bluuebunny/crossref_metadata_2025_split huggingface dataset:
Engineering Design of Gas-Condensate Pipelines With a Compositional Hydrodynamic Model
Authors: Vincent Patrick A. , Adewumi Michael A. 
Published: December 2007

SummaryGas condensation in pipelines designed to transport natural gas is common. The radical difference in the engineering design required for this system, compared with that required of "dry gas" pipelines, makes the problem of significant interest to the gas industry. Because the point and quantity of condensation is not usually known a priori, any attempt to develop a predictive capability for such a system must have an inherent means of providing this information. This requires a good coupling of the gas-phase behavior model with the appropriate hydrodynamic model. This work attempts to develop such a model. With a two-parameter equation of state (EOS) to describe the phase behavior of the natural-gas system, a multiphase hydrodynamic model developed from fundamental fluid dynamics is used to describe the hydrodynamic behavior of the resulting two phases. The model, which consists of a system of nonlinear algebraic and ordinary differential equations (ODE's), was solved numerically. Output from the model solution includes quantity of condensate at any point in the pipeline, pressure drop, and other hydrodynamic variables. The model can predict the various engineering parameters of interest in the design of such pipelines and could be used for feasibility studies and for optimal location of fluid-handling equipment.
Comparison of Pressure-Transient Response in Intensely and Sparsely Fractured Reservoirs
Authors: Johns R. T. , Jalali Younes 
Published: December 2007

SummaryA comprehensive analytical model is presented to quantify the pressure-transient behavior of a naturally fractured reservoir with a continuous matrix-block-size distribution and interporosity skin. Geologically realistic probability density functions of matrix block size are used to represent reservoirs of varying fracture intensity and uniformity. Drawdown and interference type curves are developed with rectangular probability density functions.The results obtained extend previous dual-porosity models by incorporating fracture spacing variability. In the absence of interporosity skin, intensely and sparsely fractured reservoirs show distinctions in the pressure response. Uniformity of a fractured reservoir also significantly affects pressure responses, irrespective of the degree of fracture intensity. The pressure response in a nonuniformly fractured reservoir with large block-size variability, for example, can exhibit a nonfractured (homogeneous) reservoir response. The results may be used to estimate matrix-block-size variability and the degree of fracture intensity from drawdown and interference well tests.
Injection-Time Effects on Falloff Responses From Composite Reservoirs
Authors: Ambastha A. K. , Ramey H. J. 
Published: December 2007

SummaryAn analytical solution for a radial, composite reservoir is used to establish dimensionless injection time based on the front radius as a correlating parameter for falloff responses of all front radii. Effects of short injection time on the accuracy of methods used to estimate swept volume (or front radius) are discussed. If injection-time effects are ignored, the pseudo-steady-state method may overestimate swept volume by an order of magnitude. For short injection times, model selection (a two- vs. three-region model) for type-curve matching can be difficult. Finally, a correlation is presented for the magnitude of injection time to analyze falloff data with an injectivity type curve.
Single-Trip Tubing-Conveyed Perforating, Production Testing, and Pressure-Buildup Testing in Nonflowing Wells
Authors: Barnes J. A. , Snider P. M. , Swafford C. V. 
Published: December 2007

Summary
This paper describes tools and procedures for tubing-conveyed perforating (TCP) and subsequent production testing of a well with a reverse-flow jet pump with a specially designed blanking sleeve. A downhole shut-in pressure buildup is also obtained and all equipment is pressure-actuated, eliminating the use of wireline.
Analysis of Pressure-Transient Data From Underbalanced Perforating
Authors: Centanni R. J. , Chacon E. A. , Garrett J. C. , Shealy R. A. , Ruiz S. J. 
Published: December 2007

