bluuebunny/crossref_metadata_2025_split huggingface dataset:
Performance of a Beryllium Copper Nonmagnetic Drill Collar Alloy
Authors: Dunlevey F. 
Published: December 2007

Summary
Laboratory characterization and extensive field service show the advantages of beryllium copper Brush Alloy 25 for use in nonmagnetic drill collars (NMDC)'s, stabilizers, and subs. Beryllium copper is resistant to stress-corrosion-cracking (SCC) failures at elevated temperatures and pressures in the presence of H2S and dissolved chloride solutions. The alloy is more resistant than stainless steel to galling failure in threaded joints. Its magnetic permeability is lower than stainless steel and is unaffected by service conditions.
Profitable Application of Well Logs
Authors: Kirby J.E. , Culver R.C. , Mattei J.B. 
Published: December 2007

Abstract
The well logging phase of a coordinated formation evaluation program can improve the quality of basic reservoir data while reducing the need for extensive coring and drill-stem testing. The quantitative data to be determined from log analyses are formation porosity, fluid saturation and formation water resistivity. In order for these data to be obtained successfully, the proper logging devices must be selected, accurate data on the borehole conditions must be obtained and quality control measures regarding logging techniques must be exercised. The use of core analyses and drill-stem test data on a key-well basis to confirm log calculations is a necessary requirement to assure maximum dependability of quantitative log interpretation for reservoir analysis purposes.

Introduction
Well logging is one of the most useful of the various types of open-hole formation evaluation methods. When properly applied, present techniques of well logging and interpretation can provide substantial reductions in the costs of evaluation, development and exploitation of petroleum reservoirs. The initial benefit from a good logging program is that better well completions can be made. A second and more important benefit is that a reliable calculation of oil in place can be made for reservoir analysis purposes from the location of water contacts, reservoir boundaries and the calculation of formation porosity and water saturation data. Necessary formation evaluation data can be obtained at a much lower cost by using log information to extend key-well core analyses and drill-stem test data for coverage of the entire reservoir instead of using an extensive coring and testing program.
A logging program cannot be considered successful and profitable unless the basic reservoir data obtained from the logs are valid and complete. This objective can be reached, however, if the logging program is properly planned and coordinated with the other formation evaluation methods used. It is worthy of note that even the qualitative value of logs is doubtful unless proper planning is used in the selection of the types of logs to be run and unless suitable quality control measures are followed in logging techniques.
Application of the Pseudolinear-Flow Model to the Pressure-Transient Analysis of Fractured Wells
Authors: Cinco-Ley H. , Samanlego-V F. , Rodriguez F. 
Published: December 2007

SummaryThe theoretical basis for the pseudolinear-flow model is established. It is demonstrated by use of an analytical model that the linear-flow graph (p vs. t) can be extended to the analysis of pressure data of fractured wells intersected by an intermediate- or high-conductivity fracture (CfD &gt; 5π). It appears that the fracture-conductivity effect during the pseudolinear-flow period can be handled as pseudoskin pressure drop that adds to the pressure drop caused by fluid-loss damage. The combination of the pseudolinear-flow analysis with other interpretation techniques is illustrated through examples of field cases.
Reservoir Compaction Loads on Casings and Liners
Authors: Wooley Gary R. , Prachner W. 
Published: December 2007

Summary
Pressure drawdown resulting from production causes compaction of the reservoir formation, which induces axial and radial loads on the wellbore. Reservoir compaction loads increase during the production life of a well and are greater for deviated wells. Presented here are casing and liner loads at initial and final reservoir pressures for well deviation angles of 0 to 45° [0 to 0,79 rad].
Effect of Phase Behavior on CO2 Displacement Efficiency at Low Temperatures: Model Studies With an Equation of State
Authors: Nghiem L. X. , Li Y. K. 
Published: December 2007

