bluuebunny/crossref_metadata_2025 huggingface dataset:
Examining the Phase Behavior and Retention Characteristics of Binary Inhibitor Agents for Scale Control
Authors: Lawless T. A. , Bourne H. M.
Published: December 2007

The prediction and optimisation of scale inhibitor squeeze treatments demands careful attention to both aqueous phase behaviour and the resulting retention mechanisms in consolidated core material. Phase behaviour patterns for single and binary systems of acrylate and phosphonate scale inhibitors in sea water have been generated over a range of pH values and concentrations appropriate to flooding and field conditions. The phase maps were utilised to define coreflooding strategies that would yield separate adsorption and precipitation retention mechanisms for detailed study under a controlled pH environment.

Retention and desorption characteristics of the single component inhibitor agents were performed at 80°C on Clashach sandstone core specimens in both adsorption and precipitation regimes where possible. Return curve analyses were quantified using inductively coupled plasma spectroscopy and an analytical colourimetric method for the phosphonate and acrylate respectively. Desorption profiles have been fitted to mathematical expressions and the physical significance of the models used have been interrogated.

Binary inhibitor systems capable of yielding both adsorption and precipitation phase behaviour at 80°C were selected for test purposes to establish the prevailing retention mechanisms of both agents in competition. Separate desorption profiles for each inhibitor following a binary system shut-in were generated. The role and suitability of simple mathematical models to aid the interpretation and impact for future formulations has been addressed.
Damage Caused by Clay-Based and Clay-Free Inhibitive Fluids in Sandstone Formations
Authors: Ghofrani Reza , Alaboudi M. A. Mazeel , Sengupta Pinaki
Published: December 2007

This paper describes the results of a research project about the extent of damage caused by clay based and clay free inhibitive fluids in two consolidated sandstones of permeability ranges 0.008-0.013 μm2(D) and 2.2-2.6 μm2(D) under simulated borehole conditions, using a closed loop circulating facility.

The fluids containing K+, Mg++ or Ca++ ions as well as clays, solid bridging materials and different polymers can be used either as drilling fluids or as workover, fracture and gravel pack fluids.

The damage was studied by two factors, viz, damage ratio DR (Percentage of original permeability lost after encountering the fluids) and sectional damage ratio SDR (Determined by cutting the damaged core into several segments and then determining the damage ratio of each segment relative to the original permeability of the core). The sectional damage ratio is used to determine the radius and extent of damage in the formation.

The dynamic filtration characteristics and the rheological properties of the used fluids were also evaluated.

The effects of increasing the temperature and differential pressure on formation damage and filtration characteristics of the used fluids were also investigated.

The effect of the presence of formation pore bridging materials (viz, chalk) in decreasing the extent of damage is also demonstrated here.
Alternatives to Aromatics for Solvency of Organic Deposits
Authors: Samuelson M. L.
Published: December 2007

This paper describes laboratory investigation of alternate solvent systems and their application to the removal of organic deposits. Aromatic solvents, such as toluene and xylene, have been popular remedies for near-wellbore cleanup operations. Stricter regulations governing disposal, volatile-emission limits, and flammability/handling concerns have made the use of toluene and xylene less attractive. In an effort to limit environmental and personal exposure hazards, alternate solvents have been investigated.

Theoretical solvency parameter comparisons linked with a data base search was used to initially screen alternate solvent systems. Quantitative paraffin and pipe-dope solvency tests, along with asphaltene stability titrations, were used to qualify potential solvent candidates. As a result of this work, several alternative solvents have been found which fall outside the regulatory restrictions for xylene and toluene, while maintaining effective removal of paraffin, asphaltene and pipe-dope deposits.
Successful Stimulation of Acid-Sensitive Crude Producers in the Gulf of Mexico
Authors: Picou R. A. , Ricketts Kevin , Luquette Mary , Hudson L. M.
Published: December 2007

This paper presents a case history of successful acid stimulation treatments on acid sensitive crude producers in the Gulf of Mexico at Main Pass 313 field. It shows how catastrophic emulsion and facility upset problems encountered during the flowback of the first well in a multi-well stimulation program were resolved and used as the basis for optimizing treatment design on the remaining wells. Overall, it demonstrates how taking a preventative posture through a total system approach to the stimulation process was the key to solving the acid treatment flowback problems experienced.
Formation Damage Due to Static and Dynamic Filtration of Water-Based Muds
Authors: Jiao Di , Sharma M. M.
Published: December 2007

A series of drilling mud invasion experiments were conducted on Berea sandstone cores to measure the extent and depth of formation damage by mud filtrates and mud particles. A specially designed dynamic filtration core holder was used in this study. Pressure taps along the core holder allowed us to measure the permeabilities for 3 sections of the core while circulating mud. Seven kinds of muds with different salinities and different dynamic filtration rates were circulated across the face of the core for 10 hours. After mud circulation, return permeabilities for brine and oil were measured. The effect of bentonite concentration, the effective particle size, degree of flocculation, polymer additive concentration, and oil saturation in the core were shown to influence the extent of formation damage.
Quantitative Analysis of Bulk Mineralogy: The Applicability and Performance of XRD and FTIR
Authors: Ruessink B. H. , Harville D. G.
Published: December 2007

Understanding the limitations and sensitivity of various techniques for quantifying mineral composition is essential for enhanced control of formation damage, e.g. in selecting a completion fluid and/or acid formulation.

