bluuebunny/crossref_metadata_2025_split huggingface dataset:
Experimental Studies of the Detection and Reuse of Produced Chemicals in Alkaline/Surfactant/Polymer Floods
Authors: Wang Wei , Gu Yongan 
Published: April 2006

SummaryAlkaline/surfactant/polymer (ASP) flood processes have been applied increasingly in oil fields because of their contribution to high ultimate oil recovery. However, a major technical challenge is determining how to significantly reduce the amount and the cost of chemicals used so that ASP floods can become cost-effective as well. On the other hand, some field applications show that alkali, surfactant, and polymer concentrations remain relatively high in the produced liquids of ASP floods. Thus, successful detection and reuse of these chemicals can substantially minimize the capital cost and the environmental impact. In this paper, several methods are applied to detect each chemical and quantify its concentration in the produced liquids. In addition, reinjection tests of the produced chemicals are conducted for further enhancing oil recovery. More specifically, first, the total interactions of each chemical with the oil/brine/rock system are studied. With the developed detection methods for each individual chemical used in ASP floods, the total loss of each chemical is measured. The chemical loss is caused by its chemical reactions with the crude oil and the reservoir brine, as well as its adsorption onto the rock surface. Second, coreflood tests are performed for alkaline floods (AFs), surfactant floods (SFs), alkaline/surfactant floods (ASFs), and ASP floods (ASPFs) to determine their respective tertiary oil recoveries. Hence, a better understanding of how each chemical contributes to enhanced oil recovery (EOR) is achieved. Third, typical chemical concentrations in the produced liquids are measured and compared with those in the injected slugs to determine the potential of reusing these chemicals in practice. Finally, the coreflood tests of reusing these produced chemicals are carried out by reinjecting the produced liquids into new sandpacks or Berea-sandstone cores. The reinjection coreflood-test results show that the produced chemicals can be reused effectively to enhance oil recovery. It is anticipated that the detection methods and reuse schemes studied in this experimental work should facilitate the design, optimization, and implementation of ASP field flood projects.
Effect of an Invaded Zone on Pressure-Transient Data From Multiprobe and Packer-Probe Wireline Formation Testers
Authors: Gök Ihsan M. , Onur Mustafa , Hegeman Peter S. , Kuchuk Fikri J. 
Published: April 2006

Summary
This paper examines the effect of a mud-filtrate-invaded zone on pressure transients from multiprobe/packer-probe wireline formation testers (WFTs). Invasion zones are modeled as composite zones concentric with the wellbore that have different rock and fluid properties (permeability, porosity, viscosity, and compressibility) from those of the native uninvaded formation.
The results show that for multiprobe wireline testers, the sink-(production) and horizontal-probe pressure responses are highly affected by the invaded-region properties, while the vertical-probe pressures are influenced mainly by the properties of the uninvaded zones. For the packer-probe configuration, similar results are obtained (i.e., the vertical-probe pressures are influenced mainly by the properties of the uninvaded zones, while the packer-interval pressures at early times are influenced by the invaded-zone properties). It is shown that if the invaded zones are incorporated into the interpretation process with a 3D r-θ-z single-phase, finite-difference model like the one developed in this work, simultaneous matching of spatially available WFT pressure-data sets using nonlinear regression can provide estimates of both invaded- and uninvaded-zone parameters. A synthetic example of a multiprobe test is presented to confirm the theory and procedures developed in this work.
Predicting and Preventing Wellbore Instability: Tullich Field Development, North Sea
Authors: Russell K. A. , Ayan C. , Hart N. J. , Rodriguez J. M. , Scholey H. , Sugden C. , Davidson J. K. 
Published: April 2006