Summary
In this paper, we examine the use of an equation of state (EOS) to predict the phase behavior of CO2/crude-oil systems at low temperatures. An adequate match of the experimental pressure/composition diagrams of a dead oil and two recombined oils from the Wasson field at 90°F [32°C] is obtained. The incorporation of three-phase flash calculations in a compositional model is described. The model is used to simulate CO2 slim-tube displacements and yields results that are consistent with experimental observations.
Temperature-Stable Polymeric Fluid-Loss Reducer Tolerant to High Electrolyte Contamination
Authors: Son Adelina J. , Ballard Thomas M. , Loftin Royal E. 
Published: December 2007

SummaryThe suitability of a synthetic copolymer for drilling deep, hot wells was demonstrated through laboratory and field testing. The polymer provided fluid-loss control at 400°F [204°C] to clay-free saturated-salt laboratory muds and to low-solids, nondispersed field muds contaminated with drill solids and sodium and calcium salts. High-temperature/high-pressure (HTHP) filtrate was kept at ≤15 cm3/30 min after 400°F [204°C] heat-aging of a 19-lbm/gal [2277-kg/m3] saturated-salt mud. Weighted (&gt;18-lbm/gal [&gt;2157-kg/m3]) potassium muds treated with the polymer showed heat stability and solids and green-cement tolerance.The polymer was successfully field-tested in two offshore wells where bottomhole temperatures (BHT's) reached 400°F [204°C] and salt and calcium chloride flows were encountered.
Bottom-Water and Edge-Water Effects on Low Gravity Oil Production
Authors: Knopp Charles R. 
Published: December 2007

Abstract
Water encroachment into low gravity oil reservoirs tends to be irregular because of three mechanisms -selective encroachment,water-leg tonguing andindividual well coning.
An investigation was made of 31 wells that were completed in low gravity oil sands with bottom water present in the base of the well-sand interval. It was found that initial water cuts occurred rapidly. Current average recovery for each of the 31 original completions is 10,184 bbl (31 per cent) clean oil and 22,542 (69 per cent) wet oil. Fourteen (45 per cent) of the 31 original completions have either been recompleted to other sands or are not feasible to produce because of high water-cut production. Average cumulative recovery for each original completion is now only 32,726 bbl of oil.
Four low gravity oil reservoirs with well defined fault boundaries and original oil-water contacts were studied to ascertain the effects of irregular edge-water encroachment. This study showed that initial water cuts have rapidly occurred in all 12 (including the most up-dip) wells completed in the four reservoirs; only two of these wells were completed with an original water-leg extension in the base of the well-sand interval. Comparative clean and wet oil recovery from these four reservoirs has been 419,100 bbl (34 per cent) clean oil vs 810,500 bbl (66 per cent) wet oil.
Ultimate recovery from the abandoned MG–30 reservoir is 1.9 per cent of the 8 million STB of oil initially in place. It is concluded that selective encroachment of edge water along thin, highly permeable, stratum has acted to reduce ultimate recoveries in the four reservoirs from 7 per cent - the recovery that would be expected if solution gas drive were the depletion mechanism.
Two basic remedial techniques offer a possible solution for eliminating adverse (irregular) edge-water encroachment. One of these is gas pressure maintenance. The second technique embodies the production of water from the more down-dip areas of the reservoir to balance water influx from the associated aquifer.
Microscopic Distribution of Wetting and Nonwetting Phases in Sandstones During Immiscible Displacements
Authors: Yadav G. D. , Dullien F. A. L. , Chatzis I. , Macdonald I. F. 
Published: December 2007

SummaryA novel technique has been developed and used to study the microscopic distribution of wetting and nonwetting phases in reservoir rocks during immiscible displacements. The underlying principle is the use of appropriate fluids, serving as the wetting and the nonwetting phases, that can be solidified in situ, one at a time, without altering to any significant extent the position and orientation of the phases acquired at capillary equilibrium conditions. After both phases are solidified, the rock matrix is etched and replaced by a resin to enhance the quality of polishing. Polished sections are then serially made at each 5- to 10-μm depth and photomicrographed, wherein the three phases are distinguishable from each other. Experimental results have been obtained with Berea sandstone and the phase distribution is being analyzed. Relative permeabilities measured with the other phase solidified compare very well with conventional results obtained by the Penn State steady-state method, using Soltrol™ and brine. Wettabilities of the fluid pairs were also visualized directly by this new technique.
Effect of Crude-Oil-Induced Wettability Changes on Oil Recovery
Authors: Morrow Norman R. , Lim Hau T. , Ward Jill S. 
Published: December 2007

