bluuebunny/crossref_metadata_2025_split huggingface dataset:
Analytic Two-Dimensional Models of Water Cresting Before Breakthrough for Horizontal Wells
Authors: Giger François M. 
Published: December 2007

Summary
Production with horizontal wells offers a new approach to reducing water-coning effects during oil production. This paper evaluates what effect water cresting under a horizontal well will have and determines the critical flow rate by fully analytic, two-dimensional (2D) methods developed in a vertical plane perpendicular to the axis of the horizontal well. Three production mechanisms are considered: lateral edge drive, gas-cap drive, and bottomwater drive. The theory gives the critical flow rate value in each case. A major achievement of this theory is the proof of a decreasing critical flow rate value with cumulative production by the bottomwater-drive mechanism. Results are presented in graphs for quick use. Case studies exemplify a simple evaluation method to help solve practical engineering problems.
A Laboratory Evaluation of Core-Preservation Materials
Authors: Auman J. B. 
Published: December 2007

Summary
This paper documents the results of a laboratory study of the effectiveness of available state-of-the-art core-preservation materials. The ability of the core-sealing material to prevent postpreservation changes in fluid saturations may have a profound effect on subsequent laboratory measurements. Considering the expense involved in obtaining, storing, and analyzing a native-state (oil-cut) core and the purpose for which it was cut, knowledge of exactly what materials can adequately preserve a core until laboratory measurements are made is critical and should not be overlooked. In this laboratory study, saturated Berea sandstone core plugs were preserved in a number of commonly used sealing materials. The sealed plugs were then stored in a humidity-controlled environment and periodically weighed to ascertain the degree of change that had occurred in the saturation of the plug. In addition, this paper discusses and suggests procedures for applying the recommended sealing material.
Effect of Overburden Pressure and the Nature and Microscopic Distribution of Fluids on Electrical Properties of Rock Samples
Authors: Longeron D. G. , Argaud M. J. , Feraud J. -P. 
Published: December 2007

Summary
Laboratory equipment aimed at determining the exact correlation between resistivity and water saturation under stress, pressure, and temperature conditions is described in the first part of this paper. The porous-plate method adapted to reservoir conditions is used to obtain different saturation values during both drainage and imbibition. With this equipment, the influence of the effective stress on the porosity and formation resistivity factor can be studied before the test. In the second part of this paper, the values of the formation resistivity factor and resistivity index are compared for water-wet samples from sandstone and carbonate reservoirs. These measurements indicate that the influence of the effective stress depends on the nature of the rock sample. In addition, the resistivity/water-saturation law depends on the direction of the saturation change (drainage or imbibition) and on the nature of the fluids (water/oil or water/gas).
Performance Improvement of Direct- and Indirect-Fired Heaters
Authors: Sams G. W. , Hunter J. D. 
Published: December 2007

Summary
The operating performance of direct and indirect heaters is discussed, and principles and guidelines that can be applied to effect improvements in efficiency are presented. This paper also discusses the associated heater efficiencies and several useful operating techniques to approach the maximum, steady-state heater efficiency. The techniques presented apply to all types of direct- and indirect-fired heaters: salt bath heaters, propane vaporizers, heater/treaters, production heaters, and glycol and amine regenerators.
Fluid Distribution and Reservoir Characteristics of the Big Piney Mesaverde Reservoir, Wyo.
Authors: Miles F.V. , Pedersen J.A. 
Published: December 2007

Abstract
The text presents an approach used to evaluate a productive reservoir whose hydrocarbon accumulation is under hydrodynamic control. The fluid, rock and structural factors that control the distribution of the fluids and their flow characteristics have been studied. Potentiometric and structural information have been utilized to determine the limits of the hydrocarbon accumulation and its qualitative relationship with structure. A comparison is made of predicted and actual gas-oil and oil-water contacts. The oil column was divided into two producing intervals, and capillary-pressure and relative-permeability data were utilized to evaluate their fluid distribution and transmissibility.