Summary
Innovative geomechanical, drilling, logging, and seismic techniques have been used to successfully develop a geologically complex discovery in the North Sea, Tullich field. With individual reservoir-unit thicknesses below the limit of seismic resolution, and a restricted depth window for completion, optimal placement of horizontal production wells was vital to the successful and economical development of the field. Wellbore instability was a key concern after recent experiences while drilling similar formations in nearby fields. These events had resulted in significant nonproductive time and cost overruns. A geomechanical model was constructed from data acquired during the appraisal-drilling phase and was used to make stability predictions for the proposed horizontal production wells. Wellbore instability while drilling was prevented through the application of a real-time wellbore-stability management system that validated the stability predictions by monitoring surface and downhole drilling parameters, produced solids, fluids, and log data. By combining efficient teamwork and a variety of logging and drilling technologies, the complex reservoir was successfully developed, both in terms of cost savings during well construction and subsequent oil production that exceeded expectation.
Practical Application of Pressure/Rate Deconvolution to Analysis of Real Well Tests
Authors: Levitan Michael M. 
Published: April 2006

Summary
Pressure/rate deconvolution is a long-standing problem of well-test analysis that has been the subject of research by a number of authors. A variety of different deconvolution algorithms have been proposed in the literature. However, none of them is robust enough to be implemented in the commercial well-test-analysis software used most widely in the industry. Recently, von Schroeter et al.1,2 published a deconvolution algorithm that has been shown to work even when a reasonable level of noise is present in the test pressure and rate data. In our independent evaluation of the algorithm, we have found that it works well on consistent sets of pressure and rate data. It fails, however, when used with inconsistent data. Some degree of inconsistency is normally present in real test data.
In this paper, we describe the enhancements of the deconvolution algorithm that allow it to be used reliably with real test data. We demonstrate the application of pressure/rate deconvolution analysis to several real test examples.
Minor Modifications Make Major Differences in Remote Deepwater-Brine Displacement Operations
Authors: Darring Michael T. , Shucart John K. , Claiborne Earl B. , Parks R. D. , Pillow Doug 
Published: April 2006

SummaryBrine displacements were one of several areas of focus in a continuous process to optimize completion methodology in Amerada Hess's Ceiba project wells, located in deepwater offshore Equatorial Guinea. The time between making up the cleaning string and laying it down, after displacement and filtration operations are completed, can exceed two days and cost U.S. $500,000. It is imperative that wellbore-cleaning operations are performed efficiently and correctly the first time. Amerada Hess and its brine suppliers, working together in a joint task force, have taken specific steps to minimize the time required for displacement and filtration operations.
Mathematical Modeling of Steam-Assisted Gravity Drainage
Authors: Akin Serhat 
Published: April 2006

Summary
A mathematical model for gravity drainage in heavy-oil reservoirs and tar sands during steam injection in linear geometry is proposed. The mathematical model is based on the experimental observations that the steam-zone shape is an inverted triangle with the vertex fixed at the bottom production well. Both temperature and asphaltene content dependence on the viscosity of the drained heavy oil are considered. The developed model has been validated with experimental data presented in the literature. The heavy-oil production rate conforms well to previously published data covering a wide range of heavy oils and sands for gravity drainage.
Granular-Polymer-Gel Treatment Successful in the Daqing Oilfield
Authors: Liu He , Han Hongxue , Li Zhuling , Wang Bo 
Published: April 2006

Summary
Reservoirs in the Daqing oil field are complex-fluvial, lacustrine, and delta-deposited heterogeneous pay zones with mixed porosities and various permeabilities ranging from several md to 1,200 md. Both vertical and horizontal heterogeneities are abundant. Conformance control for such reservoirs is difficult but of great importance. Recently, we used a method that employs injection of preformed gel particles to adjust the flow distribution of injected water.
This paper presents the technique that was used for the first time in a typical region in the Daqing oil field. The particles used in this project were preformed crosslinking granular polymer gels. Granule diameters were 1.5, 3, and 5 mm, which were bigger than particles used in other oil fields in China. Before actual treatment, numerical simulation was used to predict the pressure change during the process of treatment, the amount of polymer gel to be used, and the quantity of water to be injected. In actual treatment, the total injection was 3100 m3, which was injected in three plugs: pretreatment, main-plug injection, and seal-plug injection. The application proved successful. Economically improved oil production and reduced water cut were observed.
2,000,000-lbf Landing-String Developments: Novel Slipless Technology Extends the Deepwater Operating Envelope
Authors: Simpson Burnie , Payne Michael L. , Jellison Michael J. , Adams Burt A. 
Published: April 2006

