bluuebunny/crossref_metadata_2025 huggingface dataset:
Flow in Heterogeneous Porous Media
Authors: Warren J.E. , Price H.S.
Published: December 2007

Techniques for studying the performance characteristics of heterogeneous reservoirs have been developed. The effect of permeability variation on both the steady-state and the transient flow of a single fluid has been investigated. Limited comparisons with field and laboratory data have been made.

The physical models studied consist of random three-dimensional arrays of homogeneous porous blocks. The permeabilities of the individual elements are assigned according to a specific distribution function; uniform anisotropy is introduced by varying the relative dimensions of the blocks. A particular model is perturbed simply by re-arranging its elements at random. The behavior of a physical model is determined by digitally solving its numerical analogue.

Based on computational experiments, subject to the restrictions implied by the assumptions that were made, the following general conclusions have been drawn.The most probable behavior of a heterogeneous system approaches that of a homogeneous system with a permeability equal to the geometric mean of the individual permeabilities.The effects of flow geometry and anisotropy on the most probable value of the effective permeability of a heterogeneous medium are finite but not significant.The permeability determined from a pressure build-up curve for a heterogeneous reservoir gives a reasonable value for the effective permeability of the drainage area.A qualitative measure of the degree of heterogeneity and its spatial configuration are obtained from a comparative study of core analysis and pressure build-up data.

It has been indicated that these conclusions are predicated on the assumption that the core analysis and the pressure build-up data represent true reservoir characteristics. Common sources of error in these data have been discussed.

Introduction

One of the most significant problems of reservoir engineering is that of determining the nature and the disposition of the heterogeneities that inevitably occur in petroliferous formations. It is with this problem that this paper is concerned.
Design and Operational Considerations for Unsupported Offshore Pipeline Spans
Authors: Shah B. C. , White C. N. , Rippon I. J.
Published: December 2007

Design and operational considerations have been examined in determining the significance of unsupported offshore pipeline spans that may develop during pipeline installation or field operation. Allowable unsupported span lengths determined during design are generally based on strict code compliance and a design foundation encompassing the worst possible environmental and operational loads. During operation, however, unsupported spans develop beyond the allowable limits, perhaps as a result of various unforeseen local conditions. Applying original design criteria is likely to result in cost-prohibitive repair predictions, while lack of action may result in loss of production. Without the design code requirements of an existing or a proposed pipeline system being violated, realistically safe design can be approached through evaluation of the sensitivity of the key design parameters. Priorities for remedial repair of the unsupported spans can be established for the pipelines in service while operating constraints, budget, and schedule are recognized. On the basis of periodic surveys, properly formatted survey data, and reanalysis of the design parameters, pipeline span repair cost estimates and schedules can be appreciably reduced. Similar principles can be applied to a pipeline in planning and design stages to ensure a safe operating design and to eliminate an uneconomically conservative design. These design and operational considerations are illustrated through a case study.
Linear Water Flood with Gravity and Capillary Effects
Authors: Hovanessian S.A. , Fayers F.J.
Published: December 2007

The one-dimensional displacement equation for a homogeneous porous medium, including the effects of gravity and capillary forces, has been solved by a numerical method. A finite-difference scheme is developed for obtaining saturation, pressure and fractional flow profiles in waterflood recovery problems. From the numerical examples given, it is concluded that the gravitational forces have a pronounced effect on the saturation profiles and the pressure distribution curves of the system.

INTRODUCTION

Within the past 20 years, a number of papers have appeared in the literature dealing with the quantitative treatment of water flood recovery problems. In their celebrated paper, Buckley and Leverett described a method for calculating saturation profiles when the effects of capillary pressure and gravity are excluded. Terwilliger, et al, included the effect of gravity in their theoretical and experimental investigation of oil recovery problems and obtained close correlation between experiment and theory. Welge described a simplified method for obtaining the average saturation and the oil recovery from an oil reservoir. The effect of gravity can be included in this calculation.

More recently (1958) Douglas, et al, presented a method for calculating saturation profiles which includes the effect of capillary pressure. The authors start with the one-dimensional displacement equation (which is nonlinear in the derivative) and, by a change of variable, transform this equation to a semi-linear partial differential equation. This equation is then solved by a finite-difference method on a high-speed digital computer. Fayers and Sheldon obtained the solution of the one-dimensional displacement equation by directly replacing the differential equation by a finite-difference equation.
Mechanics of Gravel Placement and Packing: A Design and Evaluation Approach
Authors: Wahlmeier Mark A. , Andrews Phillip W.
Published: December 2007

Much has been written, researched, and applied toward the advancement of improving gravel-packing technology in the past 10 to 15 years. Still, gravel packing is not a routinely successful completion method to control sand production from weakly consolidated formations. One of the principal reasons for this lack of consistency is an incomplete understanding of the mechanisms involved in achieving efficient gravel placement and packing. The objectives of this study are to discuss the fundamentals of liquid/solid transport and to present the structure of a pseudo-three-dimensional (pseudo-3D) mathematical model used for aiding in the design and evaluation of gravel-packing treatments. Also presented is the validation of the mathematical algorithm in comparison to large-scale, high-pressure, deviated physical wellbore studies and actual field case histories.
Effect of Viscosity on Relative Permeability
Authors: Downie J. , Crane F.E.
Published: December 2007

