bluuebunny/crossref_metadata_2025_split huggingface dataset:
A Study of the Dual-Water Model Based on Log Data
Authors: Coates George R. , Boutemy Yves , Clavier Christian 
Published: December 2007

Summary
This paper presents log evidence in support of the dual-water model. Included are basic studies that illustrate the model from the aspect of conductivity measurements, porosity and formation factor relationship, and the contrast to the prediction of Waxman and Smits' cation exchange capacity (CEC) model (W-S model).

Introduction
Since the introduction of the theoretical dual-water model in 1977, there has been considerable conjecture on the scientific aspects of- the CEC models.
This paper intentionally avoids theoretical areas and concentrates instead on what can be observed from log, data with respect to the conductivity and porosity of shales, shaly sands, and sands. In addition, the dualwater hypothesis is expounded as a means of shedding new light on the troublesome problem of applying a formation factor relationship in shaly formations.

The Dual Water Observed
Studies of factors that influence the attenuation of electromagnetic propagation signals from EPT logs revealed that plots of attenuation rate as a function of the total porosity index always displayed similar trends, with the shales showing the greatest uniqueness. Fig. 1, which is a hand composite of several wells from a variety of geographic areas with largely different conditions, illustrates this characteristic.
Further study determined that the basic plot shape was a reflection of changes in the conductivity of the formation fluids. This is shown in Fig. 2, where constant fluid conductivity trend lines have been added to a typical attenuation/porosity plot. This knowledge led directly to the idea of correcting the EPT log t-or shaliness by modifying Rw, proportionally. Although this was done successfully, a question was raised. Do other logs that react to the volume and conductivity of formation fluids also respond to dual waters?

Micro later o log and Induction Log Data
The familiar Pickett plot (log-log plot of conductivity vs. porosity) is a convenient form for making this evaluation because it allows a relatively pure look at the data.
Pickett plots using a density/neutron-based porosity were constructed with Micro later o log (Fig. 3) and induction (Fig. 4) log data.* Two distinct data concentrations could be seen, one associated with low gamma ray values and the other with high gamma ray values.
These plots have been enhanced with an illustration of a simple Archie-type transform of some known fluid conductivities by assuming that KR=1.0 and m=2.0 in the classic equations, FR=KR/om and Cw=FRCo, (Ro,=FRRw). The Cw values chosen reflect Rw, (Cw=30.0 mho. Rmf (Cw=1.0 mho), and the theoretical clay water conductivities for the existing temperature conditions.
JPT
P. 158^
Reservoir Simulation Using an Adaptive Implicit Method
Authors: Thomas G. W. , Thurnau D. H. 
Published: December 2007

Abstract
This paper deals with a new implicit method for reservoir simulation. Rather than provide a fixed degree of implicitness in every gridblock at every time step or iteration, the adaptive implicit method operates with different levels of implicitness in adjacent gridblocks. These levels shift in space and time as needed to maintain stability. Shifting is accomplished automatically without user intervention. The technique can be applied to any simulation problem involving N unknowns. The advantage is substantial reduction in computing time and storage requirements compared to fully implicit formulations, while still yielding unconditionally stable solutions.
The mathematical procedure involves labeling the implicit/explicit mix of unknowns and then composing the matrix problem. The latter is reducible as long as there is one or more unknowns to be computed explicitly; consequently, appropriate operations are performed to put it in reduced form. This leads to matrix equations of lower order than the original problem that are solved at less cost. We demonstrate each step of the mathematical procedure with an example.
Finally, applications to a three-phase coning problem and a three-dimensional (3D) Cartesian problem are presented. By using special displays we demonstrate the degrees of implicitness in each cell and how they shift in space and time during simulation. We also present information regarding the savings in computer time and storage compared with a fixed, fully implicit procedure.
Mobilization of Residual Oil Under Equilibrium and Nonequilibrium Conditions
Authors: Lam Andrew C. , Schechter Robert S. , Wade William H. 
Published: December 2007

