bluuebunny/crossref_metadata_2025_split huggingface dataset:
Toward a Unified Theory of Well Testing for Nonlinear-Radial-Flow Problems With Application to Interference Tests
Authors: Peres Alvaro M. M. , Serra Kelsen V. , Reynolds Albert C. 
Published: December 2007

Summary
This work presents an analytical solution for the pseudopressure function that represents the reservoir and wellbore responses resulting from production at a constant oil rate in a solution-gas-drive reservoir. The solution can also be reduced to obtain the analytical solution for the corresponding single-phase-flow problem. The general analytical solution suggests a new definition for the dimensionless flow rate. The analytical solution is used to construct new type curves for analysis of interference tests conducted under multiphase-flow conditions. It is shown that if we ignore multiphase-flow effects and analyze interference data with the line-source-solution type curve, then the estimates of the permeability and porosity-compressibility product obtained may be in error by 20 to 40%.
Nomograms for Analysis of Pressure-Buildup Data Influenced By Heterogeneity
Authors: McKinley Richard M. , Streltsova Tatiana D. 
Published: December 2007

Summary
This paper presents nomograms that assist in the correct identification of the middle time region (MTR) straight line on a semilog or Horner plot of buildup data from a heterogeneous reservoir. These nomograms also provide a realistic assessment of the types of heterogeneity that affect the buildup data. The nomograms are a quantitative extension of the widely used derivative-analysis method. The heterogeneities considered cover lateral discontinuities in reservoir transmissibility, naturally fractured, and vertically stratified and lenticular formations.
Comparison of an Expert System to Human Experts in Well-Log Analysis and Interpretation
Authors: Einstein Elizabeth E. , Edwards Ken W. 
Published: December 2007

Summary
Comparisons of results produced by an expert system to those produced by log-analysis experts are discussed using case histories from a variety of wells from several countries. The results, in general, exceeded initial expectations, with the expert system showing surprisingly "intelligent" behavior in some circumstances and actually highlighting mistakes made by the human experts. In other examples, the expert system fails to emulate the human expert closely. Failures are shown to result from the application of knowledge gathered from outside the realm of log analysis or from a lack of information entered into the expert system.
Injection-Well Testing in a Light-Oil Steamflood, Buena Vista Hills Field, California
Authors: Zlegler Victor M. 
Published: December 2007

SummaryPressure-falloff and step-rate injectivity tests were performed during a light-oil steamflood at the Buena Vista Hills field, CA. Data obtained from these tests allowed determination of steam-zone properties and formation fracture pressure at an injection well. Information obtained from an offset temperature-observation well and from a heat balance corroborated the pressure-analysis results and allowed estimation of steam-zone thickness. An effective method for monitoring steamfloods, pressure-transient testing of steam-injection wells may be used with other surveillance techniques to improve reservoir management.
An Improved Regression Algorithm for Automated Well-Test Analysis
Authors: Nanba Takao , Horne Roland N. 
Published: December 2007

Summary
Automated well-test analysis is a familiar technique, but the procedure still depends on the speed and robustness of the regression algorithms used. We examine a modification of the Cholesky factorization (CF) method for the solution of nonlinear-parameter-estimation problems and show that this modification is a very beneficial adaptation of the Gauss-Newton method. The new algorithm, the modified Gauss-Cholesky (MGC) method, is more robust under unfavorable conditions than two of the most reliable existing algorithms [the Gauss-Marquardt (GM) and the Newton-Barua (NB) methods]. This robustness seems to depend on the algorithm's ability to control the rapid change of ill-defined parameters and not on computational singularity or higher-order representation.
Wettability Alteration Caused by Oil-Based Muds and Mud Components
Authors: Yan J-N. , Menezes J. L. , Sharma Mukul M. 
Published: December 2007

Summary
Wettability alteration caused by oil-based muds and mud filtrates is of great concern in coring operations. This paper shows that mud filtrates from whole muds can change the wettability of water-wet cores significantly. Individual components primarily responsible for this wettability alteration are identified.
Dual Concentric Gas-Lift Completion Design for the Thistle Field
Authors: Moore P. C. , Adair Paul 
Published: December 2007

