bluuebunny/crossref_metadata_2025_split huggingface dataset:
Alternate Environmental Testing of Drilling Fluids: An International Perspective
Authors: Jones F. V. , Leuterman A. J. J. 
Published: December 2007

ABSTRACT
Testing of drilling fluids and new additives before use offshore has become a common practice in the United States, Canada, and Europe. Standards for testing these systems vary depending on the concerns and perspective of each country. Testing within a country can also vary between regions. This complex set of testing procedures can complicate attempts to market new products. The high cost of testing products worldwide can limit the marketability of useful products and ultimately increase drilling costs.
Testing of drilling fluid systems onshore has taken on a different tack. Onshore disposal of the used mud system is the primary concern. Regulations regarding heavy metals, oil, and salt content in muds can restrict the method(s) of disposal. Because of these restrictions, most drilling operators are now requiring up front analysis of mud systems. This issue has become critical in the United States where each state has jurisdiction over disposal practices. Methods of disposal vary between states and even within states and regions depending on the state's environmental concerns.
Uniform methods of evaluation are being discussed by regulatory agencies now. In the United States, we are developing and reviewing the New Source Performance Standards which will provide a uniform method of evaluation. In Europe, the E&P Forum has developed product data flow charts to check drilling fluid systems and additives in the hopes of developing one standard to be used by all European agencies. In Canada, the regulatory agencies are also re-evaluating their methods of testing and trying to develop a uniform standard. Once these standards are in place, changing them or getting variances for new products will be difficult
This paper reviews the various test methods being used and offers a comparison. It is hopeful that this information can be used by the various regulating agencies as they develop and review their countries' standards.
Simulation Study of a Naturally Fractured, Oil-Wet, Water Drive Reservoir
Authors: Hamon G. 
Published: December 2007

ABSTRACT
A reservoir simulation study of a highly fractured reservoir was carried out to gain insights into the field behaviour.
The field is subject to a natural water drive which provides full pressure maintenance. Water breakthrough occurred in the two producers after three years of production. Laboratory imbibition experiments indicated oil wettability. The reservoir is multi-layered and the ratio between horizontal and vertical fracture permeabilities deduced from pressure transients is very high.
Interesting features of the simulation include:
checks of the exchange term accuracy for an oil wettability case, matrix block height for water-oil gravity drainage is mainly determined by the distance between low permeability streaks rather than by vertical fracture spacing, watercut matching during periods following short term shutdowns of producers can be used to quantify the gravity drainage performance, a good history match even when large overall production rate changes occurred.
Conclusions drawn from this work include the following:
the matrix block height, imbibition capillary pressure, vertical and horizontal fracture permeabilities proved to be the critical parameters to the simulation, water-oil gravity drainage can be efficient in an oil-wet fractured reservoir if the matrix is not tight, phenomenological runs indicated significant watercut sensitivity to the oil production rate : for a given oil recovery, the larger the total production rate the higher the watercut, high initial production rates in oil-wet fractured reservoirs are not detrimental to the ultimate oil recovery, the timing of recompletions and the reduction of off-take rates is essential when large amounts of water produced by a fractured, layered, oil-wet reservoir cannot be disposed of.
A Breakthrough Time Correlation for Coning Toward Horizontal Wells
Authors: Ozkan E. , Raghavan R. 
Published: December 2007

ABSTRACT
This paper presents an approximate analytical method to investigate the behavior of a water or a gas cone and to predict the breakthrough time. For long horizontal wells and large drainage radius, the method presented here requires only a numerical integration of simple trigonometric functions and is considerably simpler than the existing analytical methods. The results are also presented in the form of simplified correlations which can provide quick engineering estimates of the breakthrough time before detailed simulation studies. The method can be applied to both horizontal and vertical wells and permits us to compare horizontal and vertical well performances.
Extended Analysis of Live Reservoir Oils by Gas Chromatography
Authors: Burke N. E. , Chea C. K. , Hobbs R. D. , Tran H. T. 
Published: December 2007