This paper presents the results of a systematic evaluation of the reliability, applicability and intrinsic accuracy of the two most commonly used analytical techniques for quantitative mineral analysis: X-ray diffraction (XRD) and Fourier Transform Infra-Red (FTIR) spectroscopy. The strengths and weaknesses of each technique are related to the different scales of investigation (structural vs. molecular). The analytical accuracies of the techniques are assessed by analysing synthetic mixtures of common rock-forming minerals.

The two techniques were found to have comparable accuracies in analysing bulk mineralogy. For both techniques 90 % of the analyses of synthetic mixtures fell within 5 wt% from the actual concentrations. The results of reservoir core material were consistent with these findings. Costs and turnaround time favour FTIR. The two techniques may be used in combination to supply complementary mineralogical information on complex formations.
Prediction Of Spontaneous Ignition In In-Situ Combustion
Authors: Schoeppel Roger J. , Ersoy Demir
Published: December 2007

American Institute of Mining, Metallurgical, and Petroleum Engineers, Inc.

This paper was prepared for Oklahoma Regional Meeting of the Society of Petroleum Engineers of AIME, to be held at Oklahoma State University, Stillwater, Okla., October 25, 1968. Permission to copy is restricted to an abstract of not more than 300 words. Illustrations may not be copied. The abstract should contain conspicuous acknowledgment of where and by whom the paper is presented. Publication elsewhere after publication in the JOURNAL OF PETROLEUM TECHNOLOGY or the SOCIETY OF PETROLEUM ENGINEERS JOURNAL is usually granted upon request to the Editor of the appropriate journal provided agreement to give proper credit is made.

Discussion of this paper is invited. Three copies of any discussion should be sent to the Society of Petroleum Engineers office. Such discussion may be presented at the above meeting and, with the paper, may be considered for publication in one of the two SPE magazines.

This paper presents a theoretical study of spontaneous ignition as it could intentionally or unintentionally occur during the ignition stage of an in-situ combustion project. The study is based on a combined heat and mass transfer analysis of this low temperature oxidation situation wherein chemical reaction is also present. The mathematical approach approximates field conditions by using a radial model and determines temperature and oxygen concentrations as a function of radius and time.

From the study, it can be predicted whether the well will ignite spontaneously without use of an outside heat source, the distance from the well bore where ignition occurs, the time required to obtain ignition, and the effect of controlling variables such as the chemical activity of the crude, interfacial area, initial temperature, oxygen enrichment of injected air, pressure, and the influence of chemical agents used to promote low temperature oxidation.

In-situ combustion consists of injecting ambient temperature air into the reservoir and burning a portion of the oil to improve recovery efficiency. To start this process it is first necessary to ignite the oil in the formation and then to sustain combustion by continuous air injection. Several methods have been used to initiate the combustion process. These have used electrical and/or process. These have used electrical and/or chemical means to raise the immediate well bore surroundings to a temperature level sufficient to sustain combustion.

Spontaneous ignition is a phenomenon wherein ignition occurs spontaneously as a result of air injection into the reservoir. In the initial stages heat released due to low temperature oxidation accumulates faster than can be dissipated resulting in an increase in temperature. If heat continues to be generated at a rate greater than can be dissipated, a temperature condition is soon reached which is generally accepted as the "ignition temperature."
Drilling Performance Optimization and Identification of Overpressure Formations
Authors: Wardlaw H.W.R.
Published: December 2007

Rock-bit drilling efficiency falls off at higher rotary speeds and at higher values of weight on bit, due to higher rate of generation of rock cuttings and the need to expend mechanical energy on their removal.

A simple relationship is shown to exist between drilling efficiency and penetration rate, whether controlled by rotary speed or by weight on bit. Factors affecting either of the two parameters of this relationship are shown to be

differential pressure on bottom, mud characteristics, circulation rate, jet velocity and rock-bit design.

Examples are cited from literature.

Further analysis leads to an indication of when to expect drilling performance to depend on impact value and when on hydraulic horsepower. Two quite straightforward methods are explained for rapid determination of optimal economic rotary speed, and two for optimal economic bit weight., based on current performance. performance. Three separate methods are offered for identification of overpressured formation, using only the response of bit to standard drilling variables, thus eliminating the need to wait for a log to be run or to rely on shale determinations.

Introduction

Probably the most important single realization in rotary drilling is that not only must rock be fractured on bottom, but also the fractured particles must be removed from the rock face instantly and efficiently, to provide for further fracturing and drilling progress.