AbstractA microvisual study of residual oil mobilization that uses a relatively simple chemical system consisting of water, n-propanol, and cyclohexane is presented. Two different classes of experiments were performed to determine the sensitivity of the capillary number required to displace a particular residual oil globule from chemical equilibrium. It was found that under certain circumstances the capillary number required to mobilize the oil drop could be reduced greatly if the displacing phase contained more alcohol than it would in equilibrium with the trapped phase.Experiments clearly demonstrated that spontaneous emulsification by a diffusion and stranding mechanism could not account for the differences between equilibrium and nonequilibrium capillary numbers. Experimental observations did correlate well with the development of interfacial turbulence (Marangoni effect). Variations that, according to theory, tended to enhance the level of interfacial turbulence between the equilibrium and nonequilibrium capillary numbers were observed. The importance of the Marangoni effect relative to laboratory oil recovery experiments is discussed.A second class of experiments consisted of observing the displacement of residual oil globules that had been increased in volume (swollen) by mass transfer from a continuous phase flowing too slowly to displace the drop. Once the residual oil globule attained equilibrium with the continuous phase, the flooding velocity was increased until the swollen globule was displaced. Surprisingly, slightly swollen globules required a larger capillary number for mobilization than the original drop. Thus, the capillary number for swollen residual oil globules goes through a maximum as a function of the degree of volume increase. The precise position of the maximum varies for each globule since mobilization is a complex function of geometry.
Effect of Taxation on Valuation and Production Engineering
Authors: Breeding Clark W. , Herzfeld John R. 
Published: December 2007

Introduction
Taxes are important in the evaluation of any investment. For example, the market price of a tax exempt municipal bond will usually be higher than the market price of a fully taxable industrial bond of equivalent interest rate and security. Similarly, the buyer of a business will consider the impact of taxes in determining its potential yield and payout. The timing and extent of capital improvement programs are also influenced by taxes. For example, the time of repayment and ability to repay purchase obligations will be materially influenced by the ability to deduct the cost of improvements through depreciation or depletion charges. The oil and gas industry is affected by certain special rules of taxation which tend to make tax considerations of paramount importance to the industry. Some of these specialized concepts will be discussed and their effect upon specific transactions will be examined.

Property Unit
If the land department of an oil company secures four 160-acre leases from four different landowners, thereby securing a 640-acre tract, the operating departments of the company would likely regard such a tract as a single property for most purposes. However, under income tax rules, the company is regarded as having four properties, even though 640-acre spacing might be required, absent an election to aggregate, which will be discussed presently. Property is defined by the Internal Revenue Code as "each separate interest owned by the taxpayer in each mineral deposit in each separate tract or parcel of land". This definition places emphasis on the concept of separateness whether it arises by reason of the nature of the interest owned by the taxpayer, the various deposits under the tract of land, or the number of tracts or parcels into which it may be carved. The types of interest which may be regarded as separate would refer to the kind of interest owned by the taxpayers such as a fee simple, working interest, royalty, or over-riding royalty, etc. Regardless of how or when acquired, each such interest would be regarded as a separate property for depletion purposes, except in certain very special circumstances. If several mineral deposits are under a single tract or parcel of land, each deposit is regarded as a separate property.
Applying Instantaneous Corrosion Rate Measurements To Waterflood Corrosion Control
Authors: Wright Charles C. 
Published: December 2007

