bluuebunny/crossref_metadata_2025_split huggingface dataset:
Chromatographie Transport of Alkaline Buffers Through Reservoir Rock
Authors: Jensen J. A. , Radke C. J. 
Published: December 2007

SummaryUse of relatively low-pH alkaline buffers, such as sodium carbonate or sodium silicate, is explored as a means for overcoming sodium/hydrogen ion-exchange delay in alkaline waterflooding. A local-equilibrium chromatographic model is outlined to describe the concentration velocities for injection of alkaline buffers into a linear porous medium that exhibits reversible sodium/hydrogen exchange. The theory predicts a buffer ion-exchange wave that is substantially faster than that for equivalent-pH sodium hydroxide solutions.New experimental displacement data are presented for NaOH over a pH range from 11 to 13 and for 0.1, 0.5, and 1.0 wt% Na2CO3 flowing through a 1 wt% NaCl brine saturated Berea sandstone core at 50°C [122°F]. To permit a complete description of the system, column effluent concentrations are measured for sodium ions, hydroxide ions, H3-tagged water, and 14C-tagged carbonate. The experiments confirm that Na2C03 propagates through the Berea sand at a higher rate than NaOH. For example, at pH=11.4, Na2CO3 migrates with a velocity that is 3.5 times faster than NaOH.Comparison of experiment with the ion-exchange chromatography theory shows good agreement. We successfully model the concentration histories of tritium-labeled water, total carbon, sodium, and hydroxide, all with no adjustable parameters.This work establishes with both theory and experiment that buffered alkali significantly increases the propagation speed of hydroxide in reservoir sands in comparison with unbuffered alkali at equivalent sodium and hydroxide concentrations. Because lower-pH buffered alkali can also protect against rock dissolution loss, the validated reduction of buffer ion-exchange lag considerably improves the promise of the alkaline flooding process for field application.
Restored-State Core Analysis for the Hutton Reservoir
Authors: Wendel D. J. , Anderson W. G. , Meyers J. D. 
Published: December 2007

Summary
Wettability is a major control parameter in multiphase flow analyses such as relative permeability. When such analyses are required, the native wettability of the reservoir must be maintained in the test plug. Unfortunately for laboratory analysis, cores are increasingly being taken with wettability-altering, oil-based, surfactant-containing muds. When a core's wettability has been altered by such drilling fluids, special procedures must be used to obtain proper analyses. First, the core plug must be cleaned of wettability-altering contaminants, then restored to reservoir wettability using uncontaminated native crude before accurate relative permeabilities can be obtained.
These special cleaning and restoration procedures are described for cores from the Hutton field, located in the U.K. sector of the North Sea. Plugs taken from Hutton cores were contaminated with invert-oil-emulsion drilling mud, which made them strongly oil-wet. By use of special cleaning methods, the surfactants from the drilling mud were removed, and the Hutton reservoir was subsequently shown to be only slightly oil-wet by use of relative permeabilities on plugs that had been restored to native wettability. It was also found that some sections of the Hutton cores were neutral-wet to slightly oil-wet even when clean, possibly because of the presence of coal.
CO2 Displacements of Reservoir Oils From Long Berea Cores: Laboratory and Simulation Results
Authors: Kremesec V. J. , Sebastian H. M. 
Published: December 2007

Summary
CO2 displacements of three different reservoir oils from long Berea cores were conducted over a wide range of reservoir conditions with the pressure always above the slim-tube minimum miscibility pressure (MMP). The detailed performance of these displacements is simulated with a fully compositional simulator and the Redlich-Kwong (RK) equation of state (EOS). Oil recovery, GOR, and effluent profiles are compared with experimental results. The EOS is observed to be capable of predicting the phase-behavior transitions that occur in situ when miscibility is generated by multiple contacts. The good comparison between experimental results and the simulation has led to specification of a minimum data set for which an EOS should be able to predict before a priori simulations of displacement experiments can be made. The simulation assumed a stable one-dimensional (ID) displacement and that phase-behavior effects play the primary role in the displacement, but the number of gridblocks had to be adjusted in a rough correlation with the CO2/oil-viscosity ratio. Experimentally, final oil saturation and CO2 breakthrough time also correlate with the viscosity ratio. This suggests that viscous instabilities play a role in the experimental displacement, but in this geometry and under these displacement conditions, they can be simulated as numerical dispersion.
A Model of Limited-Entry Completions Undergoing Spherical Flow
Authors: Tang R. W. 
Published: December 2007

