bluuebunny/crossref_metadata_2025_split huggingface dataset:
Experimental Studies of In-Situ Microbial Enhanced Oil Recovery
Authors: Jenneman Gary E. , Knapp Roy M. , McInerney Michael J. , Menzie D. E. , Revus D. E. 
Published: December 2007

Abstract
Experiments were conducted to study the feasibility of using microorganisms in EOR. particularly for the correction of permeability variation. The use of microorganisms requires the ability to transport viable cells as well as the nutrients required for cellular growth through reservoir formations. Nutrients such as glucose, peptone-protein, and phosphate and ammonium ions were transported through brine-saturated Berea sandstone cores in amounts sufficient to support microbial growth. Viable bacterial cells were transported through sandstone cores of 170-md permeability. Less than 1 % of the influent cell concentration was recovered in the effluent, indicating a high degree of cell retention inside the core. The addition of nutrients to these cores and subsequent incubation to allow for microbial growth resulted in permeability reductions of 60 to 80%. These data show that the growth of microorganisms significantly reduces the permeability of porous rock.
Effect of Applied Pressure on the Conductivity, Porosity and Permeability of Sandstones
Authors: Wyble D.O. 
Published: December 2007

Abstract
A pressurizing system was designed and built to apply a radial pressure of 5,000 psi to rock samples. Samples of the Bradford, Weir and Kirkwood sandstones were subjected to radial pressures parallel and perpendicular to the bedding in the system and the changes in conductivity, porosity and permeability were determined.
Asymptotic decreases in conductivity, porosity and Klinkenberg permeability were observed over the 0- to 3,500-psi range. From these data, the increase of formation factor over the same range was calculated. The cementation exponent expressed in the Archie equation was found to increase with pressure.
The rate of change varied from formation to formation. Only small differences were observed for samples taken parallel to the bedding as compared to those taken perpendicular to it except for the Bradford sand.
Above 3,500 psi the data are not good enough to tell if the properties continue to fall-off asymptotically or in a different manner. A possible explanation for the probable limit of the asymptotic rate around 3,500 to 4,500 psi is that this represents the maximum pressure which the formations have undergone during their geological life as a result of burial.

Introduction
For many years measurements have been made in the laboratory of the properties of oil-bearing sandstones with little consideration being given to whether these properties had been changed when the samples were moved from their original position in the ground to the laboratory.
Relatively little has been reported in the literature on the effect of pressure on the properties of sandstones. The changes in permeability for eight. typical consolidated oil-bearing sandstone samples with overburden pressure (0- to 15,000-psi range) was presented by Fatt and Davis in graphical form. In 1953 Fatt also reported the relationship between porosity and overburden pressure for four typical consolidated oil-bearing sandstone samples (0- to 5,000-psi range).
Diffusional Effects in the Recovery of Methane From Coalbeds
Authors: Smith Douglas M. , Williams Frank L. 
Published: December 2007

Abstract
This paper presents evidence that the unipore model is inadequate for describing diffusional fluxes from coal over the entire timescale of desorption. Field desorption of methane from coal pieces shows pronounced curvature, which is attributable to the bidisperse pore structure generally found for coal. A model is presented that accounts for the bidisperse pore structure of coal and predicts diffusion rates for both field and laboratory desorptions. Transient diffusivities are determined for Pittsburgh bituminous and Madrid (NM) anthracite coals by using a pulse tracer technique coupled with Fourier analysis of the elution curves. This technique allows the rapid determination of the diffusion parameters with minimal experimental effort. In addition, steady-state diffusivities are determined to identify mechanisms of diffusion. Diffusion was found to be a combination of bulk, Knudsen, and surface diffusions, depending on the coal pore structure and gas pressure.
Pressure Response at Observation Wells in Fractured Reservoirs
Authors: Chen C. C. , Yeh N. , Raghavan R. , Reynolds A. C. 
Published: December 2007