Abstract
The recent availability of the instantaneous corrosion-rate measuring instrument developed by Pure Oil Co. has enabled a new approach to corrosion control. In the past either corrosion had to occur and be measured or the causes of corrosion known and measured to allow successful corrosion control. This paper shows the sensitivity of instantaneous corrosion-rate measurements to changes in operating conditions in a water flood. Response is immediate, thus allowing the plant operator to take prompt remedial measures before damage is done.
Introduction
The starting point for the corrosion-rate meter appears to be the work published in 1955 by Simmons, followed by a paper in 1957 describing experiments in which a small current was passed through a coupon immersed in a corrosive liquid. They found that the change in electrode potential per unit of current flow was apparently inversely proportional to the instantaneous corrosion rate of the coupon. This was followed, in 1958, by a paper on corrosion by Stem, who showed that there is a theoretical basis for this finding. The first practical application of polarization resistance measurements to solving corrosion problems was made by Marsh. Marsh proceeded from his early work and enlarged upon his earlier development of the electrical resistance probes for corrosion measurements. He developed a simple probe utilizing two electrodes of the same metal or alloy, thereby eliminating the need for reference electrodes and for precise knowledge of electrode potential data. In this new probe, Marsh applied a potential of 2/100 v across the two electrodes and then measured the current flow. In practice, the potential is applied for 5 to 15 seconds and the current flow is read. Then the direction of current flow is reversed by reversing the potential and the measurements repeated. Marsh calibrated his initial instrument by using two electrical resistance probes as the electrodes for his polarization resistance probe. The electrical resistance probes were used at the same time as a means of determining the actual amount of corrosion taking place. Marsh followed this with a paper in which he reported "The relative effectiveness of the inhibitor can be estimated from the corrosion rate of the electrodes as measured by the corrosion rate meter. Because the tests are quite rapid, variations in testing can be used to compensate somewhat for the artificial conditions employed in the test. Inhibitors highly effective under widely different conditions have been discovered by this technique".'
Principle of Operation
The principle of the corrosion meter may be explained as follows.
JPT
P. 269ˆ
Automation of an In-Situ Combustion Tube and Study of the Effect of Clay on the In-Situ Combustion Process
Authors: Vossoughi Shapour , Willhite G. Paul , Kritikos William P. , Guvenir Ibrahim M. , El Shoubary Youssef 
Published: December 2007

Abstract
A fully automated in-situ combustion apparatus supported by a minicomputer was designed, constructed, and tested.
Results obtained from four adiabatic dry combustion runs to investigate the effect of clay on crude oil combustion are reported. Sand mixtures of varying clay (kaolinite) content were saturated with crude oil and water. The fourth run was performed with amorphous silica powder in the sand mixture for comparison with clay results.
We concluded that the large surface area of the clays was a major contributor to the fuel deposition process. However, different oxygen utilization efficiencies obtained from both types of sand mixtures indicated that mechanisms controlling the combustion reaction also depended on the composition of the porous matrix.
A thermogravimetric analyzer (TGA) and a differential scanning calorimeter (DSC) were used to obtain kinetic data on the effects of kaolinite type clay on crude oil combustion. The addition of kaolinite clay or silica powder changed the shape of the crude oil TGA/DSC thermograms significantly, but sand had no effect. The major effect on DSC thermograms was a shifting of the large amount of heat produced from a higher to lower temperature range. Reduction of activation energy caused by the addition of kaolinite clay to the crude oil indicates both catalytic and surface area effects on combustion/cracking reactions.
Meren Field-The Geology and Reservoir Characteristics of a Nigerian Offshore Field
Authors: Poston Steven W. , Berry Peter , Molokwu Felix W. 
Published: December 2007

Summary
The Meren field is located offshore Nigeria. The field contains 1.3 billion bbl original oil in place (OOIP) and may be classed as a major oil accumulation. The more landward-lying fault blocks within the field contain an increasingly greater preponderance of oil reserves to gas reserves. All field pays display evidence of the depositional process occurring contemporaneously with fault movement. Sand sections have a tendency to become magnified in the downthrown portion of a fault block. The reservoirs are composed of sandstone with minor accumulations of authigenic kaolinite. The amount of kaolinite within a particular sand is a major factor in determining the porosity and permeability. The high porosities and permeabilities and the ability of the reservoir rock to remain unaltered by the introduction of seawater should minimize many of the operational problems ordinarily coincident with the installation of a water-injection project in the Meren field. This study indicates the possibility of using a combination of well-log interpretation with laboratory analyses of sidewall cores to help determine the areal variation of porosity and permeability within a particular reservoir.