SummaryMethods are presented in this study to determine wellbore and reservoir properties from limited-entry tests of very thick formations. This situation is often encountered in the Overthrust Belt and in geothermal operations. Most published limited-entry analysis methods assume the existence of three flow regimes during testing if wellbore storage is small. Theoretically, the regimes are (1) an early cylindrical flow period indicative of the opened interval, (2) a short spherical transition period, and (3) the late-time cylindrical data reflecting the entire productive thickness of the reservoir. The above methods are not applicable to very thick reservoirs because field data are often dominated by wellbore storage and a long spherical flow period.In this study, an analytical solution is presented to analyze the wellbore-dominated and the spherical-flow periods. The model includes cylindrical skin of the open interval and wellbore storage. The solution and resulting type curves allow direct estimates of stimulation potential in situations where wellbore storage and spherical flow dominated pressure-transient behavior. Prior methods to determine damage require late radial-flow data and separate estimates of pseudoskin caused by flow convergence. Field examples from a gas-condensate reservoir and a geothermal well demonstrate the methods. The practical aspects of analyzing other limited-entry data are discussed.
Case Study of Gas Migration in the Wasatch and Mesaverde Formations of the Piceance Basin, Colorado
Authors: Mercer James C. , Ammer James R. , Frohne Karl-Heinz 
Published: December 2007

Summary
The U.S. DOE Morgantown Energy Technology Center (METC) conducted a reservoir simulation study and an engineering analysis on gas migration for two tight lenticular sandstone units, the Wasatch formation and the Mesaverde group, in Garfield County, CO. The study quantified potential gas loss through migration from the Naval Oil Shale Reserve (NOSR) No. 3 (Fig. 1) to nearby producing wells located in the Rulison field and forecasted production for proposed NOSR No. 3 offset wells located at previously selected sites, offsetting commercial wells outside the reserve. After the reservoirs were characterized, production was forecasted by use of a reservoir simulator to history match actual production. A dual-porosity reservoir simulator, developed specifically for naturally fractured gas-producing reservoirs, and reservoir engineering calculations were used in the study. The study followed two extensive DOE field testing programs, a nearby multiwell experiment (MWX), and a special Mesaverde test well (1XM9) drilled in NOSR No. 3 (see Figs. 1 and 2). These DOE field tests provided geologic information and values for reservoir parameters that control production from this unconventional gas resource. In addition to the results from the two field experiments, the study used a detailed geologic analysis and production data from nearby industry wells to characterize the producing formations.
Rate Dependence of Unstable Waterfloods
Authors: Sigmund P. , Sharma H. , Sheldon D. , Aziz K. 
Published: December 2007

