bluuebunny/crossref_metadata_2025_split huggingface dataset:
Laboratory Seismic Methods for Remote Monitoring of Thermal EOR
Authors: Tosaya Carol , Nur Amos , Vo-Thanh Dung , Da Prat Giovanni 
Published: December 2007

Summary
Laboratory measurements of compressional (P) and shear (S) wave velocities and first-arrival amplitudes at ultrasonic frequencies (0.65 to 1.70 MHz [0.65 × 106 to 1.70 × 106 cycles/sec]) in unconsolidated tar and heavy-oil sands indicate that wave-propagation properties in these materials are sensitive to bitumen content. Studies made at elevated temperatures, overburden pressures, and pore pressures revealed that heat and oil content in Venezuelan, Californian, and Canadian reservoir samples had large effects on the measured P and S velocities and amplitudes. Similar results were obtained on well-consolidated sandstones at lower frequencies (1.60 to 3.60 kHz [1.60 × 103 to 3.60 × 103 cycles/sec]).
The velocity and relative P-wave attenuation results show that in reservoir sands with high brine-to-oil ratios, the presence of steam or gas is easily detected. In sands with low brine-to-oil ratios, with oil occupying at least half of the available pore space, the presence of steam is not easily detected, but velocities and attenuation are highly sensitive to the temperature of heated oil. Indeed, measurable seismic properties may become a powerful tool for mapping temperature distribution, and therefore viscosity distribution, within heated reservoirs.
The results suggest that seismic wave transmission and possibly reflection methods should be highly successful in locating thermal EOR fronts and in monitoring the distribution of heated tar and heavy oils within a reservoir. The application for this technique is evident: because of the potential to track heated oil remotely, field operators may be able to determine optimal placement of future production or injection wells.
The Fluid-Compensated Cement Bond Log
Authors: Nayfeh T. H. , Wheelis W. B. , Leslie H. D. 
Published: December 2007

Summary
Simulations of cement bond logging (CBL) have shown that wellbore fluid effects can be segregated from sonic-signal response to changing cement strengths. Traditionally, the effects have been considered negligible and the CBL's have been interpreted as if water were in the wellbore. However, large variations in CBL's have become apparent with the increasing number of logs run in completion fluids, such as CaCl2, ZnBr2, and CaBr2.
To study wellbore fluid effects, physical and numerical models were developed that simulated the wellbore geometry. Measurements were conducted in 5-, 7-, and 9⅝-in. casings for a range of wellbore fluid types and for both densities and viscosities. Parallel numerical modeling used similar parameters.
Results show that bond-log amplitudes varied dramatically with the wellbore fluid acoustic impedance—i.e., there was a 70% increase in signal amplitudes for 11.5 lbm/gal (1370-kg/m3) CaCl2 over the signal amplitude in water. This led to the development of a fluid-compensated bond log that corrects the amplitude for acoustic impedance of various wellbore fluids, thereby making the measurements more directly related to the cement quality.
Filtration Method Characterizes Dispersive Properties of Shales
Authors: Wilcox R. D. , Fisk J. V. , Corbett G. E. 
Published: December 2007

Summary
Laboratory and field results show that the Capillary Suction Time (CST) filtration device can be used to characterize the colloidal nature of shale particles, to determine optimal salinity for inhibition, and to analyze drilling-fluid filtrate effect on cuttings dispersion at the wellsite. The concept of potential energy developed between particles is advanced to improve the understanding of borehole stability.
Evaluation of Empirically Derived PVT Properties for Gulf of Mexico Crude Oils
Authors: Sutton Robert P. , Farshad F. 
Published: December 2007

SummaryThis paper evaluates several empirical PVT correlations for application in the Gulf of Mexico. Ideally, fluid properties are determined experimentally in the laboratory; however, these data are not always available. Correlations are consequently used to determine values for bubblepoint pressure, solution GOR, FVF, and viscosity. These values are necessary to compute oil reserves or for calculations involving flow through pipes or porous media. A review of the correlations is provided, along with the results of calculations made on 31 individual crude oil samples.
Effect of Capillary Number on the Microstructure of Residual Oil in Strongly Water-Wet Sandstones
Authors: Chatzis I. , Kuntamukkula M. S. , Morrow N. R. 
Published: December 2007