SummaryThe initial impetus for developing 2,000,000-lbf landing strings was the fact that failures in the field were being experienced with loads less than equipment ratings. This paper pertains to the technological development of a completely integrated landing system that provides the ability to extend the deepwater drilling and completion envelope. This system comprises an elevator, slipless spider, and landing string—all specifically designed to land heavy-casing strings in deepwater wells and thus overcome the load limitations of conventional equipment. All stages of evolution are analyzed, including research, development, design, verification testing, manufacturing, prooftesting, running, handling, and actual case histories detailing field use. Actual verification-testing loads were over 5,200,000 lbf, and proof-testing loads were 3,000,000 lbf. Unique manufacturing challenges and solutions associated with the production of ultrathick wall landing strings, with 2,000,000 lbf at super-premium-yield ratings1 (90% remaining body wall), a represented in detail.
Evaluation of Cement Systems for Oil and Gas-Well Zonal Isolation in a Full-Scale Annular Geometry
Authors: Boukhelifa L. , Moroni N. , James S. G. , Le Roy-Delage S. , Thiercelin M. J. , Lemaire G. 
Published: April 2006

SummaryLoss of zonal isolation in a wellbore can be caused by mechanical failure of the cement or by development of a microannulus. However, behavior of the sealant is driven by specific boundary conditions such as rock properties. Large-scale laboratory testing of the cement sheath in an annular geometry and a confined situation was performed to simulate various downhole stress conditions and evaluate the behavior of several sealants. Failure modes of the cement sheath were determined as a function of cement mechanical properties, loading parameters, and boundary conditions. Results were used to validate an analytical model that predicts cement-sheath failure.
Steady-State Flow Behavior of CO2 Foam
Authors: Kim J. S. , Dong Y. , Rossen W. R. 
Published: April 2006

SummaryFoams can improve oil recovery by reducing gas mobility and the effects of reservoir heterogeneity. Numerous studies report that foam flow in porous media comprises two regimes. In the "high-quality regime," pressure gradient is nearly independent of gas superficial velocity. In the "low-quality regime," pressure gradient is nearly independent of liquid superficial velocity. Previous published data from CO2 foam studies lie either in the high- or low-quality regime, but no single study shows both regimes. Delineating the two foam-flow regimes is essential to modeling and predicting the behavior of CO2 foam in petroleum applications.Experiments were performed with a sandpack and fired Berea and Boise sandstone cores at a backpressure of 1500 or 2000 psig, above and below the critical temperature of CO2. The data from the sandpack, Berea, and Boise sandstone experiments at room temperature do not show the two conventional foam-flow regimes. Instead, these experiments find a third regime evidently related to the low-quality regime. This same behavior was observed in the sandpack above the critical temperature of CO2. In this new regime, pressure gradient decreases with increasing liquid superficial velocity at constant gas superficial velocity. The Boise sandstone experiment above the critical temperature of CO2 did find the two conventional foam-flow regimes, however. No single experimental factor appears to explain the difference in results.Earlier theoretical work of Hirasaki and Lawson and de Vries and Wit can partially explain the flow regime seen in our study. A model combining a bundle-of-tubes approach with the effective-viscosity function of Hirasaki and Lawson predicts the behavior in this new regime.
Improved MMP Correlations for CO2 Floods Using Analytical Gasflooding Theory
Authors: Yuan H. , Johns R. T. , Egwuenu A. M. , Dindoruk B. 
Published: April 2006

