bluuebunny/crossref_metadata_2025 huggingface dataset:
The Deep Propagation Tool (A New Electromagnetic Logging Tool)
Authors: Huchital G. S. , Hutin R. , Thoraval Y. , Clark B.
Published: December 2007

This paper will discuss a new well logging tool, the Deep Propagation Tool (DPT*). The device radiates electromagnetic energy into the formation surrounding the well bore. Measurements of the attenuation and velocity (wavelength) of this electromagnetic wave will yield the resistivity and dielectric constant of the formation.

The use of an accurate measurement of formation resistivity is well known. The measurement of formation dielectric constant has recently been shown to be of use in formation evaluation for cases of variable formation water resistivity.(1)

Previous devices used to measure the dielectric constant of the formation have had relatively shallow depths of investigation. The Deep Propagation Tool uses a unique antenna array in order to return formation electrical parameters characteristic of the uninvaded formation.

The device operates at a frequency in the tens of megahertz range and performs accurate measurements of signal level and relative phase at four receivers locations. These eight measurements can then be used to return a value for the formation resistivity and dielectric constant.

The theoretical basis for the design of the tool will be presented. This will be applied to predict the environment effects on the response of the device. Attention will be paid to the effect of the borehole on the measurement, the depth of investigation of the device, and its vertical resolution.

Measurements have been made in wells in both Europe and South America. Results of these measurements are quite interesting and show that the measurement of formation dielectric constant can be used to determine the presence of hydrocarbons in zones of variable connate water resistivities where traditional resistivity measurements are not easily applied.
Effect of Fluid Flow Rates on Geochemical Processes
Authors: Dibble Walter E. , Potter Jared M.
Published: December 2007

A promising research avenue is determining the influence of fluid flow rate on mineral growth and dissolution reactions. Using flow-through hydro-thermal apparatus, we have explored experimentally the relationship between flow rate, alteration mineralogy, and reaction rates under a variety of conditions. At high flow rates, reactions occur that favor the formation of stable minerals. At low flow rates, under the same conditions, less stable phases can be produced.
Gravel Packing for High Rate Completions
Authors: McLeod Harry O. , Crawford Horace R.
Published: December 2007

Good engineering design and execution of gravel pack procedures can and have increased the oil flow rates of wells in the Gulf of Mexico by many thousands of barrels per day. However, many completions have failed to perform at design rates. The primary reason is that design methods have neglected the effect of the damaged formation around perforations. If damaged perforations are considered along with the effects of perforation washing, well flow analysis can better predict expected well productivity and help select better completion procedures.
The Influence of Placement Conditions on the Response of Gravel Packs to Production
Authors: Torrest Robert S.
Published: December 2007

Experiments in well bore models illustrate the influence of placement variables on gravel pack response to fluid production. Increasing pressure drop across packed perforations with increasing flow rates for production into the well bore was used as a measure of pack quality. With proper placement, pressure drop to 150 psi followed a smooth curve characteristic of a fixed porous medium. Otherwise, the perforation gravel is pushed back in a series of plug-like movements which show up as discontinuities on the curve and may lead to "blow-outs."
Multiphase Flow in Porous Media: II. Pore-Level Modeling
Authors: Mohanty Kishore K. , Salter Stephen J.
Published: December 2007

The pores a phase occupies and the way those pores are interconnected are shown here to determine the macroscopic transport properties of that phase. Such transport properties are dispersivity, capacitance, relative permeability and. capillary pressure. A pore-level, three-dimensional network model is presented in this paper which incorporates the structure of porous rock, pore-level fluid displacement mechanisms and saturation history. The model calculates pore-level distribution of fluids, and then computes steady-state transport properties of such distributions. The results are compared with experimentally obtained values and illustrate the nature of fluid flow and the mechanisms of mixing in strongly wetting rocks.
The Effect of Drainage Area and Production Rate on the Performance of Depletion Drive Oil Reservoirs
Authors: El-Khatib Noaman A. F.
Published: December 2007

A modified performance prediction method for depletion drive oil reservoirs that accounts for pressure and saturation variations within the reservoir is outlined. This developed method is used to study the effect of such parameters as production rate, well spacing, shape of drainage area and well location and formation damage on reservoir performance. This study shows that production rate,well spacing and formation damage significantly affect the performance while the shape of drainage area and the well location within a specified drainage area has insignificant effect on the performance. Fractional oil recovery Is found to Increase and the producing gas-oil ratio to increase at increasing production rate, increasing well spacing and increasing skin factor.
A Generalization of Production Decline Type Curves
Authors: Harrison G. H
Published: December 2007

The theoretical basis of production decline curve analysis is demonstrated by use of well-established non-empirical well-inflow performance models.