Summary
Determination of reservoir characteristics from transient pressures created by underbalanced perforating can enable an operator to decide whether a well is commercially productive before permanent completion. Several techniques exist to analyze such data. In this work, closed-chamber testing and log-log- and Cartesian-plotted short producing times are used to analyze data collected from a multiwell project in the Gulf of Mexico. Pressure data were obtained from underbalanced perforating and backsurge-washing treatments. Results of these analyses compared favorably with buildup tests performed after the wells were completed.
Quicklook Prestimulation Well Test
Authors: Ahmed U. , Husband F. J. , Tariq S. 
Published: December 2007

Summary
In this paper, we present a technique that allows one to perform a short-term well test. The short duration of the test results in reasonably good estimates of formation permeability, skin factor, and reservoir pressure. The technique, referred to as "Quicklook, " requires pressure measurement at the surface and downhole. After perforating, the formation is subjected to an instantaneous-rate drawdown or injection for a couple minutes. The instantaneous-rate period is followed by a shut-in period of sufficient duration to achieve the desired radius of investigation. Three interpretation plots are made to perform the analysis: a derivative type plot for flow-regime identification and type-curve analysis, a specialized plot [rate-convolved Homer (RCH) analysis] for certain flow parameter calculations, and a system-verification plot. A desirable feature of the technique is that the testing and perforating can be performed during the same trip. Two field examples from low-permeability wells illustrate the technique and data interpretation.
A Reservoir Model for Wireline Formation Testing
Authors: Yildiz Turhan , Langlinais Julius 
Published: December 2007

Summary
A 3D analytical model has been developed to improve the analysis of the transient pressure response of a reservoir to wireline formation testing (WFT). The mathematical model was used to evaluate the validity of current interpretation techniques and to investigate the sensitivity of transient pressure behavior to wet/bore parameters.

Introduction
WFT is an openhole-logging technique where data are used to determine initial reservoir pressure; vertical pressure distribution along an open hole, fluid contacts, and formation permeability. Formation permeability is deduced from the pressure behavior observed during the test.1–8 WFT pressure data are typically noisy, and interpretation is based on simplified flow configurations; thus, until now, only a qualitative estimate of formation permeability from WFT data has been possible.
WFT consists of one or two drawdown periods and a buildup period. A WFT tool typically has a probe, a pressure gauge, and one or two pretest chambers. Fig. 1 gives a schematic of the WFT tool. The test is performed after the packer on the tool squeezes the mudcake out and properly isolates the formation. The probe is inserted into the formation through the mudcake, and formation fluid is withdrawn until the first chamber is full; the second chamber, when present, is filled at a higher flow rate. Then, the fluid withdrawal is stopped.
During the drawdown and subsequent buildup periods, the pressure at the probe is recorded by a pressure transducer. Fig. 2 illustrates the flow-rate schedule and the expected pressure behavior at the probe for a WFT tool.
In recent years, considerable effort has been directed to obtaining the formation permeability from WFT data. The use of the WFT pressure data for permeability evaluation was first proposed by Moran and Finklea.6 Later, Stewart and Wittmann7 extended this study.
Characteristic-Time Concept in Hydraulic Fracture Configuration Evolution and Optimization
Authors: Lee T. S. , Advani S. H. , Avasthi J. M. 
Published: December 2007

SummaryThis paper introduces the concept of characteristic time as a measure to separate and to optimize the roles of Griffith surface energy and fracture-fluid dissipation energy during hydraulic fracture evolutions. The analysis reveals two separate sets of solutions that correspond to two distinct time regimes of hydraulic fracture propagation: a dominant fluid dissipation energy and a dominant fracture surface energy regime. Each influence domain is governed by a characteristic time and demarcated by a transition region, where the energy contributions of each are of the same order of magnitude. Verification of the theoretical response trends and the use of the characteristic-time concept as a design tool are also presented.
Flow Characteristics of Hydraulic Fracture Proppants Subjected to Repeated Production Cycles
Authors: Holditch S. A. , Blakeley D. M. 
Published: December 2007