Abstract
This paper describes the development and performance of a gas chromatographic method for determining the extended composition of live reservoir fluids including the permanent gases (N2, CO2,02, H2S) and the C1 through C15 hydrocarbons. The iso- and normal paraffins up through pentane are reported separately. Above pentane, the iso and normal paraffins are reported together. The heavy components of the oil are reported as a C16+ fraction. Information on the equipment used, the method development, calibration procedures, and calculations are provided. High pressure sampling valves are used for reproducible injection of pressurized samples up to 7000 psig [48366 kPa]. The technique determines the composition of the live oil in mole % and requires only a small oil sample. The procedure provides extended compositional data which can be input into reservoir and process design simulators. The method can also be used on stock tank oils, natural gases, liquefied petroleum gases, and other hydrocarbon fluids. Results from several oils are presented and compared with results from conventional gas chromatographic analyses and Podbielniak distillations.
Reduced Adsorption and Emulsion Tendencies in Sandstone Formation Through the Use of Ethoxylates
Authors: Paktinat J. 
Published: December 2007

Abstract
In recent years, nonionic surfactants have been very popular in application such as water flooding, fracturing and acidizing treatments. The most attractive features of this class of chemicals used in acidizing treatments, are their contribution to surface and interfacial tension reduction, water wetting, and low adsorption properties. Almost all surfactants, when applied at low concentrations in a system, alter the surface activities of the fluid by forming aggregates which lower free energy of the system, resulting in lower surface and interfacial tensions. However, many of these surfactants and chemicals adsorb to either the interface or to the solid media such as sandstone, reducing their effectiveness. This phenomenon may result in poor performance of these additives throughout the acidizing treatment and also, may promote emulsion tendencies which may lead to formation damage.
This paper presents results of laboratory studies of various nonionic surfactants and outlines the adsorption of these chemicals within the matrix of sandstone formations. Conditions affecting adsorption properties will also be discussed in this paper.
Prospects for Thermophilic Microorganisms in Microbial Enhanced Oil Recovery (MEOR)
Authors: Premuzic E. T. , Lin M. 
Published: December 2007

Abstract
Microbial activity in crude oils under reservoir and storage conditions has been known to exist for a long time. Such activity can cause deleterious effects in the quality and subsequent processing of crudes. In the past ten to fifteen years, however, a considerable research effort has shown that there are beneficial microbial systems which can be used in microbial enhanced oil recovery (MEOR), a promising process and the resulting biotechnology may be deliverable. In this laboratory, systematic studies are being conducted which deal with the effects of thermophilic, temperature adapted, acidophilic and chemotrophic microorganisms on the chemical and physical properties of selected types of crude oils over a wide range of temperatures, pressures and salt concentrations. Current studies indicate that during the biotreatment several properties of crude oils are affected. The oils are (1) emulsified, (2) acidified, (3) there is a qualitative and quantitative change in light and heavy fraction of crudes, (4) there are chemical changes in fractions containing sulfur compounds, (5) there is an apparent solubilization of trace metals and (6) the qualitative and quantitative chemical and physical changes appear to be microbial species dependent. In this paper, recent work with Boscan crude, a high sulfur, heavy crude oil from Venezuela will be discussed.
The Effect of Hydroxy Aluminum Disoaps on the Viscosity of Light Alkanes and Carbon Dioxide
Authors: Enick R. M. 
Published: December 2007