It thus becomes possible to generate a new set of generalized production decline log-log type-curves, of which the one existing in the literature is a subset.
An Analysis of Infill Drilling
Authors: Gould Thomas L. , Mupoz Mark A.
Published: December 2007

Infill drilling of a pattern waterflood is a common practice in order to achieve accelerated production and improved recovery. Infill drilling is also performed for tertiary oil recovery projects in order to decrease project life and improve reservoir control. The purpose of this study was to analyze the effect of reservoir and fluid properties on infill performance and determine the conditions under which infilling is economically justified. In many cases a tertiary project cannot justify the capital cost of infill wells. However, if incremental secondary oi1 was recovered as a result of infilling, this could partially or fully offset the investment.

Waterflood simulations were performed on single 1ayer and multi-1ayer five spot symmetry elements. Infilling was performed at several water cuts in order to evaluate the effect of initial saturation distribution on oil rate decline characteristics. Infill decline characteristics and "cut-cum" analysis were compared with continuation of the existing waterflood to the economic limit.

We have shown that infill drilling performance is sensitive to water cut at infill, oil viscosity, heterogeneity, and the degree of cross-flow between 1ayers. Under the right conditions, infilling has three major benefits to a project: Incremental recovery at the economic limitAccelerated oil productionReduced operating cost through lower water cuts

The results of this work can be used to estimate the amount of incremental secondary oil that will result from infill drilling an ongoing pattern waterflood.
Pressure Transient Analysis for Naturally Fractured Reservoirs
Authors: Cinco-Ley Heber , Samaniego V. Fernando
Published: December 2007

New ideas are presented for the interprtation of pressure transient tests for wells in naturally fractured reservoirs. This work is based on the transient matrix flow model formulated by de Swaan. The differences between this model and the Warren and Root model occur during the transition flow period.

It is demonstrated that the behavior of a naturally fractured reservoir can be correlated by using three dimensionless parameters. (i.e. ω, AfD, ηmaD. It is established that regardless of matrix geometry the transition period might exhibit a straight line whose slope is equal to half the slope of the classical parallel semilog straight lines, provided the transient matrix linear flow is present. In addition, information is provided on the estimation of fracture area per unit matrix volume or matrix parameters from the transition period semilog straight line. It is shown, that matrix geometry might be identified when pressure data are smooth. Field examples are included to illustrate the application and the validity of the theoretical results of this study.
The Economic Advantages of Computers in Producing Operations
Authors: Attra H.D.
Published: December 2007

Continued advances in computing technology have stimulated great interest in the objectives and the results of this activity. This paper summarizes some profitable new computing applications developed for producing operations in the fields of Economics, Planning, and Reservoir and Production Engineering. Each application is reviewed in terms of the problem to be solved, the approach used to solve it, results where available, and the requirements for long-range profit potential.

Two basic conclusions are reached. First, advanced computing methods can be adapted to a wide scope of our producing operation with profitable results, and, second, the most important requirement for successful computing is a thorough understanding of our problems and the economic potential to be gained from their solution.

INTRODUCTION

"The requirements for scientific computing have doubled each year since 1952, and the trend seems to be continuing." This statement and others like it have led to two very basic questions - How is this activity improving profits? And where is the payout? A great deal of information is available in the technical literature on new mathematical techniques for solving otherwise insurmountable problems. An equal volume of accounting literature is devoted to automated but straightforward data-handling methods that aim simply at reducing cost over manual procedures. Most of these articles stress computing techniques rather than the fundamental requirements for profitable use.

This paper discusses the basic consideration involved in applying some of the new computing techniques to economic planning studies of field producing operations Each application is discussed in terms of the basic problem to be solved, the approach used to solve it and the economic considerations involved The discussion is not intended to detail the numerical approach or data requirements used for each procedure. However, this information is available through the referenced material. In most cases, the applications do not employ mass data-handling methods or involved numerical techniques. They follow an approach which closely simulates sound engineering logic and relies upon a thorough understanding of the problem trid the economic potential to be gained from its solution. This point is better illustrated by reviewing specific problems which are being solved in the fields of Economics, Planning, Drilling and Reservoir Analysis.
Measurement of Formation Resistivity Changes Induced by In-Situ Combustion
Authors: Lee D. O. , Wayland J. R.
Published: December 2007