For this purpose, energy is brought from the surface to the rock face and applied as efficiently as possible. This energy appears in two forms:

Mechanical energy, applied through the rotary and drill string, and converted into its most useful form through the mechanism of bit cones and teeth. Hydraulic energy, applied through pump and drill string conduit, and converted into its most efficient form through correctly positioned jet nozzles, aimed at the rock face just ahead of the oncoming tooth.

It has been customary to consider the mechanical energy purely as the medium for rock fracture, and the hydraulic energy as the medium for chip removal and bottom scavenging. Further examination reveals, however, that the processes are by no means mutually exclusive. processes are by no means mutually exclusive. In fact, both types of energy play a part in both rock fracture and rock removal.

Trans
A Comparison of Field Drilling Experience with Low-Viscosity Mineral Oil and Diesel Muds
Authors: Jacques D. F. , Newman H. E. , Turnbull W. B.
Published: December 2007

Diesel has been the most widely used base-oil for oil muds. Mineral oil muds have found some application where operators wished to drill with an oil mud but wanted lower aromatic exposure to workers and the environment. Regulations have now been established that increase the difficulty of using diesel in drilling muds. From a human health, safety, and environmental issues perspective, alternates to diesel mud have merit. This paper will describe laboratory and field performance data comparing diesel oil muds with a low-viscosity, low-aromatic, low-toxicity oil or enhanced mud oil (EMO), an improvement over the early mineral oils. The physical, compositional, environmental, and human health differences between diesel and the EMO are discussed. Field data are presented which show that EMO muds have improved rate of penetration over diesel muds when used under similar conditions by 23 to 54 %.
Acquiring and Maintaining ISO Technical Quality Standards
Authors: Bryan J. K. , Dror Yehuda
Published: December 2007

Certification to the internationally accepted ISO Series 9000 quality standards is perceived as being compulsory for companies wishing to participate in the "Harmonized Europe," which is to be effective Jan. 1, 1993.

Universally, the demand for certification to ISO 9000 has grown tremendously in recent years. This demand has created a quasi-partnership between the certified company and the certifying agency, both of which have progressed steadily up the learning curve in the implementation and maintenance of an accredited quality program.

This paper describes the certification (registration) process from the vantage point of both a registered company and the certifying agency. The establishment of a procedure structure will be discussed, along with the document preparation and review, common oversights, the initial registration audit and the renewal audits.

The tangible benefits derived from ISO certification, such as less nonconformance, identification of areas needing improvement and the company-wide culture change it fosters also will be examined. The role of ISO certification in laying the groundwork for a Total Quality Management (TQM) program will be discussed.
The Market for Williston Basin Oil
Authors: Winger John G.
Published: December 2007

This paper attempts to define the probable market for Williston Basin crude oil. The total market area available to this oil is considered to lie mainly within the borders of PAW District 2. Estimates of future supply and demand in this region indicate a growing deficiency of crude oil which parallels the anticipated growth in the Williston Basin productive capacity; hence Williston production could fill the void.

The local market, embracing North Dakota and portions of Montana, South Dakota and Minnesota, is considered to be large enough and will grow sufficiently to absorb all the Williston production for the foreseeable future. The supply which will be thus replaced will be absorbed elsewhere in District 2.

Introduction

The discovery or oil in the Williston Basin has aroused keen and widespread interest. This is one of the largest sedimentary basins in Continental North America and includes portions of Montana and the Dakotas in the United States as well as Saskatchewan and Manitoba in Canada. Sporadic attempts to discover oil have been made since 1923: but there was not an intensive search until oil was actually found in April 1951. It is now one of the most active areas in the United States or Canada. Results have been encouraging and oil has been found in North Dakota, Montana, Saskatchewan, and Manitoba. The search continues and must for many years in order to explore the more than one hundred million acres in this huge geological province. After studying the potentialities of the area, some geologists have estimated that more than 2 1/2 billion barrels will ultimately be discovered.

The Williston discovery raises these questions:Will there be a market for Williston Basin oil? andIf so, how large will it be?

In this paper an attempt is made to find the answers.

Although part of the Basin extends into Canada, we are concerned here only with that portion which lies within the United States and all references in this paper are to that portion.

For the purpose of locating the Williston Basin in respect to its potential market area, frequent reference will be made to the five Petroleum Districts set up during World War II. [Figure 1]
Evaluation of Premium Threaded Connections Using Finite-Element Analysis and Full-Scale Testing
Authors: Hilbert L. B. , Kalil I. A.
Published: December 2007

The procedures developed by Exxon Production Research Company (EPR) for evaluating the performance of premium tubing and casing threaded connection designs using a combination of nonlinear finite element analysis (FEA) and full-scale physical tests are described in this paper. Over the past several years, EPR has developed advanced techniques for nonlinear FEA to accurately and efficiently calculate the stresses and deformations in threaded connections. Concurrently, EPR's Tubular Goods Test Facility (TGTF) was constructed to assist in verification of FEA models and to conduct full-scale physical tests. Evaluation procedures have been developed that are based on using the combined results of state-of-the-art nonlinear FEA and rigorous full-scale physical tests. Finite element models are "linked" to full-scale tests to form the tools for evaluating threaded connections. Several years of experience in implementing these two evaluation tools together have revealed a unique and valuable synergism between analytical models and physical tests. EPR's evaluation philosophy is to use knowledge gained from advanced accurate FEA to test fewer connections with greater confidence in the results.
Computerized Kill Sheet for Most Drilling Operations
Authors: Leitão H. C. F. , Maidla E. E. , Santos O. A. , Netto F. A. , Bourgoyne A. T.
Published: December 2007

This paper addresses a portion of what is actually needed for deep water operations involving well control procedures for directional and horizontal drilling.