Introduction
One of the main problems to be solved in evaluating a hydrocarbon reservoir is determining the fluid interfaces and their relationship with structure. This is especially vital in reservoirs where the hydrocarbon accumulation is under hydrodynamic control. The purpose of this paper is to report an approach used to determine the distribution and structural relationship of the gas, oil and water phases in the Big Piney Mesaverde reservoir, Sublette County, Wyo. In conjunction with this study, potentiometric data have been utilized to evaluate entrapment, and a study has been made of the rock and fluid properties of the reservoir which are related to saturation distributions and flow mechanics. The Big Piney Mesaverde reservoir lies approximately 100-miles northwest of Rock Springs, Wyo. The field was discovered in Aug., 1957, by the Gulf No. 1 Tresner State well located in the SW-NW Section 36–29N–113W (see Fig. 1) which produced gas and oil during drill-stem testing. Selective tests during completion in the gas and oil columns resulted in indicated capacities of 9.5 MMcf/D and 118 BOPD, respectively. The discovery was confirmed by Belco Petroleum Corp.'s completion in Jan., 1958, of Well B–34. Initial development in the field showed that the oil column possessed a low productive capacity; this subsequently was attributed to a combination of circumstances, including a low reservoir temperature, a relatively high pour-point oil and low matrix permeability. No particular difficulty was observed in producing free gas. Due to this situation, only 17 wells were completed within two years after discovery. In June, 1959, development was stimulated when Gulf Oil Corp. introduced notch-fracing, and 40 wells had penetrated the reservoir by the end of 1960. To date, production has been curtailed by market restrictions and the need of conserving gas-cap energy; however, as of Jan., 1961, the field had produced approximately 740,000 STB of oil, 1,760 MMcf of separator gas and negligible volumes of water. Fig. 1 is a plat of the producing area showing the limits of development drilling to Jan. 1, 1961, and the areal distribution of the hydrocarbons.

Geology
The Big Piney Mesaverde reservoir lies on the LaBarge Platform, a major structural feature on the west edge of the Green River basin.
JPT
P. 608^
Effect of Cleavage Rate and Stress Level on Apparent Surface Energies of Rocks
Authors: Perkins T.K. , Krech W.W. 
Published: December 2007

Abstract
As fractures are propagated through rocks, energy is absorbed near the extending crack tip. Apparent surface energies for several rocks have been measured by cleavage under dynamic conditions. At nominal crack velocities from 0.5 to 500 in./min. measurements showed that fractures propagated in discrete jumps. Calculated surface energies and moduli were relatively insensitive to nominal rate of cleavage.
In another set of experiments, rocks were cleaved under high confining stresses. The rocks were submerged in low leak-off fluids which formed a filter cake on the freshly cleaved surfaces (similar to the hydraulic fracturing process). Apparent surface energies were increased substantially as the surrounding fluid pressure was increased. Moduli in bending increased significantly upon application of the first 1,000 psi but were insensitive to stress level at greater pressures.

INTRODUCTION
For almost 20 years, hydraulic fracturing processes have been utilized effectively to stimulate oil and gas wells. During this period, some process improvements have resulted from studies of fracture orientation, mechanics of fracturing, areas generated, conductivities of cracks, etc. Yet many questions remain concerning the conditions and pressures needed during fracture propagation.
In this paper we will report additional studies of the mechanics of fracture extension. It was shown previously3 that large rock samples could be cleaved under controlled conditions so as to measure the apparent surface energy (that amount of energy absorbed per unit area of new surface created). In this paper we consider the effects of two additional factors on surface energies, viz.:effect of cleavage rate andeffect of confining stress level.

THEORY
Cleavage experiments were conducted on rock samples similar to that illustrated in Fig. 1. Blocks of rock several inches wide, 2- to 3-in. thick, and up to 3 ft in length were grooved longitudinally with shallow guide slots. A crack was initiated and allowed to extend along the web as the top of the rock specimen was pulled (or pushed) apart. Auxiliary equipment permits the measurement offorce applied at the top,separation at the top andcrack length.
(Further experimental details will be given in the next section.) The rock beams created by the crack are considered to' be cantilever beams. The deflection (or separation of the rock beams) at any point is calculated4,5 by the beam Eq. 1.
A Polynomial Approach to the van Everdingen-Hurst Dimensionless Variables for Water Encroachment
Authors: Klins M. A. , Bouchard A. J. , Cable C. L. 
Published: December 2007

Summary
Traditional water-influx calculations rely on accurate values of the van Everdingen and Hurst dimensionless variables pD and qD. We have presented six sets of simple polynomials that provide a fast, simple method to determine pD, pD’, and qD for finite or infinite radial aquifers. The results yield values as accurate as the original tables and are up to 15 times more efficient.
Mechanisms of Foam Generation in Glass-Bead Packs
Authors: Ransohoff T. C. , Radke C. J. 
Published: December 2007