Abstract
This work examines interference test data in a naturally fractured reservoir. The reservoir model examined here assumes that the reservoir can be represented by a system of horizontal fractures that are separated by the matrix. This model is identical to the deSwaan-Kazemi model.
The main contribution of our work is that we combine the parameters of interest in a simple way and present solutions that can be used directly for field application. These solutions can be used to design or analyze interference tests. We also compare the solution for unsteady-state flow in the matrix with the Warren-Root model, which assumes pseudosteady-state fluid flow in the matrix.
Fatigue Analysis of Clad and Unclad Thick-Wall Structures
Authors: Gottlieb Theodore , Mann Tarlochan 
Published: December 2007

Abstract
It is common practice to clad steel components with a relatively thin layer of a stainless material to prevent corrosion economically. Little, however, has been published regarding the effect of such cladding on fatigue life in areas of localized high stress. Large valves that are pressure-cycled often and offshore equipment, such as risers, tensioners, and wellhead flanges that are loaded cyclically by ocean currents and waves, must be analyzed for fatigue life during design. Unlike storage vessels, drilling and completion hardware generally has areas of relatively high stress concentrations because of abrupt section size changes, threads, grooves for seals, bolt holes, and other stress-concentrating geometries. While yielding or rupturing is a function of bulk stresses, fatigue life is a function of peak stresses, which typically are highest on the surface of an area of stress concentration. It has been determined that both the metallurgical characteristics of the cladding and the pressure/load history can be varied to enhance or diminish significantly the fatigue life of a clad steel component. The results and conclusions of this study are based on laboratory studies. Axial fatigue tests (R = 0.05) were performed using a side-notched fatigue specimen that produces combined axial and bending stresses in the notched area. Specimens of AISI 4130 (at HRc 20) were tested unclad and with the notched area clad with Inconel 625 or AISI 316L. Each set of specimens was tested both unpreload-ed and preloaded to produce localized yielding at the notched surface only.
The findings of this study are applicable to components subject to failure by fatigue and corrosion fatigue and sour service steel components that become locally work-hardened either in service or during overload proof testing as required by most API specifications.
An Analytical Study of Interference in Composite Reservoirs
Authors: Satman Abdurrahman 
Published: December 2007

Abstract
This paper discusses the interference test in composite reservoirs. The composite model considers all important parameters of interest: the hydraulic diffusivity, the mobility ratio, the distance to the radial discontinuity, the distance between wells, the wellbore storage, and skin effect at the active well. Type curves expressed as a function of proper combinations of these parameters are presented.
Fatigue Behavior of Large-Diameter Wire Ropes
Authors: Hanzawa M. , Yokota H. , Toda Y. , Yokoyama K. 
Published: December 2007

Abstract
Factors influencing tensile fatigue strength of 50-mm wire ropes were investigated with a wire-breakage detecting system. The fatigue strength increased with an increase in wire strength and diameter and a decrease in self-rotativity of ropes. The epoxy resin was satisfactory as a socketing material.
Hydrodynamic Model For Intermittent Gas Lifting of Viscous Oil
Authors: Schmidt Zelimir , Doty Dale R. , Lukong Peter B. , Fernandez Orlando F. , Brill James P. 
Published: December 2007

Abstract
A hydrodynamic model was developed for intermittent gas lift. Simulation results were verified by experimental tests conducted with a 60 ft high 3 in. diameter test facility using air and an oil with viscosity of 108 cp. The simulation program was also successfully applied to data gathered on an instrumented intermittent gas lift well.
Results of the study indicate that initially the liquid slug undergoes a rapid acceleration and then accelerates at a much lower rate until the surface is reached, at which time rapid slug acceleration again occurs. It was found in this study that a significant portion of the liquid produced at the surface sometimes more than 50 percent, was contributed during the afterflow (i.e. liquid recovered in the form of entrained liquid in the gas core). In addition, the study has shown that by increasing the injection pressure, a higher recovery can be achieved more rapidly, but only at the pressure, a higher recovery can be achieved more rapidly, but only at the expense of increased gas injection. The model is also capable of predicting the cuing to tubing pressure ratio at which a minimum GOR will predicting the cuing to tubing pressure ratio at which a minimum GOR will occur. This minimum GOR pressure ratio was found to be sensitive to fluid viscosity.
Mean- and Low-Frequency Wave Forces on Semisubmersibles
Authors: Pinkster J. A. 
Published: December 2007

