bluuebunny/crossref_metadata_2025_split huggingface dataset:
Evaluation of the Pseudosteady-State Method for Composite Systems in Various Flow Geometries
Authors: Issaka M. B. , Ambastha A. K. 
Published: December 2007

ABSTRACT
The pseudosteady state method, as applied to radial composite systems, has been used to estimate swept region volumes for thermal recovery projects with a good degree of success. However, the increasing scope and complexity of thermal recovery projects, as well as, the general heterogeneity of petroleum reservoirs, have necessitated the consideration of different flow geometries other than radial. Using analytical solutions, this study seeks to evaluate the applicability of the pseudosteady state method to composite systems in radial, linear, elliptical and spherical flow geometries.
To compare the solutions for the different flow geometries, the dimensionless pressure and time values have been normalized to account for the different definitions for dimensionless variables in each system. Results of the study indicate that, for the same mobility and storativity contrasts between the inner and outer regions, the dimensionless pressure derivatives for the four flow geometries can be collapsed into one curve during the period when the various systems approximate pseudosteady state flow. This observation confirms the pseudosteady state method as being independent of the regularly-shaped swept region shape.
Results also show that the pseudosteady state flow period begins at the same time for all four flow geometries. However, the time to the end of pseudosteady state varies. The linear flow geometry shows the longest pseudosteady state flow period, while the spherical flow geometry shows the shortest. The radial and elliptical flow geometries show the same duration of pseudosteady state flow.
The conditions under which a pseudosteady state flow period of a reasonable duration will occur for each of the four flow geometries are presented. Times for the start and end of the pseudosteady state flow period for each flow geometry, as functions of mobility and storativity contrasts, are also discussed. This study will help to identify the conditions under which the pseudosteady state method can be used to estimate the swept volume for thermal recovery projects under various reservoir situations.
Depth of Investigation for Elliptical Flow Problems and Its Applications to Hydraulically Fractured Wells
Authors: Liao Yizhu , Lee W. J. 
Published: December 2007

ABSTRACT
This paper presents a method to determine "depth of investigation" for elliptical flow in homogeneous and composite reservoirs. Flow toward a well with a hydraulic fracture is an example. Formulas for determining depth of investigation for elliptical flow problems presented in this paper are not reported in the literature. The familiar radius of investigation for radial flow and depth of investigation for linear flow are two limiting forms of our depth of investigation for general elliptical flow. This paper also takes a hydraulic fracture as an example case and presents a few applications of our depth of investigation for elliptical flow problems.
Analysis of Infill Drilling in Kansas Hugoton
Authors: Ryan T. C. , Oberst R. J. , Hansen C. D. 
Published: December 2007

ABSTRACT
The Hugoton Field in southwestern Kansas, western Oklahoma and northwestern Texas is the largest gas field in North America. Gas production is from the shallow (2,100+ feet to 2,900+ feet) heterogeneous, multi-layered Chase gas reservoir. This paper analyzes performance of wells in the Kansas Hugoton field. It compares volumetric and performance data from original and more recent infill wells within this field. These comparisons are shown by field, operator grouping, and infilled unit grouping using official deliverability tests and production history. The results are compared against geologic distributions, by producing layer, across the field. A cumulative comparison of the original versus infill well shut-in pressure difference is shown for the first 318 units infilled since infill drilling began in 1987. Some specific case studies are shown comparing monthly and daily well performance surveillance data. This analysis shows: (1) Some of the pitfalls of estimating initial gas-in-place (IGIP) and recoverable reserves, (2) The need to look at more than one type of analysis in reaching conclusions, and (3) Reasons why infill wells have not developed significant fieldwide incremental reserves.
Computerized Drilling Reports Strengthen Management's Decision Process
Authors: Wustermark R. V. , Hoff K. J. , Boyer C. M. 
Published: December 2007

