bluuebunny/crossref_metadata_2025_split huggingface dataset:
Hydraulic Fracturing with the Single-Point Entry Technique
Authors: Huitt J.L. 
Published: December 2007

Introduction
Hydraulic fracturing is now in its second decade as one of the most useful techniques developed for well stimulation. As fracturing became an established practice in the oil industry, the necessary experience was gained from which advancements in fracturing technology could be made. Today, some wells are treated with fluid volumes exceeding 100,000 gal and at rates approaching 100 bbl/min Fracturing fluids are compounded for the particular formation to be fractured. Treatments are now designed with a certain degree of accuracy for a given formation area to be exposed to the fracture. These and other advances in fracturing technology have been well-received by the industry and used to advantage. Even with these improvements, however, conventional fracturing has failed to effectively stimulate wells completed in some formations. A number of the failures can be attributed to inadequate capacity of the fractures.

Formation Capacity-Fracture Capacity
Formation capacity may be defined as the product of the permeability (horizontal) of the formation times the thickness of the productive zone. Likewise, the fracture capacity is the product of the permeability of the fracture times its width. For best results in well stimulation, the fracture capacity should be at least 10 times the formation capacity.
Conventional fracturing usually results in fractures having capacities of a few hundred to a few thousand millidarcy-feet. Fractures with capacities in this range are usually adequate for stimulation in zones of low permeability and/or small thickness. For example, a zone of 40 ft in thickness with a permeability of 5 md has a capacity of 200 md-ft, and a well completed in this zone should be stimulated effectively with a fracture of 2,000 md-ft capacity. This capacity fracture can often be obtained by conventional fracturing, provided the fracture is propped effectively.
Properties of Capillary Fluids at the Microscopic Level
Authors: Christenson Hugo K. , Israelachvili Jacob N. , Pashley Richard M. 
Published: December 2007

Summary
Results are presented of experimental measurements of the properties of model reservoir fluids (water and hydrocarbons) at the microscopic and submicroscopic level—i.e., when they are confined in narrow spaces comparable to the pore sizes of reservoir rocks. Measurements of capillary forces (or pressures) were carried out for curved oil/water interfaces (menisci) of radii as small as 20 A [2 nm]. The results show that the capillary pressure is accurately given by the Laplace equation for even the smallest pore radii of interest in waterflooding. The Kelvin equation describing the equilibrium radius of an oil/water interface has also been verified down to very small radii, but the effect of ions leaching out from the silicate surfaces can greatly enhance the equilibrium meniscus (Kelvin) radius and must not be ignored in such processes. The phenomenon of the spontaneous condensation of water bridges between two surfaces has been observed, highlighting an additional important mechanism for trapping residual oil. The first measurements of the microviscosity of liquids in narrow channels show that the bulk liquid viscosity pertains down to very thin films in the case of both aqueous salt solutions and hydrocarbons. Results of the effects of salinity and pH on clay-swelling pressures are also described. These show that in addition to the expected long-range repulsive electrostatic force between charged surfaces in salt solutions, there is also a short-range (&lt;20-Å [2-nm]), monotonically repulsive "hydration" force, which is an oscillatory function of distance below 15 Å [1.5 nm], with minima at discrete surface separations corresponding to the thickness of layers of water molecules: e.g., at 2.8, 5.6, 7.8 Å, etc. [0.28, 0.56, 0.78 nm]. The oscillatory force is believed to be responsible for the crystalline swelling of clays.
Application of Gradient Theory of Inhomogeneous Fluid to Prediction of Low Interfacial Tensions in CO2/Hydrocarbon Systems
Authors: Gupta Mukesh K. , Robinson Robert L. 
Published: December 2007

SummarySahimi, Davis, and Scriven recently presented predictions of interfacial tensions (IFT's) for CO2/hydrocarbon systems using the gradient theory of inhomogeneous fluid (GTIF) model. In the present paper, additional calculations from the GTIF model are presented at low IFT's, and comparisons are made with experimental measurements. The results show that the GTIF model predicts "classical" scaling behavior at low IFT's, in conflict with experimental observations. Thus, while the GTIF model has been documented by its authors to yield good predictions at high and moderate levels of IFT, it could be inappropriate for use at the low levels of IFT (σ&lt;0.1 mN/m [0.1 dynes/cm]) that may be required to enhance the oil displacement efficiencies in enhanced gas drives.
An Overview of Top-Drive Drilling System Applications and Experiences
Authors: Boyadjieff George I. 
Published: December 2007