Introduction
The Meren field is jointly owned by Nigerian Natl. Petroleum Co. (NNPC) (60%) and Gulf Oil Co. (40%); however, the field is operated be Gulf Oil Co. (Nigeria) Ltd. (GOCON). Fig. 1 shows the location of the field, offshore Bendel State and approximately 25 miles northwest of the GOCON/NNPC Escravos River Tank Farm and Export Terminal. The water depth in the field varies from 48 to 60 ft. Fifty-seven wells have been drilled in the Meren field, three of which are dry holes. The field was discovered in 1965. Production began in Sept. 1968. As of July 1, 1980. the Meren field has produced 347,194,961 STB oil, 321,545,190 Mcf gas, and 10,123,132 bbl water. Cumulative recovery is 26% OOIP.
Performance analysis has shown that the majority of the reservoirs producing from the Meren field are being affected by minimal water influx. The reservoirs appear to be producing by a depletion-drive/gas-cap expansion mechanism. In 1978 GOCON and NNPC authorized a full-fledged feasibility study to determine the true worth of enhancing oil recovery from the Meren field. The first portion of the study ascertained reservoir configurations and their reservoir rock and fluid characteristics. The following segments were contained in this preliminary field definition study.

Geological Study
The Meren field was subjected to a complete geological study. All geological data were analyzed, and proper corrections were made to the original interpretations.

Core Analysis
The Meren 57 well was drilled and cored in late 1978 to confirm the results of the coring of the Meren 5 well in 1968.
JPT
P. 2095^
Miscible Drive Field Applications in the Bisti Pool
Authors: Brooks Robert E. 
Published: December 2007

Introduction
The Bisti Lower Gallup oil pool, San Juan County, New Mexico, covers approximately 24,000 acres, is 24 miles long and 1.5 miles wide. The oil productive Lower Gallup formation is of Upper Cretaceous age, and is composed of alternating layers of sandstone, sandy shale, and shale. The reservoir is encountered at a depth of 4,900 ft and has an average gross thickness of 135 ft of which only 10 to 20 per cent will have a permeability greater than 1 md. The best developed sand follows the crest of the long, narrow sand bar.
An LPG miscible displacement pilot project was started in Aug., 1957, on a 40-acre five-spot in the upper zone of the Lower Gallup. In the pilot area the upper (producing) zone is a light grey, medium-grained, clean, well sorted sandstone with a porosity of 13 per cent, permeability of 100 md, and net pay thickness of 16 ft. The permeability varies from 400 to less than 1 md.
The stock-tank oil has a gravity of 38° API. Measured fluid properties at the bubble point pressure of 1,207 psia and reservoir temperature of 145°F are solution gas-oil ratio, 407 cu ft/bbl; formation volume factor, 1.26; oil viscosity, 0.7 cp; and gas viscosity, 0.015 cp. The flood is conducted at reservoir pressures slightly in excess of the bubble point pressure.

History of the Pilot
Early performance predictions indicated that the field primary recovery would be low because the reservoir is thin and tight, and operating under a solution gas-drive mechanism. The gas-driven LPG miscible displacement pilot project was recommended after studies of high pressure vaporizing gas drive did not indicate great benefits. The pilot consists of four producing wells spaced 40 acres apart with an injection well completed in the center of the four producers. The four pilot wells are the Sunray Mid-Continent Federal C wells No.1 and 2, British-American Marye No.1 and Phillips Hospah A No.1. Also participating in the project are EI Paso Natural Gas Products Co., Amerada Petroleum Corp. and Shell Oil Co., although they are not operating wells in the pilot area.
Fracture Penetration Through an Interface
Authors: Biot M. A. , Medlin W. L. , Massé L. 
Published: December 2007