Summary
Viscous fingering is part of the flow mechanisms that are operative in waterflooding and in a wide range of EOR methods. This work presents a laboratory and computer model analysis of the viscous-fingering dynamics that develop when a less mobile fluid is immiscibly displaced by a more mobile fluid in a permeable medium.
Physical experiments of horizontal fluid displacements conducted in a rectangular bead pack show that the amplitude/frequency character of the wave-like fingers that form depends on flow rate and mobility ratio. The nature of these wave-like features is shown for two viscosity ratios and several displacement rates. Spatial frequency domain analyses of finger shapes at fixed time intervals were conducted on digitized records of the laboratory experiments. The results of these analyses indicate that fluctuations comprising the fingered zone have a wave number corresponding to a maximum growth rate. The analyses suggest that the amplitude of flow fluctuations can be characterized by a root mean square (RMS) growth rate that is linear in time. Finite-difference solutions of a set of two-dimensional (2D) flow-in-porous-media equations were made to exhibit similar frontal instability. The linear growth rate of the mixing zone suggests that fractional flow relationships can provide an adequate and practical method of representing space-averaged two-phase flow variations for many reservoir engineering applications.
Downhole Solids Control: A New Theory and Field Practice
Authors: Hayatdavoudi A. 
Published: December 2007

Summary
The primary objective of this paper is to show the effects of total solids content on size distribution of cuttings and the penetration rate (ROP) of the insert bit in hard rock and shale drilling. The secondary objective is to introduce a new "power index" theory that relates the cutting size to total power input to the rock, hydraulics of a solids separator, and a hydraulic grinding index.
Solids-Conveyance Dynamics and Shaker Performance
Authors: Lal Manohar , Hoberock L. L. 
Published: December 2007

Summary
No comprehensive mathematical models are available that can predict solids conveyance and shaker fluid handling capacity for arbitrary solids in a specified drilling fluid. This paper addresses the solids loading problem and presents an analytical approach to the design of shale shakers, based on a dynamic model for solids conveyance off the screen and fluid flow through the screen. First, the solids loading is derived as a function of shaker geometry, solids-conveying speed, bit penetration rate, hole size, drilling fluid flow rate, particle size distribution of drilled solids, and screen opening size. Second, the solids-conveyance model is developed, based on the physics of the problem, accounting for the adhesive forces resulting from wet solids. The effect of various parameters, such as vibration pattern and normal acceleration on solids conveyance, is discussed. The solids-conveyance model can give the optimum set of shaker design parameters for efficient solids conveyance off the screen. For a given shaker, the solids conveying speed predicted by the model can also be used to obtain the flow capacity of the shaker in the presence of solids. Experimental and field results relevant to this study are also discussed.
Surfactant Transport Through Porous Media in Steam-Foam Processes
Authors: Lau H. C. , O'Brien S. M. 
Published: December 2007

Summary
Experimental and theoretical studies show that the transport of steam-foam surfactants through reservoir sands can be substantially retarded as a result of cation exchange between the surfactant solution and the formation clays. Results, however, show that a high injected salinity favors surfactant propagation by displacing divalent cations faster and by reducing partitioning when divalent cations are present.
Sweep Improvement in CO2 Flooding by Use of Foaming Agents
Authors: Casteel J. F. , Djabbarah N. F. 
Published: December 2007

SummaryThis study has two objectives: (1) to screen and select foaming agents for specific CO2 floods and (2) to determine the effectiveness of foam in improving sweep efficiency in CO2 flooding. Foaming agents were evaluated on their ability to produce ample, lasting foam and to have low loss from adsorption on reservoir rock and decomposition at reservoir conditions. Foaming agents that performed well in shaking, blender, long-term stability, and high-pressure stability tests were selected for core-flow experiments. The stability test results demonstrated that foaming agents are reservoir-specific. The extent of the loss depends on the foaming agent, reservoir fluids, reservoir lithology, and reservoir conditions.The core-flow experiments involved the simultaneous injection of CO2 into two waterflooded Berea cores. The cores were arranged in parallel and had different permeabilities. The test temperature and pressure were constant and above the critical conditions for CO2. Three types of core-flow tests, involving injection of CO2 to displace oil, injection of alternate slugs of CO2 and brine, and injection of foaming agents, were conducted. The foaming agents were injected before CO2 injection and after CO2 had displaced oil from the more permeable core.The results show that in-situ foam generation is an effective method for improving CO2 displacement efficiency. Foam was most effective when the foaming agent was injected after CO2 displaced the oil from the more permeable core. The improved sweep efficiency was caused by the tendency of the foam to be generated preferentially in the more permeable core. The foam increased resistance to flow in this core and caused more CO2 to flow through the less permeable core. The second injection method is also more applicable to field implementation.
A New Correlation for the Cementation Factor in Low-Porosity Carbonates
Authors: Borai A. M. 
Published: December 2007