Summary
Displacements in strongly water-wet cores are compared with results of similar tests for a mixed wettability condition induced by a selected crude oil. Cores exposed to crude oil showed weakly water-wet imbibition behavior and 30 to 65% improvement in microscopic displacement efficiency. Other characteristics included clean breakthrough and low relative permeability to water at residual oil saturation. Flow visualization experiments with crude oil in micromodels showed improved oil recovery from pore bodies with oil trapping in pore throats. Capillary numbers for mobilization of residual oil from weakly water-wet systems were higher than for strongly water-wet systems. Contact-angle measurements showed that adsorbed transition metal ions at a high-energy surface could have a dominant effect on wetting behavior.
A Field Scale In-Situ Combustion Simulator With Channeling Considerations
Authors: Ito Yoshiaki , Chow Allan Kwok-Yuen 
Published: December 2007

Summary
Many thermal simulators have been developed in the past few years, most based on the assumption that all the important mechanisms of the combustion process would remain intact when a laboratory-scale simulation study is scaled up to a field-scale study. In most cases, the simulators provide the users with the capabilities to achieve good history matches of laboratory results when small gridblocks (i.e., 5 cm [2 in.]) are used. When the simulators are used in a field-scale study in which gridblocks are usually greater than 10 m [33 ft], however, many problems have been encountered, including high fuel consumption and misrepresentations of the chemical reactions.
A new and numerically stable algorithm has been developed to achieve the desirable fuel consumption. This algorithm involves an oil-flow-enhancement scheme. Arrhenius-type reactions have been found to be inadequate in field-scale combustion simulation. A new pseudokinetic scheme is introduced to field-scale studies in which the reaction zone is not simulated accurately because of the large size of the gridblocks.
In some in-situ combustion projects, viscous fingering and channeling phenomena can affect the efficiency of the combustion process. A new formula of molecular diffusivity of oxygen has been introduced to represent the contact efficiency of the reactants. A new concept that represents the nonequilibrium thermal condition between the injected fluid and the resident materials (i.e., poor exchange of heat energy) is discussed.
Determination of Proppant and Fluid Schedules From Fracturing-Pressure Decline
Authors: Nolte K. G. 
Published: December 2007

Summary
A procedure is presented for designing a fracture treatment when little or no information is available. This procedure is based on fluid efficiency, which is defined as the fracture volume divided by the injected fluid volume. The fluid efficiency for a treatment was found to determine the pad size and optimum proppant schedule completely without any assumption of the appropriate fracture-geometry model or associated parameters. The efficiency was also found to determine the fluid's exposure time to temperature. This determination requires an assumption for the portion of the fracture face that is cooled during a treatment. The exposure is important for defining the fluid additives of relatively large and high-temperature treatments. The fluid efficiency can be determined from a pressure-decline analysis for a calibration treatment performed before the actual stimulation treatment. In addition, if the appropriate geometry model is assumed, the decline analysis of the calibration treatment provides inferred values of fluid-loss coefficient and fracture width and penetration. Also, for the case when the calibration treatment is smaller than the actual stimulation, analyses are presented for predicting the relative change in efficiency, width, and penetration for the treatments.
Estimating Subsurface Fracture Density in Core: Effects Resulting From Variable Fracture Spacing
Authors: Lerche I. , Narr W. 
Published: December 2007