Use of controlled source audio magnetotelluric (CSAMT) techniques to map thermal fronts associated with enhanced oil recovery (EOR) processes depends upon knowledge of the changes in formation electrical resistivity. Measurement of these changes required the development of a technique which survives high temperatures and a very corrosive environment while measuring over a frequency range of 5 Hz to 5000 Hz. The apparatus to make these measurements is described. The results from a laboratory forward dry combustion test in the University of Calgary combustion tube are presented. It is found that there is a two-decade change in the resistivity as the fire front traverses through a region. Also there are indications of the separate zones within a fire front. The importance of these results to interpreting CSAMT data are then considered. The frequency dependency of the resistivity changes suggests means of increasing CSAMT sensitivity of deep oil pay-zone mappings.
Effects of Hydraulic Parameter Cleaning Variations on Rate of Penetration of Soft Formation Insert Bits
Authors: Doiron Harold H. , Deane John D.
Published: December 2007

Effects of hydraulic cleaning parameter variations on rate of penetration response of 7 7/8 inch diameter soft formation insert bits have been measured in laboratory drilling tests. Tests were conducted in Mancos Shale rock samples at 700 psi and 4000 psi simulated overbalance pressure conditions using a 9.1 pound per gallon bentonite-barite water base drilling fluid. Bit hydraulic horsepower was varied from 0.72 to 9.5 HHP/in2 using two or three nozzles in sizes ranging from 9/32 to 14/32 inches in diameter. Some improvements in ROP at constant bit hydraulic horsepower and impact force levels were obtained with two nozzle configurations vs. three nozzle configurations, but improvements were not consistently out of the range of normal test to test variations.

Reduction in drilling costs due to the measured response of ROP to improved hydraulic cleaning is compared to increased operating costs required to provide additional hydraulics. Results indicate that bit hydraulic horsepower levels in excess of popular rules of thumb are cost effective in slow drilling due to high overbalance pressure.
The Development of Structured Cavitating Jets for Deep-Hole Bits
Authors: Johnson Virgil E. , Chahine Georges L. , Lindenmuth William T. , Conn Andrew F. , Frederick Gary S. , Giacchino George J.
Published: December 2007

The erosion and cleaning effects of jets are enhanced when the degree of cavitation occurring on or near the bottom of the hole is increased. A new, STRuctured Acoustically Tuned Oscillating Jet ("STRATOJET") system causes the formation of large discrete vortex rings that promote cavitation to depths several times greater than for conventional jets. The new nozzle designs are shown to be suitable for existing mechanical drill bits and may even enhance hole cleaning in the absence of cavitation. Recent data on the effect of drilling mud on the amplitude of excitation and some laboratory hole bottom cleaning results are also presented.
How Instantaneous are Instantaneous Shut-In Pressures?
Authors: McLennan J. D. , Roegiers J. -C.
Published: December 2007

Instantaneous shut-in pressure is a term commonly employed, but often used indiscriminately. Shut-in pressure is conventionally regarded as a static pressure-equilibrium condition existing between a slightly open fracture and the in-situ stress regime. Several techniques for determination of this pressure level, from pressure-time records, have been presented.

This report reviews the various definitions and mechanisms for shut-in pressures and critically evaluates the general validity of this concept as a stress parameter indicator. It also outlines the factors which may affect the positive identification of a distinct shut-in (i.e., leakoff, nonuniform fracture azimuth, presence and distribution of proppant and fracture length). The report also provides an alternate interpretation technique, allowing for discrimination between effects of this nature and the existing in-situ stress field.

The alternate technique is corroborated by precise laboratory testing and by back analyses of various field situations, including micro-hydraulic fracturing and hydraulic fracturing treatments.
Enhanced Recovery of Oil by Alkaline Steam Flooding
Authors: Okoye Christian Udokwu , Tiab Djebbar
Published: December 2007

The results of the laboratory studies of alkaline steam flooding of previously water flooded sandpacks and cores are presented in this paper. In these studies the applicability of alkali as chemical additives to steam in tertiary recovery of heavy oil was investigated. Four kinds of alkali: Sodium hydroxide sodium silicate, sodium carbonate and potassium hydroxide were added to steam, each on separate case, as a chemical additive to enhance oil recovery from water flooded sandpacks and cores.

These studies examined the feasibility of achieving the following goals: (1) Combination of the individual oil recovery mechanisms of steam flood and alkaline flood to improve the net recovery performance over either single process, (2) Improvement of sweep and displacement efficiencies by having alkaline condensate sweep the lower portion of the formation usually over ridden by steam, (3) Low interfacial tension displacement induced by in situ solvent drive, (4) Favorable wettability alteration, (5) Rigid film breaking, (6) Viscosity reduction, (7) Temperature reduction, below that for conventional steam flooding, in alkaline steam flooding without loss in oil recovery performance, (8) Determination of the optimal temperature range for alkaline steam flooding in tertiary oil recovery processes and (9) Evaluation of the recovery performance of alkaline steam flooding at low residual oil saturations.

