bluuebunny/crossref_metadata_2025 huggingface dataset:
Perforation Geometry and Skin Effects on Well Productivity
Authors: Todd B. J. , Bradley D. J.
Published: December 2007

A computer model based on the Darcy solution to the Radial Diffusivity Equation was written to evaluate perforated oil well completions. The model was verified using standard well testing techniques and compares favorably with similar models written previously. The results of this study clearly point to these conclusions: Normal amounts of well and perforation damage reduce four shot per foot (0.305 m) productivity to an unacceptable level. Twelve shots per foot (0.305 m) is recommended for future completions.Gun phasing affects productivity. Sixty degree phasing gives the best results, with productivity reductions for larger angles.Perforation length should be maximized at the expense of hole diameter, down to a diameter of 0.25 inches (0.64 cm).Gun standoff decreases penetration of small diameter, through-tubing guns. These guns should be avoided where possible.
Curve Fitting of Real-Gas Pseudopressure and Its Practical Application
Authors: Schafer-Perini A. L. , Miska S. Z.
Published: December 2007

The real gas pseudo pressure concept is a very useful technique for calculating gas well deliverability and in the analysis of pressure transient tests. Current use of the real gas pseudo pressure requires application of numerical integration and interpolation methods. Here, an approximation of the m(P) function is proposed which eliminates the need for numerical intergration. A simple power type equation is found to fit the m(P) function over a broad range of gas properties and reservoir conditions. Practical examples are provided to illustrate the usefulness of the proposed approximation.
The Effect of Injected Fluid Volume on Heavy Oil Displacement in a Porous Medium
Authors: Reitman V. , Rajan V. S. V. , Heidrick T. R.
Published: December 2007

In situ recovery of heavy oil generally involves the use of steam or hot water to displace the oil. The recovery is controlled by the extent to which the displacing fluid can mobilize the oil and saturate the pores of the reservoir. Modelling of any such recovery process requires a knowledge of the permeabilities of the oil-water-rock system.

Relative permeabilities are often measured in cores using displacement experiments. These permeabilities are measured as a function of saturation and are sometimes correlated as power law functions of the initial water saturation, Swc, and residual oil saturation, Sor. The "end" of the displacement process is assumed to be after four to five pore volumes of fluid injection with the exact value somewhat arbitrarily chosen by each particular researcher, often on the basis of capillary number considerations.

In this paper, the method of characteristics solution of the one-dimensional flow equations is used to investigate the effects of various parameters, such as mobility ratio, on the number of pore volumes of injected fluid that are required to reach the residual oil saturation. For some heavy oils, it is shown that of the order of one hundred or more pore volumes of injected water may be required before reaching the residual oil saturation. The apparent steady saturation profile observed by some researchers may have resulted in premature termination of some experiments. Also, the apparent " end-effect" observed by many researchers can be attributed in part to the extreme variations in the permeability-saturation profile.

The main advantage of this analysis is an iterative approach which enables a researcher to design suitable experiments for relative permeability determinations. Also, with an assumed mathematical form of the permeability versus saturation relationship, the total curve can be generated from a limited number of displacement experiments.
Financial and Technical Decision Making for Surfactant Flooding
Authors: Barua J. , Prescott T. , Haldorsen H. H.
Published: December 2007

This paper presents a method for making prudent business and technical decisions for surfactant flooding projects in spite of the uncertainty associated with reservoir properties, surfactant flood performance, and oil price forecasts. A hypothetical surfactant flooding project is used to demonstrate this method and each algorithm is explained in detail.

This method optimizes the operational decisions of a surfactant flood and presents the economic assessment of the project. The accuracy of this assessment depends on the uncertainty in the project but this method quantifies both the effect of this uncertainty and the financial risk.

Surfactant flooding is used as the example in this study but the algorithms can be applied to all oil & gas development projects.
The Effect of Dissolved Gas on Geothermal Brine Viscosity
Authors: Ostermann R. D. , Paranjpe S. G. , Godbole S. P. , Kamath V. A.
Published: December 2007

Reservoir brines typically contain dissolved salts and gases. While correlations have been published for prediction of viscosity as a function of temperature, pressure and salinity, little data is available regarding the effect of dissovled gases on brine viscosity. In the current work, the viscosity of methane and ethane saturated water and brine has been measured at 100, 150, and 250°F over a pressure range of 0-7,500 psig.