Abstract
Mean- and low-frequency wave drift forces on moored structures are important with respect to low-frequency motions and peak mooring loads. This paper addresses prediction of these forces on semisubmersible-type structures by use of computations based on three-dimensional (3D) potential theory. The discussion includes a computational method based on direct integration of pressure on the wetted part of the hull of arbitrarily shaped structures. Results of computations of horizontal drift forces on a six-column semisubmersible are compared with model tests in regular and irregular waves. The mean vertical drift forces on a submerged horizontal cylinder obtained from model tests also are compared with results of computations. On the basis of these comparisons, we conclude that wave drift forces on semisubmersible-type structures in conditions of waves without current can be predicted with reasonable accuracy by means of computations based on potential theory.
The Convergence of Upstream Collocation in the Buckley-Leverett Problem
Authors: Allen Myron B. , Pinder George F. 
Published: December 2007

Abstract
Upstream collocation is a fast and accurate scheme for simulating multiphase flows in oil reservoirs. In contrast to standard orthogonal collocation, upstream collocation yields numerical solutions to the Buckley-Leverett problem that converge to correct solutions physically. The failure of standard orthogonal collocation is not surprising, since the Buckley-Leverett problem as commonly stated is posed incompletely. The equal-area rule of Buckley and Leverett and the Welge tangent construction both specify additional constraints needed to close the problem properly. An error analysis of upstream collocation shows that this method forces convergence through an artificial dissipative term analogous to the "vanishing viscosity" used in shock fitting. This constraint is mathematically equivalent to the more familiar constructions and should prove beneficial in stimulating EOR schemes based on frontal displacement.
Analysis of Finite-Conductivity Fractures Intercepting Multilayer Commingled Reservoirs
Authors: Bennett Curtis O. , Raghavan Rajagopal , Reynolds Albert C. 
Published: December 2007

Summary
The response of a fractured well in a multilayered reservoir is the primary subject of this study. Both analytical approximations and numerical results are presented. The analytical solutions served three important functions: (1) they enabled us to verify the numerical solutions used in this study; (2) they provided information on the structure of the solution and thus increased physical understanding; and (3) most importantly, they suggested a method whereby we were able to correlate multilayer solutions with single-layer solutions. We introduce the concept of dimensionless reservoir conductivity and show that in most realistic cases this parameter can be used to correlate commingled-reservoir solutions with the single-layer solutions available in the literature throughout the infinite-acting period. This concept and its utility in correlating solutions are the main contributions of this work.
We also consider the analysis of buildup data following a short producing time. As in the drawdown case, we show that the multilayer buildup solutions can be correlated with single-layer buildup solutions through the concept of dimensionless reservoir conductivity.
The Effect of Nozzle Diameter on Jet Impact for a Tricone Bit
Authors: Warren T. M. , Winters W. J. 
Published: December 2007

Abstract
Conventional techniques used to optimize the hydraulic conditions run with tricone bits usually are aimed at maximizing either jet hydraulic horsepower or jet impact force. A basic assumption underlying these optimization methods is that increased energy at the nozzle produces increased energy at the bottom of the hole. Conventional tricone bit nozzles are aimed at the "comer" of the borehole. The jets exist in a crossflow due to the return path of the fluid from under the bit. Many studies document the deflection and diffusion of a submerged jet stream in a crossflow. Studies were conducted with an 8½-in. [21.59-cm] Intl. Assn. of Drilling Contractors (IADC) Series 6-1-7 bit to determine the area and magnitude of the jet impact under a tricone bit. Flow rates up to 565 gal/min [35.6 dm3/s] and jet velocities up to 400 ft/sec [122 m/s] were used. The impact area was determined by (1) observing the location of an eroded zone beneath the bit in a block of Indiana limestone and (2) measuring the dynamic pressure beneath the bit in a test cell. Both tests indicate that a larger fraction of the jet energy reaches the hole bottom with small jets than with large jets. The tests also indicate that a larger fraction of the jet energy reaches the hole bottom when two jets are used instead of three.
Sensitivity of Steamflood Model Results to Grid and Timestep Sizes
Authors: Abou-Kassem Jamal Hussein , Aziz Khalid 
Published: December 2007