The optimal process or processes for alkaline steam flooding was deduced from six aspects of caustic steam flooding conducted on water flooded glass bead-packs in a previous investigation.2 Based on the recovery performances of the six cases examined, the processes of alkaline steam flooding following conventional water flooding were adopted to evaluate the oil recovery performance of the four alkali on sandpacks and berea cores.

Sodium hydroxide, sodium silicate and potassium hydroxide - steam floods in sandpacks recovered, each, about 9 percent more of initial oil in place than conventional steam flood. With berea core as the displcaement media, caustic steam flooding and sodium silicate - steam flooding recovered 10 and 6.5 percent respectively more of initial oil in place than conventional steam flooding. Caustic potash steam flood was not conducted in berea core because of the non-unique performance in the sandpack test and the high cost both of which will render it uneconomical for practical applications. Sodium carbonate steam flooding failed in both sandpack and core tests having recovered far less oil than conventional steam flooding in both situations.
Further Investigator of Pressure Transient Testing in Steamflood Projects
Authors: Messner Gregory L. , Williams Richard L.
Published: December 2007

In a previous work3 it was demonstrated that pressure transient analysis techniques could be applied to steam injection wells, providing important information regarding the progress of a steamflood project. In an extension of that study, the authors have examined several other aspects and applications of pressure transient analysis in steamflood projects. Through the analysis of actual steam injection well pressure falloff data and numerical simulation results, the application of the real gas law and the effects of the gravity segregation of steam have been addressed. Also, the feasibility of interference testing has been studied.
Evaluation of Reservoir Risks and Economic Assumptions in Bank Lending
Authors: Pelley William E. , Constable Richard W.
Published: December 2007

The significant factors in oil and gas loan evaluation have been shifting in recent years. Although reserve analyses and their associated production rates remain basic to an analysis, the economic factors of pricing may frequently involve a greater sensitivity to loan safety than reservoir interpretation.

This paper comments on these changes and on the problems of political risk. A plea is made for realistic evaluations and a recognition that problem credits hurt the borrowing institutions as well as the lenders.
Automatic Control of the Wattenberg Gas Field, Colorado
Authors: Reese Charles P.
Published: December 2007

This paper discusses the successful implementation of automatic control in the Wattenberg Gas Field in northern Colorado. Also discussed is the use of solar powered Amocams equipment to affect continuous monitoring and control of these tight gas wells.

The control system includes an algorithm which continuously adjusts the production cycling based on changes in the individual well's producing pressures and flow rates. This strategy has been successful in enhancing production and reducing the number of wells logged off due to excessive fluid buildup.

A review of the benefits derived from this system are enumerated and the impact on field operations are discussed.
Fiberscopic Inspection of Pipe Provers
Authors: Williams Iva J.
Published: December 2007

Measurement of crude oil constitutes the last stage of production operations. Lease Automatic Custody Transfer (LACT) units are commonly utilized to measure crude oil volumes throughout the industry. LACT units consist of a meter to measure the quantity of oil and a sampling system to retain a representative sample for later quality measurements. The meters typically are calibrated with a device known as a pipe prover by comparing the known volume throughput of the pipe prover to the volume registered on the meter totalizer. American Petroleum Institute (API) standards require the calibration of pipe provers once every five years to establish the known volume. If the prover volume changes during this period, then the calibrated volume and the meter factors obtained will no longer be accurate. Consequently, the actual volumes transferred and the volumes reported as transferred for accounting purposes will be different. Internal coating degradation will result in the producer being credited with less oil than is actually transferred. Approximately 1300 meter factors will be determined by one prover pipe in a year, thus, the economic impact due to coating degradation can be substantial.

The use of fiberoptics has provided an improved means for the inspection of a pipe prover's measurement chamber to check coating integrity. In fact, at locations where the coating has "bubbled" due to a gas entrainment, subsequent coating sloughing has been documented. Worn coating, scratches, primer and base metal are detectable. In cases where the coating and primer have been removed, the condition of the base metal is easily discernable. The fiberoptic inspection provides a field screening method to determine the need for recalibration when coating degradation has occurred.
Effect of Temperature and Pressure on the Density of Drilling Fluids
Authors: McMordie W. C. , Bland R. G. , Hauser J. M.
Published: December 2007

Laboratory data are presented on the changes in the densities of 11–18 lb/gal oil and water base drilling fluids in the temperature and pressure ranges of 70°–400°F and 0–14,000 psig. Results indicate that the change in density of a given type of drilling fluid appear to be independent of the initial density of the fluid, and as oil base drilling fluids are subjected to high temperatures and pressures, they become more dense than water base drilling fluids. The test apparatus and calibration are also described.
Use of a NovelLiquid Gelling Agent for Acidizing in the Levelland Field
Authors: Leggett Brude , Norman Lewis R. , Colbert Jason R. , Nelson David O.
Published: December 2007

The San Andres dolomite formation of the Level land Field in Hockley County, Texas is typically stimulated by acidizing. The types of treatments include workovers of production and injection wells, and initial stimulations of infill drilled wells. This formation is naturally fractured and normally produces a large quantity of released fines following an acidizing treatment. Gelled acid systems are beneficial in stimulation of these type formations due to decreased fluid leakoff and improved fines suspending ability. Several types of acid gelling systems based on polymers are presently available. The use of residual polymer or degraded polymer residue in the Levelland Field may prevent complete recovery of treating fluids and fines.