Summary
A unique dual concentric gas-lift completion was installed in two wells in the Thistle field during 1987. This paper outlines the completion concept and design, including vertical-lift performance and tubing movement/stress analysis. Results of field performance after 1 year of production history are presented and compared with predicted values.
Ion Exchange and Dissolution/ Precipitation Modeling: Application to the Injection of Aqueous Fluids Into a Reservoir Sandstone
Authors: Bazln Brigltte , Labrld Jean 
Published: December 2007

SummaryIon exchange and dissolution/precipitation processes are of considerable concern when aqueous fluids are injected into reservoir sandstones, as in waterflooding or alkaline flooding or in well treatments. This paper describes a flow model that takes into account several ion exchange equilibria and the precipitation/dissolution of carbonates and hydroxides. Its validity is tested through simulations of laboratory experiments dealing with brine and alkali injection. Some insights into the effects of ion exchange and precipitation on flow properties are given.
A Study of the Morphologies and Inversions of Model Oilfield Dispersions
Authors: Smith Duane H. , Lim Kyung-Hee 
Published: December 2007

Summary
Using the surfactant/oil/water system C4H9OC2H4OH/n-C10H22/brine (0.01-M NaCl) and electrical-conductivity measurements, we determined the emulsion morphologies and the phase volume fractions at which inversion occurred at temperatures below the lower critical endpoint temperature and above the upper critical endpoint temperature. In both cases, inversion occurred at 45±5 vol% internal phase when that phase was the water-rich phase and at 60±5 vol% internal phase when that phase was the oil-rich phase. These results contradict the correlation between phase behavior and emulsion morphology that has been almost universally reported in the oil-recovery literature, but are in much better agreement with models for emulsion inversion that are based on packing arguments.
The Effect of Flow Rate on the In-Situ Gelation of a Chrome/Redox/Polyacrylamide System
Authors: Marty Luc , Oreen D. W. , Wlllhlte Q. Paul 
Published: December 2007

Summary
This paper presents experimental data on the gelation of a polyacrylamide/thiourea/Cr(VI) gel system in unconsolidated sandpacks at flow rates typical of those encountered beyond the immediate vicinity of a wellbore. At these low rates, in-situ gelation during flow was characterized by an abrupt increase in flow resistance that occurred over a short distance at a specific location along the sandpack. The location of this region was a function of flow rate, and its distance from the inlet increased as flow rate increased. Filtration of gel aggregates appears to be the mechanism causing this behavior.
Oilfield Applications of Colloidal Silica Gel
Authors: Jurinak J. J. , Summers L. E. 
Published: December 2007

Summary
A practical reservoir fluid-flow control system based on colloidal silica gel was developed. Colloidal silica gel is an environmentally benign system that provides easy surface handling, reliable gel-time control at temperatures up to 250°F, and high in-situ performance. Extensive laboratory testing was completed and is discussed elsewhere. Colloidal silica gel has been used in 11 well work-overs for water-injection-profile modification (four wells), water-production control (three wells), and remedial casing repair (four wells). Only one of the four injection-well treatments was a clear-cut technical success, with failure typically caused by pressure parting the gel plug after the well treatment. Two of the three water-production-control jobs were technical and economic successes. Temporary success was achieved in three of the four casing-repair treatments.
Electrical Conductivities in Oil-Bearing Shaly Sands
Authors: Waxman M.H. , Smits L.J.M. 
Published: December 2007

ABSTRACT
A simple physical model was used to develop an equation that relates the electrical conductivity of a water-saturated shaly sand to the water conductivity and the cation- exchange capacity per unit pore volume of the rock. This equation fits both the experimental data of Hill and Milburn and data obtained recently on selected shaly sands with a wide range of cation-exchange capacities.
This model was extended to cases where both oil and water are present in the shaly sand. This results in an additional expression, relating the resistivity ratio to water saturation, water conductivity and cation-exchange capacity per unit pore volume. The effect of shale content on the resistivity index- water saturation function is demonstrated by several numerical examples.