AbstractNumerical simulation of complex processes in oil reservoirs has become a standard tool. The grid size and timestep sensitivity of a simulator are of prime concern in reaching the correct conclusions in any study. This paper presents an analysis of the sensitivity to timestep and grid size of a one-dimensional (1D) and two-dimensional (2D) compositional multiphase steamflood model used to simulate a heavy-oil reservoir.The behavior of primary variables before breakthrough in the 1D and 2D cases is presented for clearer understanding of steamflooding heavy-oil reservoirs. The peculiar features exhibited by primary variables of the production and injection blocks for the 1D reservoir plus timestep and grid-size effects on primary variables for 2D cases studied are discussed.Sensitivity studies of grid and timestep size are meaningful only if each is carried out while the other variable has minimum truncation error. The recovery performance parameters are less sensitive to timestep size than to grid size. They are also less sensitive in the 2D runs than in the 1D runs. The time/pore-volume-injected (PVI) relationship is very sensitive to grid size, and to a lesser extent, to timestep size.
Efficiency of D4 Gaussian Elimination on a Vector Computer
Authors: Stringer James C. , Thomas L. Kent , Pierson Ray G. 
Published: December 2007

Abstract
The efficiency of D4 Gaussian elimination on a vector computer, the Cray-1/S, is examined. The algorithm used in this work is employed routinely in Phillips Petroleum Co. reservoir simulation models. Comparisons of scalar and vector Cray-1/S times are given for various example cases including multiple unknowns per gridblock. Vectorization of the program on the Cray-1/S is discugsed.
Using Heat in Combination With Solvents To Clean Up Formation Flow Channels
Authors: Rollins J.T. , Taylor L.C. 
Published: December 2007

Abstract
A new stimulation technique has been developed for restoring blocked permeability in both injection and production wells. The method utilizes a combination of heat and chemical solvents to remove organic and inorganic deposits that have accumulated in formation flow channels and on the face of the wellbore, during operation. The treatment is conducted in two-stages. First, a gelled oil, carrying a suspension of 20–60 mesh magnesium pellets, is injected into the pay zone. This is followed by 15 per cent hydrochloric acid which, reacting with the magnesium pellets already in the well, liberates considerable heat (8,400 BTU/lb of magnesium). As a result, the temperature of the formation may be raised several hundred degrees. The spent acid is now produced from the well, followed by the oil which has picked up many paraffin and asphalt deposits liquefied by the liberated heat. In addition, the acid solution used to release the heat reacts with any lime, oxide or sulfide deposits on the face of the pay, dissolving and removing them. To date, this new heat application has been successful on about 60 per cent of production and injection wells treated. Many of these wells have failed to respond to other type treatments. As refinements and improvements are made in treating procedures and selection of wells for treatment, a higher success ratio may be expected.

Introduction
Many wells show good output after initial stimulation treatments, but after a short time production falls off more rapidly than would be expected on the basis of formation pressure and permeability. The cause for such abnormal declines is usually either an equipment failure or change in formation characteristics. In the latter case, the trouble is frequently caused by some foreign material which partially plugs the flow channels, hindering the migration of reservoir fluids into the wellbore. Such plugging may result from either organic or inorganic mineral deposits, or both. The buildup of organic deposits often results from a decline in reservoir pressure which allows dissolved gas to break free.
The Effect of Foam on Surface Kinetics in Fracture Acidizing
Authors: Ford William G.F. , Roberts Loy D. 
Published: December 2007