Summary
When fracture proppants are subjected to cyclic loading, the conductivity of the fracture is reduced. This paper presents laboratory results to quantify the degradation of sand and intermediate-strength proppants (ISP's) as closure stress is loaded cyclically to the proppant. The results imply that, if a deep gas well is opened and then shut in repeatedly, permanent damage to the hydraulic fracture will occur.
Field Application and Benefits of Wellsite Buildup Technology
Authors: Roach M. K. 
Published: December 2007

Summary
For many rod-pumped wells in the U.S., conventional buildup tests are too costly relative to the apparent potential benefits. Yet with lower oil prices and declining production volumes, the need for such data to optimize recovery is even greater. Mobil has eliminated this dilemma on a number of its fields by turning to the latest in acoustic buildup technology to reduce the cost of these tests.
Assessment of the Mechanical Stability of High-Angle Wells in Block 22/11, Nelson Field Discovery
Authors: Kwakwa K. A. , Batchelor A. S. , Clark R. C. 
Published: December 2007

Summary
This paper summarizes the theory of using a practically oriented simulator to assess the mechanical stability of a wellbore in a triaxial, linearly elastic stress field. The model can be used to determine the range of mechanically stable well inclinations in a given formation and to produce mud-weight programs tailored to efficient and safe drilling, even in difficult conditions. In the Nelson discovery in Block 22/11 of the North Sea, the model was used to evaluate mechanical instability experienced during drilling of deviated appraisal wells through overpressured Oligocene shale. Simulation results showed that, within a range of drilling-mud densities, wells of any orientation can be drilled through the shale. However, practical considerations of formation heterogeneity, swab and surge pressures, and possible chemical interaction dictate that inclined wells beyond about 65° should not be attempted until more field data are acquired to enhance confidence in the use of the model in Block 22/11.
Fines Migration and Formation Damage: Influence of pH and Ion Exchange
Authors: Vaidya R. N. , Fogler H. S. 
Published: December 2007

SummaryThis paper elucidates the influence of pH and ion exchange on formation damage caused by fines migration. The experimental results affect waterflooding, design of drilling muds, and alkaline flooding. In-situ release of naturally existing fines (generally clays) results from changes in colloidal conditions of the permeating fluid. Such processes can cause extensive formation damage in sandstones, thereby reducing oil production. Our recent studies clearly indicate that the release process is started by a combination of high pH and low salinity. We present experimental results that suggest and confirm the interdependence between changes in salinity, cation exchange, and pH, leading to drastic permeability reductions. These results therefore provide new insight into the phenomenon of formation damage caused by water sensitivity or injection of incompatible brines. We also describe a unified approach to understanding these results and the findings of previous investigators. Predictions obtained from a physicochemical model based on ion exchange and colloidal chemistry agree well with experimental observations. The effect of different cations on formation damage also was investigated. This study can be extended to predict migration of bacteria and other particulates that cause formation damage.
Migration of Particles to a Hole Wall in a Drilling Well
Authors: Walker Richard E. 
Published: December 2007

Abstract
The rate at which a particle will migrate from the rotating drill pipe to the hole wall was calculated as functions of the mud properties, pipe rotational speed, and hole size. The information can be used to estimate the relative carrying capacity of one mud compared to another Then the changes that need to be made when a hole. is not cleaning can be determined. An adaptive control process for field use is suggested
Two major simplifying assumptions are that axial flow does not influence the liquid viscosity and that the viscous resistance to particle movement in the radial direction is proportional to the particle's velocity. The calculations assume a power model liquid, spherical cuttings, and concentric pipe in a round hole. A concept of "theoretical zones" where the calculations are valid interspersed with areas where the particles are uniformly redistributed, is used to relate the simplified theory to actual hole conditions.