Summary
The density of subsurface joint-type fractures in bedded rock is estimated quantitatively from the calculation of probabilities of core-fracture intersections for a range of fracture densities. The true fracture density is estimated by the determination of the value that yields a calculated number of fractured beds equal to the observed number of fractured beds. Core diameter, bed thicknesses, and geometric corrections necessitated by bedding dip and fracture pitch are accounted for. Fracture density is considered a function of the ratio of bed thickness to fracture spacing.
Fracture spacing may not be distributed normally about a mean, and the value of the statistical estimate of fracture density, and its standard error, is sensitive to the form of the fracture-spacing distribution. A functional form of the fracture-spacing distribution can be estimated from the core data for use when fracture density is derived.
Expressing the relationship between bed thickness and fracture spacing by a linear function may not always be reasonable. When the data set warrants a higher-order function, a solution may be found by approximating the function by several linear segments and solving for the fracture density of each segment of the data set.
Shape Factor, CA, Expressed as Skin, sCA
Authors: Fetkovich M.J. , Vienot M.E. 
Published: December 2007

Summary
This work presents the conversion of the shape factor, CA, to a pseudosteady-state skin term, sCA. When the shape factor is expressed as a skin term, it becomes easier to see the effect that a well placement in a given drainage area will have on the wells performance. Skin factors for published drainage shapes and well locations are given.

Discussion
In attempting to calculate interference effects of well locations on production forecasts, it was found very convenient to express the shape factor, CA, as a pseudosteady-state skin term, sCA. When using pseudosteady-state flow pseudosteady-state skin term, sCA. When using pseudosteady-state flow equations, the effect of a well not located in the center of a radial or square drainage area becomes immediately apparent when the shape factor is expressed as a skin term. The general pseudosteady-state equation in terms of CA for oil, gas, or water can be written as
..........................................(1)
By using an effective drainage radius, r,', to maintain an equivalent reservoir volume
..........................................(2)
and the shape factor for a well at the center of a circular drainage area (CA =31.62), we can obtain the familiar radial flow pseudosteady-state equation
..........................................(3)
Introducing a reference shape factor term, we can write
..........................................(4)
..........................................(5)
Defining a pseudosteady-state skin factor, sCA, as
..........................................(6)
we have, referencing to the center of a circle (the classic analytical solution) with CA, ref = 31.62,
..........................................(7)
or, referencing to the center of a square (field and model situations) with CA, ref = 30.8828,
..........................................(8)
Values of scA referenced to the center of a circle or square are tabulated in Table 1. Values of CA in Table 1 were obtained from Ref. 1 Constant wellbore pressure production forecasts for wells not in the center of a circle are made conveniently by using the concept of effective wellbore radius with and from Ref. 2 and .

Nomenclature
A = drainage area, ft2 [M2] B = formation volume factor CA = shape factor D = nondarcy flow constant
JPT
February 1985
p. 321
Case Histories of Analyses of Characteristics of Reservoir Rock from Drill-Stem Tests
Authors: Ammann Charles B. 
Published: December 2007

Abstract
The presented case histories of analyses of characteristics of reservoir rock from drill-stem tests illustrate that drill-stem test analysis may be used to evaluate a formation within the vicinity of a wellbore. The examples presented show that an analysis will determine to a practical degree such properties as true pressures and potentiometric surfaces, transmissibilities, actual and in situ producing capacities and permeabilities, productivity index, damage ratio, production rates, distance to any apparent barrier interferences near the wellbore and the approximate drainage radius during a test.
The properties thus determined are dependable enough to enable an operator to decide just what is going on in a particular formation, if a formation is worth any effort and expense to complete for production and if a treatment of some type may be needed during completion. They are dependable enough to make comparisons of the rock matrices of different well locations in a reservoir, aiding in a determination of the degree of reservoir homogeneity.
The pressures and potentiometric surfaces determined are dependable enough to determine reservoir continuity between wells and to determine which reservoirs are within the same pressure system. Utilizing pressure-elevation graphs, gas-oil and oil-water contacts (which may not be obvious by other means such as electric logs) may be determined from the pressures obtained. In many cases the extrapolated pressures are the initial reservoir pressures, and the drill-stem test is the only means by which they are obtained.