A gelling agent based on surfactant rather than polymer chemistry has been found to exhibit some unique foam properties in laboratory experiments. Acid gelled with this novel thickener required no additional foaming surfactants, gave higher quality foams than polymer thickened acids of equal viscosity, and allowed stable foams to be prepared which contained less than 50% nitrogen.

An evaluation of this gelling-foaming system has been done in the Levelland Field. A comparison is made based on field results between regular acid and other gelled acid systems. Wells with similar pay quality were selected using log and other analyses and comparative treatments were performed. Details of these treatments and production results are given in the paper. Cumulative production data one year after treatment revealed foamed surfactant gelled acid to be the most effective treatment for initial stimulations.

Further evaluation of acid gelling systems is presented in the paper through a composite of results from surfactant gelled and conventional acid treatments involving workovers of producing wells.

Although many treating variables were not constant, production results from surfactant gelled acid indicates substantial improvement over more conventional acid systems.
The Response of Interwell Tracer Tests in Watered-Out Reservoirs
Authors: Hagoort Jacques
Published: December 2007

A study has been made of the response of production wells to the injection of a tracer pulse into an injector in watered-out reservoirs. Two response functions can be distinguished: (i) the tracer production rate and (ii) the cumulative tracer recovery both as functions of time. It is shown that the tracer response to pulse injection can be obtained from the results of a unit-mobility-ratio, equal-density miscible displacement. The cumulative tracer recovery is identical with the production rate of the displacing phase. The tracer production rate follows from differentiation of the production rate of the displacing phase with respect to time.

For some simple flow systems, analytical solutions are presented that bring out the general features of the responses of interwell tracer tests. Linear flow solutions indicate the effect of longitudinal mixing to be negligible, whereas transversal mixing is important in layered reservoirs only if the individual layers are relatively thin (cm-dm scale). Solutions for a homogeneous two-spot show the effect of a pattern. The production-rate response is slide-shaped: a sudden rise followed by a fairly extensive fall-off period. This fall-off period becomes shorter for more linear patterns. In stratified reservoirs each layer produces its own ‘slide’ response. The responses of the less prolific layers, however, may be completely swamped by those of the more prolific layers.

A procedure is indicated to model ‘single-colour’ and ‘multi-colour’ field tracer tests with the help of a conventional black oil simulator. It is based on the mathematical similarity that exists between two-phase immiscible flow and two-component miscible flow. For accurate simulation results a fine grid system (at least seven grid blocks between injector and producers) must be employed.

The study may find application in the planning, design and interpretation of field tracer tests in watered-out reservoirs. The results of this study also apply to tracer tests in gas cycling projects.
Experiences with Natural Gamma Ray Spectral Logging in North America
Authors: Fertl W. H. , Frost E.
Published: December 2007

The last few years have brought on the inclusion of natural gamma ray spectral logging devices as an integral part of optimized wireline logging programs. Recorded in both open hole and cased hole environments, such logs have proven invaluable in solving the complex interpretation problems encountered in many wells. Interpretive concepts have advanced both at the wellsite and for detailed digital analyses at central processing centers.

Current wellsite evaluation techniques, as well as several recently developed digital interpretive methods for shaly sands and complex and fractured reservoir rocks, will be discussed. Inherent environmental constraints of natural gamma ray spectral logging devices are also highlighted.
The Impact of Common Completion and Workover Activities on the Effective Costs of Geothermal Wells
Authors: Carson Charles C. , Mansure A. J.
Published: December 2007

Drilling and completing wells at minimum initial cost may not be the most cost effective way to exploit the geothermal resource. The impacts of completion practices on production and maintenance costs must also be considered. To evaluate alternative completion and workover technologies, a simple model has been developed that compares total well cost to total production or injection. This paper briefly discusses the model and focuses on results from its application to different completion and workover strategies.