Drillpipe pressure schedules were investigated together with the analysis of surface pressure gauge limit to avoid further gas influx and predict the onset of casing shoe fracture.

Examples are run mainly using directional and horizontal well data illustrating the procedure and operation.
Hydraulic Fracturing in Horizontal Wellbores
Authors: Hudson P. J. , Matson R. P.
Published: December 2007

The creation of hydraulic fractures from horizontal wellbores is often characterized by unusual injection pressure behavior and has resulted in inconsistent post-treatment production. A methodology is presented for the design and evaluation of hydraulic fractures from horizontal and extended-reach wellbores, including economic analysis based on improved production forecasts. The requirements for designing appropriate treatments are stated, and the significance of each parameter is discussed. Reservoir scenarios are outlined and specific examples cited to describe specific production predictions relative to anticipated fracture morphology. The results from laboratory testing are used to exemplify the relationship between the orientation of the wellbore, in-situ stresses, and created fractures. In addition, effective perforating strategies and wellbore notching techniques for optimizing fracture initiation and propagation are described.

A knowledge of the orientation and magnitude of principal stresses is required in order to anticipate successful implementation of a treatment design. The ability to reduce the effects of near-wellbore restrictions is possible by influencing the initiation and, therefore, intersection of the fracture with the wellbore. Sealed experiments suggest this may be accomplished by controlled wellbore notching techniques, and in some cases, high-density perforating procedures. Predictions made using a production simulator can be used to explore possible scenarios and by using a non-Darcy correlation can provide improved accuracy in forecasting results.
The Redevelopment of Depleted Queen Waterflood Projects in the Permian Basin
Authors: Hickman T. S. , Hunter C. D.
Published: December 2007

Significant future reserve additions in the Permian Basin of West Texas and Southeastern New Mexico will come about through improved oil recovery techniques (IOR) applied to existing reservoirs. The major companies have an impressive list of improved or enhanced recovery projects on their strategic lists. On the other side of the street, independents are competing to acquire the major's non-strategical properties that are judged to have IOR potential. The Permian Basin is certainly one of the world's most mature producing provinces, but it is also a frontier for advanced IOR technology.

Primary development of the world class Permian Age producing horizons in the Permian Basin occurred from the mid- 1930's through the 1950's. The 1960's was the era of secondary recovery with the establishment of many of the Basin's water injection projects. A majority of these waterflood projects were probably based on the "Tank Model" concept of a reservoir, involving little or no geologic input. The fallout from the initial failure of some of these projects started industry on the road to developing a joint geological/engineering approach. One of the earlier papers to appear in engineering literature discussing the geological aspects was Dowling's 1970 paper titled "Application of Carbonate Environmental Concepts to Secondary Recovery Projects(1). A recent contribution in this area is a 1991 SPE Paper by Holtz, Ruppel and Hocott with the Bureau of Economic Geology at the University of Texas(2). Reading these two papers together shows the advances in carbonate geology and it's application to reservoir exploitation.

On the engineering side, much of the emphasis has been infill drilling. A 1974 paper by Driscoll listed nine factors that influence additional recovery through infill drilling(4). In 1976, Stiles authored a paper on optimizing waterflood recovery in the Clearfork(4). This was the first of several papers by Stiles and his colleagues at Exxon that has served as the foundation for the technology that has evolved into reservoir characterization. A good summary of what has been accomplished through infill drilling and reservoir characterization in West Texas carbonates is contained in a 1991 article by Wu et.al.(5)
Determination of Oil Core Flow Velocities and Porosities Using MRI
Authors: Robinson M. A. , Deans H. A. , Bansal Sitanshu
Published: December 2007

Magnetic resonance imaging (MRI) is used to obtain local values of the porosity and fluid flow velocity in a water-saturated sample of Casper sandstone during water injection. Histograms of the porosity and axial flow velocity are shown. In addition, the correlation between local fluid velocity and local porosity is shown graphically and indicates that the average velocity increases with porosity, as it should.
Simultaneous Determination of Dynamic Rock Properties by Critical Angle Wave Propagation Techniques
Authors: Schroeder R.H. , Gray K.E.
Published: December 2007

Critical angle wave propagation measurements were taken at atmospheric pressure on slate and Green River shale pressure on slate and Green River shale samples to study the effect of stratification on dynamic elastic rock properties. The rock samples were taken in 10 degrees increments, from 0 degrees to 90 degrees to the plane of cleavage or bedding.