Summary
Changes that occur with increase in capillary number in the detailed structure of residual oil trapped in water-wet sandstone core samples have been investigated. The technique of using a non wetting phase that can be solidified and separated from the porous medium has been applied with styrene monomer as the nonwetting phase and 2% CaCl2 brine as the wetting phase. The size distributions of residual oil blobs, obtained under various flow conditions, were measured by both image analysis and Coulter counter techniques. Specific features of blob shapes and dimensions were checked by optical and electron microscopy. The changes in size distribution and shapes of blobs provide insight into the mechanisms of trapping and mobilization of residual oil.
Comparison of Hydraulic-Fracture Orientation Techniques
Authors: Lacy L. L. 
Published: December 2007

Summary
Knowledge of the orientation of hydraulic fractures can be important in determining optimum well locations in recovery from tight gas sands, waterflooding, and EOR. The diagnostic technology used to determine fracture orientation in single wells has matured during the last few years so that reliable field-proven techniques exist. Five fracture-orientation techniques have been investigated extensively in multiple wells and in several fields in east Texas and Alaska for well depths up to 12,000 ft [3600 m]. The techniques reviewed include active fracture mapping with tiltmeter arrays and a triaxial borehole seismic (TABS) tool. The active fracturing techniques are compared with the predictive techniques of stress relief, thermal expansion, and sonic velocity measurements on oriented sandstone cores. Sufficient field tests have been performed to evaluate the reliability and accuracy of the data, and the theory by which the data are interpreted. All the field and laboratory techniques investigated proved to be reliable and provided good agreement between four or five independent tests in the same wells and zones. Accuracy of the various field tests varied from 5 to 20° [0.09 to 0.35 rad], and methods for improving this accuracy are reviewed.
A Study of the Behavior of Bounded Reservoirs Composed of Stratified Layers
Authors: Lefkovits H.C. , Hazebroek P. , Allen E.E. , Matthews C.S. 
Published: December 2007

Abstract
A rigorous study was made of the behavior of reservoirs composed of horizontal layers, unconnected except at the well and filled with a compressible fluid. The report is presented in two parts. Part I deals with the practical implications of the results obtained; Part II contains the mathematical derivation of the solution. The main portion of Part I is concerned with application of the results to reservoirs composed of two layers. Relative rates of depletion of the layers are studied, and it is shown that differential depletion between layers exists in the transient stage of the reservoir, which generally is of an order of magnitude longer than the transient stage in a single-layer reservoir. In the transient stage, the more permeable layer is depleted faster than the less permeable. However, the reservoir approaches a steady-state situation where both layers contribute equally to production. Theoretical build-up curves from such reservoirs are presented, and the influence of a skin effect and flow into casing and tubing are also evaluated. The build-up curves are predicted to have, first, the familiar logarithmic straight-line section and, subsequently, a rising and flattened section. The results found are compared with an extension of an approximate theory, and it is found that this simplified theory is applicable over most of the life of the reservoir. Extensions to reservoirs containing more than two layers are indicated, and examples of the performance and build-up curves for three-layered reservoirs are presented. The theoretical results on build-up curves were applied to field examples of such reservoirs, and satisfactory results were obtained. From the build-up curve, the permeability-thickness product, the wellbore damage and the static pressure are obtained. However, it apparently is not possible to determine the properties of the individual layers from the combined build-up curve.
A New Approach to the Development of Fire-Resistant Wellhead Equipment
Authors: Karr Michael A. 
Published: December 2007