The model development project had three aspects: 1) the establishment of a data base for the cost and effectiveness of various geothermal completion and workover activities; 2) the development of a computer model built around these data; and 3) application of the model to specific cases. The data collected include geothermal production characteristics; initial costs and effectiveness of common workover equipment and operations; the frequencies of and times required to perform work-overs; etc. The model facilitates comparisons of completion and workover alternatives. Its primary purpose is the evaluation of potential impacts of proposed geothermal completion technologies in order to aid the management and direction of the DOE/Sandia Geothermal Technology Development Program.

The results discussed include an analysis of the impact of variations in well lifetime. Additional lifetime beyond 10 to 15 years adds little value to the well. A comparison of mechanical descaling of geothermal wells to chemical scale inhibition indicates that for certain conditions chemical inhibition is more cost effective. Results of an analysis of injectivity decline are also presented, as are studies of original well cost, initial flow rate, and productivity decline for production wells. Other results involving underreaming, changing casing profiles, perforating, and hydraulic fracturing are also discussed.
Testing of Gas-Tight Joints Under Extreme Conditions
Authors: Marx Claus , Krug Gerhard
Published: December 2007

During production from high-pressure gas wells, the casing and tubing strings are subjected to a combination of extreme loads due to internal pressure, axial loads, temperature, and sometimes bending. All loads may vary greatly during production cycles or production and shut-in periods. Testing facilities and programs are needed for evaluating the functional behavior of pipe connections during load and temperature cycles simulating actual field conditions.

The paper describes a complete testing set-up with high capacity and flexibility. The unit allows internal gas pressure up to 3500 bar, axial loads of 3000 kN, bending loads of 3600 kN, and temperatures up to 185°C at the joint.

Furthermore, the paper presents results derived from a large number of tests on tubing and casing of various sizes,grades and joints, including 2–3/8" tubing and 10-3/4" heavy wall casing.
Mathematical Modeling of Gas Field Development and Production Optimization
Authors: Zakirov S. N. , Kolbikov S. V. , Kalra S. K.
Published: December 2007

A complex mathematical model has been presented to analyze reservoir and production performance of gas wells and to assist management to achieve the best economic indices in the development of the field. The model was applied in one of the biggest gas fields in the USSR in Siberia - Medveje. The paper describes the numerical model of gas reservoir and algorithms describing two-dimensional areal single-phase unsteady state filtration of gas and water, respectively, in heterogeneous porous media for water drive, steady state flow of gas in each well and gas gathering system equipped with or without compressors. Algorithms to calculate optimum production rates from each well with minimum loss of formation energy have been included. The model also permits one to calculate economic indices and to evaluate reservoir parameters based on its actual performance (history matching). The results obtained for the Medveje gas field show that the model permits one to select the optimum variant of development of the gas field, i.e. maximum profit with an optimum value of the total gas recovery factor.
Applications of Foam Cement
Authors: McElfresh Paul M. , Go Boncan Virgilio C.
Published: December 2007

Foam cement offers a versatile and economical means of cementing wells with low density, high strength material. Several common applications of foam cement are available, and these include placing strong cement across weak or highly fractured zones without losing circulation; filling vugs or porous thief zones; or simply as an inexpensive light-weight filler slurry.

The various aspects of slurry design, including their methods of determination, are discussed. It was found that thickening times could be determined directly on the foam cement in existing equipment with only minor modifications; the fluid loss and the rheology could be measured directly with no modifications; and the compressive strengths were determined in a special cell to prevent water invasion from the curing chamber. Since these parameters are determined by the nitrogen content, their relationships to density are also discussed.

Job procedures for pumping foam cement are discussed in two methods, i.e., constant nitrogen rate (variable foam density) and constant density (variable nitrogen rate). Included in this discussion is the description of an improved atomizer for generating foam cement. From yard tests utilizing field equipment, it was found that this device improved the foam stability by means of better disbursement of the nitrogen in the cement slurry. The computer program which calculates the surface gas injection rates to achieve the desired density at specified depths is discussed and evaluated. Case histories are then presented to illustrate the effectiveness and versatility of foam cement as well as its relative ease of application. The case histories deal with repairing casing leaks and lost circulation problems in weak formations.
Foamed Cement — Solving Old Problems with a New Technique
Authors: Benge O. G. , Spangle L. B. , Sauer C. W.
Published: December 2007

A new method of combining nitrogen with an intermediate-weight cement slurry (13 to 15 1 b/gal) to generate a stable foam has solved many of the problems associated with the use of conventional lightweight cements in oil-field operations.

Foaming permits placing relatively high-strength, lightweight (6 to 11 lb/gal) cement slurries into the casing-formation annulus economically. Lightweight filler cement is often needed to provide a complete cement sheath along the length of the casing, where lost circulation is encountered or long lifts of cements are required. Various methods have been used in the past to obtain this lightweight slurry. These include the use of natural and chemical extenders, glass bubbles, ceramic bubbles and the combination of intermediate-weight cement slurries with gases. While the process of foaming cement to make lightweight slurries is not new, the technology for applying this process to oil and gas well cementing has been lacking.