For methane in pure water, viscosity increases by up to 6%. At pressures above 2,000 psig, the viscosity is independent of saturation pressure. Dissolved ethane showed no measurable effect on water viscosity. Brine viscosity also increases with methane saturation pressure. A correlation is presented for the correction of brine viscosity to account for gas saturation.
Experimental and Simulation Studies of Laboratory In-Situ Combustion Recovery
Authors: Onyekonwu M. O. , Pande K. , Ramey H. J. , Brigham W. E.
Published: December 2007

This paper discusses the effects of some parameters on the in-situ combustion process. The paper is in two parts. The first part discusses a laboratory in-situ combustion tube run. Important design parameters such as fuel concentration, air requirement, oxygen utilization efficiency and combustion front velocity may be determined from the analysis of laboratory tube run data. The second part of the paper discusses numerical simulation of the laboratory tube run and results from in-situ combustion simulation studies. A thermal simulator was used to investigate the effects of relative permeability, rock thermal conductivity, heat losses, API gravity of oil, initial conditions, oxygen concentration, and other parameters on fuel availability and combustion front velocity.

Results from simulation studies show that oil viscosity, residual oil saturation (gas/oil system) and oxygen mole fraction in the injected gas should have the greatest effect on fuel availability. Relative permeability data and rock thermal conductivity also affect the amount of fuel available for combustion. Factors which may cause an increase in combustion front velocity may also cause an increase in the amount of fuel burned if the heat front moves slower than the combustion front. The use of a thermal simulator for this study made it possible to study a wide range of parameters which would involve a substantial effort to investigate experimentally.
Application of the Parallel Resistance Concept to Well Test Analysis of Multilayered Reservoirs
Authors: Mavor M. J. , Walkup G. W.
Published: December 2007

A new development of a multi-layered reservoir model is presented which considers the layers to be in communication only at the well. The importance of the presentation is the simplicity of the mathematical model and the use of the model to derive improved well test analysis techniques for both single and double porosity reservoirs. Analysis techniques based upon both pressure and flow rate data required to determine individual layer properties are presented.

Through the use of the Laplace Transformation, the behavior of a multi-layered reservoir system can be treated as an equivalent resistance network in which the total resistance to fluid flow can be obtained by adding the resistances to fluid flow in each layer using the elementary concept of resistances in parallel. The resistance functions for both single and double porosity layers with infinite, closed, or constant pressure outer boundaries are presented. The effects of wellbore storage are included.

Development of layered reservoir models where the layers are of different type (single or double porosity), with differing rock and fluid properties, and with differing outer boundaries is easily accomplished with the parallel resistance approach. Solutions for the wellbore pressure and the pressure in the reservoir for constant rate tests as well as solutions for the rate response during a constant pressure test are discussed.

A method to include wellbore storage into any reservoir model is presented as is a method for directly extending single porosity solutions to double porosity systems.
Slug Test and Drillstem Test Flow Phenomena Including Wellbore Inertial and Frictional Effects
Authors: Saldana-C. M. A. , Ramey H. J.
Published: December 2007

During the flow period of a drillstem test from deep and highly-productive wells, the liquid column inside the wellbore can experience rapid acceleration changes. Also, flow velocities in the pipe can become extremely large. Therefore, inertial and frictional forces can be expected to be important in a dynamical relationship between flow rate and bottomhole pressure.

A mathematical formulation including the effects of inertia and friction on the wellbore liquid column during a drillstem test is presented in this paper. Solutions for this formulation are obtained by assuming a large initial cushion and laminar flow during the test. This leads to a linear mathematical problem that is solved in the transformed Laplace-space. Solutions, in terms of the dimensionless groups of physical parameters that govern the response of practical wellbore-reservoir systems, are calculated by applying the Stehfest algorithm for numerical inversion of Laplace transformations.

The results presented in this paper provide criteria useful to evaluate the magnitude of inertial and frictional effects from rough estimates of the properties of a wellbore-reservoir system. These criteria can be utilized to minimize undesired inertial and frictional effects through design of a drillstem test. Results also indicate practical conditions under which inertial and frictional effects are significant. The solution method presented in this paper can be used to estimate reservoir properties by matching bottomhole pressure data measured during the flow period of a drillstem test. Also, the flow rate solutions provided by this method can be considered in pressure buildup data analysis of a subsequent shut-in period during a drillstem test.
Geological and Geochemical Techniques for Mapping Fractures and Fluid Flow Patterns in Geothermal Reservoirs
Authors: Moore J. N. , Nielson D. L.
Published: December 2007

Permeability in high-temperature geothermal systems is dominantly fracture controlled. However, fracture characteristics and cross cutting relationships among fracture sets are generally difficult to define from cuttings samples alone. In addition, the sparse number of wells in most systems limits the data that can be obtained on the areal fracture distribution. Despite these inherent difficulties, petrologic techniques and mathematical simulations can be used to develop the models of fracture geometry, permeability, and alteration that must be addressed by reservoir engineers. Our fracture studies have taken two approaches; first, establishing predictive structural models, and, second, documenting fluid-rock interaction using alteration mineralogy and geochemistry. Examples of the use of these techniques from active geothermal fields in the U. S. and Canada are described.
Laboratory Determination of Effective Liquid Permeability in Low-Quality Reservoir Rocks by the Pulse Decay Technique
Authors: Amaefule J. O. , Wolfe K. , Walls J. D. , Ajufo A. O. , Peterson E.
Published: December 2007

This paper discusses the application of transient pulse decay technique for determination of effective liquid permeabilities in low-quality reservoir rocks. Effective oil and water permeabilities ranging in values from 0.5 md to 290 nd (2.9 × 10−4 md) were determined by this technique with excellent reproducibility.