Summary
A testing procedure has been developed that considers the response of the total wellhead system (vs. individual seal components) to fire conditions. This paper details the mechanics and results of this program for tests to 2,000°F [1100°C] flame at pressures of 3,750 psi [25.9 MPa]. Significant behavioral differences were observed during the development and testing of specially designed fixtures incorporating metal-to-metal seals for the tubing head, tubing hanger, and lower master valve. As a result, more stringent design criteria evolved for the sealing technology and structural integrity of the wellhead, because it became apparent that solving sealing and material problems in one sealing area or component invariably created new problems in other locations.
Highest priority was given to seal development because it seemed to be the most critical area of concern. It was concluded that meaningful tests could be conducted only when several related seals were allowed to interact in response to fire conditions. Tubing, annulus, and connector seals were considered appropriate seals for wellheads.
Dynamics of Subcritical CO2/Brine Floods for Heavy-Oil Recovery
Authors: Rojas G. A. , Ali S. M. Farouq 
Published: December 2007

Summary
Immiscible CO2 flooding is an important, field-proven heavy-oil recovery method, particularly suited for thin, marginal, or otherwise poor heavy-oil reservoirs, where thermal recovery processes are likely to be uneconomical. This paper describes the dynamics of this recovery technique on the basis of experiments conducted in a scaled model. The experiments represent a medium-heavy oil (1032 mPa·s at 23°C [1,032 cp at 73°F]) occurring in a shallow, thin sand. CO2 was injected together with brine at subcritical conditions (5.5 MPa and 21 to 23°C [800 psi and 70 to 73°F]).
The CO2 and brine superficial velocities were varied from 0.18 to 2.9 m/d [0.6 to 9.5 ft/D]. This broad range of velocities permitted the study of the effect of the viscous, diffusive, and gravitational forces on the CO2 slug (20% HCPV) process for heavy-oil recovery. It was found that viscous forces completely dominated CO2 injection. Also, the mass transfer between CO2 and oil had a stabilizing effect on the brine injection. Although the molecular diffusion of CO2 in oil was high, it was not high enough to mobilize appreciable amounts of oil from uninvaded zones.
The scaled experiment results showed that oil recoveries at CO2 and brine breakthroughs were rate-dependent. While recovery at CO2 breakthrough decreased with increasing rate, recovery at brine breakthrough increased. Reduction of interfacial tension (IFT) between brine and oil, leading to the formation of brine-in-oil emulsions, was found to be an additional effective mechanism of heavy-oil recovery by CO2/brine injection.
Technical Advancements in Submersible-Pump Power Cable for Harsh Environments
Authors: Guzy R. , Vandevier J. 
Published: December 2007

Summary
In artificial-lift systems, such as electrical submersible pumps, the power cable provides the link between the surface equipment and the pumping unit. New cable designs are constantly being introduced. This paper discusses these designs and their materials. Information on a new approach to cable manufacturing and on use of downhole materials in harsh environments is also provided.
This paper includes work on cable designs that incorporate a new, unique, elastomeric composition that resists rupture of jacketing materials used on downhole cables, eliminating the need for tape and braid. Cable history is also reviewed, classifying the cables by use temperatures and relative cost. Criteria for selecting materials suitable for the entire range of downhole environments are included.
A Comparison of Pressure-Transient and Tracer-Concentration/Time Data for Layered Reservoirs Under Injection
Authors: Mishra Srikanta , Ramey H. J. 
Published: December 2007

Summary
Hypothetical tracer and pressure-transient test responses were computed for a production well in a developed, five-spot, unit-mobility-ratio injection/production pattern. The reservoir was a noncommunicating Dykstra-Parsons layered system. Layer effects were evident in tracer results, but pressure-transient results indicated a single layer of averaged properties. Conventional layer system "humps" were not present for the buildup pressure-transient data.
Response of the Carbon/Oxygen Measurement for an Inelastic Gamma Ray Spectroscopy Tool
Authors: Roscoe Bradley A. , Grau James A. 
Published: December 2007

