bluuebunny/crossref_metadata_2025_split huggingface dataset:
Removal of Oil-Phase Muds From Wells in the Anadarko Basin
Authors: Goode D. L. , Phillips A. M. , Williams D. A. , Stacy A. L. 
Published: December 2007

ABSTRACT
Oil-phase drilling muds are widely employed in the Anadarko Basin where they offer improved temperature stability and drilling efficiency in these hot, geopressured zones.
Diesel/mutual solvent remedial treatments have been used in the Anadarko wells to remove oil-phase mud from the wellbore area and fractures. These treatments reduce the mud viscosity in a reversible manner such that subsequent exposure of the mud to water can cause an increase in mud viscosity and potential plugging of the well. The diesel/mutual solvent leaves the exposed zone in an oil-wet state which can lower the productive capacity of the well. In addition, the diesel/mutual solvent treatments are expensive and particularly hazardous at the high surface treating pressures encountered.
A laboratory investigation was performed in which alternative mud removal systems were tested. An Aqueous-Based Cleanup System has been developed to remove oil-phase muds following drilling. The system incorporates 2% KCl with an organic solvent and a surfactant blend. The treatment irreversibly reduces oil-phase mud viscosity while suspending mud solids for removal from the reservoir. The Aqueous-Based Cleanup System restores the mud-damaged zone to a water-wet state for maximum hydrocarbon productivity. This system offers a less expensive and safer alternative to the diesel/mutual solvent treatments.
This paper presents laboratory data comparing the effects of several mud removal systems on oil-phase muds and their associated wetting tendencies. Anadarko Basin case histories of Aqueous-Based Cleanup System treatments are presented. Significant production increases were achieved with the treatments.
An Approximation of Continuity of Lenticular Mesaverde Sandstone Lenses Utilizing Close-Well Correlations, Piceance Basin, Northwestern Colorado
Authors: Peterson R. E. , Kohout Julie 
Published: December 2007

ABSTRACT
Mesaverde Group sandstone units in 13 closely-spaced wells in the central and southern Piceance Basin of Colorado were correlated utilizing wireline log response quantitatively and qualitatively. Based on these correlations, the environmental subdivisions of the Mesaverde Group were characterized as follows:Paralic (upper mixed-marine) zone, occuring in the uppermost Mesaverde Group, includes thick sandstone units which are interpreted to be regionally continuous.Fluvial zone, containing point-bars 20 to 30+ ft thick, is interpreted to be correlatable to a maximum of 6,300 ft.Paludal zone has insufficient data to adequately characterize the sand units. However, 63 percent of the units are correlatable across at least 139 ft.
An approximation of the dimensional characteristics of Mesaverde sandstone units has potential applications in designing hydraulic fracturing treatments and estimating gas reserves more accurately.
The Prediction of Hydraulic Fracture Azimuth Through Geological, Core, and Analytical Studies
Authors: Clark J. A. 
Published: December 2007

ABSTRACT
Results of 10 different methods for determining the maximum horizontal principal stress direction at the DOE's Multi-Well Experiment site in the Piceance Basin, Colorado show remarkable consistency. The methods included surface geological observations (e.g. fracture mapping, lineament analysis, and faulting), analyses of oriented core from the Multi-Well Experiment (e.g. strain relaxation, differential strain analysis, acoustic velocity anisotropy, natural fractures), and computer modeling of expected stresses caused by topographic loads. The mean direction predicted for the maximum horizontal principal stress is N79.6°W. The very small standard deviation about this prediction of 5.5° indicates the extreme consistency among the methods. Similar methods could be utilized in other low permeability reservoirs to determine stress orientation and hence hydraulic fracture propagation direction.
A Method for Selection of Optimum Proppant in the Cotton Valley
Authors: Clark H. C. 
Published: December 2007