Summary
Top-drive drilling has become one of the new technologies of the 1980's. Application of this seemingly old concept is now widespread in most offshore areas of the world. Top-drive drilling may be one of the biggest changes made to the rotary-drilling method since the development of the rotary table.
This paper analyzes why the concept of drilling with top drive, similar to the very old concept of a power swivel, has suddenly become so successful. Applications and locations are presented to show the system's worldwide use. Results of more than 50 systems currently in operation are analyzed to present benefits and trends.
The results show surprising benefits for almost any type of well, and overall time savings generally exceed 20%. Benefits from the extended-reach potential associated with top drives are enormous. These results explain the primary motivation for most applications of the system.
History of a Milham Sand Water Flood Following Accidental Stimulation
Authors: Jones Frank T. 
Published: December 2007

Abstract
A brief history of the Waggoner "ABC" Milham sand waterflood project, in Wilbarger County, Tex., is presented. This water flood, operated by Cities Service Oil Co., has been successful in spite of irregular well spacing and injection patterns. Injection of slightly less than 19.5 million bbl of water over the past 11 years has resulted in the recovery of 2.77 million bbl of secondary oil. Efforts to maintain economical rates of production and injection on an individual well basis have resulted in sizeable frac treatments on both producing and injection wells. Results of these jobs are tabulated, and it is concluded that this method of well stimulation has extended the profitable life of individual wells.

Introduction
The Waggoner ABC water flood is located 13 miles southeast of Vernon, Tex. The name "Waggoner ABC", for the purpose of this report, applies to all leases supplied with injection water from the Waggoner ABC water station. Therefore, this term includes several offset leases acquired by the operator as the water flood expanded as shown in Fig. 1. Interest has been expressed in the performance of the Waggoner ABC water flood for several reasons.It is the oldest flood in Wilbarger County; consequently, a longer history is available for study and comparison.A high secondary recovery has been achieved.It has an irregular development pattern.Relatively large frac treatments of both injection and producing wells have been made.

Geology
The Milham sand of Pennsylvanian age is found at approximately 2,350 ft along a trend deposited on the south flank of the Red River uplift. The trend has the general appearance of an offshore bar, but it is believed to have been deposited further at sea as a result of current action on a shelf. Table 1 summarizes the reservoir information.
The Ultrashort-Radius Radial System
Authors: Dickinson W. , Anderson R. R. , Dickinson R. W. 
Published: December 2007

SummaryA group of interrelated horizontal drilling and completion technologies, collectively called the ultrashort-radius radial system (URRS), was developed and is being progressively applied in the field. Multiple radiais can be placed at the same level and on multiple levels. Three-dimensional (3D) surveying is supplied. Horizontal completions can be provided, including 100%-fill gravel packing, in-situ electrolytic perforation and cutting, and flexible sand barriers (FSB's). Initial field applications were in unconsolidated formations.
A Preliminary Investigation on the Objective Function of Penetration Cost Applied to Optimized Drilling
Authors: Guo X. Z. 
Published: December 2007

Summary
This paper describes a theoretical analysis of the penetration-cost objective function, specifically its first- and second-order differentiability, convexity, and feasibility, and presents the location and method of searching for the optimum drilling parameter. It discusses the features and practical significance of a combined isocost graph, such as determining the maximum economic results for each combination of bit weight and speed and providing a scientifically sound basis for modifying drilling parameters. This paper also gives a case study of the Zhong Yuan oil field.
The PVT Behavior of Methane in the Gaseous and Liquid States
Authors: Matschke Donald E. , Thodos George 
Published: December 2007