Abstract
Preliminary results have indicated that hydroxyaluminum disoaps, particularly hydroxyaluminum di(2-ethyl hexanoate) and hydroxyaluminum di (mixed iso-octanoate), can increase the viscosity of propane, pentane and hexane when present in dilute concentrations. These compounds are insoluble in dense carbon dioxide at 293K. Although it is unlikely that these compounds can dissolve in pure methane, they may serve as effective thickneners for hydrocarbon miscible gas mixtures since a large amount of the light alkanes which can be thickened by these compounds is used to enrich the gas.
These disoaps can form extremely high molecular weight, rodlike micelles in solution which increase solution viscosity by several orders of magnitude. These thickeners are water insoluble, and slightly soluble in a North Slope crude oil. Therefore, the partitioning of a small amount of the disoap into the crude oil should not result in a significant loss of mobility control.
Light alkane- and carbon dioxide-miscible cosolvents, such as carboxylic acids or alcohols, can be used in dilute concentration to increase the solubility of these compounds in light alkanes while greatly reducing the time required to achieve dissolution. Most cosolvents will decrease the solution viscosity, but increase the stability of the solution. The capability of various cosolvents to enhance the solubility of these thickeners in dense carbon dioxide is currently being evaluated.
Viscosity Behavior of Alkaline, Surfactant, Polyacrylamide Solutions Used for Enhanced Oil Recovery
Authors: Nasr-EI-Din H. A. , Hawkins B. F. , Green K. A. 
Published: December 2007

Abstract
An experimental study was conducted to examine the effects of various alkalis, surfactants and brines on the viscosity of dilute aqueous solutions of Alcoflood 1175L, a partially hydrolyzed polyacrylamide polymer, over a wide range of parameters.
In general, the viscosity-shear rate relationship exhibited a Newtonian behavior at low shear rates and a power-law behavior at high shear rates. Adding a non-ionic species (Triton X-100) had an insignificant effect on the viscosity-shear rate relationship. However, adding an ionic species, (sodium chloride, calcium chloride, or an anionic surfactant) reduced the hydrodynamic size of the polymer molecule (physical change), changing the viscosity-shear rate relationship. The viscosity-shear rate relationship was found to be a strong function of cation type only at salt concentrations less than 4 wt%. For a given polymer concentration, the power-law constants were found to be exponentially related.
The effect of alkalis on the viscosity of polymer solutions was complex as they affected the polymer chain both physically (charge shielding) and chemically (hydrolysis). For alkali/polymer solutions, the viscosity was found to be a function of alkali type, concentration and time after initial mixing. The effect of these parameters on the viscosity of alkali/polymer solutions diminished by adding NaCl. The addition of anionic surfactants at low concentrations slightly decreased alkali/polymer solutions viscosity. However, a significant viscosity enhancement for alkali/polymer solutions was observed at higher surfactant concentrations and over a narrow range of alkali concentrations.
A Case Study of High-Temperature Wells Fractured Using Multiple Fluids To Improve Conductivity and Well Performance
Authors: Wheaton W. E. , Lipari S. A. , Morris M. D. , Boney C. L. , Thomas R. L. 
Published: December 2007

ABSTRACT
A study, directed at the improvement of hydraulic fracturing treatments performed in the Lobo Wilcox formation in south Texas, is presented. During the study, the performance of numerous gas wells fractured using a single-fluid (organometallic crosslinked) or a multiple-fluid (organometallic and borate crosslinked) technique was determined. During the multiple-fluid treatment (MFT) the organometallic-crosslinked fluid is pumped followed by a borate-crosslinked tail-in fluid.
The field study indicates Lobo Wilcox wells fractured using conventional high-temperature fracturing fluids (organometallic-crosslinked fluids) exhibit poor production in comparison to wells fractured using multiple fluids. Improved fracturing fluid recovery and improved well performance were observed in wells fractured with multiple fluids. The improved well performance is attributed to less conductivity impairment by the borate tail-in fracturing fluid. This technique can be used in any high-temperature well to "economically" improve fracture conductivity.
Control of Core Wettability With Crude Oil
Authors: Jia Duo , Buckley J. S. , Morrow N. R. 
Published: December 2007