SummaryLocal displacement efficiency from CO2 gas injection is highly dependent on the minimum miscibility pressure (MMP). Correlations are sometimes used to estimate the MMP where the injected fluid may or may not contain impurities such as methane. These correlations, however, are based on a limited set of experimental data and, as such, are not widely applicable. They also do not account accurately for the more complex condensing/vaporizing (CV) displacement process.This paper presents new MMP correlations for the displacement of multicomponent oil by CO2 and impure CO2. The approach is to use recently developed analytical theory for MMP calculations from equations of state (EOSs) to generate MMP correlations for displacements by pure and impure CO2.1–8 The advantage of this approach is that MMPs for a wide range of temperatures and reservoir fluids can be calculated quickly and accurately without introducing uncertainties associated with slimtube MMPs and other numerical methods. The improved MMP correlations are based solely on the reservoir temperature, the molecular weight of C7+, and the percentage of intermediates (C2–C6)in the oil. The MMPs from the improved correlations are compared to currently used correlations and 41 experimentally measured MMPs. Correlations are also developed for impure-CO2 floods, in which the injection stream may contain up to 40% methane. The new correlations are more accurate for a wider range of conditions than the currently used correlations.
Measurement of Three-Phase Relative Permeability With IFT Variation
Authors: Cinar Yildiray , Orr Franklin M. 
Published: April 2006

SummaryIn this paper, we present results of an experimental investigation of the effects of variations in interfacial tension (IFT) on three-phase relative permeability. We report results that demonstrate the effect of low IFT between two of three phases on the three-phase relative permeabilities.To create three-phase systems in which IFT can be controlled systematically, we used a quaternary liquid system composed of hexadecane (C16), n-butanol (NBA), water (H2O), and isopropanol (IPA). Measured equilibrium phase compositions and IFTs are reported. The reported phase behavior of the quaternary system shows that the H2O-rich phase should represent the "gas" phase, the NBA-rich phase should represent the "oil" phase, and the C16-rich phase should represent the "aqueous" phase. Therefore, we used oil-wet Teflon (PTFE) bead packs to simulate the fluid flow in a water-wet oil reservoir. We determined phase saturations and three-phase relative permeabilities from recovery and pressure-drop data using an extension of the combined Welge/Johnson-Bossler-Naumann (JBN) method to three-phase flow. Measured three-phase relative permeabilities are reported.The experimental results indicate that the wetting-phase relative permeability was not affected by IFT variation, whereas the other two-phase relative permeabilities were clearly affected. As IFT decreases, the oil and gas phases become more mobile at the same phase saturations. For gas/oil IFTs in the range of 0.03 to 2.3 mN/m, we observed an approximately 10-fold increase in the oil and gas relative permeabilities against an approximately 100-fold decrease in the IFT.
Productivity of Selectively Perforated Horizontal Wells
Authors: Yildiz Turhan 
Published: April 2006

SummaryThis paper investigates the effect of selective perforating on horizontal-well performance. Theoretical investigation is based on a general 3D analytical model that was published previously. For a given perforation design, the changes in flow rate, pseudosteady-state productivity, and cumulative production can be computed using the solution. The investigation shows that the ratio of total-perforated length to the drilled-well length is the most dominant parameter controlling the long-term performance of the selectively perforated horizontal wells. The other important parameters are the degree of formation and perforating damage.We additionally examined the effect of the so-called "oriented perforating" on the horizontal-well performance in isotropic and anisotropic formations. Our research shows that accurately oriented perforating could significantly improve the well productivity in anisotropic formations.
Incorporating Uncertainties in Well-Count Optimization With Experimental Design for the Deepwater Agbami Field
Authors: Narahara G. M. , Spokes J. J. , Brennan D. D. , Maxwell G. , Bast M. 
Published: April 2006

