment of the surface-casing programs for these new wells.
The results presented are based on two parallel and complementary investigations: full-scale physical testing and nonlinear finite-element analysis. The physical tests provided information about the performance of the casing and connections under high compressive loads. Data were used to verify the accuracy of corresponding finite-element models with three different criteria: strain-gauge data from the coupling and pin surfaces, failure mode comparison, and failure load comparison. An excellent match was achieved between the strain-gauge data and the analytical strain results, the actual vs. modeled failure mode (i.e., compressive bulging in the pipe body), and the actual vs. modeled failure load. Once verified, the models were used to investigate the effects of field-related parameters that were not tested. These included variations in makeup condition, pipe-wall thickness, thread taper angle, and casing length. Finally, these results enabled the selection of suitable surface-casing materials and connections for arctic operations.
Improved Interpretation of Casing Logs for Casing Failure
Authors: Wooley G. R. , Hatcher M. 
Published: December 2007

Summary
Casing inspection logs may be used to interpret the nature of a casing failure downhole. This paper provides data to improve interpretation for casing failures and presents results of laboratory tests of four commercially available tools. The tools are tested in five casing specimens, corresponding to five types of failures.
Results indicate that although standard casing inspection logs can detect the existence of a casing failure in a well and define its location, interpretation of additional details with regard to the type of failure requires special efforts. Calibration procedures and interpretation techniques that are not commonly practiced in the field are presented to allow distinction between a split and a part and to define details of the split or part. Also, recommendations are made with regard to running speeds and sensitivity settings.
A Practical Approach to Jarring Analysis
Authors: Wang Jaw-Kuang , Kalsl Manmohan S. , Chapelle René A. , Beasley Thomas R. 
Published: December 2007

Summary
To fulfill the practical needs of drilling personnel routinely involved in jar selection and use, a computer program based on stress-wave theory was developed. This approach provides an accurate, fast, and simple-to-use method for jar selection and optimization. It eliminates the need for large computational facilities, long solution times, and a high level of engineering expertise that are commonly associated with state-of-the-art transient dynamic finite-element methods (FEM's).
The program's accuracy was verified through comparisons with FEM results. The program produces a large matrix of results over the specified range of jarring variables within a few seconds of processing on a personal computer. The results provide an insight into the interaction between jarring variables and guidance in the optimum jar placement. Some application results are presented to show its usefulness in assisting drilling personnel in jar selection and placement. Typical results for the bottomhole assemblies (BHA's) containing heavyweight drillpipe (HWDP) show some interesting and not-so-obvious problems in such assemblies.
Dynamic Surge/Swab Pressure Predictions
Authors: Mitchell R. F. 
Published: December 2007

Summary
It is generally accepted that the pulling and running of pipe causes pressure surges. The prediction of pressure surges is of economic importance in wells where the pressure must be maintained within narrow limits to prevent lost circulation and formation-fluid influx. For these wells, the drilling engineer needs the best possible method of calculating surge pressures to drill wells with a minimum of trouble.
This paper presents a dynamic surge/swab model that extends existing technology with the following features: (1) pipe and annulus pressures are coupled through the pipe elasticity; (2) longitudinal pipe elasticity and fluid viscous forces determine pipe displacement; (3) fluid properties vary as a function of temperature and pressure; and (4) formation elasticity, pipe elasticity, and cement elasticity are all used to determine the composite elastic response of the wellbore.
Comparisons between the model and field data demonstrate good agreement. Data matches have been made for both water- and oil-based muds in both shallow and deep wells. Furthermore, the model matches data that had not been previously matched by other models.
Modifications To and Experience With Air-Percussion Drilling
Authors: Pratt C. A. 
Published: December 2007