Ultrasonic pulses with a frequency of approximately six megacycles per second were used to determine the velocity of dilatational and shear waves through rock samples immersed in a mineral oil bath.

Results indicate a considerable variation of elastic properties with orientation of the bedding or cleavage plane. Data for slate samples indicate general constant values of dynamic elastic properties for cleavage plane orientation properties for cleavage plane orientation angles from 20 degrees to 60 degrees. Anisotropy was indicated for orientation angles near parallel and near normal to the cleavage planes.

Green River shale lean in kerogen content exhibited a sharp change in values for elastic properties as orientation of the bedding planes increased from 0 degrees to 30 degrees. The measured rock properties continued to change, but at a lesser rate, as the bedding plane orientation increased from 30 degrees to 90 degrees.

Data for samples of Green River shale rich in kerogen content were so widely scattered for individual orientations that only general trends were evident. Generally, S-wave velocities and shear modulus values were higher for GRS-2 than GRS-1, while values for bulk modulus and Poisson's ratio were lower. Poisson's ratio were lower

Introduction

The transmission of acoustic waves through a discontinuity surface has been studied both theoretically and experimentally by many investigators. Although the law of reflection for light waves was known to Euclid and that of refraction was discovered experimentally by Snell, Knott seems to have been the first to derive general equations for reflection and refraction of acoustic waves at a plane boundary.
Numerical Modeling of Multilayer Fracture Treatments
Authors: Elbel J. L. , Piggott A. R. , Mack M. G.
Published: December 2007

A substantial proportion of hydraulic fracture treatments are performed in formation and well completion settings conducive to the extension of multiple fractures, a process not adequately described by existing hydraulic fracture simulators. This paper introduces a procedure for the simulation of multilayer fracture treatments. The approach uses an analytical PKN fracture model to describe the behavior of each fracture and couples the behaviors using a set of constraints describing conservation of volume and continuity of pressure. The performance of the simulator is demonstrated by application to several examples.
Drillpipe for Horizontal Drilling
Authors: Smith J. E.
Published: December 2007

Horizontal or extended reach drilling is a rapidly emerging technology that, in some areas, can be considered the norm rather than the exception. While most horizontal drilling is done with the same pipe that would be used in the same size vertical hole, a different pipe or tool joint type may improve the overall drilling performance and efficiency. This paper discusses drill pipe selection based on the influence of: Pipe weight on torque and drag,Pipe OD and ID dimensions on torsional strength, buckling capacity, fatigue resistance and hydraulic efficiency, 3) Tool joint dimensions on torsional strength and hydraulic efficiency.
Biological Treatment of Petroleum Oily Sludges
Authors: Hahn W. J. , Loehr R. C.
Published: December 2007

Biological liquid/solids treatment (LST) processes can be an economical treatment alternative for meeting treatment and disposal requirements for tank bottoms and other petroleum oily sludges. The major factors affecting the choice of this alternative relate to: a) the characteristics of the sludges requiring treatment, b) the process operating conditions, c) the fundamentals of biological treatment as applied to these wastes, d) air emissions from the process, and e) the characteristics of the treated residues that require disposal. This paper a) discusses the fundamentals of biological treatment that affect use of this process with petroleum oily sludges, b) describes the analytical parameters used to evaluate biological treatment processes, and c) illustrates the application of the process for such sludges.
An Integrated Electronic Flow Measurement (EFM) System for Gas-Gathering Operations
Authors: Dunham R. D. , Trosper R. L.
Published: December 2007

Phillips 66 Natural Gas Company is the largest natural gas processor in the State of New Mexico. With over 2,000 miles of low pressure gathering line and approximately 2,000 meter connections, efficient collection of gas flow information is important.

In 1990, Phillips embarked on a development program to integrate electronic flow measurement, high speed digital telemetry, networked gas-management software and an extensive wide area communications network to pilot an advanced gas measurement and surveillance system.

The system is comprised of electronic flow meters located at individual measurement stations and connected to 4800 baud 900 MHZ digital radios. These radios communicate with one of three digital telemetry repeaters situated to provide wide geographic coverage of Southeast New Mexico. In Hobbs, New Mexico, the hub of the system, data is collected from each of the telemetry repeaters and processed in a networked configuration. After compilation and processing, the information is transferred over a wide area network to Bartlesville, Oklahoma and elsewhere as needed.
Remote Data-Entry System for Production Accounting
Authors: Parker J. N. , Gibbs S. G. , Lynch W. C.
Published: December 2007

INTRODUCTION

Efficient selection, installation, operation and maintenance of available technology can improve oilfield operations as well as reduce safety hazards. This paper describes a remote data entry system (RDES) for production accounting which improves both safety and efficiency.