ABSTRACT
This paper discusses the benefits and difficulties with the implementation of a daily drilling report system using personal computers (PC's) at rig site throughout the Panhandle Region. The system's purpose being to capture and send data daily to the Borger, Texas office.
In 1991, laptop PC's were introduced to rig site operations. Training of field and office personal was essential, but proved to be less demanding than originally anticipated.
Benefits of the new system: A much higher accuracy (92%) of critical data compared to 62% of the old main frame system.Detailed daily costs are captured and are checked against the AFE cost estimate for discrepancies.Management is using the daily cost information for timely budget decisions rather than waiting for invoice payment system to provide cost information.
The main problems experienced are with the modems and cellular telephones. When operations are in fringe areas of coverage, equal distance between towers, or bad weather is moving through, loss of clear signals affects communication.
Overall the improved quality and quantity of data has more users asking for and receiving, in a convient, timely manner, the needed information to a number of myriad decisions and reports necessary to support an active drilling and completion program. PC's have been accepted by both office and field supervisors as an efficient way of doing today's business.
Case Study: Isolation and Restimulation of Granite Wash Zone in Mendota, NW Field Using Inflatable Packer Frac Liners
Authors: Hailey R. G. , McKaughan C. A. 
Published: December 2007

ABSTRACT
The Mendota, NW (Granite Wash, SW) field in east central Roberts, County, Texas produces gas and gas condensate from the Cherokee Granite Wash section. Due to multiple producing intervals spread over a long vertical section, many of the wells in this field were fracture stimulated using the "limited entry" diversion technique1. Later comparison of actual gas recovery versus volumetrically calculated gas-in-place indicated very low gas recovery for wells originally stimulated by limited entry. It was concluded that some of the zones in these wells did not receive adequate treatment and would benefit from restimulation.
In order to fracture stimulate individual zones in wells with multiple open producing intervals, it is necessary to isolate the individual zone to be treated from the other open intervals. For the first well in the study area to be restimulated, a frac liner was configured utilizing two inflatable packers straddling a segment of tubing covering the upper producing intervals. This enabled fracture stimulation of the deepest zone with the treatment pumped down the casing and through the short liner interval, allowing an adequate injection rate with a reasonable injection pressure.
Research and Development Wells for Technology Transfer
Authors: Hansen J. T. , Perry K. F. 
Published: December 2007

ABSTRACT
The Gas Research Institute (GRI) has developed a project that is aimed at accelerating the transfer of several hydraulic fracturing related technologies to the marketplace. The project, known as the "Research and Development (R&D) Wells for Technology Transfer", was initiated in the spring of 1992 and to date has been applied with nine producers on a total of 18 wells. The primary technology transfer vehicle used in the project is the cooperative research well, which is jointly sponsored by GRI and the participating producer, Emphasis is placed on heavy hands-on technology training and application by the producer, rather than on conventional GRI contractor involvement.
The new technologies that are being promoted in this project include: special core tests and analysis; formation stress testing; expanded logging programs; three-dimensional fracture modeling using FRACPRO; fracture diagnostics; fracture fluid quality control; and special well clean-up techniques.
Results from the project indicate that technology transfer using this technique can be effective under the right circumstances. The success is heavily dependent upon training, producer involvement, timing, and previous experience with hydraulic fracturing theory and technologies.
Proppant Effects on Fracturing Fluid Friction
Authors: Downie R. C. , Fagan R. E. 
Published: December 2007

SUMMARY
During a fracturing treatment, bottom hole fracturing pressure is used to evaluate the progress of the job. Direct measurement of bottom hole pressure is difficult. Surface treating pressure is commonly used to estimate bottom hole pressure, and must be corrected for fluid hydrostatics and friction losses in the tubing and perforations. This paper will illustrate the errors that can be made in fracturing treatment evaluation if proppant effects on fluid friction are not properly accounted for.
Static and Dynamic Rock Mechanical Properties in the Hugoton and Panoma Fields, Kansas
Authors: Yale D. P. , Jamieson W. H. 
Published: December 2007