Low quality reservoir rocks commonly characterized by high porosity but very low permeability, are generally friable, sensitive to stress, fluid velocities, and volumes of fluid throughput. Effective liquid permeabilities are usually determined by the dynamic displacement technique. This method, which involves the flow of large volumes of fluid throughput before flow rate and differential pressure stability is achieved, is time consuming and not particularly suited to low quality rocks. In contrast, the pulse decay technique, previously developed for measurement of tight gas permeability, easily permits rapid determination of effective oil and water permeabilities with minimal pore volumes throughput at low velocities.

This paper reviews mathematical computational techniques and outlines proper experimental protocols for accurate determination of liquid permeabilities in low quality rocks. The experimental techniques allow for simultaneous determination of liquid compressibility needed as input data in most reservoir engineering calculations. Effective oil and water permeability data generated by the transient pulse decay are needed to predict fluid recoveries in low quality reservoirs.
Type-Curve Techniques for Hydraulically Fractured Lenticular Formations
Authors: Yousef O. M. , Evans R. D.
Published: December 2007

The development, analysis, and evaluation of type curve matching techniques for lenticular gas bearing formations are presented. The type curves are generated using a three dimensional, single phase, transient reservoir simulator modified to take into account lenticular sand lenses and hydraulically created fractures. The gas bearing sand lenses are assumed to be randomly distributed in orientation and space throughout the formation. Type curves are generated for an unfractured formation and vertically fractured formation with finite conductivity. Assuming different sand lense fractions, type curves are generated and compared with type curves developed for continuous (so called blanket) sand formations. The results of this comparative analysis indicates that the type curves for lenticular formations are significantly different from those of the blanket sand case that it may be possible to assess the degree of lenticularity of a given formation. Conclusions are drawn from the research presented and recommendations given concerning future research efforts.
Beauty or Beast: Tyler Formation Waterflooding in Central Montana—Field Results
Authors: D’Hooge J. A.
Published: December 2007

Currently, twenty-four projects have been, or are being, waterflooded in the Pennsylvanian age Tyler Formation of Central Montana. The heterogeneous nature of the Tyler sandstone reservoir lends itself to quick injected water breakthrough, reservoir discontinuities, poor areal sweep efficiency, and considerable difficulity in geologic interpretation. Despite all the negative factors, the Tyler secondary projects have exhibited favorable results. This case study shows that reservoir quality plays an important role in realizing higher recovery efficiencies. An understanding of the nature of the beast is required in order to maximize the recoveries from the Tyler Formation. In addition, polymer augmented waterflooding provides a possible means of enhancing these projects.
Reservoir Characteristics and Stimulation Techniques in the Bakken Formation and Adjacent Beds, Billings Nose Area, Williston Basin
Authors: Cramer D. D.
Published: December 2007

In the Billings Nose area, the Bakken formation is a shale and silty carbonate sequence, capable of producing oil in association with adjacent beds when naturally fractured, Oil/surfactant breakdown and gelled oil fracture treatments have been commonly utilized to stimulate these zones. The best fracturing results have been attained with use of small quantities of fluid loss additives and high concentrations of proppant. However, pre-frac acidization, in association with a selective perforating method, may improve completion efficiency.
A Study of the Economic Impact of Enhanced Oil Recovery in Wyoming
Authors: Terry R. E. , Varma J. K.
Published: December 2007

Various enhanced oil recovery (EOR) methods were considered in an economic analysis of the twenty-six largest fields in Wyoming. This analysis indicates that a majority of the fields are currently best suited to polymer augmented waterflooding or CO2 flooding, based on an average price of $1.25/Mscf for CO2 and $2.50/lb for polymers. With these prices, all floods were economically viable in reservoirs less than 6000 feet deep at a base price of about $26.00/bbl for oil. In deeper reservoirs, most CO2 floods were uneconomic when using a twelve percent minimum acceptable rate of return as the basis of decision. A lower CO2 price, in the range of $0.50 – $0.75 per Mscf, would make most of the CO2 floods economic in reservoirs up to 12000 feet deep.