Introduction
Considerable time and effort frequently are expended to establish, with a degree of confidence, the PVT behavior of pure substances. In particular, a great deal of experimental information contributed by a number of investigators is available in the literature. The data of each investigator, although significant in themselves, cannot be used with a high degree of confidence until they are compared with the continuum of information presented by others.
Current interest in thermodynamic and transport properties, for not only the gaseous state but the condensed state as well, requires that PVT information be presented for both regions. The density dependence on temperature and pressure, when presented as a continuum, is of considerable value in itself, especially since the available equations of state fail to properly account for the PVT behavior in the condensed state. For this reason and to incorporate PVT data recently presented in the literature, this investigation was carried out.
In their studies concerned with the thermodynamic properties of methane, Matthews and Hurd in 1946 utilized the data of Kvalnes and Gaddy and Olds, Reamer, Sage and Lacey to establish the PVT behavior of methane in the superheated region and the saturated liquid densities of Keyes, Taylor and Smith in conjunction with the Clapeyron equation to develop the densities for the saturated envelope.
Current activity sponsored by API Project No. 44 under the direction of F.D. Rossini has led to a tabular presentation of compressibility factors for gaseous methane in the superheated region. These values were obtained by using smoothed residuals, developed from experimental data and the Benedict-Webb-Rubin equation, to establish internally consistent compressibility factors for the real gas. This approach offers probably the most precise presentation of PVT information for gaseous methane to date.
The PVT behavior of methane also can be represented accurately by equations of state such as the Benedict-Webb-Rubin equation or the Martin-Hou equation. These equations, although valuable for analytically representing the PVT behavior, lack precision in the compressed-liquid region.
Current Status and Future Trends of Jet-Bit Drilling in China
Authors: Kexiang Li 
Published: December 2007

Summary
Three levels in the development of jet-bit drilling in China are discussed, showing significant economic results for each higher pump-pressure level. Drilling practice in China has shown that there is still much room for a further increase of pump pressure and specific hydraulic horsepower. The development of jet-bit drilling is the main direction in upgrading drilling techniques in the near future. Laboratory studies have proved significant rock-cutting action by the combination of hydraulic and mechanical power. Bit hydraulics can do much more than bottomhole cleaning, and hydraulic parameters can be selected beyond the range of the Fullerton chart or the Amoco hydraulic drillability curve. More attention should be paid to rock-cutting by hydraulic power. The bit-weight/rotary-speed selection and mud performance should be optimized, along with the best use of hydraulic power. This approach should be followed as long as it results in a higher drilling rate and lower cost.
Increased ROP of Jet Drilling From Improvement of the Bottomhole Flow Field
Authors: Liao Rongqing 
Published: December 2007

Summary
With the wide application of jet drilling, continuous research has been carried out to utilize fully the bit hydraulic power at the hole bottom. This paper describes an experimental study of fluid-flow direction in the flow field and discusses its application. The undesirable flow patterns of vortex, backflow, and stagnation were found to be the main factors affecting bottomhole scavenging efficiency. Improving the bottomhole flow field of a jet bit will increase the rate of penetration (ROP) and reduce the cost of jet drilling.
Geologic Problems Related to Characterization of Clastic Reservoirs for EOR
Authors: Szpakiewicz M. , McGee K. , Sharma B. 
Published: December 2007

Summary
Geologic problems encountered in four U.S. DOE-sponsored EOR projects in clastic reservoirs were analyzed. The reservoir heterogeneities were grouped into four categories: depositional, diagenetic, structural, and formation-fluid composition/distribution. Each category had a variable effect on the performance of the EOR projects.
Requirements for developing one static geologic model for each category of heterogeneity are proposed. The interrelationship of geologic factors and the effect of heterogeneities resulting from the origin and timing of geologic events are described.
Besides heterogeneities associated with the depositional environment, which has a significant effect on EOR performance, diagenetic effects resulting from geochemical alterations and different types and polymorphs of clays are also important but are often neglected. The structural component of the model needs to be improved through the application of new methodology or improvements in existing technology (e.g., remote sensing, high-resolution seismic). A realistic prediction of fluid movement in clastic reservoirs subjected to EOR requires the integration of the four models that define all the heterogeneities.
Completion of a Deep, Hot, Corrosive East Texas Gas Well
Authors: Schulz R. R. , Stehle D. E. , Murall J. 
Published: December 2007