ABSTRACT
Consistent laboratory studies of the effect of wettability on fluid displacement in core flood experiments have long been hampered by the lack of cores with well defined, reproducible wetting states, other than strongly water or oil wet. There is ample evidence that wettability is an important factor in determining the outcome of core floods. Wetting can be altered using organic reactants, however the wetting state produced may not be representative of realistic wetting conditions. In this study, the control of wetting using crude oils at various aging conditions is explored.
Berea core plugs, saturated with brine, were flushed with crude oil and aged at a set temperature ranging from 22-90°C. Two crude oils were used, one from West Texas and the other from the North Sea. After aging, the crude oil was displaced by mineral oil and wettability was assessed using a variation of the Amott imbibition test. The procedure was developed for testing the effect of drilling mud filtrates on wettability for a range of wetting conditions.
Variables which affected the wettability index were often interdependent. They included the crude oil, the temperature at which the cores were aged with the oil, the initial water saturation, the aging time, and the volume of crude oil with which the core was flushed. Cores with wettability from strongly water-wet to neutrally wet could be produced by varying the conditions of crude oil exposure. Aging temperature and initial water saturation have predominant influence on the wettability induced by a given crude oil. However, all of the factors mentioned above must be considered in order to reproduce the state of wetting from one core plug to another. Stability of the altered wetting states was found to be reasonable for tests in which the cores were stored for two months in mineral oil.
A Model for Evaluating the Hidraulic Performance of Well Perforations
Authors: Shaw David C. , Dozzo Joseph A. 
Published: December 2007

ABSTRACT
Perforation design is an important aspect of the completion of production and injection wells. Significant penalties can be incurred both through productivity loss or additional perforation costs if the design is not accurately optimized. These penalties are especially severe in the case of high-rate gas wells.
The Well Perforation Performance Model (PERF) was developed as a collaboration between SSI, London and BP Exploration, Aberdeen. It allows different perforating methods to be evaluated and compared to select the ideal gun and charge for a given perforation job.
A major technical feature of the program is the finite element simulator, which allows accurate modelling of complex geometries. It can analyze great detail on small computers.
The program allows the analysis to carried out in detail, using a state-of-the-art finite-element simulator, or more rapidly using a set of industry-standard nomographs. A database of gun and charge characteristics is provided, which records the results of API laboratory tests, so that typical perforating problems can easily be set up.
The results, in terms of a productivity index or flow efficiency, can be viewed graphically as a function of the main physical parameters, including: Shot Density, Perforation Length and Diameter, Phasing, Damage and Compaction, Gravel Packing.
Comparisons are provided against earlier published theoretical and experimental work, demonstrating improved accuracy and usability of the technology.
The Effect of Temperature and Interfacial Tension on Oil-Water Relative Permeabilities in Consolidated and Unconsolidated Porous Media
Authors: Okoye C. U. , Hayatdavoudi A. , Oungpasuk Piya , Wang Pin-Hu 
Published: December 2007

ABSTRACT
Several displacement tests for primary and secondary oil recovery processes using conventional steam and caustic steamfloods (0.5% and 1.0% NaOH concentration by weight) were conducted to determine the oil-water relative permeabilities. The results of the test show that oil-water relative permeabilities are temperature and low tension sensitive. The tests for each oil recovery process were run at various temperatures ranging from 200°F to 400°F. Using the displacement data and oil-water physical properties, the relative permeability curves were constructed and the multiple regression analysis was employed to generate correlation equations. The relative permeability curves generated with the correlation equations fit fairly well the data points evaluated from experimental results.
The oil-water relative permeability curves shift toward higher water saturation with increase in temperature and/or decrease in interfacial tension. The oil relative permeability curve shifts for all test cases examined are substantial while the shifts of water relative permeability curves are relatively small for steamfloods and virtually coincident for caustic steamfloods. It was also observed, that for the same increase in temperature, the oil relative permeability curve shift is much larger tor caustic steamflooding processes than lor the conventional steamflooding. This observation clearly shows the effect of low tension systems on oil-water relative permeabilities.
PDC Bit Selection Method Through the Analysis of Past Bit Performances
Authors: Fernando Fontenelle Dumans Carlos , Edgar Maidla Eric 
Published: December 2007