Introduction
Four case histories were chosen to illustrate the practical usefulness of a drill-stem test analysis to determine a reservoir's characteristics and to show the limitations of an analysis. The case histories chosen illustrate the different types of drill-stern tests which may be taken. The methods and calculations used to make the analyses are presented.
Estimating Reserves for High-Rate Devonian Shale Oil and Gas Completions With Limited Production Data
Authors: Mason R. A. 
Published: December 2007

Summary
Much of the activity in West Virginia in recent years has focused on the development of high-rate oil and gas completions in the naturally fractured Devonian shale. With a limited understanding of the reservoir production mechanisms, realistic estimates of oil and gas reserves early in the life of a high-rate well appeared unattainable. Early reserve estimates are necessary because typical completions produce the majority of their reserves in the first 18 months of continuous operations.
Material-balance considerations, however, can be successfully applied to high-rate Devonian shale oil and gas reservoirs to enable an estimation of reserves to an assumed abandonment pressure. The procedure uses Tracy's form of the Tarner material-balance method in conjunction with an empirically derived permeability-ratio curve. Necessary data are simply and economically collected early in the life of the well and include (1) production data for at least one continuous month, (2) corresponding initial and final measured bottomhole pressures (BHP's), (3) pressure-variant fluid properties, and (4) a representative permeability-ratio curve.
Evaluation of Silurian-Niagaran Reef Belt in Northeastern Michigan
Authors: Aminian K. , Ameri S. , Bomar R. M. 
Published: December 2007

Summary
Silurian pinnacle reefs have remained the main exploration targets in the Michigan basin over the last decade. Recent discoveries have extended the reef belt into new areas in the western and northeastern parts of Michigan's lower peninsula. Meanwhile, the exploration for these reefs has continued in more developed areas of the belt in northern Michigan, southwestern Ontario, and southern Michigan.
The results of exploration activities in northeastern Michigan in Cheboygan, Montmorency, and Presque Isle counties is different from the rest of the northern portion of the belt. A detailed study used the data available from the exploration activities in this area to determine the reef belt characteristics and reserves potential in northeastern Michigan and its extension into Lake Huron.
The results indicated some interesting features, including the narrowing of the belt as it approaches Lake Huron. It was concluded that the different depositional environment during the Silurian Age had affected the development of the belt and the hydrocarbon accumulation in the pinnacle reefs in this part of the basin.
An Extended Analysis Method for Two-Pulse Tracer Logging
Authors: Anthony J. L. , Hill A. D. 
Published: December 2007

Summary
Radioactive tracer logs are commonly used logs for quantitative determination of injection profiles. In particular, the velocity-shot method is used for quantitative analysis. In this technique, the transit time for the passage of a slug of radioactive tracer material between two stationary detectors is measured. From such transit times, the velocity of the fluid is calculated at various depths in the wellbore, yielding an injection profile. The accuracy of the velocity-shot method, however, is diminished by variations in wellbore diameter or by fluid exiting the wellbore between detector locations.
To increase the accuracy of radioactive tracer logging, the two-pulse method was developed. In wellboremodel experiments, pulses of a tracer material were injected into a fluid stream in a circular pipe with fluid exiting through perforations. The pulses were also monitored above and below abrupt diameter changes. The accuracies of the two-pulse and velocity-shot methods in a region of wellbore-diameter change or in a fluid-loss zone are compared on the basis of these experiments.
Technical Drilling Data Acquisition and Processing With an Integrated Computer System
Authors: Chevallier J. J. , Quetier F. P. , Marshall D. W. 
Published: December 2007

Summary
Sedco Forex has developed an integrated computer system to enhance the technical performance of the company at various operational levels and to increase the understanding and knowledge of the drill crews.
This paper describes the system and how it is used for recording and processing drilling data at the rig site, for associated technical analyses, and for well design, planning, and drilling performance studies at the operational centers. Some capabilities related to the statistical analysis of the company's operational records are also described, and future development of rig computing systems for drilling applications and management tasks is discussed.