Summary
The use of common correlations for the cementation factor, m, has led to discrepancies between log interpretation and actual test results in several tight carbonate formations offshore Abu Dhabi. While logs indicate high water saturations, production tests resulted in unexpected dry hydrocarbons.
The existing common correlations for carbonates yield constant m (Archie) or an increasing m with a decrease in porosity (Shell formula). In the carbonates found offshore Abu Dhabi, m decreases with decreasing porosity. Based on core and log data from five formations in 14 structures, a more representative correlation for m has been derived. This new correlation successfully eliminates the discrepancies between log and test results. Examples confirming the validity of the new formula are included.
Compositional Gradients in the Anschutz Ranch East Field
Authors: Metcalfe R. S. , Vogel J. L. , Morris R. W. 
Published: December 2007

Summary
Experimental data from analyses of more than 20 recombined fluid samples show that a significant compositional gradient exists in the Anschutz Ranch East field. The gradient can be correlated as a linear function of depth. Using the correlation, an engineer can estimate compositions for any bottomhole location and then use other methods to estimate fluid properties and/or depletion performance.
Compositional Effects in Gravity-Dominated Nitrogen Displacements
Authors: Ypma Jan G. J. 
Published: December 2007

Summary
In this paper, the role of compositional effects during secondary, gravity-stable nitrogen displacements in (dipping) light-oil reservoirs, such as the Statfjord reservoir in the Brent field, is discussed. Displacements of both a gas condensate from the top of the Statfjord hydrocarbon column and a volatile oil from a more downdip location in this column are discussed. The main compositional effects in such vaporizing-gas-drive-type displacements are the following.
The displacing vapor at the displacement front is not nitrogen, but a rich hydrocarbon gas liberated from the reservoir fluid upon contact with nitrogen. This hydrocarbon vapor is miscible with the reservoir fluid in the case of the gas condensate, but just fails to develop miscibility in the case of the oil-like reservoir fluid. The remaining oil is a degassed, more viscous oil than the original reservoir fluid.
In addition to equation-of-state (EOS) programs, both a compositional simulator and an analytic, dispersion-free model for vaporizing-gas drives have been used to quantify the effect of phase behavior on recovery efficiency. These compositional calculations indicated that next to the phase behavior, the longitudinal dispersion level and, in the case of the oil-like fluid, the degree of gravity segregation at the displacement front are key factors determining displacement efficiency. Results are presented of a systematic investigation into the relative contributions of phase behavior, physical dispersion, and gravity drainage to the recovery process. A comparison of predicted results and slim-tube and coreflood experiments is made. The extent to which these laboratory experiments might be representative for reservoir-scale displacements is also briefly discussed.
A New X-Ray Absorption Method for Measurement of Three-Phase Relative Permeability
Authors: Oak M. J. , Ehrlich R. 
Published: December 2007

Summary
A new X-ray absorption method has been developed for simultaneous measurement of water, oil, and gas saturations during three-phase relative permeability experiments. This method permits saturation measurements as a function of axial position in a core for both transient and steady-state conditions.
Muldoon Field: An Evaluation of Behind-Casing Pay Zones in a Freshwater Environment
Authors: Hull R. L. , Johnson D. E. 
Published: December 2007