The new method requires special treatment and slurry design to obtain a hydrostatically balanced slurry along the entire length of the casing, but can be performed with current equipment and field personnel. Laboratory data and case histories have been used to describe these designs. The added safety requirements which must be in effect to successfully complete this type of cementing operation are discussed.
Determination of Average Pressure in Gas Reservoirs From Pressure Buildup Tests
Authors: Ziauddin Zia
Published: December 2007

A well known method for determination of average reservoir pressure in bounded systems from pressure buildup tests is the method utilizing the Matthews-Brons-Hazebroek (MBH) (1) functions. The MBH functions were developed using the solution of the diffusivity equation obtained by assuming viscosity compressibility product to be small and constant. The use of MBH functions for gas can produce erroneous average reservoir pressures even if the pseudo-pressure transformations are utilized. The use of pseudo-pressures still leaves the diffusivity equation as a non-linear equation. A solution of this non-linear equation provides a correction term for the MBH functions when used for gas reservoirs. This correction term takes into account the variations in viscosity compressibility product with pressure. More realistic results are obtained by using this correction term. The same correction term can also be used for modifying the various published dimensionless pressure solutions developed for the oil case, for use with problems involving real gas flow. This paper describes the method for calculating this correction term and its application.
New Approach to Casing-Lading Practice Based on Results of Oil Field Measurements
Authors: Arpashi Miklos
Published: December 2007

Increasing drilling depths and the growing ratio of natural gas fields require some modification of the theory and practice of casing landing.

Some field measurements were concluded to examine the relation between the casing landing practice, derived from theoretical considerations utilizing the theorem of elastic stability, and the actual stress/deformation behaviour of the casing string thus set.

Utilizing the measured data a new calculation method was elaborated taking into consideration the actual stress conditions and the influencing loads, further on the geotechnical conditions in Hungary.
Recovery Economics of Coalbed Methane and Cost Implications of Pipeline Hookup
Authors: Dickehuth Debra A. , Adams Margaret A. , Hayoz Fred P.
Published: December 2007

For Appalachian coal mines, the totaled methane emission rates exceed 180 MMCF/D, with active mines pushing deeper into virgin seams having higher relative gas contents. While most of this gas currently is vented into the atmosphere to prevent gas-related explosions, the technology exists to develop this valuable gas resource either in conjunction with mining or independently.

In 1977, the U.S. Department of Energy (DOE) began the Methane Recovery from Coal beds Project (MRCP) to characterize and help encourage utilization of this resource. Since the projects inception, TRW has been involved in the collection and analysis of data, and is in the process of forming a coherent picture of the coalbed methane resource potential for the entire Appalachian region. Preliminary analysis indicates an estimated in-place coalbed methane resource in the Appalachian Basin of up to 150 TCF. Eastern coal operators are beginning to better understand the production potential of coalbed methane. In Buchanan County, Virginia, the Island Creek Coal Company produced up to 434 MCF/d from 12 horizontal boreholes drilled into the mine face. In Alabama, U.S. Steel's mines recently began commercial production and sold 25 MMCF of pipeline quality gas in December of 1981.

This study examines the recovery economics of coalbed methane, and specifically addresses the cost implications of pipeline hook-up. An analysis which addresses the size of a project, pipeline construction costs, and anticipated contract gas price helps determine an economical project-to-pipeline hook-up distance.
Stimulation Evaluation in the Appalachian Tight Gas Sands
Authors: Charles John G. , Hydock Kevin D. , Udick Thomas H. , Hall Donald R.
Published: December 2007

Hydraulic fracturing is the most common method used to improve production from wells drilled into "tight" formations. Accurate fracture design is essential in order to obtain highly conductive and deeply penetrating fractures. In the past, many stimulation treatments in the northeastern United States had little basis for design. Thousands of wells have been fractured and comparative analysis of different techniques was extremely difficult. This paper attempts to evaluate fracture design in relation to tight gas sands in the northeast.

A review of the major variables affecting hydraulic fracture design is included and a discussion of three pressure transient methods used in the evaluation is presented. Pressure buildup analysis was used to determine effective reservoir permeability and pressure. Type curve matching was used to approximate fracture lengths and to predict production resulting from changes in fracture geometry. Computer reservoir simulation analysis helped in more accurately modeling the reservoir to support the production forecasting.