INTRODUCTION
A principal aim of well logging is to provide quantitative information concerning porosity and oil saturation of the permeable formations penetrated by the borehole.
For clean sands, the relationships between measured physical quantities and porosity or saturation are well known. However, the presence of clay minerals greatly complicates log interpretation, particularly the electrical resistivity and SP logs, and considerably affects evaluation of hydrocarbon-bearing formations. The conductance and electrochemical behavior of shaly sands and their relation to log interpretation have been studied by many workers. Wyllie and Lynch reviewed this work in some detail.
Virtually all laboratory measurements of electrical resistivity and electrochemical potential of shaly sands published to date are the work of Hill and Milburn.
Case History of Drillstem Failures Offshore West Africa
Authors: Sweet R. G. 
Published: December 2007

Summary
A high incidence of drillstem (or drillstring) failures was experienced by Conoco Inc. during drilling of exploration wells offshore West Africa. A data base of failure information was used to identify quickly where the majority of the problems occurred. Almost all failures were related to fatigue and corrosion. A study resulted in several recommendations that included improved practices in drillstem selection, quality assurance, and corrosion control. After the recommendations were implemented, a significant reduction in failures was recorded. This increased operating efficiency, reduced drilling costs, and improved safety.
A New General Pressure-Analysis Procedure for Slug Tests
Authors: Peres Alvaro M. M. , Onur Mustafa , Reynolds Albert C. 
Published: December 2007

Summary
A new analysis procedure for determining formation flow capacity and skin factor from slug-test data is presented. The procedure arises from exact deconvolution equations that convert measured slug-test pressure data into equivalent pressure and pressure-derivative responses that would be obtained if the well were produced at a constant surface flow rate. The converted data then can be analyzed by use of existing wellbore-storage and skin type curves for the particular reservoir or well model represented by the field data. For cases where the slug test is short, we show that flow rate convolution can be incorporated to improve analysis reliability. The analysis procedures do not require direct knowledge of the sandface flow rate.
Experiences With Pumping Well Testing
Authors: Kabir C. S. 
Published: December 2007

SummaryThis paper presents our recent experiences with pumping well testing using the acoustic method. Three areas of testing are examined: computation of changing liquid density throughout the liquid column at every timestep, interpretation of the test with simultaneous downhole pressure and flow-rate data, and static and dynamic responses of the acoustic device. An algorithm is developed to incorporate the gas/oil mass transfer effect (solubility) so that accurate gas velocity and, in turn, improved liquid density in the annu-lus can be computed. The effect of gas solubility is to reduce gas volume and hence the total bottomhole flow rate (BHF) without affecting bottomhole pressure (BHP) significantly. Transient interpretation improves when the gas solubility is taken into account.This study reviews some commonly used wellbore two-phase correlations. The Godbey-Dimon model is modified to simulate the moving liquid column during a buildup test. Field examples are used to examine both the static (accuracy) and dynamic (resolution) responses of the acoustic device. The literature suggests that the acoustic method can faithfully reproduce the absolute static gauge BHP. This study shows that the results from dynamic (buildup) tests compare very favorably with those from downhole measurements.
An Analytical Model for History Matching Naturally Fractured Reservoir Production Data
Authors: Watson A. Ted , Gatens J. Michael , Lee W. John , Rahim Zillur 
Published: December 2007

Summary
This paper presents a method for analyzing production data from naturally fractured gas reservoirs. A normalized time is used to modify analytical solutions to model gas flow in finite, dual-porosity reservoirs. Procedures for validating the dual-porosity reservoir model, determining the suitability of simpler reservoir models, and determining the best parameter estimates are illustrated with field data from naturally fractured reservoirs.
Study of Nordgren's Equation of Hydraulic Fracturing
Authors: Kemp L. Franklin 
Published: December 2007