Introduction

The general application of Darcy's law to natural rocks has already been challenged in the literature. The evidence shows that the permeability as calculated from the Darcy equation can be a function of the pressure drop and the salt concentration of the water phase. Most explanations for aberrant behavior involve clays and their properties and have been qualitatively satisfactory. Recently, however, Odeh revived the theoretical views of Yuster. Since Yuster's concept implies a fundamental error in using Darcy's relationship for two-phase flow, and not merely that conditions may limit its use, Odeh's experimental support arouses considerable interest. However, Odeh's work as presented is thought to be inadequate. He has omitted important information about his materials and procedures; therefore, acceptance of his conclusions should be withheld. Since a clay effect is possible, Odeh should have been allowed space to present a more detailed account of the rocks which he used and the precautions which he took to avoid confounding the effects of clay and fluid circulation. In addition, it follows from Odeh's discussion that the oil relative permeability should increase as the viscosity ratio increases. Odeh presents data corroborating this deduction. It also follows that the oil relative permeability should decrease as the viscosity ratio of oil to water decreases. However, our results show that a high relative permeability, when once attained by using a viscous oil, may be maintained when that oil is replaced by an oil of much lower viscosity.
The PVT-Behavior of Ethane in the Gaseous and Liquid States
Authors: Phillips Edward M. , Thodos George
Published: December 2007

A reduced density correlation for the gaseous and liquid regions of ethane has been developed from all the experimental PVT data available in the literature for this substance. Saturated vapor and liquid densities reported for methane, propane and n-butane were utilized to establish the rectilinear-diameter line for ethane. This line was then used with the saturated-vapor data for ethane to produce the saturated envelope for this substance. Most of the saturated liquid data reported for ethane were found to be inconsistent with the saturated-liquid curve resulting from this study.

The correlation covers the regions 0.65 less than TR less than 6.0 and 0 less than PR less than 15. For regions for which no experimental data have been reported, the isobars of the correlation were extended by the use of the theorem of corresponding states. This correlation is presented both on rectilinear and log-log coordinates.

Introduction

At the present time, there is considerable interest in the exact PVT behavior of pure hydrocarbons. Matschke and Thodos recently have developed a comprehensive compilation of experimental vapor and liquid density data for methane. Similar studies have been conducted for other pure substances. In the present study the density data available in the literature for gaseous and liquid ethane have been critically reviewed and utilized to develop a reduced density correlation for this substance.

SATURATED LIQUID AND VAPOR DENSITIES

The rectilinear-diameter rule proposed by Cailletet and Mathias states that the sum of the saturated liquid and vapor densities of a pure substance is a linear function of temperature which passes through the critical point. This law, although empirical, has been well established by continued verification since its conception in 1886. This rule has been applied to the saturated density data of methane, propane and n-butane to produce the straight lines presented in Fig. 1 which pass through the critical point TR = 1.00, PR = 2.00.
Investigating Completion Strategies— Cormorant Field, U.K. North Sea
Authors: Stiles Jess H. , Valenti Nicholas P.
Published: December 2007

This paper describes studies by Esso E&P U.K. that evaluate various completion strategies for new subsea wells in the Cormorant field, U.K. North Sea. These studies, which complement work done by the field operator (Shell U.K. E&P), include detailed reservoir description work to define oil-in-place (OIP) and permeability distribution and a waterflood simulation for a representative reservoir cross section. Wellbore, flowline, and pipeline hydraulics for the complex production/injection system are included to model well rates more accurately. The results provide general insight into the nature of displacement during waterflooding of a stratified section with a limited number of wells. They also provide specific guidance on (1) dual vs. single completions; (2) perforating, testing, and stimulation sequence; and (3) the benefits of partially perforating high-permeability sands.
Gullfaks A Subsea Well System: Development, Completion, and Production Startup
Authors: Grinrød Mads , Inderberg Olav , Knudsen Tor W.
Published: December 2007

This paper discusses the philosophy, development plan, technical and functional descriptions, and experiences in the various phases, including startup, of the Gullfaks A subsea production system. The wells are connected to the Gullfaks A platform, which is a processing, drilling, and living quarters platform. Subsea operations were accomplished.
Review of Microbial Technology for Improving Oil Recovery
Authors: Bryant Rebecca S. , Burchfield Thomas E.
Published: December 2007

Microbial treatments are potentially cost-effective for increasing oil production, even in today's economic conditions. Field applications that use microorganisms can range from single-well to full-scale waterflooding, but both processes require some knowledge of the reservoir conditions. Coordinated laboratory and field testing is needed to develop microbial oil recovery technology further.
Critical Heterogeneities in a Barrier Island Deposit and Their Influence on Various Recovery Processes
Authors: Sharma Bijon , Honarpour M. M. , Szpaklewicz M. J. , Schatzinger R. A.
Published: December 2007