ABSTRACT
Numerous laboratory tests on Cotton Valley core samples have been conducted that compare Ottawa sand and sintered bauxite in terms of their ability to perform as a propping agent under varying closure stresses. Computer simulation has also been used as an aid in selecting the optimum proppant type and pack configuration for a given fracture treatment. However, in spite of the information obtained from these sources, there remains some uncertainty as to the value of closure stress at which a high strength proppant should be incorporated into the fracture treatment design.
Data obtained from Cotton Valley wells indicates that the producing rate was significantly reduced beyond the normal decline when a certain closure stress was reached. An examination of offset wells that experienced a lesser closure stress or were fractured with bauxite reveals that this abnormal decline is not present. This comparison indicates the fracture conductivity, and consequently the producing rate, were significantly altered as a result of sand crushing.
A New Approach to Air-Hole Interpretation in the Canyon Sands of Central Texas
Authors: Foret R. P. , Diggons W. F. , Grace L. M. 
Published: December 2007

ABSTRACT
The Canyon Sands of Central Texas have been exploited by air-drilling techniques since the mid-1950's, and the activity level has increased because of tight gas prices and the prospect of eventual deregulation. This paper introduces a new approach to air-hole interpretation which combines old and new techniques and provides additional information for the exploitation of this area.
The Canyon Sands are characterized by low permeabilities, high clay content, and small amounts of water production. Previous methods of evaluation include an FDC* Density/CNL* Neutron log and a Temperature survey.
Advances have been made in establishing an accurate neutron porosity, and the addition of an Induction log has allowed a Three-Perm Coriband* log to be computed. The Audio* log is run in combination with the Induction log to confirm temperature anomalies and to find previously overlooked gas entries.
This suite of logs ensures better treatment and, therefore, greater production. Well stimulation and design are further enhanced by Producibility logs. The overall air-hole package is the most up-to-date wireline method for the interpretation of air-drilled gas wells.
The Relation Between Recovery Deformation and In-Situ Stress Magnitudes
Authors: Blanton T. L. 
Published: December 2007

ABSTRACT
In this paper a theoretical basis is developed for calculating in situ stress magnitudes from recovery deformations measured in rock. The constitutive theory used assumes that the rock is linearly viscoelastic, homogeneous, and non-aging. These assumptions yield explicit integral equations relating strain as a function of time to stress history, which is taken to be instantaneous unloading of the rock. Solutions are obtained for recovery of isotropic and transversely isotropic core in which time-dependent behavior is contained in creep compliance terms and Poisson's ratio terms are constant. The main results for both cases are equations that allow calculation of horizontal principal stresses from vertical stress, principal recovery strains, and material properties that do not depend on time. For the isotropic case, the only material property required is Poisson's ratio. For the transversely isotropic case, two Poisson's ratio terms as well as the ratio of creep compliances are required. This last solution assumes that the vertical stress is parallel to the axis of material property symmetry.
Numerical Solution for Height and Elongated Hydraulic Fractures
Authors: Palmer I. D. , Carroll H. B. 
Published: December 2007

Abstract
Vertical hydraulic fractures, used to enhance the release of natural gas, can reach thousands of feet in length, while extending only a few hundred feet in height. When a payzone is bounded above and below by zones which have a substantially higher minimum in-situ stress, conditions are optimal for restricting a fracture's vertical growth. By theoretically calculating the height and shape of a fracture, our goal is to study how well higher stress zones adjacent to a blanket payzone confine the vertical growth.
Previously we presented a model1 for fracture expansion which assumed an elliptical fracture perimeter. The fracture height was determined by applying at the wellbore a fracture mechanics criterion, involving a critical stress intensity factor. When this criterion is applied to all points of the fracture perimeter, the entire fracture shape may be determined. This is the approach of this paper. As it turned out, the elliptical fracture shape gave a reasonable approximation for height and bottomhole pressure, and the previous model was able to predict, by way of a parameter study, fracture height growth in a variety of likely situations.
The effects of leakoff, previously neglected, are now included.
Microcomputer Models for the Design of Hydraulic Fractures
Authors: Cleary M. P. , Keck R. G. , Mear M. E. 
Published: December 2007