Summary
Shell Canada Ltd. has air-percussion drilled 48 wells since Fall 1983. The industrial hammer was used predominantly, but the older oilfield hammer was used occasionally. A total of 117 solid-head bits were run. Experiences with the industrial percussion hammer indicated that tool modifications were required to reduce hole spiraling and the tendency of bits to go undergauge. High penetration rates (ROP's) with the new hammer required excessive blowing on connections, leading to the modification of a computer program for air-volume requirements. Because minor equipment failures were causing lost time, modifications were made to the jet system, sample catcher, and downhole floats.
Interpretation of Pressure Decline for Minifracture Treatments Initiated at the Interface of Two Formations
Authors: Moschovidls Z. A. 
Published: December 2007

SummaryThis paper extends the classic pressure-decline analysis to the more complex case where the minifracture is initiated near the interface of two formations and penetrates two or more formation layers of different leakoff characteristics. The development shows that the classic analysis is still valid, but it gives an effective or average leakoff coefficient that depends on the areal extent of the minifracture at the end of pumping in each individual layer. Examples demonstrate how to estimate individual layer leakoff coefficients with this theory, minifracture pressure-decline field data, and the fracture geometry predicted by a 3D fracturing simulator. Finally, the results obtained are used to explain field fracturing observations.
A Study of the Methods for Preventing Rod-Wear Tubing Leaks in Sucker-Rod Pumping Wells
Authors: McCaslin K. P. 
Published: December 2007

Summary
Because of the high cost associated with tubing replacement, rod-wear tubing leaks are one of the most costly types of subsurface failures on sucker-rod-pumped wells. While severe hole deviation is most often blamed for rod-wear tubing leaks, case studies show that most rod-wear leaks are caused by accelerated corrosion, which is the result of the removal of a protective corrosion scale from the inside of the tubing. For this reason, the key to eliminating rod-wear tubing leaks economically is correctly identifying the problem as either mechanical wear or corrosion wear and then implementing the appropriate corrective measures.
Four case histories involving a total of 90 problem wells are presented to illustrate the methods used to differentiate between corrosion wear and mechanical wear. In these fields, tubing leaks were reduced by as much as 80% by proper identification of the cause of the leaks.
Use of Single-Well Simulators and Economic Performance Criteria To Optimize Fracturing Treatment Design
Authors: Anderson Robert W. , Phillips Alice M. 
Published: December 2007

Summary
Low-permeability reservoirs are currently being propped with sand, resin-coated sand, intermediate-density proppants, and bauxite. This wide range of proppant cost and performance has resulted in the proliferation of proppant selection models. Initially, a rather vague relationship between well depth and proppant strength dictated the choice of proppant. More recently, computerized models of varying complexity that use net-present-value (NPV) calculations have become available. The input is based on the operator's performance goals for each well and specific reservoir properties. Simpler, noncomputerized approaches include cost/performance comparisons and nomographs. Each type of model, including several of the computerized models, is examined here. By use of these models and NPV calculations, optimum fracturing treatment designs have been developed for such low-permeability reservoirs as the Prue in Oklahoma. Typical well conditions are used in each of the selection models, and the results are compared. The computerized models allow the operator to determine before fracturing how changes in proppant type, size, and quantity will affect postfracture production over time periods ranging from several months to many years. Thus, the operator can choose the fracturing treatment design that best satisfies the economic performance goals for a particular well, whether those goals are long or short term.
Flow of Clay Suspensions Through Porous Media
Authors: Baghdikian Serge Y. , Sharma Mukul M. , Handy Lyman L. 
Published: December 2007

Summary
This study was undertaken to investigate the transient behavior of particulate plugging of porous media. The objectives of the experiments were to study in detail a well-characterized system and to check the validity of theoretical predictions. Experiments included injection of clay suspensions under different conditions into sandpacks, measurement of pore-size distribution, and monitoring of permeability and effluent particle concentrations.
Kinetics of Crude-Oil Coke Combustion
Authors: Vossoughi Shapour , El-Shoubary Youssef 
Published: December 2007