This paper synthesizes geologic information, acquired from the literature and field studies, and provides detailed maps of geologic heterogeneities, obtained from log and core data, of the Bell Creek field, MT. Geologic heterogeneities were correlated with fluid production data to identify the heterogeneities that have a dominant effect on fluid production. Integration of new and existing information from various geological, geophysical, and engineering disciplines allowed us to identify heterogeneities that influence production during different recovery operations.
Calculation of Transient Oil Production in a Radial Composite Reservoir
Authors: Closmann P.J. , Ratliff N.W.
Published: December 2007

Production of oil by expansion from a cylindrical reservoir composed of twoconcentric regions of different properties has been determined as a function oftime for a reservoir producing at constant terminal pressure.. The parametersinvolved are permeability, porosity, compressibility and oil viscosity. Resultsagree with those of a generally accepted method for uniform reservoirs when allparameters are taken as uniform. Cumulative production at any given time isreduced below that of the uniform reservoir when a region of considerably lowerpermeability adjoins the well; cumulative production increases when ahigh-permeability region adjoins the well. Curves are presented illustratingquantitative effects of these variations.

INTRODUCTION

Most petroleum reservoirs can be exploited by release of pressure andconsequent expansion of underground fluid. During part of the productionhistory of certain reservoirs by this mechanism, fluid compressibility can beconsidered small and constant. Cumulative fluid produced by this means as afunction of time was calculated for a uniform reservoir by van Everdingen andHurst.1 For certain cases where a production well has been damagedor where an acid treatment has been used, a zone of properties different fromthose of the reservoir may be created around the production well. In such acase, expansion of the reservoir fluid takes place in a system composed of twoconcentric cylindrical regions of different reservoir properties. Suchcomposite systems were studied in connection with heat flow byJaeger2 who presented a solution for temperature distribution in aradial system with an infinitely large outer radius. Similar heat flow problemshave been studied by other authors;3 Oil production from compositereservoirs was studied for constant production rate by Hurst,4Loucks and Guerrero,5 and Carter.6

THEORY

This work considers constant terminal pressure. Cumulative flow iscalculated for a composite bounded system in which no flow takes place acrossthe outer boundary (Fig. 1). Since the flow is considered to be purely radial, the problem involves only one space dimension and time. It is convenient todefine the following dimensionless pressure drops (Fig. 1).
A New Method for Petroleum Fractions and Crude oil Characterization
Authors: Miquel Jaume , Hernández Jacobo , Castells Francese
Published: December 2007

A new procedure for petroleum fraction and crude oil characterization is proposed that is based on pseudocomponent breakdown by the integral method. The method requires only the atmospheric true-boiling-point (TBP) distillation curve and whole-fraction density. The pseudocomponents are obtained by sequentially applying an optimization procedure in which the mass balance is accomplished exactly and the molar-balance error is minimized.
Saturated-Steam-Property Functional Correlations for Fully Implicit Thermal Reservoir Simulation
Authors: Tortike W. S. , Ali S. M. Farouq
Published: December 2007

Current methods for determining saturated-steam properties are to look them up in steam tables and interpolate and to use discontinuous polynomial approximations to the experimental data. The latter require heavy computation and are restricted to certain regions of the saturation envelope. This paper presents a complete suite of properties as functions of simple continuous polynomials throughout almost the entire saturation envelope.
Effective Design of Insulated Tubing for a Sour Environment
Authors: Cormier Ken
Published: December 2007

In recent years, significant advances have been made in the performance and durability of insulated tubing. Shell Canada Ltd. has paid particular attention to design considerations that ensure long-term thermal performance of sealed-jacket insulated tubing. The most notable modification to date has been the successful application of "getters" to mitigate the negative thermal effects of hydrogen contamination of the tubing annulus.
Solids-Free Brine-in-Oil Emulsions for Well Completion
Authors: Ezzat A. M. , Blattel S. R.
Published: December 2007

An invert emulsion fluid composed of brine (e.g., NaCl, NaBr, CaCl2, CaBr2, and ZnBr2) emulsified into hydrocarbon oil (e.g., diesel, crude, or mineral) was formulated with a mixture of nonionic surfactant emulsifiers. Laboratory investigations were conducted to define the emulsion characteristics and to develop methods for controlling the fluid's rheological properties and emulsion stability at elevated temperatures. This system has oil as the external phase, and the stability of the emulsion in most cases is linked to the homogeneity and fineness of the brine-dispersed droplets. The emulsion stability is also related to its viscosity and to the strength of the interfacial film formed by the emulsifiers that coat the brine droplets. For packer-fluid applications, the solids-free invert emulsions offer several advantages over conventional oil- and water-based muds. For example, the fluid is virtually nonconductive, providing greater corrosion protection than conventional water-based muds and clear brines. It can also provide formation protection characteristics and can solve such problems as clay swelling and solids invasion. This new completion fluid is ideal for perforating, drilling in, under-reaming, and gravel packing. The emulsion can be filtered through a less-than-10-μm cartridge filter and can be reclaimed and used again. This new completion fluid was used successfully in the field as a packer fluid and as a perforating fluid for testing a reservoir that was drilled with conventional oil-based mud.
Numerical Analysis of the Effects of Gravel Packing on Gas-Well Productivity
Authors: Oyeneyin M. B.
Published: December 2007