ABSTRACT
An understanding of the mechanical properties of petroleum reservoirs is important for drilling, well stimulation and horizontal well development. Static and dynamic rock mechanical properties were measured on a suite of core samples taken through the Chase and Council Grove carbonate sequences of the Hugoton and Panoma fields, Kansas. The purpose of the study was to characterize the mechanical properties of the different facies and calibrate the dynamic mechanical properties so acoustic well logs from other wells can be utilized more effectively in determining areal and lithologic variation in mechanical properties of the field.
The mechanical properties of rocks can be measured in the laboratory from triaxial tests ("static" tests) or they can be estimated from wireline measurements of compressional and shear acoustic velocities and rock density ("dynamic" tests). Static measurements on cores are much more indicative of the mechanical properties of the reservoir than the dynamic results, however, the information from acoustic well logs covers much more of the reservoir than core measurements and is less expensive. Since there can be significant differences between static and dynamic values, it important to be able to translate the "dynamically" derived mechanical properties to the static values which better represent the reservoir.
Results of the tests show that Young's modulus correlates strongly with lithofacies and porosity. The Chase and Council Grove carbonate sequences can be separated into six "mechanical facies", defined by their modulus-porosity trends and their lithology. Only small percentages of secondary minerals (dolomite and anhydrite) appear necessary to alter the rocks properties significantly. Poisson's ratio is less sensitive to lithology but correlates with porosity. The dynamic Young's moduli are higher than the static values but dynamic and static Poisson's ratios correlate well with each other for liquid saturated samples.
Dynamic to static transforms based on lithofacies were developed from these data to correct the acoustic log derived mechanical properties to static values appropriate for reservoir deformations. The corrected mechanical properties along with the trends observed between mechanical properties, lithofacies, and porosity allow for the design of more effective hydraulic fracture treatments by utilizing accurate values for the reservoir's mechanical properties and their variability.
Development and Testing of a Semi-Analytical Hydraulic Fracture Model for Multistress Media
Authors: Rueda J. I. , Rahim Zillur , Holditch S. A. 
Published: December 2007

Abstract
Over the past 25 years, numerous hydraulic fracture models have been developed to predict the behavior of underground fracture propagation.1 Typical fracture propagation models predict fracture height, length, and width based on formation mechanical and fracture fluid properties.2 Fracturing fluids and effects of leakoff also have great influence on ultimate fracture dimensions. A recent paper by Warpinski et al.3 illustrates the diversity that still exists in the fracture propagation modeling problem.
There are basically two types of three-dimensional fracture models. Pseudo-three-dimensional models, that run efficiently on microcomputers, are mostly applicable in reservoirs bounded by high in-situ stress layers that can suppress rapid fracture height growth. Full three-dimensional models, on the other hand, require more computer memory, run time, and user expertise to design and evaluate a fracture treatment. Reducing CPU time is important, particularly during a fracture design optimization process, since numerous fracture predictions and sensitivity analyses are needed to determine the optimal fracture design.
In this paper, we will illustrate how to couple the equations describing formation elasticity, fracture fluid flow, and fracture mechanics and develop an efficient semi-analytical technique to determine fracture geometry. We have assumed a quadratic pressure and stress profile fit to approximate the fluid pressure inside the fracture and the in-situ stress profile in a multilayered system. We have tested our new model using different reservoir conditions. We provide a detailed sensitivity analysis on reservoir and fluid parameters in order to help us understand how these parameters influence the design of a hydraulic fracture treatment.
Slug Flow: Occurrence, Consequences, and Prediction
Authors: Hill T. J. , Wood D. G. 
Published: December 2007