ABSTRACT
A method to evaluate the performance of PDC and tricone bits is presented based on their cost, on a foot basis, and the rock strength properties (shear stress for PDC bits and compressive stress for tricone bits). The results showed that much data is needed for PDC performance evaluation when compared to a similar procedure for tricone bits, mainly due to the better description of the tricone bit when using the currently proposed IADC classification system.
Front Tracking Applied to the Simulation of Water Flooding in a Braided River System
Authors: Sovold Knut , Rian Dag Terje , Sandvik Arnfinn 
Published: December 2007

ABSTRACT
This paper describes the application of a front tracking simulator for studying flow in a 2D crosssection of a braided river systea. The internal sand body geometries were based on a braided river outcrop from the USA. Rock properties were derived from a North-Sea oil field.
Front tracking represents a direct, accurate and fast method to simulate oil and water flow in highly heterogeneous reservoirs. In the front tracking simulator the saturation solution is decoupled from the grid and its accuracy is to a large extent independent of grid block sizes and geometry. This makes the reservoir simulator well suited for modelling of complex geological architectures. The simulator has been compared with analytical methods and traditional finite difference simulators.
Results from a water-oil displaceaent process in a braided river systea are presented, showing fingering of the saturation fronts due to peraeability contrasts. For coarse grid systems, the front tracking simulator proved superior to the finite difference simulator with respect to the numerical solution.
An automstic grid fitting option that utilizes triangular grid cells enabled an easy and fast construction of the complex geological model.
Horizontal Well Performance Simulation
Authors: Prasad Raj K , Coble Larry E. 
Published: December 2007

ABSTRACT
A single well, single phase, r-θ-z simulator was used to analyze a well test conducted in a horizontal well. Apart from the usual features of general numeric simulators, the simulator used for this work accounted for the effects of wellstorage, variable skin on different portions of the wellbore, turbulent flow, cross-flow between layers, hydraulic fractures with variable conductivity and partial penetration. Because of these features, the simulator is extremely versatile for well test analysis.
The horizontal well was modeled by using the horizontal portion of the well as an axis to set the radial grids which ensure radial flow around the wellbore. This near-wellbore radial flow condition cannot be modeled accurately during early test times with the Cartesian blocks used in most black oil simulators. In the r-θ-z simulator, top and bottom reservoir boundaries are defined using several r-θ blocks and eliminating grid blocks outside the boundaries as illustrated on Figure 1. Reservoir limits in the horizontal directions are defined by using several blocks along the well (z) axis and multiple radial blocks.
This r-θ-z simulator has been used to analyze buildup tests in horizontal wells where conventional analysis methods did not yield meaningful results because:
the early time data were influenced by the wellstorage and the top and bottom boundary effects and the so-called pseudoradial flow regime necessary for conventional analysis were absent due to insufficient test times.
Production Logging in Horizontal Wells: Applications and Experience to Date
Authors: Chauvel Yves Leon , Oosthoek Paul 
Published: December 2007

ABSTRACT
Reservoir drainage by means of horizontal wells has become a new frontier in the oil industry, and all the divisions of this industry: drilling, cementing, logging, completion, stimulation and production are active in this endeavour, both at the research level and in the field. One of the most relevant reasons why horizontal wells are drilled and completed resides in the favourable productivity indices that are associated with horizontal well production.
In order to evaluate the flow mechanisms leading to these gains in productivity, production logging is becoming a common practice, in spite of some operational’ difficulties many of which have been overcome by means that we shall review. Production logs are used in horizontal wells to diagnose unwanted-fluid entries, to obtain flow profiles, to locate producing fractures or for transient testing.
In this paper we shall review the essential characteristics of production logging in horizontal wells. Some are due to the effect of the environment: flow regimes, well geometry. Some come from limitations of the current sensors, caused by the unorthodox position of the tool string as opposed to its traditional near-vertical position in standard wells. We shall also review the application of some measurements which have not been widely used, but which carry a high potential for diagnosis.
We shall give examples of data acquisition and interpretation, showing that satisfactory answers of often excellent quality can be obtained in many types of flow regime and completion configuration, in spite of the hostility of the environment.