This paper presents an aid in the effective design of a comprehensive optimum gas-well completion program involving the gravel-packing method of sand control to ensure maximum productivity for a long period. A numerical approach using PI as a measure of eventual well performance is used in analyzing the productivity of gravel-packed gas wells with a computer. An outline of the comprehensive equations needed to compute PI under steady- and semisteady-state flow conditions based on modified Darcy's law for gas flow is presented. The final analysis with the computer package centers on how best to design a gravel-packed gas-well program that will ensure maximum productivity.
Comparison of Solutions of the Nonlinear and Linearized Diffusion Equations
Authors: Odeh A. S. , Babu D. K.
Published: December 2007

Analytical solutions to the nonlinear partial-differential equation (PDE) that describes pressure behavior during the flow of slightly compressible fluid through porous media are presented. The solutions are compared with the generally accepted solutions of the linearized version of the original nonlinear PDE. It is shown that for routine engineering applications, the solutions to the linearized equation are satisfactory. However, the nonlinear solutions show that some accepted concepts based on the linear solutions are not valid. Moreover, if one is looking for small differences between the field-measured pressure values and the theoretically calculated ones, the solutions to the nonlinear equation should be used in place of the linear solutions.
Optimizing Hydraulic-Fracture Length in the Spraberry Trend
Authors: Barba Robert E.
Published: December 2007

Between 1982 and 1986, more than 3,000 new wells were drilled in the Spraberry trend in west Texas. All these wells have been hydraulically fractured with ever-increasing volumes of fracturing fluids and proppant. Little work has been done to date to establish an optimum hydraulic-fracture length. A group of wells drilled in Midland County was studied with use of data from geological mapping, cores, openhole logs, postfracture pressure-transient testing, and production declines. From these data, a model was developed to predict production declines before completion. By combining this with well- and completion-cost data, an optimum fracture length can be determined with an internal rate of return (IRR) method.
Accurate Resolution of Physical Dispersion in the Multidimensional Numerical Modeling of Miscible and Chemical Displacement
Authors: Gupta Akhil Datta
Published: December 2007

This paper presents a finite-difference scheme for numerical modeling of the convection-dominated flows common in miscible or chemical flooding in porous media. The proposed difference operator possesses desirable phase and amplitude properties capable of resolving sharp fronts with negligible over- and undershoot. The scheme is generalized to multidimensions. Difference analogs have been derived for variable grid sizes for large-scale compositional simulations. Application to 3D miscible displacement problems and comparison with other standard industry methods have demonstrated the scheme's effectiveness in controlling numerical diffusion and grid-orientation sensitivity without any significant additional computational effort.
The Effect of Rock Wettability on Water Blocking During Miscible Displacement
Authors: Lin Eugene C. , Huang Edward T. S.
Published: December 2007

The influence of rock wettability on water blocking of oil during miscible displacements is investigated through both laboratory coreflood experiments and numerical simulations. For non-water-wet cores, the amount of oil remaining in the cores depends on solvent throughput. A solvent-throughput-dependent water-blocking function is proposed for a numerical model to account for the slow release of oil.
Compaction Within the South Belridge Diatomite
Authors: Chase C. A. , Dietrich J. K.
Published: December 2007

Compaction is incorporated into a field-scale finite-difference thermal simulator to allow practical engineering analysis of reservoir compaction caused by fluid withdrawal. Capabilities new to petroleum applications include hysteresis in the form of limited rebound during fluid injection and the concept of relaxation time (i.e., creep).
Field Application of Minifracture Analysis To Improve Fracturing Treatment Design
Authors: Tan Hyok C. , McGowen James M. , Sollman Mohamed Y.
Published: December 2007

This paper presents a comparison of different minifracture analysis techniques, correction of field data to incorporate the effects of temperature and fluid compressibility, determination of closure pressure from various methods to perform the minifracture analysis accurately, field application of minifracture analysis to improve design fracturing treatment, and case histories of full-scale fracturing treatments designed with the parameters obtained from minifracture analysis.
The Effects of Abrasives on Electrical Submersible Pumps
Authors: Wilson Brown L.
Published: December 2007

The electrical submersible pump (ESP) is a high-speed rotating device. Its operational life in oil wells can depend on the type and quantities of abrasives present in the produced fluid. This paper reports on a set of experiments performed in a specialized abrasive test loop. In the test, the size and quantity of abrasives were varied along with flow rate through the pump. This paper also examines recent literature on sand production and explores some of the practical problems in sand measurement.
Use of a New Four-Component Drilling System in the Attaka Field
Authors: Sawolo N.
Published: December 2007