Summary
Coke is a solid or semiliquid material that deposits on the sand-grain surface area and is eventually burned as a fuel during an in-situ combustion process. Its combustion is the main source of energy to sustain the fire front. This study investigates the effects of different variables—such as specific surface area, oxygen partial pressure, and oil content—on the coke combustion by thermogravi-metric analysis (TGA). Each variable was varied while the others were kept constant. The TGA and the derivative thermogravimetric (DTG) curves were subjected to kinetic analysis. The rate equation produced indicated that the rate of coke combustion was proportional to the coke content yet to be burned, oxygen partial pressure, and sand-grain specific surface area. The rate constant followed an Arrhenius-type equation for the temperature dependency. The rate equation was tested for the range of specific surface areas of 0.126 to 24.3 m2/g [615 to 119,000 ft2/lbm], oil content of 10 to 58 wt%, and oxygen partial pressure of 5 to 50 kPa [0.05 to 0.50 atm]. The model's validity was tested for various crude oils from different geographical locations in the U.S., Canada, and Latin America.
Designing and Selecting Demulsifiers for Optimum Field Performance on the Basis of Production Fluid Characteristics
Authors: Berger P. D. , Hsu C. , Arendell J. P. 
Published: December 2007

Summary
A method for characterizing and predicting the performance of emulsion breakers has been developed that involves the relationship between the preferred alkane carbon number (PACN) of the demulsifier and the equivalent alkane carbon number (EACN) of the crude oil and the salinity of the emulsified aqueous phase. This procedure can be used both to choose the proper demulsifier for field use and to develop effective new compounds by determining the effect of changes in molecular architecture and interfacial properties on performance. Parameters studied include chemical type, molecular weight, degree of branching, partition coefficient between the water and oil phases, interfacial-tension (IFT) reduction, and interfacial-viscosity changes. The importance of each of these properties to performance is discussed.
Use of Water-Vapor Desorption Data in the Determination of Capillary Pressures at Low Water Saturations
Authors: Melrose J. C. 
Published: December 2007

Summary
The equilibrium conditions applicable to a single liquid phase held by capillary forces within the pore space of a reservoir rock sample are reviewed. It is shown that if the conditions for both chemical and capillary equilibrium are satisfied, an extended form of the classic Kelvin equation is obtained. With available thermodynamic data, it is also shown that the classic form of the Kelvin equation can be used to compute air/brine capillary pressures for core-plug samples. Experimentally, it is only necessary to allow such samples to reach equilibrium in a constant-vapor-pressure environment. Thus the conventional methods for determining capillary pressures can be usefully supplemented by vapor-phase desorption experiments. Although such experiments require relatively long equilibration time, they are simple to perform and are free from the difficulties common to other methods. A convenient way to establish a constant-vapor-pressure environment is to use saturated solutions of such salts as BaCl2, KNO3, and K2SO4. The available vapor-pressure data for these solutions are reviewed and tabulated. From these data, Kelvin capillary pressures are calculated for a range of NaCl brine compositions and temperatures. Some preliminary data obtained by this technique are reported for a pair of matched Berea core plugs of about 10 cm3 PV.
When Is a Reservoir Limit Test Applicable?
Authors: Matthews C.S. 
Published: December 2007

Technology Today Series articles provide useful summary information on both classic and emerging concepts in petroleum engineering.Purpose:To provide the general reader with a basic understanding of a significant concept, technique, or development within a specific area of technology.
As discussed in an earlier paper in this series (" Transient, Semisteady-State, and Steady-State Flow," April 1986 JPT, Pages 385–86). after an extended time of production at constant rate in a bounded reservoir, the pressure decrease becomes proportional to time. The period in which this occurs is called semisteady state and is illustrated in Fig. 1.
The contributory pore volume, Vp, of the reservoir may be calculated from the slope of the production curve after it reaches semisteady state. For this reason, the constant-rate production test has been called a reservoir limit test. The applicable equation follows.