ABSTRACT
This paper describes approximate models which yield credible descriptions of hydraulic fracturing processes and are amenable to calculations on microcomputers. These models provide the basis for both analysis of conventional fracturing treatments and for proposing/designing new procedures suitable to varied reservoir conditions. Satisfying a shortterm need for realistic analysis that offer improved fracture designs, the models also admit considerable upgrading as more detail/realism is described by more complex simulators. The two levels of analysis presented are:
Lumped models, in which the spatial variation is represented by integral coefficients. Although simple enough for use on a microcomputer or programmable calculator, the models are detailed enough to describe geometries varying from long Perkins & Kern-type, through circular shapes, to high CGD (Christianovich et al.)-type fractures. More complex pseudo-three-dimensional (P3DH) models (which require at least a small microcomputer for proper implementation); these divide the 3D problem into coupled sets of equations governing one-dimensional lateral fluid flow and two-dimensional growth of vertical cross sections. A major feature is a refined mesh that moves with the fracture, rather than one fixed to the reservoir; the result is detailed tracing of evolving geometry, pressure distribution and flow throughout the job and after shut-in.
Although not as complex as our full 3D simulations under development, these approximate models contain most important elements governing fracture evolution. They compute such significant design evaluation quantities as length, height, width and pressure variation with specified injection rate (or vica versa). To date, the models have produced many significant results that aid in explaining observed pressure profiles and may, in the future, be used at the wellhead for real-time control of fracturing operations.
A Method for Evaluation of Formation Damage Due to Fracturing Fluids
Authors: Volk L. J. , Gall B. L. , Raible C. J. , Carroll H. B. 
Published: December 2007

Abstract
The extent of formation damage due to invasion of fracturing fluids during the hydraulic fracturing process was studied. An apparatus, which can simulate reservoir conditions, is described for measuring permeability before and after fluids are pumped across the surface of a core. Dynamic fluid loss was also measured of fluid which passes through the core plug.
After the fluid pump schedule was completed, high gas pressure was applied in the reverse direction from fluid leak-off to measure fluid cleanup and the extent of core damage. The system had a wide dynamic range and the measurements have been automated.
Recent Petroleum Mergers and Acquisitions: An Oil Analyst's Perspective
Authors: Petrie T. A. 
Published: December 2007

Abstract
The last several years have seen the most active period of petroleum related merger and acquisitions activity in the several decades since World War II. When the history of the current era is written, an important chapter will address the substantial, de facto restructuring of the petroleum industry which is occurring as a result of recent acquisitions and mergers.
The comments contained herein are based on analysis of some 42 announced proposals and actual transactions in the last five years. In all, these deals represent total market values at the time of announcement of some $36 billion.. By way of comparison, the total energy components now account for approximately 17°Lof the Standard and Poors 400 industrial index and have an aggregate market value of the order of $170 billion.
Breaking these deals down by the nature of the transaction, seven, and nearly all of the very largest deals, represent defenses against hostile or unsolicited offers by third parties, seven are internally or management initiated reorganizations/rationalizations of corporate businesses, another nine or part of the corporate liquidations, and the remaining 20 are outright sales of the entire company.
A New Model for Well Test Data Analysis for Naturally Fractured Reservoirs
Authors: Lai C. H. , Bodvarsson G. S. , Tsang C. F. , Witherspoon P. A. 
Published: December 2007

Abstract
A new model for the analysis of constant rate well test data from naturally fractured reservoirs is presented. The model considers three sets of orthogonal fractures with fluid flow from the fractures to the well and from the rock matrix to the fractures. In comparison to other models for naturally fractured reservoirs the present model allows fully transient fluid flow from the rock matrix to the fractures and a cubic geometry of the matrix blocks.
The model has been used to develop type curves for the analysis of drawdown and build-up tests as well as pressure transient data from observation wells. The reservoir systems considered include an infinite and a finite (no-flow outer boundary) system and a system with a constant pressure outer boundary. The effects of wellbore storage and skin are illustrated. The model is applied to field data to illustrate the method of analysis and the applicability of the model.
Viscosity Stability of Aqueous Polysaccharide Solutions
Authors: Glass J. E. , Soules D. A. , Ahmed H. , Egland-Jongewaard S. K. , Fernando R. H. 
Published: December 2007