Introduction
This theoretical study was conducted to improve the understanding of hole cleaning and how various drilling conditions and muds influence the ability to lift cuttings to the surface. The primary object of the study was to see how fast a particle might move from the drill pipe to the hole wall and how factors of drilling and liquid properties influence the rate of radial movement. The rate of movement may be important as the centrifugal force set up by the rotating drill pipe tends to force the particle toward the hole wall, an area of low vertical mud velocity and, therefore, poor lifting.
Correlations of Mud Rheological Properties With Cuttings-Transport Performance in Directional Drilling
Authors: Becker T. E. , Azar J. J. , Okrajnl S. S. 
Published: December 2007

Summary
An experimental study comparing the effects of mud rheological parameters on annular drill-cuttings buildup was conducted in a large-scale flow section. Rheological parameters examined were mud yield point (YP); plastic viscosity (PV); YP/PV ratio; power-law exponent; consistency index; Fann™ V-G Meter dial readings at 600, 300, 200, 100, 6, and 3 rev/min; effective viscosity (calculated by the power-law derivation); and initial and 10-minute gel strengths. Fifteen bentonite/polymer water-based muds were used, ranging from water to a mud with YP and PV values of 20 lbf/100 ft2 and 40 cp [19.6 Pa and 0.04 Pa·s], respectively. For each mud, flow tests were run at annular velocities from 120 to 240 ft/min [37 to 73 m/min] and hole angles from 30 to 90° from vertical. The effective drilling rate for all tests was 50 ft/hr [15 m/h]. Altogether, 180 tests are analyzed.
When data were correlated with annular cuttings volume in steady-state flow, the best fit was obtained with low-shear-rate parameters. These parameters include the 6- and 3-rev/min dial readings and initial gel strength. Correlation coefficients for these were often from 0.9 to 0.95. For hole angles ≤45° (from vertical), increasing values of these parameters improved cuttings removal (i.e., reduced cuttings volume). The same was observed at angles near horizontal, but only in the laminar flow regime. Cuttings volumes were always smaller in the turbulent regime during near-horizontal flow.
New Friction Correlation for Cements From Pipe and Rotational-Viscometer Data
Authors: Shah Subhash N. , Sutton David L. 
Published: December 2007

Summary
This paper presents the results of 24 discrete slurries tested on a pipe flow loop while data were taken simultaneously with a flow-through rotational viscometer. Each slurry was pumped through four different pipe sizes at rates from low laminar to high turbulent flow regimes. Test slurries varied from very thixotropic to highly dispersed and from lightweight to dense.
Analysis of pipe-flow data showed a correlation best described by a Bingham-plastic model. Standard flow properties calculated from the rotational-viscometer data were correlated to flow properties derived from the pipe-flow data. These results could be used to calculate pipe pressure losses with improved accuracy.
Correlations for estimating friction losses of cement slurries in laminar and turbulent flow regimes and for predicting laminar/turbulent transition were developed. Results of these correlations are compared with the findings of previous investigators. An example illustrates the use of these correlations.
Application of Probabilistic Reliability Methods to Tubular Designs
Authors: Payne Mike L. , Swanson John D. 
Published: December 2007

Summary
Standard tubular design methods are based on a specific margin (i.e., "safety factor") between the maximum anticipated field load and the published rating of the tubular. This technique minimizes the risk of failure but promotes overdesign because of the conservativeness in the tubular rating and in the assumed high-load case. To quantify the safety of a particular design, we developed a new method that accounts for the variation of field loadings and tubular performance. Probability distributions for load and capacity are developed on the basis of assumed field-load histories and actual test results on tubular performance. Reliability design methods, originally used in civil engineering, are used to combine these distributions and to quantify the probability of failure. Results show that current design factors do not provide an effective reliability measurement. As a result of these limitations, true-cost/reliability decisions on designs cannot be made with conventional techniques. If reliability is quantified with the proposed method, decisions can be made that properly balance economics, safety, and uncertainty. This paper should assist engineers who need alternative design approaches and managers interested in a better understanding of how existing tubular design methods relate to risk exposure and optimal costs.
Drill-Bit Diagnosis With Neural Networks
Authors: Arehart R. A. 
Published: December 2007