SummaryThe fundamental, pore-level mechanisms of foam generation are investigated in monodisperse bead packs. First, direct visual observations identify the following generation mechanisms: lamella leave-behind, gas-bubble snap-off, and lamella division. Then, to ascertain the relative importance of these mechanisms, quantitative experiments are pursued on the role of bead- pack permeability (bead sizes from 0.25 to 1 mm [0.01 to 0.04 in.]), gas-phase velocity (0.001 to 0.8 cm/s [0.0004 to 0.3 in./sec]), gas-phase fractional flow (0.60 to 1.0), permeability variations, and surfactant type [sodium dodecyl benzene sulfonate (SDBS), sodium dodecyl sulfate (SDS), Chevron Chaser SD1000™, and Suntech IV 1035™]. We discover a critical velocity, above which a "strong" foam is generated and below which only "weak" foam is formed. The snap-off mechanism is the primary mechanism responsible for the formation of the strong foam. A simple model, based on the concept of a "germination site," is developed to predict the onset of snap-off at higher gas velocities. New experimental data obtained in the homogeneous glass-bead packs for the critical capillary number necessary to form a strong foam are in excellent agreement with the proposed germination- site model.
North Sea Development Drilling, South East Forties: A Case Study
Authors: Denholm J. M. 
Published: December 2007

Summary
The development of the South East Forties field began in July 1984, when a 16-slot subsea template was transported to location and installed by the semisubmersible drilling vessel (SSDV) Sedco 707. Thereafter, 14 subsea development wells were drilled before the installation of a minimum-facilities jacket, to which the wells would be tied back and completed. This field development was identified as an ideal candidate for the optimization of the drilling operation. The result of this optimization campaign was a significant reduction in well-drilling times and associated costs.
Designing Well Paths to Reduce Drag and Torque
Authors: Sheppard M. C. , Wick C. , Burgess T. 
Published: December 2007

Summary
A deviated well with an undersection trajectory (i.e., a trajectory lying below the conventional tangent section and constantly building to target) can exhibit lower drag and torque than a conventional well geometry in certain circumstances. The influence of well geometry on drag and torque is discussed, making use of the results of the theoretical model. Although an undersection well may have a reduced overall drag, the side forces in the drill collars will be increased. This can lead to a greater danger of sticking in the bottomhole assembly (BHA). Furthermore, because of the enhanced side forces near the bit, an undersection well may also exhibit greater torque. The relative merits of constant-build and catenary trajectories are discussed.
Analysis of Borehole Images and Their Application to Geologic Modeling of an Eolian Reservoir
Authors: Plumb Richard A. , Luthl Stefan M. 
Published: December 2007

Summary
New wellbore imaging techniques significantly enhance geologic descriptions of reservoirs. These new techniques include electrical images formed by the Formation MicroScannerSM (FMS) tool and acoustic images made by a digital borehole televiewer tool (BTT). Quantitative image-analysis software is described that provides strike and dip measurements of tectonic and sedimentary structures and the orientation of the contemporary stress field. This software was used to map geologic features from images acquired in a North Sea reservoir. Quantitative geologic models constructed from these image data highlight the interrelated effects that fractures, anisotropic stress, and bedding may have on the directional permeability in this reservoir.
An Experimental Investigation of Fatigue-Crack Growth in Drillstring Tubulars
Authors: Dale B. A. 
Published: December 2007

Summary
Drillstring failures continue to plague the oil industry, often costing millions of dollars each year. This problem is frequently intensified with the drilling of deep, deviated wellbores or "hard rock" drilling conditions. The drilling industry attempts to guard against these costly failures by performing periodic nondestructive inspections to remove damaged tubulars from service. This paper describes the results of full-scale fatigue-crack-growth tests of drill collars under rotating and bending loads. In addition, corrosion fatigue-crack-growth data are also presented for API drillpipe steels in air and in three representative water-based drilling-fluid environments. Based on this experimental investigation. the test data support the practical application of fatigue-crack-growth mechanics principles for the development of nondestructive inspection intervals to reduce drillstring failures.
A Study of Excitation Mechanisms and Resonances Inducing Bottomhole-Assembly Vibrations
Authors: Besaisow Amjad A. , Payne Mike L. 
Published: December 2007

Summary
This paper presents a study of important excitation mechanisms and resonances that cause bottomhole assembly (BHA) vibrations during drilling operations. The study is based on dynamic vibration data gathered in a test well with our Advanced Drillstring Analysis and Measurement System (ADAMS) surface measurement system. The data were gathered while three different BHA's were used to drill portions of this well to 800 ft [244 m]. A case study for a large-diameter hole in an actual field well is also presented.
The data showed many velocity-dependent excitation mechanisms, including 1×ω, 2×ω, 3×ω, a drillstring walk mechanism, and drillstring whipping mechanisms that were dependent on the drillstring and hole geometries. The data also show important resonances that may be excited, including resonances with strong local contributions, and axial and torsional resonances. When the excitation mechanisms match these resonances, damaging vibrations can be induced.
This study identifies the presence of more fundamental excitation mechanisms than the l×ω and 3×ω mechanisms. These should be used in models that predict drillstring and BHA vibrations. The study also shows important resonances that should be considered when BHA vibrations are predicted.
Rubber Drillpipe Protectors Reduce Rotary Torque
Authors: Corbett Kevin T. , Dawson Rapier 
Published: December 2007