Abstract
The viscosity stability of carbohydrate polymers under thermal-oxidative, mechanical and acid-catalyzed hydrolysis is examined and compared with the performance of a synthetic water-soluble polymer, hydrolyzed (30%) poly(acrylamide) (HPAM). Under thermal-oxidative conditions HPAM is the most stable polymer and the carbohydrate polymers prepared by fermentation systhesis (i.e., Xanthan gum (XCPS) or Sclerotium glucanicum polysaccharide, (SGPS) are more stable than non-fermentation polysaccharides (i.e., guar gum, hydroxyethyl cellulose, cellulose sulfate ester, etc.). In acid catalyzed hydrolysis the same differential performance between fermentation and non-fermentation carbohydrate polymers is observed. This difference is correlated with an ability to form helical aggregates which protects the repeating acetal linkage in carbohydrate polymers from oxygen and proton attack. Additives that disrupt hydrogen bonding among pyranose units and therefore disrupt helical aggregate structures in fermentation polymers decrease their solution viscosity stabilities. A molecular weight dependence is not observed under either thermaloxidative or acid catalyzed degradation conditions, but a dependence is observed in mechanical degradation. Lower molecular weight polymers are more stable. For mechanical stability, a rigid-rod conformation is sufficient for stability; some non-fermentation polymers exhibit stability equivalent to fermentation polymers. Less mechanically stable carbohydrate polymer solutions (i.e., hydroxyethyl cellulose, xanthan gum in a 4M urea or SGPS in alkaline solutons) are more stable than conformationally and segmentally flexible synthetic water-soluble polymers (i.e., HPAM or polyethylene oxide).
The influence of oxygen as an antagonist to polymer stability is investigated in the presence of two stabilizing additives, magnesium oxide (MgO) and tetraethylenepentamine (TEPA). In oxygen saturated solutions thickened with non-fermentation carbohydrate polymers, both function effectively, primarily by inhibiting the formation of hydroperoxide groups. In aqueous systems containing oxygen scavengers, MgO is ineffective; TEPA continues to be effective due to its ability to chelate transition metals, modify the scavenger's activity and intercede in the synergistic interaction of these activators with oxygen. The use of either of these additives in field applications can result in well bore problems.
Selection Criteria and Formation of a Surfactant Slug for High-Temperature, Moderate Salinity Reservoir Conditions
Authors: Sharma A. K. , Pithapurwala Y. K. , Shah D. O. 
Published: December 2007

ABSTRACT
The main objective of this investigation was to formulate a surfactant system for a water-flooded reservoir at 80°C and having a salinity in the range of 20-30 gms/liter. The equivalent alkane carbon number (EACN) of the crude oil at 80°C was found to be 9.3 as determined by a comparison of its optimal salinity with those of pure hydrocarbon oils. Isopropyl alcohol, isobutyl alcohol, secondary butyl alcohol and tertiary amyl alcohol (TAA) were employed as cosolvents in this study. The optimal salinity at 80°C of a petroleum sulfonate (TRS10-80), crude oil and any of the above alcohol containing system was found to be less than 1.3%. A phosphated ester (KF AA-270) was used as a cosurfactant with TRS10-80 in the weight ratio of 2/5 which increased the optimal salinity in the range of 25-35 gms/liter. However, the addition of this cosurfactant decreased the solubilization parameters drastically. In order to improve the solubilization of brine and oil in the middle phase microemulsion, inorganic salts such as Na2CO3 and sodium tripolyphosphate were added to the formulation. The partitioning of alcohol in various phases was determined by gas chromatography. It was found that only TAA partitioned in the excess oil phase and middle phase whereas other alcohols partitioned in the middle and excess brine phase. Displacement tests were carried out at 80°C in sandpacks and Berea cores. The tertiary oil recovery efficiency was 92% when 0.2 PV of TAA containing surfactant slug was injected while the tertiary oil recovery efficiency was poor in systems containing other alcohols. It is concluded that the choice of alcohol and its partitioning behavior are important criteria for designing formulations for high temperature reservoir conditions. In the present study, the partitioning of alcohol in the oil phase seems to correlate with greater oil displacement efficiency for the surfactant system studied. It is proposed that the mass transfer of alcohol (TAA) from the aqueous surfactant slug to the oil phase in porous media promotes the oil displacement presumably due to the ultra-low IFT associated with this mass transfer process.
The tertiary oil recovery for surfactant slugs having different alcohols correlated with surfactant breakthrough in the produced fluids. It was observed that the higher surfactant recovery in the produced fluids and a delayed surfactant breakthrough corresponded to a greater oil recovery.
Limiting Conditions for the Use of Hydrolyzed Polyacrylamides in Brines Containing Divalent Ions
Authors: Zaitoun Alain , Potie Brigitte 
Published: December 2007