Summary
The wells in the Muldoon field, first drilled in 1952, produce from shallow, high-porosity, freshwater Eocene sands. Production may be either oil or gas. Vintage Petroleum Corp. purchased the field in June 1984 with the objective of reworking the existing wells and increasing field production through the selective plugging of zones and the opening of new zones currently behind casing. To accomplish this, it was necessary to determine oil/water contacts, water zones, and potential pay zones as yet unproduced. Serious obstacles to this objective were lack of adequate logs [most wells had only an electric log (ES) or induction electric log (IES)] and the very fresh formation waters (1,500 ppm chlorides).
These obstacles were overcome through application of state-of-the-art "formation evaluation through casing." An induced gamma spectrometry log, compensated neutron log, and gamma ray log were used to evaluate the formations accurately and indicated not only oil/water contacts and watered-out zones, but also oil and gas zones.
Because of the favorable production results, the structure has been re-evaluated and seven new well locations have been chosen. This paper will discuss the interpretation and results of the three wells that were initially evaluated and show how this re-evaluation has led to an increase in field production.
Performance of Equipment Used in High-Pressure Steam Floods
Authors: Owens M.E. , Bramley B.G. 
Published: December 2007

Abstract
The high temperature and pressures encountered in steam flooding have necessitated the use of premium and, in many cases, unique equipment. Field results from three steam flood installations give an insight as to the performance of high-pressure equipment when subjected to the accompanying high temperatures. Performance of the equipment and factors entering into the selection of equipment for steam flood installations are discussed.
Introduction
Recovery of low-gravity, high-viscosity crude oil from relatively shallow reservoirs is becoming feasible through the application of steam flooding. Pan American Petroleum Corp. initiated a pilot steam flood with a 5.36 million Btu/hour, 1,500-psi steam generator at the Winkleman Dome field in west central Wyoming in March, 1964. After one year of operation, this steamer was replaced with a larger unit capable of 12 million Btu/hour at 2,500 psi. Two other pilot steam flood projects were started at that time using 12 million Btu/hour, 2,500-psi steam generators, one at the Salt Creek Shannon field and another at the Fourbear field, both in Wyoming. This paper discusses the equipment used in high-pressure steam flooding and reviews some of the problems encountered in the application of the equipment. Where determined, a suggested solution is presented. The discussion follows the conventional flow of water and steam: water treating. steam generation, steam control and transmission, wellhead and subsurface equipment, and instruments and data collection (Fig. 1). The steam generation and transmission equipment discussed in this paper has been designed for 2,500-psi saturated steam service. Maximum operating conditions have been 1,875 psi and 626F.
Water Treating
Successful operation of steam generation equipment depends primarily upon a good source of water combined with an effective water treating system. Experience gained in the past two years of pilot steam flood operation indicates the majority of steamer down-time is caused by water treating problems.
The quality of raw water dictates the amount of treating required; therefore, it is imperative that the best water available should be used. Some criteria for a good quality raw water are:
the water should be free of oil or filming amines; dissolved gases such as O2, C2 and H2S, should be absent or at least present only in trace amounts; total hardness should be low; and suspended solids concentration should be low.
Since the quality requirements of water used in a single-pass steam generator are extremely stringent, it is unlikely that the available raw water can be used without some form of treatment.
JPT
P. 1525ˆ
Catalytic Effect of Heavy Metal Oxides on Crude Oil Combustion
Authors: Drici Ouarda , Vossoughi Shapour 
Published: December 2007

Summary
Differential scanning calorimetry (DSC) and thermogravimetric analysis (TGA) were applied to crude oil combustion in the presence and absence of metal oxides. It was found that the effect of titanium oxide was similar to that of silica and alumina. Vanadium, nickel, and ferric oxides behaved similarly in enhancing the endothermic reactions. In the presence of a large surface area such as with silica, the surface reactions are predominant and unaffected by the small amount of metal oxide present. Kinetic analysis of the DSC curves revealed that the activation energies and the frequency factors of the hydrocarbon and the coke combustion reactions, estimated for all the metal oxide additives including silica and alumina, followed the same normal compensation trend. The crude oil mixture of 90% ferric oxide was the only exception to this trend.