AbstractBP Exploration currently has an interest in hundreds of kilometres of operating multiphase flowlines. Most of the company's proposed field developments also involve multiphase flowlines. A large number of these do or will experience slug flow, either as the normal flow regime, or as a result of transient behaviour.Data on flow regime and slug flow characteristics have been collected from many lines over the past 8 years. Information on slug characteristics from a number of different systems is presented in this paper, including velocity, length and holdup. Some unfavourable consequences of slug flow on both process performance and system integrity are highlighted, including plant shutdowns and mechanical damage.The need to be able to predict slug flow for the design of future systems, and to advise the operators of existing systems, remains a high priority for R&D activities, as ever longer and more complex multiphase systems are proposed. BP's latest slug frequency method is described, followed by guidelines for pipework layout, and comments on current R&D on corrosion in multiphase flow.
The Interactive Visualization of Spatial Uncertainty
Authors: Srivastava R. M. 
Published: December 2007

Abstract
Though stochastic and geostatistical methods can produce numerous equally likely models of a petroleum reservoir, most practical case studies that use such probabilistic methods do not explore the entire space of uncertainty but focus instead on a single outcome. When displayed using powerful visualization tools, this single outcome is often mistaken for reality. The traditional graphical displays that geostatisticians use to combat this false belief in the certainty of a single image do not convey uncertainty in an intuitive manner; these traditional displays therefore tend to be less compelling than the slick and polished graphical displays that modern visualization tools provide.
The visualization of spatial uncertainty can be made more intuitive with dynamic displays in which each frame is a plausible outcome that differs only slightly from the previous one. The same approach can be enhanced to allow interaction with the display so that users have a more direct sense of exploring the space of uncertainty.
Interactive visualization tools improve decision-making in the face of uncertainty by confronting engineers and geologists with the spatial uncertainy that is often critical in a comprehensive risk analysis of EOR projects.
Interpretation of Hydraulic Fracture Mapping Experiments
Authors: Warpinski N. R. 
Published: December 2007

Abstract
Simple mechanical models of the response of a reservoir to hydraulic fracturing have been developed in order to interpret the response of microseismic and downhole-tilmeter diagnostic systems and determine the important reservoir and treatment parameters that influence the response. For microseisms, results of this study can be used to delineate the width of the seismically active zone and possibly distinguish different types of signals. For downhole tiltmeters, the results can be used to interpret the measured tilt response and provide information on height growth, closure pressure and proppant placement.
Acoustic tomographic difference imaging of dynamic stress fields
Authors: Scott T. E. , Ma Q. , Roegiers J. -C. , Reches Z. 
Published: December 2007

Abstract
Acoustic tomographic imaging was conducted on a complex stress field generated during indentation into a Berea sandstone core sample. The imaging process used 130 ultrasonic raypaths and 97 pixel elements to construct tomograms perpendicular to the indentation direction. ‘Zeroed velocity’ acoustic difference tomograms were made by subtracting the initial velocity tomogram from the seven successive indentation tomograms up to stresses of 110 MPa. The tomograms illustrate a marked development of a high velocity zone beneath the indenter. The high velocity maximum continues to increase with increasing application of indentation stress. At the highest indentation stress levels the rate of change in velocities with added deformation is lower than at low stress levels. This observation is attributed to the closure of cracks and pore spaces at high stress levels. These results indicate that it may be possible to image changes in stress fields created during petroleum extraction and production operations.
Results from reservoir depressurisation simulation incorporating phenomena revealed in a reactive reservoir analogue
Authors: Smart B. G. D. , Tehrani D. H. , Olden P. W. H. , Jin M. 
Published: December 2007