As a result of the anticipated increase in enhanced oil recover revenues to the state through royalties and taxes were also estimated. The total amount of EOR oil recoverable by the use of currently available EOR techniques is estimated to be about 1.5 billion barrels. Assuming that one-third of the potential target--500 million barrels--is recovered in the next thirty years, the present value of the state revenues (at an, eight percent discount rate) would be about 1.1 billion dollars. This is based on an inflation rate of five percent. Five other situations with varying crude oil prices and inflation rates were also investigated.

Oil recovery should be aided by CO2 development in southwestern Wyoming, scheduled to begin in 1987. As a result, CO2 floods may replace polymer floods as the process of choice in some fields.
Detailed Core Description of a Dolomite Sample From the Upper Madison Limestone Group
Authors: Honarpour M. M. , McGee K. R. , Crocker M. E. , Maerefat N. L. , Sharma B.
Published: December 2007

Improvements in reservoir characterization can greatly enhance reservoir performance predictions. Heterogeneity within most reservoirs, such as the Madison Group, can be better understood from integration of results from detailed core analyses. A fractured dolomite core sample from the Upper Madison Group, near Carter Creek gas field in southwest Wyoming was studied in detail to supplement the current methodology for delineating heterogeneities in core samples. Directional permeability, fracture system orientation, and other heterogeneities related to the core sample fabric were determined and quantified by studies of: impregnated thin-sections and use of computed tomography x-ray intensity, x-ray diffraction, scanning electron microscopy, and energy dispersive spectroscopy. Computed tomography (CT) is a fast, nondestructive, qualitative and quantitative tool for the evaluation of fracture systems and associated mineralogy. The scanning procedure employed involved assigning a density range that would highlight minerals having characteristic CT densities. This procedure helped to identify variations of fracture infilling materials. The core analyses data were integrated with the regional geology, downhole logs, and production data for final evaluation.
Carbon Dioxide Corrosion in Oilwell Cements
Authors: Bruckdorfer R. A.
Published: December 2007

Carbon dioxide corrosion studies of oil-well Portland cements were initiated using a new micro-sample technique to determine the effect of carbonic acid on portland cement slurry formulations and to develop a high carbonic acid corrosion-resistant cement for carbon dioxide Enhanced Oil Recovery applications.

Earlier results from studies using two-inch API cement cubes showed carbonic acid had essentially no effect on cement after relative short test periods at elevated temperatures. Similar results with two-inch API cement cubes also were reported in recent literature. Because carbonic acid corrosion in cements was difficult to observe and measure using two-inch API cement cubes, a new microsample technique was developed. Use of this new technique, which represents an accelerated testing method, showed oil-well cements undergo a rapid deterioration in a wet carbon dioxide environment. Similar tests with two-inch cubes showed essentially no cement deterioration under the same conditions.

Experimental details of this new microsample technique are discussed. Data relating cement strength loss and carbon dioxide penetration depths to cement type and slurry formulation are reviewed. Included in the discussion is a new cementing formulation which shows significant promise as a high carbondioxide-resistant, oil-well cement.
Erosion Damage in Oil and Gas Wells
Authors: Venkatesh E. S.
Published: December 2007

Erosion damage in oil and gas wells are inevitable at high velocities. This is especially true when solid particles are produced.Current method of reduced production velocity as recommended by API is not satisfactory. Research in the direction of obtaining insight into erosion damage in oil field equipment indicates much work is required. This paper is an attempt in that direction.
Economic Consideration of Certain Weather and Oceanographic Problems Arising in the Petroleum Industry
Authors: Glenn A.H.
Published: December 2007

Introduction

During the past ten years the petroleum industry has been expanding rapidly to meet a major increase in the demand for its products. This expansion, carried on during periods of manpower and materials shortages, has required maximum efficiency in the exploitation of existing resources, and a vigorous campaign to locate and develop new resources. In such an unprecedented program of increasing production under adverse economic conditions certain problems, formerly considered of negligible importance, have become particularly troublesome. One such group of problems is the weather and oceanographic difficulties that are encountered through the gamut of petroleum operations, from management planning, through production practices, to the delivery of products to the consumer. Experience acquired in working on these problems during the past six years indicates that the amount of money involved incorrect decisions vs. incorrect decisions where weather and oceanographic conditions are a factor is of significant decisions where weather and oceanographic conditions are a factor, is of significant economic importance. This paper endeavors to indicate the economic scope of the weather and ocean problems in the petroleum industry, and summarizes some of the experience gained in attempting to arrive at an efficient method of attacking these problems.