Summary
A 19,011-ft [5795-m] wildcat in Houston County, TX, was successfully completed in March 1984. It tested the Lower Cotton Valley sand, which produced 14.5 MMscf/D [411×103 std m3/d] at a flowing tubing pressure of 8,671 psig [59.8 MPa]. The produced gas contained 4.9% CO2 and 24 ppm H2S. A bottomhole temperature (BHT) of 400°F [204°C] and bottomhole pressure (BHP) of 17,000 psig [117.2 MPa] intensified the corrosion potential. Tubular corrosion protection was provided by a 13% Cr production liner and a combination tubing string of 13 and 22% Cr alloys. The high pressure necessitated a 6,200-psig [42.7 MPa] underbalance liner top test. This paper outlines the completion and the supporting logic. It includes a discussion of the liner cementing, hole displacement, packer selection, tubing design, perforating, wellhead selection, and flowline design.
Evaluation of Reservoir Compaction and Its Effects on Casing Behavior
Authors: Chla Y. P. , Bradley D. A. 
Published: December 2007

Summary
Many reservoirs along the gulf coast are overpressured and undercompacted. Depletion of these reservoirs usually results in a large pore-pressure drop and sediment compaction. Because casing strains with sediment, significant casing deformation may occur in the vicinity of reservoirs. Such a potential casing failure poses a serious threat to petroleum production from overpressured reservoirs. An axisymmetric finite-element model was developed to simulate sediment deformation, fluid flow, and casing deformation simultaneously. This model includes a section of 7-in., 35-lbm/ft [17.8-cm, 52-kg/m] casing from 11,400- to 12,800-ft [3475- to 3900-m] depths, a 2-in. [5-cm] -thick cement annulus, and a 3,400-ft [1036-m] radius of sediment. Frictional slippage was considered along the interface between cement and soil. Data from core measurements were used for various physical properties of soils.
Single-well production from three sand reservoirs interbedded with shale formations was modeled. The results indicate that depletion causes severe vertical compaction in the sand reservoirs. Sediment compaction also occurs in confining formations as the pore fluid flows from shales into sand reservoirs. As a result, high axial compressive stresses and strains are developed in the casing string, not only in the depleting reservoirs, but also within the adjacent shale formations. However, slippage of soil against cement and casing tends to reduce the axial casing strain greatly. This model allows assessment of sediment compaction and casing deformation during reservoir depletion and provides criteria for designing the well completion against casing failure.
The Bighorn No. 1-5: A 25,000-ft Precambrian Test in Central Wyoming
Authors: Collins J. C. , Graves J. R. 
Published: December 2007

Summary
Between Oct. 1983 and Aug. 1985, Monsanto Oil Co. drilled a 24,877-ft [7583-m] -deep well on the Madden anticline in Wyoming's Wind River basin to evaluate the unexplored potential below the 17,000-ft [5182-m] -deep Cretaceous Cody formation. Three casing strings from surface and four liners were run, including a record depth and weight 16-in. [40.6-cm] string. The well tested at 20 MMcf/D [566 × 103 m3/d] with minimal drawdown from the Mississippian Age Madison formation at 23,800 ft [7254 m].
A Three-Dimensional Semianalytical Model of Hydraulic Fracture Growth Through Weak Barriers
Authors: Luiskutty C. T. , Tomutsa L. , Palmer I. D. 
Published: December 2007