Abstract
Field observations of rock mechanical phenomena made in reactive analogues are presented, along with the output from coupled simulation models of reservoirs incorporating these phenomena. The models demonstrate that fault activation occurs during depressurisation, altering conductivities and hence controlling the flow of fluids towards the producing wells.
Als reaktive Analoge gemachte Feldbeobachtungen gesteinsmechanischer Phänomene werden zusammen mit dem Output aus gekoppelten Simulationsmodellen von Speichern, die diese Phänomene aufweisen, vorgestellt. Die Modelle demonstrieren das Auftreten von Fehleraktivierung und Scherung der Ablagerungsebene während einer Druckminderung, wodurch Leitfähigkeiten und damit auch die Kontrolle des Flusses von Flüssigkeiten zum Produktionsbohrloch geändert werden.
Les phénomenes rocheux mécaniques observés sur le terrain dans des systemes analogiques réactifs sont présentés accompagnés des sorties obtenues de modeles couplés de simulation de reservoirs présentant ces phénoménes. Les modéles démontrent que 1'activation de faille et le cisaillement de plan de stratification se produisent å la dépressurisation donnat des modifications de conductivité affectant 1' écoulement des fluides vers le puits de production.
Fluid-Saturated Solid Flow with Propagation of a Yielding Front
Authors: Geilikman M. B. , Dusseault M. B. , Dullien F. A. L. 
Published: December 2007

ABSTRACT
Sand production instability is considered as the result of wellbore fluid pressure reduction (drawdown) below some critical level. A continuum model for massive continued sand production is developed by considering coupling of fluid flow with the flow of the granular matrix. The model provides a physical mechanism describing propagation of a yielding front away from the wellbore as sand production continues. Solid flow proceeds by "unravelling of fabric" because yield front motion is opposite to the direction of solids mass transport. Short-term enhancement of fluid production because of simultaneous sand production turns out to be dependent not only on instantaneous sand flux, but also on the current radius of the yielded zone around wellbore, that is, the history of sand production for the well. Long-term enhancement is stipulated mainly by growth of a yielded, highly permeable zone around the wellbore.
Effect of the Fracture Process Zone in Directed Crack Propagation in Borehole Blasting
Authors: Exadaktylos George , Agioutantis Zacharias , Lambrou Eleftherios 
Published: December 2007

Abstract
The growth of directed radial cracks originating from diametrically opposite notches in a blasthole, is analyzed. The cracks are considered to be composed from a traction free portion and a microcracking zone where cohesive forces act. A preliminary energy balance approach showed that the length of this zone has an effect on the blast results. Subsequently, a coupled non-linear displacement discontinuity model was applied in order to verify this effect.
Geomechanical Analysis of Small Earthquakes at the Eleveld Gas Reservoir
Authors: Roest J. P. A. , Kuilman W. 
Published: December 2007

Abstract
A distinct relationship exists between the production of natural gas and small earthquakes near the reservoir. Simple models show that the sensitivity for fault activation due to differential compaction evidently depends on the fault-reservoir geometry. A very sensitive geometry, leading to several small earthquakes, is found in the Eleveld gasfield. The observed magnitudes correlate well with estimates from a more complex model. In this specific geological setting residual tectonic stresses are assumed to be negligible. For the coming decades, pressure depletion is expected to amount to only a fraction of the pressure depletion up to now. Therefore the potential magnitudes of possible future earthquakes in this area are expected to become only marginally higher.
Temporal and Spatial Structures of Triggered Seismicity in Romashkinskoye Oil-Field
Authors: Turuntaev S. B. 
Published: December 2007

Abstract
The analysis of spatial-temporal organization of seismicity on the Romashkinskoye oil field (Tatarstan, Russia) was made. The object of analysis was the catalog of about 360 seismic events (0.1&lt;M&lt;4) being registered since 1986. It was found that the slope of magnitude-frequency relationship ship was the same as it is usual for induced seismicity. The analysis of temporal behavior of seismic regime was made in terms of two variables, they are "the activity of seismic process" and "the velocity of activity change". It was shown that the studied seismic process can be consider as Markov chain rather than Poisson' process. Abnormally great number of shocks close in time to each other is observed. The analysis of spatial distribution of such events was made. Correlation between seismic activity and extraction of fluids, injection of water and difference in volume between them was investigated.