Summary
A nonlinear partial differential equation modeling the propagation of a vertical hydraulic fracture first derived by Nordgren is studied. When properly posed, Nordgren's derivation constitutes a Stefan problem and requires another boundary condition—namely, that the velocity of the fluid at the crack tip equals the velocity of crack propagation. With this addition, Nordgren's similarity solution in the no-leakoff case is perfected by a power-series solution. New shut-in solutions are derived in the large- and no-leakoff cases where the crack of the large-leakoff shut-in solution retracts and the crack of the no-leakoff shut-in solution extends forever. This study ignores the effect of crack-tip rock strength on crack propagation.
Velocity Profile Survey in a 16-in. Custody-Transfer Orifice Meter for Natural Gas
Authors: Shen Joseph J. S. 
Published: December 2007

Summary
This paper describes a research project conducted at Chevron U.S.A. Inc.'s Venice, LA, facility to ascertain that the flow condition inside a nominal 16-in. [406-mm] custody-transfer orifice meter was in compliance with American Gas Assn. (AGA) requirements. The survey was conducted at four flow rates ranging from 160 to 200 MMscf/D [4.53 × 106 to 5.66 × 106 std m3/d] of processed natural gas at 880 psia [6.1 MPa]. Experimental data were collected by a portable data-acquisition system driven by a lap-top microcomputer. The measured profiles indicated that the flow was nearly fully developed at the orifice plate location, and no significant swirling motion was detected.
This test successfully demonstrated the techniques and equipment developed for determining actual flow distributions inside orifice meters in the field under normal operating conditions. This technology can be used to detect detrimental flow profiles and to verify compliance with AGA requirements on flow conditions in custody-transfer orifice meters.
Pulsed-Neutron Monitoring in the Bunter Sands of the Esmond Complex
Authors: Johnson Alan , Scanlon M. E. 
Published: December 2007

Summary
The fields in the Esmond complex (Esmond, Forbes and Gordon) produce gas from the Triassic Bunter sandstone forma tion. Production started from all three fields in 1985, and an annual cased-hole, pulsed-neutron-monitoring program was initiated in 1986. The main objective of this program was to detect changes in formation water saturation resulting from invasion by influx from the aquifer.
Initial interpretation of the pulsed-neutron logs was hampered by two factors that make the Esmond complex a borderline environment for this type of logging: a large, gas-filled borehole that attenuates the tool response and a halite cement in the formation with a very high capture cross section. Increased understanding of these factors has improved the reliability of interpretations. Recent results indi cate water advance in all three fields. Currently, water production has been observed only on Forbes, the smallest of the three fields. Observed pressure behavior, however, does show the effects of water influx in all three fields, confirming the log indications. Detailed analysis of the log results led to the identification of different modes of water influx, either as an overall rise in the gas/water contact or as fingering along permeable layers. This information is valuable in production planning.
Temporary Chemical Block Brings Efficiency and Economy to Eastern U.S. Workover Operations
Authors: Terracina J. M. , McCabe M. A. , Cramer J. W. , Legenza J. E. 
Published: December 2007

Summary
Gel plugs (GP's) have been used in the eastern U.S. for many years. They are a versatile and simple method of temporarily plugging a well. Gel plugs are often used to control a well while remedial workovers are performed. This paper describes the various types of gel plugs and their applications. Case histories are given for gel plug applications.
Explicit Pore-Pressure Evaluation: Concept and Application
Authors: Alixant Jean-Louis , Desbrandes Robert 
Published: December 2007

Summary
A general method was developed to determine pore pressure in undercompacted shales on the basis of explicit relationships among measured shale properties, shale porosity, effective vertical stress, and pore pressure. Although calibration may be necessary, this technique neither uses empirical correlations nor requires establishment of normal trend lines. A modular approach allows users to implement custom equations. This paper outlines the concept and focuses on its application to real-time pore-pressure evaluation based on resistivity measurements.
The Unsteady-State Nature of Sorption and Diffusion Phenomena in the Micropore Structure of Coal: Part 2—Solution
Authors: Kolesar J. E. , Ertekin Turgay , Obut S. T. 
Published: December 2007