Unocal Indonesia Ltd. significantly reduced drilling time and cost by introducing a four-component drilling system in the Attaka field. The new drilling system includes use of polycrystalline-diamond-compact (PDC) bits, a low-toxicity oil-based mud (LTOBM), a measurement-while-drilling (MWD) survey tool, and a steerable positive-displacement mud motor. This paper presents a case study that shows the advantages of the new drilling system over the conventional drilling technique.
Distributed Pressure Measurements Allow Early Quantification of Reservoir Dynamics in the Jene Field
Authors: Bunn G. F. , Wittmann M. J. , Morgan W. D. , Curnutt R. C.
Published: December 2007

The Jene field is an undersaturated oil reservoir in a carbonate reefal buildup. Initial production was accompanied by a rapid pressure decline that clearly outlined the need for early pressure maintenance. The widely varying petrophysical properties—in particular, the presence of extensive "tight" streaks—complicated the decisions on location and capacity of water injectors. This, in turn, affected plans for infill drilling, field- and well-production strategies, and estimates of recovery at abandonment. Early production data, combined with systematic pressure measurements, were used to fine-tune a reservoir simulator just a few months after the onset of production, with only about 0.5% of the estimated original oil in place (OOIP) produced.

Matching data included well flowing and shut-in pressures, pressure-buildup tests, and interference tests, and most importantly, layer pressures as derived from Repeat Formation Tester (RFT™) surveys. The matched model was used to evaluate various development strategies to maximize recovery. This paper critically compares the various options and evaluates the sensitivities of the predictions to variations of input parameters. A model update was performed after the original paper was presented. Some interesting results of this update are discussed and appropriate conclusions drawn.
Design of Fracturing Treatments in Multilayered Formations
Authors: Naceur K. Ben , Roeglers J. C.
Published: December 2007

The propagation of a set of hydraulically induced fractures is simulated with boundary-integral methods. The technique allows simulation of a single fracture in a varying stress field, as well as a set of arbitrarily oriented fractures. Applications relate to interacting parallel and collinear fractures. Fracture geometry is shown to be affected significantly by the interaction of these fractures.
Stimulation-Fluid Systems for Naturally Fractured Tight Gas Sandstones: A General Case Study
Authors: Sattler A. R. , Raible C. J. , Gall B. L. , Gill P. J.
Published: December 2007

Extensive production testing and core analyses show that production from the low-permeability sandstones in the Mesaverde formation at the U.S. DOE Multiwell Experiment (MWX) field laboratory is dominated by natural fractures. Stimulation data strongly suggest that damage to the narrow natural fractures significantly affects poststimulation production. This paper summarizes the field data that show evidence for production from natural fractures and for damage to those narrow natural fractures by stimulation fluids, resulting in decreased gas production. The nature of these interactions was clarified through laboratory studies on the degradation of stimulation fluids and the permeability damage to artificially fractured core exposed to the fluids. Evidence confirms that stimulation-fluid damage to the narrow natural fractures restricted the production of gas in early MWX stimulations, consistent with the partial reversibility of fluid damage to natural fractures following a long-term shut-in. A controlled breaker system was designed for use with temperature-stable biopolymer foam. Use of this fluid system in a later MWX stimulation substantially increased gas production and reduced the evidence of damage.
Pore Geometry in High- and Low-Permeability Sandstones, Travis Peak Formation, East Texas
Authors: Soeder D. J. , Chowdiah Prasan
Published: December 2007

Petrographic and petrophysical analyses have revealed that tight sandstone possesses distinct petrological properties that differentiate it from conventional sands. Diagenetic alteration changes a wide variety of fluvial, deltaic, and marine sands into similar low-permeability rocks with nearly identical pore structures. In this paper, changes in the pore geometry and petrology as conventional sandstones become tight are examined within a single East Texas sandstone formation.
A Brief History of the Wasson EOR Project
Authors: Bullock Gary W. , Wood Terry B. , Konecki Mark L.
Published: December 2007

Amoco Production Co. and its partners embarked on a CO2-based EOR project in 1982 at the Wasson ODC Unit (WODCU), Wasson field, Yoakum County, TX. Many years of studies and carefully coordinated planning preceded the project's approval. This paper reviews several aspects of the project and details the WODCU CO2 removal plant.
A Simple Correlation for Estimation of Multiphase Pressure Drop in an Oil Pipeline
Authors: Behnia Masud , Ilic Vojislav
Published: December 2007

A basis for developing a simple-to-use multiphase-pressure-drop correlation that could be applied to the design or assessment of pipelines with flows of oil and gas mixtures was established. Simple correlations for predicting the pressure drop are proposed and tested with a data bank from the oil industry.
Design of Concentric Tubular Members
Authors: Imm Gary R. , Stahl Bernhard
Published: December 2007

New design equations are developed for several types of concentric tubular-member systems. The design methodology currently used for platform conductors is extended to analyze deepwater conductor systems, telescopic pile-sleeve systems, and pile-jacket leg systems. The resulting equations, which are similar to the widely known American Inst. of Steel Construction (AISC) equations, provide an accurate means of assessing the buckling and ultimate strength capacity of a concentric tubular-member system.
A Shallow-Gas-Kick Simulator Including Diverter Performance
Authors: Starrett Michael P. , Hill A. Dan , Sepehrnoori Kamy
Published: December 2007