SummaryA high minimum in-situ stress contrast between pay and bounding zones can be very effective in restricting vertical fracture- height growth. For a highly elongated fracture, the fracturing-fluid flow can be approximated by one-dimensional (1D) flow along the pay-zone direction. If the stress contrasts are smaller (i.e., weak barrier), however, the height growth is greater and two-dimensional (2D) fluid flow needs to be incorporated into the modeling. This major difficulty has been solved only recently by a fully numerical solution. The goal of this research was to develop a fracture model for length/height ratio ≤ 4 that includes 2D flow (and a line source corresponding to the perforated interval) but makes approximations that allow a semianalytical solution, with large computer-time savings over the fully numerical model. The height, maximum width, and pressure at the wellbore in this semianalytical model are calculated and compared with the results of the fully three-dimensional (3D) model. There is reasonable agreement in all parameters, the maximum discrepancy being 24%. Comparisons of fracture volume and leakoff volume also show reasonable agreement in volumes and fluid efficiencies. The values of length/height ratio, in the four cases in which agreement is found, vary from 1.5 to 3.7. The model offers a useful first-order (or screening) calculation of fracture-height growth through weak barriers (e.g., low stress contrasts). When coupled with the model developed for highly elongated fractures of length/height ratio ≥ 4, which are also found to be in basic agreement with the fully numerical model, this new model provides the capability for approximating fracture-height growth through barriers for vertical fracture shapes that vary from penny to highly elongated. The computer time required is estimated to be less than the time required for the fully numerical model by a factor of 10 or more.
Effect of Pore Structure on Miscible Displacement in Laboratory Cores
Authors: Bretz R. E. , Specter R. M. , Orr F. M. 
Published: December 2007

Summary
Observations of pore structure in thin-sections are related to the performance of stable, first-contact-miscible displacements in reservoir cores and then to simulations of displacement performance of CO2 corefloods. Results of effluent composition measurements are reported for miscible displacements in seven core samples—three sandstones and four San Andres carbonates from west Texas or eastern New Mexico. Those displacements are interpreted by fitting the measured effluent compositions to the Coats-Smith (C-S) model, which represents the flow as occurring in flowing and stagnant fractions with mass transfer between them. Observations of thin-sections, including measurements of pore-size distributions and a simple measurement of spatial correlation of pore sizes, are also reported. Comparison of displacement results and thin-section data indicates that wide pore-size distributions and preferential flow paths are characterized in the C-S model by high dispersion coefficients and low flowing fractions. Simulations of the interactions of phase behavior and flow in nonuniform pore structures indicate that wide pore-size distributions and preferential flow paths can significantly increase residual oil saturations (ROS’s) in CO2 floods over those for uniform pore structures. Thus, heterogeneities observable at the scale of a thin-section have significant effects in laboratory core but much smaller effects in displacements at field scale. Large-scale heterogeneities present in field floods, however, probably cause similar increases in residual saturation in some fields.
A Regression-Based Method for Estimating Relative Permeabilities From Displacement Experiments
Authors: Watson A. T. , Richmond P. C. , Kerig P. D. , Tao T. M. 
Published: December 2007

Summary
We address the process of estimating relative permeability curves from data collected during unsteady-state displacement experiments. We introduce B-splines for use as functional representations of relative permeability curves. With B-splines, polynomial splines of any order can be conveniently implemented in the estimation procedure. This feature allows greater flexibility for incorporating inequality constraints into the parameter-estimation process.
We present a method for choosing an appropriate number of spline partitions for representing permeability curves. The method is based on considerations for obtaining the most accurate estimates of the relative permeability curves. We illustrate the method with both hypothetical and actual experimental data. We demonstrate that serious estimation errors may be encountered when relative permeability curves are represented with functions containing too few parameters—e.g., power-law functions.
Analysis and Implications of In-Situ Stress Changes During Steam Stimulation of Cold Lake Oil Sands
Authors: Wong S. K. 
Published: December 2007

Summary
During steam stimulation in the Cold Lake oil-sand deposit, the reservoir is often fractured to obtain sufficient injectivity. The fracturing, pressurizing, and heating of the reservoir induce stress changes. These changes are analyzed with a finite-element program. Results suggest that the induced stress changes have implications for field operations.
Two-Point Method for Determination of Undisturbed Reservoir Temperature
Authors: Kritikos W. P. , Kutasov I. M. 
Published: December 2007

Summary
The modeling of primary oil production and the design of EOR operations require knowledge of the undisturbed reservoir temperature. The drilling process, however, greatly alters the temperature of the reservoir immediately surrounding the well. In this paper, we present a method to determine the undisturbed reservoir temperature based on temperature measurements taken a short time after cessation of drilling.