Summary
A single-phase, 1D mathematical model, formulated in Part 1 of this study, is used to study unsteady-state micropore sorption in the composite micropore/fracture coalbed-methane-transport problem. The mathematical model is solved numerically by writing the transport equations in finite-difference form and linearizing the residual form of the difference equations with the generalized Newton-Raphson procedure. The numerical model is used to compare methane production rates predicted by unsteady- and quasisteady-state sorption formulations. Results indicate that the two models give different rates during early degasification periods. The high rates predicted by the unsteady-state model, however, generally approached lower quasisteady-state rates within the first few months of simulation.
The numerical model is also used to examine the time-dependent response of concentration gradients in the micropores to changes in fracture pressure, to compare diffusion rates predicted by spherical and cylindrical micropore elements, and to construct dimensionless type-curve solutions to the coalbed-methane flow problem.
Evolution of a Hybrid Fracture/Gravel-Pack Completion: Monopod Platform, Trading Bay Field, Cook Inlet, Alaska
Authors: Grubert D. M. 
Published: December 2007

SummaryPlacing a small fracture job before an inner-casing gravel pack has evolved as the preferred completion method for some reservoirs in Cook Inlet, AK. The hybrid completion gives the theoretical benefit of higher initial rates provided by the fracture and continuity of production provided by sand control.
Encapsulated Breaker for Aqueous Polymeric Fluids
Authors: Gulbis Janet , King M. T. , Hawkins G. W. , Brannon H. D. 
Published: December 2007

SummaryConventional breakers reduce fracturing-fluid viscosity much too rapidly, even at moderate temperatures (140 to 200°F), to be used at the high concentrations required to degrade polymers within proppant packs. A delayed-release, encapsulated breaker was developed that permits the use of high breaker concentrations and thus significantly increases fracture conductivity.
A Method for Selection of Cement Recipes To Control Fluid Invasion After Cementing
Authors: Beirute Robert M. , Cheung P. R. 
Published: December 2007

Summary
A method to scale down well parameters to laboratory conditions for more realistic testing of cement recipes to be used to control wellbore invasion/migration of formation fluids after cementing is introduced. The scale-down procedure proposed here addresses a worst-case scenario. It assumes that the offending gas zone (source of the invading gas) has enough permeability, thickness, and gas volume to invade fully and to pressure-charge the cemented annulus (cement column), if conditions allow. The method is demonstrated in conjunction with the use of a certain laboratory gas-flow apparatus. This general scale-down procedure can be used with other test equipment.
An imaginary set of well conditions is used to illustrate the mechanics of the use of the technique. Tests run with the procedure and the computer-monitored gas-migration test cell are described. A preliminary set of criteria for selecting a cement recipe for a given well is presented. A field case illustrates the use of the procedure.
Visualization of Fluid-Loss Polymers in Drilling-Mud Filter Cakes
Authors: Plank J. P. , Gossen F. A. 
Published: December 2007

Summary
The appearance of fluid-loss polymers in freeze-dried drilling-mud filter cakes was studied with scanning-electron-microscope (SEM) photography. Three fluid-loss polymers were studied: starch, polyanionic cellulose (PAC), and a high-temperature- (HT)-stable, sulfonated polymer. The effects of electrolyte contamination (NaCl, CaCl2, and MgCl2) and temperature (200 to 350°F) on the appearance of the fluid-loss polymers were also studied. A correlation between API filtrate and polymer appearance was sought.
A Decade of Drilling Innovation and Progress in the Paris Basin
Authors: Canter D. B. , Simon J.-M. 
Published: December 2007

Summary
Since 1979, Esso Rep has drilled more than 150 exploration and development wells in the Paris basin. A cost-per-foot reduction of more than 40% was achieved despite a near doubling of rig rates. This paper discusses the unique directional drilling approach used and the drilling, formation evaluation, and contracting techniques.
Heavy Oil From Fractured Carbonate Reservoirs
Authors: Briggs P. J. , Beck D. L. , Black C. J. J. , Bissell Robert 
Published: December 2007

Summary
This paper investigates the recovery mechanisms for steam injection into naturally fractured, carbonate, heavy-oil reservoirs. Interim ideas and results of laboratory and simulation studies are presented and topics for further investigation are suggested. Results so far indicate that both imbibition and internal gasdrive are effective at driving oil into the fracture network.