A computer simulator of the flow and pressure behaviors in wellbores and diverters (large horizontal flowlines from the wellhead) was developed to predict performance during shallow gas blowouts. The model is based on the solution of the unsteady-state mechanical energy-balance equation for pipe flow. Four main regions are considered: the reservoir, the two-phase gas/liquid region in the wellbore, the liquid being displaced ahead of the two-phase region, and the diverter. For the reservoir, equations for transient radial gas flow are used. In the two-phase region, Aziz et al.'s two-phase flow model is used to calculate liquid holdup and factional pressure drop. For liquid ahead of the gas, pressure losses caused by the acceleration of the liquid column are considered. Flow in the diverter allows for two-phase critical flow at the diverter exit. At each timestep, the model calculates the pressure, fraction of each phase present, and velocity throughout the well and the diverter by use of an iterative procedure. The model has shown that the pressure and velocity behaviors depend strongly on the initial difference between bottomhole pressure (BHP) and reservoir pressure and on the wellbore and diverter diameters.
Downhole Pneumatic Turbine Motors Testing and Simulation Results
Authors: Lyons William C. , Miska Stefan Z. , Johnson Philip W.
Published: December 2007

A new motor was developed for use in air/gas drilling operations. Numerical simulation indicated that such a motor was feasible, and a prototype was built. The prototype underwent extensive bench testing and two successful field tests. The downhole pneumatic turbine drilling motor is expected to prove useful in directional drilling operations in areas where formation damage is a problem.
In-Situ Combustion Process Study With a Combined Experimental/Analytical Approach
Authors: Sibbald L. R. , Moore R. G. , Bennion D. W.
Published: December 2007

Analysis of combustion-tube data produced from experiments performed under realistic reservoir conditions is currently the most valid method of investigating the in-situ combustion process. This paper describes an approach that uses a differential moving-frame descriptive model to analyze data from stabilized combustion processes produced in combustion-tube experiments. The approach is applied to a set of dry-air combustion runs. This study revealed consistent values for the fuel-combustion-reaction-kinetics parameters, showed that oxygen consumption was not confined to the high-temperature (300°C) combustion zone, and gave insight into the relationship between injected-gas flux and the distribution of energy liberation rate with implications for process stability.
Scaled Model Studies off CO2 Floods
Authors: Rojas G. A. , Zhu Tao , Dyer S. B. , Thomas Sara , Farouq All S. M.
Published: December 2007

Immiscible CO2 floods with alternating water injection are promising for heavy-oil formations ill-suited for thermal treatment. This investigation uses scaled models to show that a 20% PV slug of CO2 can recover 5 to 50% of the oil in place (OIP), depending on the operating conditions. The CO2 requirement is small, < 100 std m3/stock-tank m3.
A Mechanistic Interpretation of the Torchlight Micellar/Polymer Pilot
Authors: Raterman Kevin T.
Published: December 2007

This paper describes laboratory studies to interpret the production- and observation-well data obtained from the Torchlight micellar/polymer pilot. The underlying causes for poor pilot performance were identified through correlation of laboratory field core tests and phase-behavior studies to pilot data.
Field Experiment of Lignosulfonate Preflushing for Surfactant Adsorption Reduction
Authors: Hong S. A. , Bae J. H.
Published: December 2007

Lignosulfonate was field tested as a sacrificial adsorbate in conjunction with the ongoing Glenn Pool surfactant flood expansion project. A 2 wt% lignosulfonate solution was injected for 10 days as part of the preflush in this project. Results of the analyses of two observation well samples were interpreted for the effect of lignosulfonate on sulfonate adsorption and process performance. Even though the evidence was ambiguous, we concluded that the low-cost lignosulfonate preflushing was beneficial to surfactant flooding.
Analysis of Pressure-Buildup Data From a Well in a Multiwell System
Authors: Onur Mustafa , Serra Kelsen V. , Reynolds Albert C.
Published: December 2007

This work investigates the buildup response of a well located in a system of producing wells completed in a closed, bounded reservoir. Using an analysis method based on the pressure derivative, we show that the drainage area of the well (at the instant of shut-in) and the flow-capacity (permeability-thickness) product can be computed directly from the derivative of pressure-buildup data even in cases where conventional semilog straight lines are not well defined. The analysis methods assume that the buildup-surveyed well has established its own drainage area before shut-in. For a system of wells located in a closed, bounded reservoir, this means that pseudo-steady-state flow prevails at the instant of shut-in. We also present a second method for estimating a well's drainage area from pressure-buildup data. The second method relies on the fact that during buildup, the well's shut-in pressure increases to a maximum and then decreases as a result of interference from neighboring producing wells. It is shown that the maximum shut-in pressure, and the time at which it occurs, often can also be used to compute the well's drainage area at the instant of shut-in and the average pressure in this drainage area.
Laboratory Measurements of Eleotrical Resistivity at Reservoir Conditions
Authors: Mahmood S. M. , Maerefat N. L. , Chang M-M.
Published: December 2007