Summary
A neural network was constructed to determine the grade (state of wear) of a drill bit while it is drilling. With a three-layer neural network and back-propagation as the learning algorithm, the system was trained with laboratory data collected using bits of known grades drilling through known lithologies. The inputs to the neural network were rate of penetration (ROP), weight on bit (WOB), torque (T), revolutions per minute (RPM), and hydraulic horsepower per square inch (HSI). The network was tested on synthetic formations of various bed thicknesses constructed from the test data.
Bit Whirl—A New Theory of PDC Bit Failure
Authors: Brett J. Ford , Warron Thomas M. , Bohr Suzanne M. 
Published: December 2007

Summary
This paper presents the results of a study showing that the most harmful polycrystalline-diamond-compact (PDC) bit vibrations can be attributed to a phenomenon called "bit whirl." During whirl, the instantaneous center of rotation moves around the face of the bit, and the bit whirls backward around the hole. Cutters on a whirling bit can move sideways, backward, and much faster than those on a true rotating bit. The impact loads associated with this motion cause PDC cutters to chip, which, in turn, accelerates wear. Laboratory and field results show the detrimental effects of whirl on PDC bit rate of penetration (ROP) and life.
Eliminating the Rugosity Effect From Compensated Density Logs by Geometrical Response Matching
Authors: Flaum Charles , Holenka J. M. , Case C. R. 
Published: December 2007

Summary
A theoretical and experimental effort to understand the effects of borehole rugosity on individual detector responses yielded an improved method of processing compensated density logs. Historically, the spine/ribs technique for obtaining borehole and mudcake compensation of dual-detector, gamma-gamma density logs has been very successful as long as the borehole and other environmental effects vary slowly with depth and the interest is limited to vertical features broader than several feet. With the increased interest in higher vertical resolution, a more detailed analysis of the effect of such quickly varying environmental effects as rugosity was required.
A laboratory setup simulating the effect of rugosity on Schlumberger Litho-DensitySM tools (LDT) was used to study vertical response functions. These functions were used to derive matching filters, enabling a significant improvement in the compensated log response in the presence of rugosity. The data served as a benchmark for the Monte Carlo models used to generate synthetic density logs in the presence of more complex rugosity patterns. The results show that proper matching of the two detector responses before application of conventional compensation methods can eliminate rugosity effects without degrading the measurement's vertical resolution. The accuracy of the results is as good as that obtained in a parallel mudcake or standoff with the conventional method. Application to both field and synthetic logs confirmed the validity of these results.
Fracturing Oil Shale With Electricity
Authors: Melton Noel M. , Cross Theodore S. 
Published: December 2007

Abstract
Laboratory studies to evaluate the use of electricity for fracturing various grades of Colorado oil shale were started in 1964. Breakdown voltages varied greatly from one grade of shale to another, ranging from a minimum of 300 v to a maximum of 15,000 v. With few exceptions, the shale samples were readily fractured at relatively low current levels. On the basis of encouraging results obtained in the laboratory, experiments were expanded to field tests to study electrical characteristics of oil shale when subjected to overburden pressure. These tests generally confirmed the laboratory experiments. Fracturing was accomplished at all electrode spacings used. The spacings varied from 3 to 129 ft. Based upon results obtained in these field experiments, additional fracturing tests were conducted in four shallow wells drilled in an oil shale formation. Some new permeable zones were created between wells. The induced permeability was improved by detonating two conventional nitroglycerin wellbore shots in one of the wells.

Introduction
Before an in situ retorting process can function, it is necessary to develop techniques to increase the permeability of the oil shale formation. Induced fracturing, the best method of increasing the effective permeability of oil-shale deposits, may be accomplished by hydraulic pressure, high explosives, high-voltage electricity or combinations of two or more of these. This article discusses the laboratory experiments and preliminary field tests being made to study high-voltage electricity as a method of fracturing oil shale. Fracturing is the first phase of the electrocarbonization process and is the phase with which this investigation is primarily concerned. Several investigators have studied the electrocarbonization process as applied in coal, petroleum and oil shale formations, but none has reported making field tests in Green River oil shale.