Scope Of Weather and Ocean Problems

The following list summarizes some problems that have arisen during the past several years. The list is broken down into categories according to the departments in which the project was carried on.ProductionDesign studies for coastal and offshore facilities48-hour operational weather and sea forecasts for planning and safety in offshore construction, drilling and production.Weather and oceanographic instrumentation for developing design data for coastal and offshore drilling.Hurricane evacuation problems.Radar weather warnings (line squalls and northers)
Simplified Methods for Investment Analysis in the Petroleum Production Industry
Authors: Wade F.R. , Evert D.E.
Published: December 2007

This paper presents a number of abbreviated methods for determining the investment merit of projects in the petroleum production industry. The use of these simplified methods facilitates the analysis of investments without sacrificing essential accuracy. The valuator is not restricted to a single valuation of an investment but may easily determine a range of values corresponding to the probable range of the principal risks, and this may be done with a minimum of time and effort. The projected schedules of income of many investments in the petroleum production industry lend themselves admirably to the use of the time-saving methods that are outlined.

Several methods of calculating rate of return are rigorously defined, and the results of the calculation are compared with an example. Standard methods for performing rate-of-return calculations are suggested. The merit of rate of return as a "single number" index for investment valuation is challenged. Multiple analysis of the range of variables and profitability profiles are used to assist in the understanding of risk and are recommended to supplement rate-of-return calculations. Charts and tables of relationships derived in the Appendix are presented to facilitate use of the methods.

Introduction

Plagued by shrinking margins and diminishing returns from exploration, the oil industry must seek new approaches for maintenance of profit. A greater emphasis on economics has resulted from the present economic climate of the industry. Fewer opportunities for highly profitable investment mean that a more careful analysis of those investments available must be made to maintain a reasonable rate of return. A satisfactory approach to investment analysis can be one of the key factors for success in an industry with narrowing profit margins.

Recent publications have developed the technical and economic theory which is the basis for this paper. Many investments in the petroleum production industry result in a schedule of future income which may be considered either constant, declining according to one of the hyperbolic decline equations, or a combination of constant and declining income. The primary purpose of this paper is to present several methods of investment analysis which are easily computed and have an accuracy commensurate with the data employed for analysis.
Challenges of Modern Management
Authors: Shuman Sidney
Published: December 2007

Shuman, Sidney, Reed International, Inc., Houston, Tex.

This paper was to be presented at the 41st Annual Fall Meeting of the Society of Petroleum Engineers of AIME, to be held in Dallas, Texas, October 2–5, 1966, and is considered to an abstract of not more than 300 words, with no illustrations, unless the paper is specifically released to the press by the Editor of the Journal of Petroleum Technology or the Executive Secretary. Such 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 Society of Petroleum Engineers Journal is granted on request, providing proper credit is given that publication and the original presentation of the paper

Modern management faces three important challenges: developing good working relations between business and government, making the best uses of advancing technology, and ensuring constructive social change. Because of government's increasing influence on business, it is essential that business and government function as partners. Business also must get across to government that social progress is possible only if the profit motive is encouraged. To do this, business must improve its working relations with government. Business must make maximum use of the great technological advances taking place in industry, but must also apply its technical knowledge and management skill to the solution of social problems. This requires more active participation in politics, greater attention to such matters as urban renewal, waste disposal, transportation and increased assistance to schools and colleges both with money and ideas.

Acknowledgment

Edmund F. Martin, chairman and chief executive officer, Bethlehem Steel Corporation, addressing the American Iron and Steel Institute in New York City on May 25, 1966.

Text:

Gentlemen:

In searching for a subject that would be meaningful for you today, I came across an address delivered in New York earlier this year by Edmund F. Martin, chairman and chief executive officer of Bethlehem Steel Corporation. Mr. Martin spoke to the American Iron and Steel Institute, and some of the particulars of what he had to say were aimed primarily at an audience of steelmen. But the bulk of his comments were as applicable to all of us here today as they were to his audience in New York.
Rig Site Drilling Program Development for a Hand-Held Computer
Authors: Quentin K. M. , Creamer A. D.
Published: December 2007

Conoco was prompted by the demise of programmable calculators to reevaluate drilling engineering programs used at the rig site. In early 1984, commercial drilling engineering software for field use did not exist for hand-held computers. The decision was made to develop a comprehensive software package in-house which made maximum use of the most powerful hand-held computer then available. The cost in time and money was substantial and changing computer technology was constantly at issue with management. Some twenty members of the headquarters drilling staff organization were involved as subject experts and/or programmers. The approach used was to develop and manufacture three 32K byte custom ROM's in chip form.

Most of the two year project time was consumed in extensive research of engineering reference materials and conversion of subject matter experts from computer illiterates to programmers. An added benefit of program development was an upgrading of our current calculation techniques.