A case history detailing this method of evaluation in the Medina Formation is discussed. Actual field data are compared to the predicted results.
Outlook for U.S. Gas Energy, Demand, and Competitiveness
Authors: Schlesinger Benjamin
Published: December 2007

The gas transmission and distribution industry believes that available supplies of gas energy will range from 23 to 31 trillion cubic feet (Tcf) by the year 2000, as conventional gas production is increasingly supplemented by supplies from supplemental and non-conventional sources. Under the right set of price and regulatory conditions, gas demand can increase in the traditional heating, industrial fuel and feestock applications, as well as in such new non-traditional uses as cogeneration, natural gas vehicles and select gas use with coal. Gas prices are rising rapidly enough under the existing law between now and 1985, so that concerns of a sudden price increase after deregulation in that year may be somewhat overstated -- as long as indefinite price escalators, take-or-pay, and other issues in gas purchase contracts are fully resolved beforehand.
A Review of Marine Systems Use in Developing Alaskan Natural Gas
Authors: Hederman W. F.
Published: December 2007

The successful development of the major supplies of natural gas in Prudhoe Bay, Alaska was expected to follow the President's selection in 1977 of the Alaskan Highway proposal to construct a pipeline across Canada and deliver Arctic natural gas to the lower-48 states. Five years later, the proposed Alaska Natural Gas Transportation System (ANGTS) continues to encounter serious obstacles to its successful development.
Prediction Of Tracer Behavior In Five-Spot Flow
Authors: Brigham W.E. , Smith D.H.
Published: December 2007

Equations are developed to predict the time of tracer breakthrough, the peak concentration of the tracer, and the general form of the breakthrough curve in a 5-spot flood. It is shown that these results depend on the amount of stratification of the reservoir, the volumes injected and produced, the natural dispersion coefficient of the tracer in the reservoir, the amount of tracer injected, plus all the reservoir volume parameters (i.e. well spacing, porosity, thickness).

Many laboratory data are available on the breakthrough characteristics of a 5-spot flood, also much data is available on the natural linear dispersion coefficients of reservoir rock. To derive the equations, these data were combined and several assumptions were made. It was also necessary to graphically differentiate the breakthrough data. Thus it should be recognized that the final equations likely have some error. However, this should not invalidate their use, for the method and logic behind the derivation are sound, and thus the form of the final equations should be close to correct. In this paper, the prediction equations are used in a reverse sense. That is, the detailed tracer production history from a field test is used to estimate permeability variation in a 5-spot.

Introduction

Tracers have been used for many years in reservoir floods to help the operating engineer understand the flow characteristics. Generally this use has been entirely qualitative. The results of time-of-flight, peak concentrations at the producing wells, concentration history, and directional flow have been used only to substantiate that channelling does nor does not exist. No attempts have been made to predict quantitatively the tracer breakthrough behavior that might be expected from different reservoir characteristics.

In the past couple of years it has become apparent that some prediction technique could be well used to supplement the other tools available to the reservoir engineer. It is becoming increasingly important that maximum recovery be obtained from a flood, and any quantitative information about the reservoir can be of help in achieving this maximum. The work reported here is a step in this direction — an attempt to quantify the tracer behavior.

Equations are developed to predict the time of tracer breakthrough, the peak concentration of the tracer, and the general form of the breakthrough curve in a 5-spot flood. Tracer production history from a field test are compared to the behavior as predicted by the equations.
Investment Evaluations in Inflationary and Unstable Scenarios
Authors: Rosbaco Juan Antonio
Published: December 2007

Two different methodologies to evaluate investments in inflationary and unstable scenarios are described. These techniques have been successfully applied, and are mainly useful because they enable changes in the inflation rate throughout the whole life of the project. These models allow us to evaluate the influence of different events on the project yardsticks. In this case, the examples presented enable us to point out some aspects related to the deferred payments.
The Development Decision: Value of Information
Authors: Warren J. E.
Published: December 2007

In the petroleum industry, the decision to develop newly discovered hydrocarbon resources must be made under conditions of uncertainty; i.e., with less than perfect information available. However, both the degree of uncertainty and the economic consequences which are associated with such decisions can, and do, vary widely. Of particular interest are frontier areas where either a premature or an overdue decision can jeopardize the viability of a multibillion dollar project.

Although uncertainty can always be reduced by simply buying more information--additional delineation wells, 3-D seismic surveys, extended well tests, detailed design studies, etc., there must be a point at which the cost of additional information exceeds its benefit. This paper examines the problem of determining the point at which the development decision should be made; it specifically considers the following two principal sources of uncertainty:

The estimated distribution of the hydrocarbon reserves. The cost of development--assumed to be related directly to the projected distribution of the development period.

A realistic procedure, based on the concept of the optimal development plan, is presented and discussed; criteria related to the time for decision making and to the decision itself are established; and, the real value of information is determined. Finally, to demonstrate the use of the suggested approach, a comprehensive example--typical of a frontier area--is included.