Summary
In the inelastic mode of operation, a gamma ray spectroscopy tool (GST) performs a measurement of the carbon and oxygen in the formation and borehole on the basis of a spectral analysis of gamma radiation induced by fast neutrons. The carbon-to-oxygen ratio contains valuable information concerning the location of oil-and/or gas-bearing rock. Hundreds of laboratory formation measurements have been performed to determine the partitioning between formation and borehole response of this tool. An interpretation model has been developed for the carbon-to-oxygen ratio that determines the borehole effects as a function of the following parameters: borehole size, borehole fluid composition, borehole fluid displacer size, casing size, casing weight, and formation porosity.
Design and Installation of a 20-Slot Template in the Gulf of Mexico in 760 ft of Water
Authors: Brinkmann P. E. , Barbier G. J. , Rodriguez W. 
Published: December 2007

Summary
This paper describes the design, fabrication, and offshore operations associated with the installation of a 20-slot mudline drilling template for 760 ft [232 m] of water in the Gulf of Mexico. The basic design criteria, project scheduling, installation considerations, and associated engineering studies are discussed. Economics highlighting potential project cost savings is included.
Deflocculation of Fractionated Montmorillonite by Sodium Polyphosphates
Authors: Jessen F.W. , Turan Faruk H. 
Published: December 2007

Abstract
The gel strength and viscosity of two different suspensions of fractionated montmorillonite clay were measured by using a Stormer viscosimeter and Fann V-G meter. The amount of sodium polyphosphate (sodium hexametaphosphate, sodium tetraphosphate and sodium acid pyrophosphate) adsorbed by the clay particles was determined. A relationship seems to exist between the amount of polyphosphate adsorbed and the nature of the surface, edge or plate, assumed to be the principal sites for selective adsorption. Reduction in viscosity and gel strength was found to be directly related to the adsorption. Both chemical bonding and physical adsorption seem involved in deflocculation. Some indication of the axial ratios of particles of .1- to .04-micron average size is possible through study of the adsorption mechanism.

Introduction and Purpose
A knowledge of surface areas of clay particles in a suspension and a precise determination of phosphate adsorption should provide a basis for a better understanding of reduction in viscosity and gel strength caused by molecularly dehydrated phosphates. The purpose of this investigation was to study the adsorption of sodium polyphosphates on suspensions of fractionated sodium montmorillonite. Although there is considerable uncertainty regarding details of the structure of montmorillonite, a generally accepted one is that suggested by Hofmann, Endell and Wilm. The structure shown in Fig. 1 is an idealized one, and Marshall has postulated that it is possible for several isomorphous replacements to occur. Thus, aluminum may replace silicon, in which case an exchangeable cation would go along with the aluminum to neutralize what would otherwise be a net negative charge on the structure. There is disagreement among various investigators as to the particle size and shape of montmorillonite clays. Marshall reported the following results for the mean lateral dimensions of a Putnam clay (montmorillonite) - 3,730 A for particles having average diameters ranging from 500 to 1,000 A, and 750 A for those with an average diameter less than 200 A. The latter particles were estimated at 50 A in thickness, which would correspond to a stack of five unit cell layers. On the other hand, Shaw has interpreted micrographs as indicating that particles of montmorillonite are readily broken down to the individual cell layers by dispersion in water.
Application of a Mass Flowmeter for Allocation Measurement of Crude Oil Production
Authors: Liu K. T. , Canfield D. R. , Conley J. T. 
Published: December 2007

Summary
Mass flowmeters have been used to improve crude oil measurement at individual wells throughout the Little Knife field. This type of meter uses the principle of the Coriolis effect to measure the mass flow rate of fluid. Mass measurement eliminates problems encountered by conventional volumetric flowmeters because of the presence of free gas in the liquid phase.
After 5 years of operation, mass flowmeters have proved to be a significant improvement over conventional flowmeters. Excellent agreement has been consistently achieved between the sum of the measurement from the allocation meters and the custody transfer meters, which receive the commingled oil. In addition to the performance improvement, significant capital and operating cost savings were realized compared with a more conventional oilfield approach.
Cormorant: Development of a Complex Field
Authors: Stiles J. H. , McKee J. W. 
Published: December 2007