Summary
This paper describes a methodology for incorporating uncertainties in the optimization of well count for the deepwater Agbami field development. The lack of substantial reservoir-description data is common in many deepwater discoveries. Therefore, the development plan must be optimized and proven to be robust for a wide range of uncertainties. In the Agbami project, the design of experiments, or experimental design (ED) technique, was incorporated to optimize the well count across a wide range of subsurface uncertainties.
The lack of substantial reservoir-description data is common for many deepwater discoveries. In the Agbami project, the uncertainty in oil in place was significant (greater than a factor of 2). This uncertainty was captured in a range of earth (geologic) models. Additional uncertainty variables, including permeability, fault seals, and injection conformance, were studied concurrently. Multiple well-count development plans (high, mid, and low) were developed and used as a variable in ED. The ED technique allowed multiple well counts to be tested quickly against multiple geologic models. With the net present value (NPV) calculated for each case, not only was the well count for the overall highest NPV determined, but discrete testing of each geologic model determined the optimum well count for each model. The process allowed for testing the robustness of any well count vs. any uncertainty (or set of uncertainties).
A method was demonstrated quantifying the difference between perfect and imperfect knowledge of the reservoir description (geologic model) as it pertains to well locations.
Cattle and inequality: herd size differences and pastoral production among the Fulani of northeastern Senegal
Authors: Sutter John W. 
Published: April 2006

Opening ParagraphThere is a growing body of research that addresses issues of income distribution and the mechanisms of inequality in rural farming communities in Africa (see, for example, Hill, 1972; Matlon, 1981; Kitching, 1980; Sutter, 1981; Watts, 1983). Unfortunately a recognition of the importance of economic inequality in African societies dependent on animal husbandry has lagged behind. Much of the research on pastoral systems of production of the past several decades has been carried out by anthropologists whose work, to the extent that it addresses issues of economic heterogeneity at all, has emphasised the types of ‘levelling’ and ‘adaptive’ mechanisms common to pastoral systems. Recurrent issues of focus have been the ideology of equality which tends to predominate in pastoral societies, the limited development of political hierarchies, the limitations on herd size imposed by family labour and ecology, the wide-spread transfer of assets at critical moments in the life cycle, and the apparent similarities in consumption levels of different households (see, for example, Barth, 1961; Goldschmidt, 1971; Dahl, 1979a; Schneider, 1979).
The socio-ecology of firewood and charcoal on the Freetown peninsula
Authors: Cline-Cole R. Akindele 
Published: April 2006

Opening ParagraphIn a country which in the last 200 years has undergone continuous and often momentous political, economic and social changes, few things are capable of conveying as strong an impression of stability and changelessness as wood fuel (charcoal and firewood) consumption and production; and nowhere is this more striking than on the Freetown or Western Area (formerly Colony) peninsula. In this region, which has always accounted for the major share of national electricity, kerosene and cooking gas (LPG) consumption, not only is current percentage household firewood consumption only fractionally lower than in the nineteenth century but a much higher proportion of households consume charcoal now than at any time in the last two centuries (Cline-Cole, 1984a). Today firewood and charcoal combined supply a minimum of 80 per cent of total peninsula energy demand for both domestic and non-household uses (Davidson, 1985). Freetown's firewood consumption also represents some 10 per cent of the national total (Atlanta, 1979).
Photography in Sierra Leone, 1850–1918
Authors: Viditz-Ward Vera 
Published: April 2006

Opening ParagraphIn recent years scholars have shown considerable interest in the early use of photography by non-Western peoples. Research on nineteenth-century Indian, Japanese and Chinese photography has revealed a rich synthesis of European and Asian imagery. These early photographs show how non-Western peoples created new forms of artistic expression by adapting European technology and visual idioms for their own purposes. Because of the long history of contact between Sierra Leoneans and Europeans, Freetown seemed a logical starting point for similar photographic research in West Africa. The information presented here is based on ten years of searching for nineteenth-century photographs made by Sierra Leonean photographers. To locate these pictures, I have visited Freetonians and viewed their family portraits and photograph albums, interviewed contemporary photographers throughout Sierra Leone, and researched in the various colonial archives in England to locate photographs preserved from the period of colonial rule. I have discovered that a community of African photographers has worked in the city of Freetown since the very invention of photography. The article reviews the first phase of this unique photographic tradition, 1850–1918, and focuses on several of the African photographers who worked in Freetown during this period.