An experimental study to investigate the influence of variations in test conditions and laboratory procedures on the electrical properties of rocks is presented. Results suggest that the cementation and saturation exponents in Archie's equation should be determined in the laboratory at near-reservoir conditions to prevent an error of up to 8% from being introduced during the determination of water saturation.
Laboratory and Field Evaluation of a Combined Fluid-Loss-Control Additive and Gel Breaker for Fracturing Fluids
Authors: Cantu Lisa A. , Boyd Phil A.
Published: December 2007

More than 200% increase in fracture conductivity and permeability was obtained when a new degradable fluid-loss-control additive was used in place of silica flour (SF) in 40-lbm crosslinked hydroxypropyl-guar (HPG) fracturing-fluid systems. The new additive, an organic acid particulate (OAP), slowly degraded into water-soluble monomeric units at temperatures > 150°F after fracture stimulation experiments. The high-acid-content degradation product then acted as an excellent HPG gel breaker and effectively cleaned the proppant packs.

As a fluid-loss-control additive, the measured wall-building coefficients were as good as, or better than, those of SF in crosslinked-gel, linear-gel, and N2-foam systems. This paper summarizes a 2-year study of the evaluation and application of this new product in fracturing-fluid systems.
Simultaneous Wireline Operations From a Floating Rig With a Subsea Lubricator
Authors: Hopper Christopher T.
Published: December 2007

In 1987, an extensive wireline program was completed on two subsea wells in the Highlander field in the central North Sea with a subsea lubricator deployed from a drilling rig that was drilling and working over adjacent wells. Working on two wells concurrently is a way to reduce the operating costs of a subsea development significantly.
A New Method To Predict Two-Phase Pressure Drop Across Perforations
Authors: Perez Godofredo , Kelkar B. G.
Published: December 2007

Two-phase high-velocity dimensionless equations are derived to model the flow across the crushed zone of idealized perforated completions. The effects of GOR, perforation pressure, and size on pressure drop across perforations are investigated. A simplified form of the equations is proposed and used in the evaluation of a field test.
Characterizing Permeability Heterogeneity in Core Samples From Standard Miscible Displacement Experiments
Authors: Houseworth James E.
Published: December 2007

Permeability heterogeneity in porous media is evaluated with standard-pressure and production-history measurements from miscible displacements. Variations in the production history with mobility ratio and deviations of the pressure history from an idealized response provide complementary information on permeability heterogeneity. These heterogeneity tests have been developed to assist in core sample selection for unsteady-state relative permeability tests and other transient displacement tests.
Modeling Reservoir Geometry With Irregular Grids
Authors: Helnemann Z. E. , Brand C. W. , Munka Margit , Chen Y. M.
Published: December 2007

This paper describes a practical method in which irregular or locally irregular grids are used in reservoir simulation with the advantages of flexible approximation of reservoir geometry and reduced grid-orientation effects. Finite-difference equations are derived from an integral formulation of the reservoir model equations equivalent to the commonly used differential equations. Integrating over gridblocks results in material-balance equations for each block. This leads to a finite-volume method that combines the advantages of finite-element methods (flexible grids) with those of finite-difference methods (intuitive interpretation of flow terms). Grid-orientation effects are investigated. For grids based on triangular elements, the more isotropic distribution of gridpoints diminishes the orientation effect significantly. Numerical examples show that the regions of interest in a reservoir can be simulated efficiently and that well flow can be represented accurately.
Relationship of the Volume-Balance Method of Compositional Simulation to the Newton-Raphson Method
Authors: Wong Terry W. , Firoozabadl Abbas , Aziz Khalld
Published: December 2007

This paper provides an analytical exposition of the relationship between two fully compositional, isothermal, three-phase, numerical simulator types in the literature. The Newton-Raphson (NR) method is based on the standard NR solution of the mass- or mole-conservation equations and associated constraints. The volume-balance (VB) method is based on the principle that, in each simulator block, the PV equals the combined fluid volume of all the phases. These two types of models have been regarded as different approaches to the same problem. An analytical demonstration, however, proves rather surprisingly that, although the two model types were developed from fundamentally different viewpoints (i.e., mass conservation vs. volume conservation), they lead to the same matrix system of the finite-difference equations. This understanding yields many advantages, including (1) methods to improve efficiency in both model types, (2) fully implicit and iterative forms of the VB model, (3) the assignation of physical meaning to groupings of terms from the NR Jacobian matrix, and (4) an understanding of how to decouple the mass- or mole-conservation equations from the thermodynamic equilibrium constraints. Also, a unified approach is possible that offers the best features of both simulation model types.
Modeling of Gravity-Imbibition and Gravity-Drainage Processes: Analytic and Numerical Solutions
Authors: Bech Niels , Jensen Ole K. , Nielsen Birger
Published: December 2007

A matrix/fracture exchange model for a fractured reservoir simulator is described. Oil/water imbibition is obtained from a diffusion equation with water saturation as the dependent variable. Gas/oil gravity drainage and imbibition are calculated by taking into account the vertical saturation distribution in the matrix blocks.
Asphaltene Adsorption and Desorption From Mineral Surfaces
Authors: Dubey S. T. , Waxman M. H.
Published: December 2007