Summary
Rubber drillpipe protectors have very low friction coefficients when they rotate against smooth or polished casing surfaces in drilling mud. A polished casing surface can be obtained by placing one protector on each joint of drillpipe run inside the casing. In this situation, casing polishing will occur in the course of normal drilling, and the resultant low friction coefficients will lead to reduced drilling torque in directional wells.
The friction coefficient between casing and drillpipe protectors is controlled by the roughness of the casing surface. Coefficients range from 0.50 for badly rusted casing to 0.05 for a polished surface. The smooth casing surface needed for low friction will be obtained during 50 to 100 hours of rotation with drillpipe protectors inside the casing. A field test of this concept gave friction coefficients below 0.10 and a significant reduction in drilling torque.
Skjold Field, Danish North Sea: Early Evaluations of Oil Recovery Through Water Imbibition in a Fractured Reservoir
Authors: Oen P. M. , Engell-Jensen M. , Barendregt A. A. 
Published: December 2007

Summary
This paper reviews the performance of a fractured chalk oil reservoir in its first 3 years of production and evaluates future development options. The relatively low degree of undersaturation of the oil required that evaluations of pressure-maintenance potential be made early in the field’s life. To this end, many performance data have been collected, primarily through the use of observation wells. The performance data [pressures and free-water level (FWL) in fractures] are presented and their evaluation is described. In particular, the evaluation of the oil production performance through water imbibition is discussed. This evaluation has led to the initiation of pressure maintenance through water injection.
Re-Evaluation of Solvent Requirements for a Hydrocarbon Miscible Flood
Authors: Asgarpour S. , Singhal A. K. , Card C. C. , Wong T. W. , Springer S. 
Published: December 2007

Summary
The required slug size for a patterned hydrocarbon miscible flood in the Upper Devonian reef at Fenn-Big Valley, central Alberta, was computed on the basis of dispersion/diffusion calculations at the leading and trailing edges of the solvent slug. This slug size included consideration of microscopic heterogeneities and a safety factor so that sufficient slug remained to ensure miscibility. This calculated slug size formed the design basis for a pilot experiment in part of the pool. After 3 years of pilot operation, sufficient performance and tracer results were available to enable a re-evaluation of the design basis. The motivation behind re-evaluation was to extend the recovery process to a much larger part of the pool.
Whereas local heterogeneities and transport considerations indicated that a moderate slug size (6% HCPV) was required, regional and interwell heterogeneities, flooding patterns, and geometry of flood propagation indicated that about twjce this slug size was needed. Because of this, it was concluded that the realistic design basis for a field-scale project must fully consider regional and interwell heterogeneities. This paper deals with the supporting data and procedures used in developing the revised design basis for the project.
Fluid-Velocity and Reaction-Rate Effects During Carbonate Acidizing: Application of Network Model
Authors: Hoefner M. L. , Fogler H. S. 
Published: December 2007

Summary
Coreflood experiments were performed and a network model developed to study flow and matrix dissolution in carbonates during acidizing treatments. Wormholing in carbonates is controlled by the relative rates of flow and dissolution, which are characterized by a Damköhler number, NDa, for the process. Acid penetrates only as a result of wormholing, and well-defined channels will not form if NDa is either very high or very low. Effects of acidizing differ markedly between limestone and dolomite because of differences in the mineral dissolution rates.
Interference Testing: Detecting a Circular Impermeable or Compressible Subregion
Authors: Grader Abraham S. , Horne Roland N. 
Published: December 2007

SummaryA practical consideration of the effects of a single, circular, heterogeneous reservoir subregion on interference transient pressure testing is presented. The production well and the observation wells are external to the circular subregion. The internal circular boundary is considered as a constant-pressure source or as an impermeable subregion. The constant-pressure subregion has significant effects on interference pressure responses regardless of the size of the subregion. Ignoring the presence of a neighboring compressible portion of the reservoir, such as a gas or a steam cap, may yield erroneously high storativities and transmissivities. Multiple interference tests may suggest the probable location of the gas cap. The effects of an impermeable subregion are subtle, and in some cases, large, impermeable portions of the reservoir may not be detected by neighboring interference wells. Some interference tests in the presence of an impermeable subregion may yield high values of reservoir storativities, stemming from a pressure response similar in shape to the line-source response. A map of the positions of interference wells that do not permit the detection of an impermeable subregion is presented.