Abstract
This paper summarizes the main parameters acting on the stability of hydrolyzed polyacrylamides in brines containing divalent ions. For dilute solutions the critical hydrolysis degree τc2+ above which the polymer may be precipitated by Ca ions is τc = 35% at room temperature and 33% at 80°C. For τ &lt; 60% the precipitated polymer redissolves at high CaCl2 or NaCl concentrations. Intrinsic viscosity measurements of the solutions near the precipitation point show a slow decrease in coil expansion and an increase in the Huggins constant as expected near θ conditions. Neither precipitation phenomena nor viscosity can be predicted from the divalent-ion content without taking into account the overall ionic environment.
A Comprehensive Fracture Diagnostics Instrumentation Fielding Program
Authors: Hart C. M. , Engi Dennis , Morris H. E. 
Published: December 2007

ABSTRACT
Economic development of low permeability gas reservoirs often necessitates the use of massive hydraulic fracturing. Assessment of the effectiveness of the induced fracture requires knowledge of the dimensions, orientation, and spatial characteristics of thefrac-ture in relation to the gas-bearing formation. |A comprehensive characterization of fracture propagation not only aids in fracture treat?ment design for the reservoir, but can also help specify well spacings which will minimize interference of drainage patterns and thus maximize economic-recovery potential.
This paper presents an approach to the development of a comprehensive fracture diagnostics program. The fracture diagnostics subprogram for the Multi-Well Stimulation Experiment I is discussedin detail, including fielding descriptions and operational pro?cedures. Synopses of measurement techniques are given with emphasison the fracture parameters one would expect to estimate from the individual instrumentation systems.
Microscopic Analysis of Dry Cement Blends
Authors: Reeves N. K. , Bailey D. E. , Caveny W. J. 
Published: December 2007

SUMMARY
With the use of a microscope equipped with polarization and fluorescence, and simple laboratory techniques, the presence of and/or contamination by cementing additives can be confirmed in field-blended cementing compositions. The initial learning process involved in this procedure is observing and learning the appearance of neat cements and the various additives using plain, polarized and fluorescence light microscopy. When individual characteristics such as color, sixe, shape and texture of each additive are noted, these can easily and euickly be qualitated when viewed under the microscope, whether they are present as the only additive in a blend or with various other additives.
Continuous Cleanup of Oilfield Waste in an Environmentally Acceptable Manner
Authors: Wally R. F. , Dowdy S. A. 
Published: December 2007

ABSTRACT
After several years of research and field testing, a process has been developed which can economically treat reserve pit waste. This continuous process converts the reserve pit contents into two environmentally acceptable products: a relatively dry, non-leachable cake-like solid material, and water which is purified for recycle or release directly into the environment.
A Comparative Analysis of Reactivities of Commercial Iron and Zinc Compounds Used in the Removal of H2S From Drilling Fluids
Authors: Evers J. F. , Olson G. A. 
Published: December 2007

Abstract
Five commercial H2S scavengers for drilling fluids were experimentally tested for scavenging ability under various conditions of pH, pressure and temperature. These consisted of both iron and zinc based compounds. Conditions were: pressures of 500 psi, 1000 psi, and 1500 psi, temperatures of 100°F and 200°F, and pH of 6.4 and 12.0.
The zinc reactions were quick, predictable, and irreversible under normal well conditions. The iron scavenger had somewhat higher reactivity (gm H2S/gm scavenger) than most zinc scavengers when tested at pH 12, and much higher reactivities when tested at a pH of approximately 6.5.