Summary
The development plan of Cormorant field exemplifies changes required as the nature of a large, complex field becomes better known. The number and locations of wells and the completion method have changed as the structural, stratigraphic, and diagenetic natures of the field became better known. A better understanding of a key development constraint—the drilling reach—has allowed changes to the development plan at significant cost savings. Close surveillance of geological results and field performance has been necessary to allow almost continuous updating. This paper discusses studies and evaluations undertaken by Esso E&P U.K. to evaluate such changes for each of the field's four fault blocks. These studies complemented work done by the operator, Shell U.K. E&P.
Influence of Shape and Skin of Matrix-Rock Blocks on Pressure Transients in Fractured Reservoirs
Authors: de Swaan Abraham 
Published: December 2007

Summary
A formulation for pressure transients in terms of the intrinsic, or core, properties of the two media that compose the fractured reservoir establishes the influence of these properties on—and their corroboration from—the pressure/time relationship observed in well and interference tests. The influence of the following reservoir characteristics are analyzed: the area of fractures transverse to flow; the dimensions, shape, and properties of rectangular parallelepiped matrix-rock blocks; and permeability reduction in the block surfaces.
A restatement of the so-called quasisteady-state intermedia flow provides Warren and Root's α and λ parameters with the physical meaning they lacked and allows direct determination of the blocks' minimum dimensions.
Underbalanced Perforation Characteristics as Affected by Differential Pressure
Authors: Regalbuto John A. , Riggs Robert S. 
Published: December 2007

Summary
Underbalanced, tubing-conveyed completions are increasing because of the apparent advantages of cleaner perforations, reduced completion times, and stimulation treatments. Radial-flow Berea sandstone core specimens are used to determine the perforation characteristics resulting from time-dependent pressure differentials between core pressure and wellbore pressure during the completion process.
The primary perforation characteristic studied [radial flow ratio (RFR)] is defined as the ratio of the perforated flow rate to the flow rate of the unperforated core. The perforation flow tests included pressure differentials from 500 psi [3450 kPa] overbalanced to 1,000 psi [6900 kPa] underbalanced, with immediate or delayed surging.
The RFR was affected most by the 500-psi and 1,000-psi [3450- and 6900-kPa] underbalance. The surged RFR's were from 50 to 58% greater than the no-surge RFR's.
Perforation hole volumes were increased as much as 55% by the surge, indicating some elimination of the compacted, damaged-zone material. Underbalanced surge conditions (1,000 psi [6900 kPa]) increased hole volume to four times that resulting from 500 psi [3450 kPa] overbalanced, no-surge conditions.
Underbalanced surging, either at the instant of perforation or subsequently, appears to improve the flow characteristics of shaped-charge perforations by simultaneously reducing the thickness of the low-permeability crushed zone and increasing the perforation surface area.
Additional Thermal Data for Porous Rocks--Thermal Expansion and Heat of Reaction
Authors: Somerton W.H. , Selim M.A. 
Published: December 2007

Abstract
Thermal expansions and beats of reaction of three typical sandstones were measured in the temperature range of 250° to 1,000°C. The significance of these data in subsurface heat-transfer calculations is discussed.
Linear thermal expansions were measured both parallel and perpendicular to the bedding planes. Volume expansions are reported as the perpendicular expansion plus two times the parallel expansion. Expansion behavior of the sandstones was found to be controlled by the expansion characteristics of the quartz content. Differential expansion of the quartz grains and other minerals included in the sandstones caused permanent de formation of the heated samples after they were cooled to room temperature. Structural damage resulting from heating is probably an important cause of the reduction of thermal conductivity of heated samples.
Measurements of heats of reaction were based on the known heat required for a-ß quartz inversion. Thermal reactions, which probably include dehydroxylation of clay minerals and decomposition of carbonate minerals contained within the samples, were found to require more than one-fourth of the amount of heat necessary to raise the temperature of the rock alone. In shales and limestones, the reaction heat could be substantially greater than that required from specific heat considerations alone.

Introduction
In earlier work, methods of measuring thermal properties were developed and thermal data for several sedimentary rock types were reported. Data included thermal conductivity, specific heat and thermal diffusivity. In addition, calculations of heat transfer in subsurface formations may require data on the thermal-expansion characteristics of rock and the heats of reaction of mineral constituents.