This paper reports results of asphaltene adsorption/desorption on clay minerals, silica, and carbonates. It also describes the effect of adsorbed asphaltenes on rock wettability and a screening pyrolysis-flame-ionization-detection (P-FID) test to evaluate the ability of solvents to remove asphaltene from kaolin and formation core material.
Improved Demulsifier Chemistry: A Novel Approach in the Dehydration of Crude Oil
Authors: Staiss Friedrich , Böhm Roland , Kupfer Rainer
Published: December 2007

With the ever-growing demand for more efficient dehydration and desalting of crude oil, classic demulsifiers no longer perform satisfactorily in most cases, and new chemical systems are required. This paper describes new emulsion breakers, generally polyester amines, and gives detailed laboratory studies of their advantages over classic demulsifiers: more complete migration to the interface, improved emulsion breaking and coalescence, improved effluent water quality, and partial corrosion inhibition. These new demulsifiers combined with classic emulsion breakers have been successfully tested.
Laboratory Study of Borehole Friction Factor With a Dynamic-Filtration Apparatus
Authors: Maidla Eric E. , Wojtanowicz Andrew K.
Published: December 2007

This paper discusses a medium-scale borehole friction tester with dynamic-filtration capabilities that showed that friction coefficients are affected by mud quality, mudcake, and lubricant addition in low-solids, water-based muds (WBM's). Most measured values, including those from oil-based muds (OBM's), were between 0.2 and 0.3. This paper also reports on new effects of filter cake and solids deposition on borehole friction.
Phase Behavior of CO2/Hydrocarbon Systems: Amendments to Previously Predicted Phase Diagrams
Authors: Quiñones-Cisneros S. E. , Blackburn M. B. , Scriven L. E. , Davis H. T.
Published: December 2007

In using the Peng-Robinson equation of state (PREOS) described by Sahimi et al., we found discrepancies with their results. By using two separate methods of computation, we deduced that their method is correct, but that some code or implementation errors must have caused the observed discrepancies.
Geochemical Monitoring of Drilling Fluids: A Powerful Tool To Forecast and Detect Formation Waters
Authors: Vuataz François-David , Brach Michel , Criaud Annie , Foulllac Christian
Published: December 2007

This paper describes a method based on the difference between the chemical compositions of formation and drilling fluids for analyzing drilling mud to forecast fluid-producing zones. The method was successfully applied in three boreholes in crystalline rocks in France. Subsequent geophysical logs and hydraulic tests confirmed the occurrence of flowing fractures.
Improved Steam-Foam Formulations: Concepts and Laboratory Results
Authors: Lau H. C. , Borchardt J. K.
Published: December 2007

Kern River pilot results show that a steam-foam formulation based on an alpha olefin sulfonate (AOS) containing 16 to 18 carbon atoms in the hydrocarbon chain improves sweep efficiency and oil recovery of the steamdrive but propagates relatively slowly and leaves the same residual oil saturation (ROS) as steam. Research has identified potentially superior formulations that form stronger foams, propagate faster, and/or reduce ROS below that to steam in the laboratory.
Transient Flow Behavior of Horizontal Wells: Pressure Drawdown and Buildup Analysis
Authors: Odeh Aziz S. , Babu D. K.
Published: December 2007

Four flow periods may occur during the transient behavior of a horizontal well. Drawdown and buildup equations describing the flow behavior of each of the four flow periods are given. Methods for analyzing data obtained from testing the well to determine permeability anisotropy in its drainage volume and the skin factor are presented. Calculation procedures are illustrated by examples.
Formation Damage From Fine Particulate Invasion: An Example From the Lost Soldier Tensleep Formation
Authors: Rickford R. L. , Finney T. P.
Published: December 2007

The Tensleep formation in the Lost Soldier field has been pattern waterflooded since 1976. Injection wells have historically exhibited large declines in injectivity and required frequent workovers. Because those declines were originally attributed to near-well damage from poor injection-water quality, a cleanup program was initiated that significantly reduced the amount and size of suspended particles in the injection water. Despite these improvements, injectivity continued to decline in many wells. Subsequent analyses of well histories, pressure-falloff tests, and reservoir petrophysical properties suggest that the reservoir damage in many instances was not only a sandface phenomenon, but also a result of deep particle invasion. Workover procedures were altered to treat the formation beyond the near-wellbore area, resulting in increased injectivities compared with the historical norm.
Causes of Blown Port Plugs
Authors: King G. E. , Packard B. R.
Published: December 2007

After several incidents of blown port plugs in used and new perforating guns, a study was initiated to determine the causes of plug loss. The study included (1) an examination of the swelling characteristics of a heavy-wall, reusable perforating gun, (2) an examination of new guns from which plug loss had and had not occurred, and (3) construction of a port-plug test cell in which plug loss factors could be studied. The results of the study identified at least three major factors and nine minor factors that could operate singly or jointly to contribute to plug loss.