Abstract
This paper presents a combined theoretical and experimental investigation of fracture penetration through an interface. The results have application to hydraulic-fracture containment in sandstone or limestone reservoir strata bounded by shale layers. Several simplifying assumptions and approximations are made. We assume that the interface separates dissimilar but adhering materials that are elastic to first order. We consider only differences in material properties and take stresses to be locally uniform. Approximations are made that reduce the fourth-order equation of plane strain elasticity to the second-order Laplace equation. Crack shape is taken to be sinusoidal and fluid leakoff is ignored.
Additional simplifying assumptions are made about the shape of the crack tip as it passes through the interface. Using a virtual work analysis, we derive a relation for internal fluid pressure required to extend the crack through the interface. This pressure is related to the equilibrium pressure needed to hold the crack barely open. A simple relation is obtained involving only the shear modulus and surface energy of the materials on either side of the interface.
The theory was tested in laboratory experiments with Plexiglas™/resin bonds. Test blocks of several configurations were used with various kinds of external loading. Cracks were initiated by applying grease pressure in thin notches. Pressures required to hold cracks in equilibrium were compared with those required to penetrate interfaces. Results were consistent with the theory within limits of precision in measuring surface energy. We conclude that the theory explains field observations of containment in a number of reservoirs that have been fractured hydrualically. However, practical value is limited by inability to estimate surface energies from logging or other wellbore data.
Miscible Drive Field Applications in the Block 31 Field
Authors: Kern L.R. , Kimbler O.K. , Wilson R. 
Published: December 2007

Introduction
Pressure maintenance by gas injection has been in operation for the past eight years in the Devonian formation of the University Block 31 field. The object of this operation is to achieve miscible displacement of the oil and consequently increase the ultimate field recovery. It is estimated that miscible high pressure gas displacement will yield three times as much recovery as by natural depletion (solution gas drive) mechanism.
Earlier papers have dealt with the mechanics of miscible displacement and a description of this operation. We will not attempt to expand upon this subject further here, but merely state that by laboratory experiment it has been found that in order to achieve miscibility between injected gas and this Devonian reservoir fluid, it is necessary to maintain 3,500 psi pressure at the displacing gas front. Although the average reservoir pressure has declined below 3,500 psi, the injection pressure has been sufficiently high to maintain at least 4,000 psi pressure at the gas front in all injection wells.
After two years of injecting gas into the G–2 well it was noted that this area was not increasing in pressure as expected. It was suspected that injected gas was leaking to other formations because there was less repressuring than predicted by material balance. This paper deals with one approach to the problem of gas losses and the corrective and control measures involved.

Reservoir Description and Injection Operation
The Block 31 Devonian field covers about 7,000 acres. The Devonian formation is on an anticlinal structure at a depth of 7,900-ft subsurface at the crest. The gross thickness is 1,000 ft. The field boundary is defined by water closure at 9,000-ft subsurface. The main producing section is located 450 to 800 ft below the top of the structure. This interval contains 85 per cent of the total in-place oil.
Seventy-three wells are presently completed in the Devonian on about an 80-acre spacing. Fifteen of these wells are currently being used for gas injection, basically in nine-spot injection patterns.
Mixed Finite Element Method for Miscible Displacement Problems in Porous Media
Authors: Darlow B. L. , Ewing R. E. , Wheeler M. F. 
Published: December 2007

Abstract
Effective numerical simulation of many EOR problems requires very accurate approximation of the Darcy velocities of the respective fluids. In this paper we describe a new method for the accurate determination of the Darcy velocity of the total fluid in the miscible displacement of one incompressible fluid by another in a porous medium. The new mixed finite-element procedure solves for both the pressure and velocity of the total fluid simultaneously as a system of first-order partial differential equations. By solving for u = (− k/μ) ∇p as one term, we minimize the difficulties occurring in standard methods caused by differentiation or differencing of p and multiplication by rough coefficients k/μ.
By using mixed finite elements for the pressure equation coupled in a sequential method with a finite element procedure for the concentration of the invading fluid, we are able to treat a variety of problems with variable permeabilities, different mobility ratios, and a fairly general location of injection and production wells. Mixed finite-element methods also produce minimal grid-orientation effect. Computational results on a variety of two-dimensional (2D) problems are presented.