Conoco's Engineered Drilling Rigsite Chip (CEDRIC) is a unique, useful working and learning tool. Designed for drilling foremen and engineers, it encompasses field applications of traditional drilling engineering calculations including such diverse programs as optimum hydraulics, casing design check, leakoff test analysis with corrections, cement slurry design check, directional survey projection, and well control with bubble expansion. This paper outlines the history of the CEDRIC project and offers suggestions for anyone contemplating a similar computer adventure.
Applications of Microcomputer-Aided Design/Drafting (CADD) Software in the Petroleum Industry
Authors: Goldstein K. M. , Goldstein L. F.
Published: December 2007

The application of computer-aided design/drafting (CADD) software in the Petroleum industry had been advanced by the recent development of low-cost commercial CADD packages that run on microcomputers, rather than on mainframes. The cost/ benefits, and ease of use, and established base of more than two million microcomputers nationwide has led to the availability of powerful new tools for the Petroleum professional.
Some Implications of Applying the Theory of the Economics of Exhaustible Resources to Oil and Gas Pricing
Authors: Inyang E. D. , Stultz-Karim S. P. , Thackeray F.
Published: December 2007

The theory of the economics of exhaustible resources is reviewed and discussed in terms of its applicability to the complex structure of the international petroleum industry. Particular attention is given to the implications of uncertainty in reserves estimations for corporate, public, and financial institutions which have the responsibilities of oil and gas pricing and depletion policy formulation. A modification of the model of the economics of exhaustible resources under a freely competitive market structure is analysed to determine the effect of uncertainty in reserves estimations on the optimal net price and on depletion profiles.

The uncertainty in the resultant time until economic exhaustion and the discounted present value is found to be directly proportional to the uncertainty in the reserves estimations. These results should be carefully considered in the difficult conflicts between short-term profit maximisation and long-term social objectives in the formulation of public and private pricing and depletion policies.
Design, Specification, and Implementation of Drilling Operations Database Program
Authors: Dunn M. D. , Payne M. L.
Published: December 2007

An effective system of managing daily drilling information generated from the rigsite is a recognized method of optimizing those same operations. Such a system would quickly and thoroughly analyze data and present results in a fashion that would promote efficient monitoring of the operation and execution of engineering analyses. The program would compile the data and generate reports that would permit more timely and accurate decisions by engineers and managers.

This type of database management is very well suited for the computer hardware and software on the market today. Using an integrated departmental super-mini computer in ARCO's Southern District, a project was executed to automate the processing of drilling information. This paper covers the conceptual design, detailed specification, and physical implementation of the database system. The process used by ARCO to design and specify this program will benefit drilling personnel involved in managing operational data and costs.
Real-Time Treating Pressure Analysis Aided by New Correlation
Authors: Lord D. L. , McGowen J. M.
Published: December 2007

A scale-up correlation derived from laboratory experimentation and calibrated with field tubing data provides improved real-time estimates of bottomhole treating pressure (BHTP) during displacement of delayed-crosslink HPG fluids with or without proppant. Current real-time hydraulic fracturing pressure analysis requires knowledge of BHTP throughout treatments. Measurement of this pressure indirectly at the surface through a live annulus or directly by a downhole gauge is not always feasible, practical, or economically justifiable. In these situations, this pressure is estimated by adjusting measured surface treating pressure to downhole conditions.

Hydrostatic head is added and friction pressure losses subtracted from surface treating pressure to adjust to downhole conditions. Friction pressure loss estimates typically depend on laboratory, yard test, or field annular flow based, semi-empirical correlations. Correlations developed from data collected by these methods are shown not to be applicable to friction loss predictions for flow of these particular fluids down long vertical tubing strings. Verification of this point is presented in the form of comparison of directly measured values to values predicted by correlations based on these methods presented in this paper and in the literature.

A laboratory correlation developed in this paper was found to possess some unique characteristics which lend themselves readily to field calibration with actual tubing friction loss data. Field calibration, combined with a capacity to consider various tubing diameters, flow rates, and gel/proppant concentrations creates a powerful tool for estimating tubing friction pressure loss and hence BHTP when injecting these fluids on a real-time basis.
Mini-Frac Analysis Based on Ellipsoidal Geometry
Authors: Lee W. S.
Published: December 2007

When Nolte1 pioneered an analysis of pressure decline after fracturing in 1979, the method was available for only one fracture geometry model, namely the Perkins-Kern constant height model. Since then, this method of analysis has gained increasing attention in the industry. Consequently, the method has been extended to three more geometry models, namely the Christianovich and Zheltov constant height model, the Penny-shaped model2 and the Ellipsoidal-shaped3 model. In this paper a new method of analyzing pressure decline data will be presented applicable to all four geometry models, with the emphasis on ellipsoidal geometry. The method of pressure decline analysis based upon the type curve method originally developed by Nolte1 and the method described in this paper will be referred to respectively as the conventional method and the new method.
Analysis of Dispersion in a Layered Porous Medium with Micro-heterogeneity of Arbitrary Shapes and Size Distribution
Authors: Lee S. T. , Okuyiga M.
Published: December 2007

This paper presents a study of the dispersion phenomena associated with a linear miscible displacement in a stratified porous medium with interbedding of permeable and tight layers. The permeable layer contains microporous grains in the form of slabs, cylinders or spheres having a varying size distribution. The model incorporates various mechanisms for mass transfer including convection parallel to the bedding, intergranular longitudinal dispersion, and intragranular molecular diffusion.