Self imposed restrictions and those prescribed by governmental groups make the simple act of gauging a stock tank a difficult activity for an oil producer. To combat the hazards of hydrogen sulfide, the buddy system and/or extensive use of breathing equipment is required. This is not cost effective in the present day of low product prices and high labor costs. The subject method is predicated on ground level gauging (GLG) to reduce personnel exposure to hydrogen sulfide and slips, trips and falls as a result of climbing tank stairways and/or ladders, often in inclement weather.

The system outlined in the paper complements and extends others being used (ref 1) in that it is an integrated data gathering and computational system.
Evaluation of Surfactants for CO2-Foam Mobility Control
Authors: Tsau Jyun-Syung , Heller J. P.
Published: December 2007

The effectiveness of surfactants, for C02-foam mobility control in dolomite limestone formations, is evaluated at surfactant concentrations below their critical micelle concentra-tions (CMC). The candidate surfactants are commonly used foamants which are either nonionic or anionic types of surfactants.

The evaluation procedures to be discussed, and the data to be presented, include the determination of foamability of surfactants and foam durability of C02-foam, the measurements of adsorption parameters of surfactant onto reservoir core samples, and the measurements of C02-foam mobility in reservoir rock samples. All of the experiments except the adsorption measurements are conducted at reservoir conditions. Adsorption of surfactant onto reservoir rocks is measured using a modified drop-weight method in a direct flow-through measurement at ambient conditions.

The C02-foam activities are found to be affected by the presence of crude oil in the foam durability test. However, C02-foam mobilities are still reduced effectively inside the rock samples containing some residual oil. It is also found that an additional amount of surfactant over the surfactant concentration required for C02-foam propagation is needed to satisfy the permanent adsorption. At surfactant concentrations below the CMC, the effectiveness of mobility reduction of C02-foam as well as the amount of surfactant adsorption vary with the type of surfactant and its concentration in reservoir brine.

Through the entire evaluation procedures, the best candidate surfactant and the most suitable concentration are determined for a particular rock sample at a certain reservoir condition.The laboratory evaluation procedures can be carried out in relatively uncomplicated fashion and are applicable to different reservoir conditions.
Application of a Polymer Gel System to Control Steam Breakthrough and Channeling
Authors: Hunter B. L. , Buell R. S. , Abate T. A.
Published: December 2007

A novel means of mitigating steam channeling and premature steam breakthrough in steamdrives has been successfully applied in the West Coalinga Field, California. A unique polymer gel system, organically crosslinked in-situ, has shown the ability to divert steam from pre-existing steam channels thus, improving areal steam sweep efficiency.

Small volumes of this specially designed polymer gel system (<500 bbls [<79.5 m3]) were injected in six steamdrive injection wells. The applied treatments required only a minor interruption to continuous steam injection and were performed without any interruption to project production.

Analyses of treatment performances have shown positive results in less than one month. Sustained performance of the first treated injector lasted over six months. Others have continued five months without signs of significant degradation. In treating early steam. breakthrough cases, effective polymer gel placement has reduced casing effluent (steam) rates and casing pressures. Reduced casing pressure combined with increased pumping efficiency has resulted in oil production rate increases. By reducing the volume of live steam produced out of the casing, the project thermal efficiency has been improved through increased utilization of injected heat.

Temperature observation well data have shown substantial reservoir temperature decreases two months after injecting the gel system. These data suggest a redistribution of reservoir heat thus, improved areal sweep.
Compositional Changes in Distilled, Steam-Distilled, and Steamflooded Crude Oils
Authors: Richardson W. C. , Fontaine M. F. , Haynes Stewart
Published: December 2007

Steamflooding of heavy and especially light oil reservoirs involves steam distillation of reservoir fluids. Accurate description of the steam distillation behavior of the reservoir oil is required in evaluation of reservoirs for steamflood potential and in the numerical modeling of reservoir performance using compositional simulators. The present work describes an experimental investigation into the effect of heat and water on the properties of crude oils with emphasis on compositional changes important for steamflooding.

Four crude oils in the gravity range (13 – 33° API) have been studied by steam distillation, coreflooding, gas chromatography, and actual distillation by ASTM D-2892. Some of the products from these experiments have been further characterized by a pseudo compositional analysis, densities, and molecular weight. Extensive compositional analyses on these effluents provide an insight toward understanding the steam distillation process.

Laboratory simulated distillation closely agreed with the total boiling point measured by ASTM D-2892. Boiling fractions collected from the TBP analysis were further characterized by composition (simulated distillation) and molecular weight.