Summary
A method of calculating acid spending of foams in a fracture has been developed. Experimental data are presented for foamed acid flow in limestone and dolomite laboratory-prepared fracture systems 60 in. [152.4 cm] long at 70 deg. F at [21.1 deg. C]. The surface reaction in an HCl-limestone system is fast compared to the mass transfer to the rock surface. The overall acid spending rate is to a large degree dependent on the extent of fluid mixing in the fracture. This is called a mass-transport- or diffusion-controlled reaction. The surface reaction rate in an HCl/dolomite system is finite compared with the rate of mass transfer to the rock surface. This is called a "kinetic-controlled" reaction. Earlier work showed that whether the acid was gelled or weighted, diffusion control still would be dominant for the HCl/limestone system and kinetic control would dominate the HCl/dolomite system. A method of predicting the penetration of foamed acid is presented based on combining the mass transfer coefficient of the acid in the fracture with the surface reaction that occurs at the fracture surface. Example calculations are presented to show the effect of various variables,

Introduction
The use of foamed acid in fracture acidizing treatments has gained widespread acceptance in the past few years. Various properties of foamed acid have been investigated and its successful use in stimulation treatments has been reported. Surface reaction kinetics in fracture acidizing have been studied for nonfoamed systems by several authors. This paper describes work where acid spending of foams has been measured directly and the effect of foam on surface kinetics in fracture acidizing has been studied. Laboratory data are presented that describe the effects of foam quality, foam flow rate, and foam stabilizers on the surface reaction kinetics of foamed acid on limestone and dolomite.

Mathematical Model
A mathematical model describing the spending of foamed acid was developed similar to that presented earlier by Guin and Roberts. The model for foamed acid spending is illustrated in Fig. 1. The foam leakoff velocity, V, is assumed constant over the fracture length. Assuming the foam quality is constant and there is steady-state flow in a vertical fracture, the mass balance equation for foam in a fracture is
(1)
where u and V represent the foam velocity components in the x and y direction, respectively. Gamma represents the foam quality (volume fraction of N in foam) and C the concentration of acid in the foam. (D+D ) represents the effective diffusivity. Eq. 1 must be solved subject to the following boundary conditions.
(2a)
(2b)
(2c)
The velocity components u and V are functions of x and y, satisfying the continuity equation:
(3)
These partial differential equations can be transformed into ordinary differential equations (Appendix A) to give
(4)
(5)
and
(6)
Eqs. 4 through 6 were derived by following the procedures proposed by Roberts and Guin for acid penetration for plain acid fracture treatments.
JPT
P. 89^
Optimal Reservoir Production Scheduling By Using Reservoir Simulation
Authors: See Bertrand A. , Horne Roland N. 
Published: December 2007

Abstract
This paper addresses the optimization of field operations under a given set of technical and economic constraints and demonstrates that an optimal control procedure may be applied to any industrial oil and/or gas reservoir at reasonable cost and at acceptable accuracy level. Both primary and secondary recovery processes can be considered.
The method proposed here is presented in two main sections. First, the modeling phase provides an approximately and locally linear model of the reservoir. A previously calibrated reservoir simulator model is used to perform a series of experiments, and a multiple variable regression analysis is used to fit the experimental data. The experimental design was one of the key issues in this work. Second, the optimization phase is performed with a linear programming algorithm. Nonlinear effects, such as those generated by the presence of gas, are approximated by several procedural iterations.
The application of this method to the case of a hypothetical reservoir demonstrates the validity of the optimal control procedure and shows convergence within an acceptable number of iterations.
Recovery of Retrograde Condensate from Naturally Fractured Gas-Condensate Reservoirs
Authors: Castelijns J. H. P. , Hagoort J. 
Published: December 2007

AbstractThis paper considers the flow behavior of retrograde condensate in naturally fractured gas-condensate reservoirs and the possibility of recovering part of the condensate by gravity drainage. The analysis is applied to calculate the potential for retrograde condensate recovery in the Waterton reservoir in Alberta. The calculated results are in agreement with field observations: for fracture density, matrix permeability, and reservoir-layer thickness typical of the Waterton reservoir, a small part of the retrograde liquid will accumulate within a practical time span. Condensate accumulation and recovery will significantly increase if the reservoir pressure is restored—e.g., by lean gas or nitrogen injection.