Based on the mathematical model, a Laplace-space analytical solution was derived for the effluent concentration. Then, analytical expressions for the moments of the effluent concentration were derived; from this, an expression for the effective dispersion was obtained. The formulae derived permit a quantitative examination of the reservoir parameters that affect dispersion, and thus the displacement efficiency for processes of interest.

Other theoretical and qualitative results obtained which are also of fundamental importance include: From a theoretical analysis of the effective dispersion, the contributions of the interlayer and intragranular mass transfers are shown to be equivalent to Taylor's dispersion.The longitudinal dispersion is of minor importance in the overall dispersion of the process, especially at higher velocities.For fixed void fractions, the spherical microporous grains give the smallest dispersion of all porous grain shapes considered.The effect of a non uniform particle size is to increase dispersion.

Our model was then compared to the Coats-Smith (C-S) model. An effective mass transfer coefficient, equivalent to that used in the C-S model, was derived based on the second moments of both models. Finally, we propose an approach that can alleviate the problem of parametric non-uniqueness when performing parameter estimation for linear miscible models.
The Influence of Water and Carbon Dioxide on the Phase Behavior and Properties of a Condensate Fluid
Authors: Ng H. -J. , Robinson D. B.
Published: December 2007

The behavior of condensate fluids in the presence of water and carbon dioxide is of considerable interest because of the effect these compounds can have on some of the reservoir fluid properties.

This paper describes a series of experimental measurements on a typical condensate reservoir fluid and gives compressibility factors above the retrograde dew point to a pressure of over 49 MPa at 177.8°C for both the dry and water-saturated fluid. It also gives vapor-liquid and vapor-liquid-liquid phase compositions at 10.34 and 20.68 MPa and temperatures of 37.8° and 93.3°C respectively. Condensation curves are presented for the water-free fluid at 177.8°C and for the water-saturated fluid at 37.8°, 93.3°C and 177.8°C.

Experimental results are also presented for the initial carbon dioxide crystallization temperature for the condensate separator gas after flashing at −28.9°C and 7.38 MPa.

The experimental and calculated results are compared using a cubic equation of state.
An Experimental Study of Drilling Fluids Dynamic Filtration
Authors: Vaussard A. , Martin M. , Konirsch O. , Patroni J. -M.
Published: December 2007

An experimental study was carried out by the ARTEP research group on the filtration of drilling fluids under borehole conditions and on its main consequences (differential pressure sticking, rate of penetration, damage to formations).

The filtration of drilling fluids has long been recognized as an important parameter for drilling operations, but filtration properties and cake characteristics under borehole conditions are not usually well estimated, as laboratory testing procedures only consider static conditions.

Laboratory tests performed with special apparatus on three mud types allowed a better knowledge of the phenomena.Dynamic filtration is dependent upon cake build-up. The results show the relation between shear rate and fluid loss; the time necessary for dynamic filtration stabilization can be long. The main parameters of dynamic filtration seem to react differently to those of static filtration.Differential sticking: a comparative study underlines the importance of fluid nature and filter cake characteristics on the pull-out force required to free a stuck pipe.Rate of penetration: generally accepted rules were confirmed, but in some circumstances the effect on R.O.P. of actual filtration under the bit can also depend on other parameters (mud type, bit selection).Damage to permeable formations: damage to clean (non clayey) sandstone can be limited by controlling cake quality. Special attention must be paid in the case of oil-based muds, whose dynamic filtration and cake properties can be unexpectedly detrimental.
A Study of Pressure Transient Behavior in Bounded Two-Layered Reservoirs: Shengli Field, China
Authors: Joseph J. , Bocock A. , Nai-Fu F. , Gui L. T.
Published: December 2007

A series of pressure transient tests was recently conducted on several wells in the Shengli Field in China. This paper contains a new approach to the analysis of such tests. Limitations of the results, alternative interpretations and recommendations for improving multi-layer well testing are also discussed.

The most versatile plot for identification and diagnosis of reservoir heterogeneities (including the effects of layering, boundaries, and deviation from homogeneous behaviour in general) is the combined pressure/derivative of pressure format. The high accuracy attainable in modern pressure gauges makes this approach both plausible and reliable. It has been used extensively in the present study.

An analytical model of the two-layer bounded system is utilised. It is capable of treating skin, wellbore storage, and both crossflow and commingling of the reservoir fluids. Finally, field datasets displaying layering (supported by geologic evidence) are analysed.
Relative Diffusion Flux: A Practical Concept for Characterizing Fracture to Matrix Gas Transfer—Application to Fractured Reservoir Model
Authors: Sener I.
Published: December 2007

This paper introduces the concept of "relative diffusion flux", a new and practical approach to characterize the dissolution and diffusion regulated transfer of gas from the gas filled fracture space to the matrix oil in a dual porosity /permeability system.