Compositional analysis of laboratory coreflood effluents in a light oil (33° API) steamflood suggests preferential efficient recovery of light and middle boiling fractions.
Improved Phase Behavior Representation for Simulation of Thermal Recovery of Light Oils
Authors: Fassihi M. R.
Published: December 2007

This paper describes a procedure that can be used to account for the compositional effects on phase behavior of light oils in the presence of air or flue gas. A light oil system, described by an equation of state (EOS), was used in the Amoco fully compositional model to study recovery mechanisms involved in the flue gas injection process. It was found that the interaction between the flue gas and oil contributes significantly to the production of oil and should be included in thermal simulation in some manner. The results of the compositional model were compared with another model that uses compositional dependent K-values to describe the phase distribution. The latter was accomplished by using correlations of K-values as a function of the composition of CO2 in the liquid phase. Finally, a black oil thermal simulator with constant K-values at a specific pressure and temperature was used. The fluid properties and K-values for the black oil model were obtained by matching the in-situ phase mobilities and compositions from the previous two models. The recovery responses from these three models were in close agreement, indicating that this procedure is comparable to using an EOS description.
Heat Transfer and Two-Phase Flow in Fractured Reservoirs
Authors: Mukhopadhyday Sumit , Sahimi Muhammad
Published: December 2007

We use two- and three-dimensional, fractal and non-fractal networks of interconnected fractures as models of a fractured geothermal field, and study two-phase flow and heat-transfer in such a system. We show that a fractal fracture network is much more efficient than a non-fractal network in heat recovery from a hot matrix. Moreover, the efficiency of a geothermal reservoir is very sensitive to its structure and the location of the producing well, and there may be an optimum configuration of the producing and injection wells for extracting heat and vapor from the reservoir.
Estimation of Effective Permeabilities for Heterogeneous Reservoirs
Authors: Hatzignatiou D. G. , Reynolds A. C.
Published: December 2007

This study investigates the effects of heterogeneities on the estimates of effective or relative permeabilities from well-test pressure data obtained from a well producing a solution-gas-drive reservoir. The heterogeneous system considered in this work is that of a two-zone composite reservoir with different absolute permeability and/or relative permeability curves in the two regions. The estimation of effective (or relative) permeability values as a function of sandface oil saturation or wellbore pressure for both drawdown and buildup tests is presented. It is shown theoretically and computationally that for the two-zone problem of this work, one usually can obtain only one of the outer zone effective (or relative) permeabilities (either oil or gas) evaluated at the sandface value of oil saturation. It is also shown that the effective permeabilities estimated from pressure drawdown or buildup data reflect, at early times, the inner zone effective permeability data, and at later times reflect the outer zone effective permeability data for the oil phase. If the initial reservoir pressure is above the reservoir bubble-point pressure then the effective oil permeability of the inner or the outer zone might be obtained from the analysis of drawdown and/or buildup pressure data.
Gravity Stable Displacement of Oil by Hydrocarbon Gas After Waterflooding
Authors: Hustad O. S. , Holt Torleif
Published: December 2007

This paper presents experimental and simulated results from two vertical core floods. The core floods consisted of injecting equilibrium gas and separator gas from the top of the core after water flooding from the bottom, respectively.

The results show that an oil bank was formed in both experiments. When separator gas was injected, oil was also recovered by vaporization.

Compositional analysis of the produced fluids during separator gas injection shows that considerable amounts of intermediate components were produced as condensate after gas breakthrough. Significant end effects were observed in the final water saturation profiles due to capillary hold-up. Analysis of the final oil saturation in the core indicates a significant gradient due to vaporization, and greater than that modeled by the compositional simulator based on an equation of state.
Performance Analysis of Several Polyacrylamide Floods in North German Oil Fields
Authors: Maitin B. K.
Published: December 2007

Several reservoir units in the oil fields of a North German sediment basin have been polymer-flooded since 1975. Although the reservoir brine of these units has a relatively high- original salinity, polyacrylamide solutions prepared in fresh water have been injected for enhanced recovery.

After the inplacement of the required polymer slugs, these units have been water flooded for several years and thus have a complete displacement performance history.

The producers included in these floods show distinct oil banks. The production profiles, with water cut, salinity development, and polymer concentration demonstrate the relationship between oil bank and various reservoir and project parameters.

After a brief description of different flood concepts applied during project implementation, this paper will discuss the displacement efficiency of a typical polymer flood. Well-by-well analyses of production performance confirm some basic principles of the polymer flood process
A Flexible Low-Cost Approach To Improving Oil Recovery From a (Very) Small Minnelusa Sand Reservoir in Crook County, Wyoming
Authors: Bala G. A. , Duvall M. L. , Jackson J. D. , Larsen D. C.
Published: December 2007

The Moorcroft West Minnelusa Sand Unit is a confined reservoir that provides an ideal setting for evaluation of EOR technologies because there is minimal opportunity for off pattern operations to influence interpretation of results. The unit initially represented a marginal waterflood prospect with two wells (40 acre spacing) in the reservoir producing a total of 4 BOPD. Although unsupported by geological analysis, reservoir engineering. and fluid analysis suggested strongly that the two wells were producing from a common 805 ac-ft reservoir. Oil recovery and cash flow projections indicated that if the reservoir would respond to water injection, a polymer augmented process would markedly increase recovery. Design and installation of a multipurpose waterflood plant was staged to keep monetary investment and risk at a minimum until communication between the wells was demonstrated. In August, 1989, oil production increased from 3 to 6 BOPD demonstrating well communication. Thereafter, a skid-mounted water injection plant containing a dry solids feed system, liquid chemical storage and proportioning equipment, and a small triplex pump was installed. Polymer injection for volumetric sweep improvement was started in October 1989. An alkaline/polymer (A/P) process designed to reduce residual oil saturation was initiated in September 1991.
Enhanced Recovery From Lower Muddy Fluvial Sandstone Reservoirs of the Northern Powder River Basin, Wyoming
Authors: Goolsby J. E. , Neumiller W. P.
Published: December 2007

This paper, in part, represents results of a study supported by North Finn, a small oil an gas producer. It includes 13 Muddy Sandstone waterfloods located in the Northern Powder River Basin of Wyoming. The value of the study to the on-going North Carson Muddy Unit Flood is also discussed.

Fluvially deposited lower Muddy Sandstone reservoirs of early Cretaceous age have never been successfully flooded in the area. Upper Muddy sandstones deposited in marine dominated environments had varying degrees of success. North Finn's proposed flood was in a lower Muddy, fluvially deposited reservoir. Detailed study of the earlier waterflood failures encouraged North Finn to take certain precautions which have led to the first successful flood of a lower Muddy Sandstone in this area.
Use of Horizontal Wells in Vertical Miscible Floods, Pembina Nisku, Alberta, Canada
Authors: Patel R. S. , Broomhall R. W.
Published: December 2007

Esso operates fifteen reservoirs in the Pembina Nisku area, and of these, seven are being miscibly flooded (Vertical Hydrocarbon Miscible Floods). The miscible floods are now in an advanced stage of depletion. As the oil banks in these reservoirs continue to thin, solvent coning is becoming a concern and individual wells have to be choked back. The objective of drilling horizontal wells in these reservoirs is to allow us to maintain oil productivity without solvent coning and also to increase reserves by decreasing the sandwich loss.

The first horizontal well was drilled in the Pembina Nisku "K" pool in 1989. The well initially produced solvent but was successfully worked over and has now been producing at solution gas oil ratios for approximately one year. Since then, Esso Resources Canada Limited has drilled two more horizontal wells in the Pembina Nisku "M" and "Q" pools.
Horizontal Wells in a Steamdrive in the Midway Sunset Field
Authors: Carpenter D. E. , Dazet S. C.
Published: December 2007

Three horizontal wells have been drilled in a low pressure, mature steam drive at the D&E Unit of the Midway Sunset Field, Kern County, California. Simulation studies indicate that horizontal wells in thermal projects can increase recovery efficiency due to better areal sweep, accelerate production which improves the oil-steam ratio (OSR), shorten project life, and increase project profitability.

The D&E Unit was selected as a test site for horizontal wells because gravel packs were not required for sand control. Low reservoir pressures and moderately sorted, sub-rounded sands contribute to the success of slotted liner completions. The reservoir is composed of well sorted, thick turbidite sands which dip at about 45°. The first two wells were drilled at an oblique angle to dip with approximately 400’ laterals. The third well was drilled on strike with slightly more than a 700’ lateral. Radius of curvature is approximately 40'. The three wells were drilled as short radius horizontal wells due to well and lease spacing constraints. The short radius design allows the rod pump to be placed in the vertical section of the hole with minimal drawdown sacrifice. The lowest point of the laterals is 10’ above the oil-water contact. All wells are completed with slotted liners.

The three horizontal wells cost 2-3 times more than vertical wells. Oil production rates increased 2-3 times more than vertical wells in the two wells with 400’ laterals. The third well with a 700’ lateral is more prolific with 6 times the production rate of a vertical well. At this time, the wells are too immature to accurately predict ultimate recovery. This paper will discuss the drilling and completion design of the wells, steam soak data, temperature logs in the horizontal section and current production results.
Technical and Economical Performance of Horizontal Wells For Carbon Dioxide Flooding
Authors: Ammer J. R. , Enick R. M. , Flanders W. A.
Published: December 2007

The technical performances of horizontal and vertical wells were examined for a tertiary, carbon dioxide miscible flood in a 240-acre (97 ha) area of a west Texas field using a black-oil, pseudo-miscible simulator. Although a 40 acre (16 ha), inverted five-spot pattern was used initially for both vertical and horizontal wells, the spacing was increased to 80 acres (32 ha) for the horizontal wells to maintain the miscibility pressure in the reservoir. Horizontal injection and production wells, 1,320 feet (402 m) in length, completed at the bottom of the formation, recovered 14 to 22 percent more oil than vertical wells. Economic analyses for the horizontal injectors and producers were compared to economic analyses conducted for vertical injectors and producers. Project economics were significantly effected by the capital expense for drilling new wells. The vertical wells provided the better rate of return if no new drilling- or only one new well for every six patterns was required. If horizontal wells could be drilled from existing vertical wells- or from the surface at 1.5 times the cost of vertical wells, the rate of return was comparable- or better than vertical wells requiring one new well for every three patterns. Horizontal wells drilled from the surface at twice the cost of vertical wells provided the lowest rate of return.