The proposed concept is analogous to the relative permeability concept in that the "effective diffusion (or transfer) flux" is determined as the product of the "absolute (maximum) diffusion flux" capacity of the matrix and the current level of "relative diffusion flux". It is shown that the latter can be expressed as a function of the current dissolved gas concentration in the matrix oil. This functional relationship between the "relative diffusion flux" and the dissolved gas concentration in the matrix oil is similar, in concept, to that between the relative permeability to a phase and its saturation level.

It is also shown that, using the proposed method, representation of the gas transfer mechanism is reduced to a simple exchange-type relationship between the fractures and the matrix. This is achieved without having to determine an appropriate diffusion coefficient and the task of handling gas transfer by diffusion is significantly facilitated for fractured reservoir simulators.

In the paper the concept of "relative diffusion flux" is developed, a method for obtaining the required data from a suitable laboratory experiment is provided, and the basic equations for the application of the new concept to fractured reservoir simulation are derived.
Development of a Well Spacing Program for the South Womack Hill Field, Clarke and Choctaw Counties, Alabama
Authors: Daigre R. G. , Wood R. T. , Wiggins G. B.
Published: December 2007

The degree of heterogeneity that can exist in carbonate reservoirs and the effect that heterogeneity can have on recovery efficiency has long been recognized. In sandstone reservoirs, the degree to which heterogeneity can exist and its effect on recovery efficiency is often overlooked or not considered in the development of a well spacing program. A recent study was conducted to determine the appropriate spacing for a newly discovered reservoir in Alabama. The results of this study indicated that in order to maximize recovery efficiency and present worth, closer spacing of wells would be required due to reservoir heterogeneity, reservoir size and configuration, the thickness of the reservoir and the amount of oil in place.
Characterization of the Austin Chalk Producing Trend
Authors: Chen H. Y. , Poston S. W. , Wu C. H.
Published: December 2007

Fracture patterns and reservoir dual-characteristics are presented for a portion of the fractured Austin Chalk producing trend. The production histories of 1,235 wells from Giddings Field covering portions of Lee, Burleson, Washington, and Fayette counties were analyzed by decline curve analysis. Production of the average Austin Chalk well is usually characterized by an early rapid decline and a later slow decline. The average initial effective decline rate is about 90% per year, and lasts about six months to one year. For the later, less dramatic decline, the average is about 35% per year.

Statistical results of well performance indicate no difficulty in finding oil in the Austin Chalk producing trend. However, areas of high fracture density must be encountered for a well to be profitable. A contour map of the iso-reserves was prepared for a better understanding of the fracture system and reservoir characteristics. Besides the general northeast-southwest production trend, the map shows anomalies in the fracture system and reservoir characteristics. A simple, rapid technique to estimate reservoir parameters directly from the double-decline behavior of log (rate) versus time curves is given. Values of flow capacity, storage capacity, dimensionless fracture storage parameter (ω), and dimensionless interporosity flow parameter (λ) can be estimated by this technique.
Evolution of a System Approach to the Design and Organization of Oilfield Producing Facilities
Authors: Kretzschmar K.H. , Smith M.A.
Published: December 2007

The usual approach to the design and organization of producing facilities results in inefficient utilization of equipment and manpower. A more effective approach is suggested, in which all facilities related to the producing, gathering, processing and transportation of reservoir fluids are regarded as constituting a single, integrated system. System design concepts are outlined, and three case histories are presented to show how these concepts have been successfully applied to large scale operations.

It is concluded that a further extension of the system approach to its ultimate objective must inevitably lead to a functional reorganization of the various corporate identities engaged in finding, producing and exploiting sources of oil and gas, with benefits to all concerned.

Introduction

The development of oilfield producing facilities in a given field normally parallels very closely the course of development drilling in that field. The location of production centers or batteries, at which testing, treating, storage and custody transfer take place, is usually determined on the basis of geographical apposition with a conveniently sized group of wells and the pipe line gathering facilities. As development drilling proceeds, duplicate production centers are added in the same manner.

This approach encourages redundancies in facilities and equipment. These redundancies result in overall development costs which are excessive in relation to production volumes. Utilization of labour is inefficient and operating costs are higher than necessary in relation to the functions performed. Flexibility to meet changing conditions is poor, and a significant improvement in operating efficiency can only be achieved through a comprehensive reorganization of the existing facilities.

It is the purpose of this paper to demonstrate how an integrated system approach to the design of producing facilities can forestall involvement in these problems, or help to solve them effectively where they already exist.