bluuebunny/crossref_metadata_2025 huggingface dataset:
Case Study of a Gulf Coast Layered Reservoir Using Multirate Transient Testing
Authors: Morris C. W.
Published: December 2007

This paper presents the results of the first application of multilayer, multirate transient pressure testing techniques to the evaluation of a well located in an offshore area of North America. The primary purpose of the case study was to understand the depletion mechanisms of individual layers within the multilayer reservoir. The evaluation was performed using multirate transient pressure analysis and production logging techniques.

The study, performed in a well with a three-layered reservoir completion, illustrates the potential for understanding many of the production and reservoir system problems found in complex geologic environments like the Gulf Coast. The reservoir parameters (permeability, skin factor and pressure) were estimated for each of the layers and the results were compared to those from conventional analyses. The results indicate that the depletion mechanisms of the separate layers are different and that production may be lost because of aquifer water influx from one layer. The understanding of the real reservoir behavior allows workover procedures to yield the optimum hydrocarbon recovery.

Multilayer well test techniques were used, i.e., sequential flow tests with continuous downhole flow rate and pressure measurements at the top of each layer obtained using production logging tools. The analysis techniques utilized for the multilayer reservoir evaluation include convolution, deconvolution, pressure derivative and rate normalization. The interpretation was substantiated using a nonlinear regression to fit the measured downhole flow rate or pressure data with a layered reservoir model.

This case study shows that these advanced reservoir evaluation techniques can have widespread applicability in offshore wells. The multilayer testing technique can be used as a monitoring device to develop pressure depletion profiles of different layers and optimize the recovery of reserves.
An Analytical Model for Composite Reservoirs Produced at Either Constant Bottomhole Pressure or Constant Rate
Authors: Olarewaju J. S. , Lee W. J.
Published: December 2007

In this paper, we present a model of the complete characteristic transient response from a composite reservoir including the effects of skin, wellbore storage and phase redistribution at the well. We present six flow regimes and the combined effects of wellbore storage and phase redistribution on pressure behavior in composite reservoirs.

Using an automatic history matching approach, we analyzed three buildup tests and a pressure falloff test. This method eliminated the serious uniqueness problem associated with type curve analysis. We demonstrate that incorrect reservoir parameter estimates and incorrect production performance predictions would result from the use of any model that lacks the capabilities of the model we present in this paper. We also demonstrate possible misinterpretations of pressure data that may result from not recognizing the presence of phase redistribution in the buildup test data or not recognizing the composite reservoir behavior.
Applications of Well Logging for Compaction and Subsidence Studies in the Orinoco Oil Belt, Venezuela
Authors: Ramirez M. O. , Zubillaga J. I.
Published: December 2007

A pilot study project is presently carried out in the unconsolidated low gravity oil sands of the Orinoco Oil Belt, in the eastern part of Venezuela, one of the largest heavy oil accumulations in the world. The objective is to evaluate the interactions and environmental impact of Compaction and Subsidence due to fluid withdrawal.

Thirteen injection-production and two observation wells were drilled for this purpose. The optimal location of the latter was determined after detailed log evaluation of the injection-production wells. The logging program for the observation wells was designed for a thorough evaluation of the geological, petrophysical, and geomechanical reservoir characteristics. In addition, a large number of radioactive bullets were placed along the boreholes, in the observation wells, for compaction or deformation monitoring.

This paper presents the results of the extensive logging program carried out including those of the Field Subsidence Monitoring Tool (FSMT). The methodology used in the evaluation of the shaly intercalations on sands is particularly referred.
Development of the Lisburne Reservoir
Authors: Paige K. T. , Dayton J. S.
Published: December 2007

This paper provides an overview of the Lisburne, the most recent producing reservoir on the North Slope of Alaska. It will briefly touch on the geology of the Lisburne Field and then move into the development history and reservoir description. Following this, there will be a discussion on the first phase of development, and the paper will close with a brief look at the future.

The Lisburne is a naturally fractured carbonate reservoir and was the geologic target for drilling of the Prudhoe Bay State No. 1 in 1968, which discovered the shallower Sadlerochit Reservoir. Due to the Sadlerochit's immense size, relative to the Lisburne, development of the Lisburne was delayed until the early 1980's. The Lisburne started-up on December 15, 1986 at a rate of approximately 40,000 barrels of oil per day. This was the first time a fully integrated North Slope major production facility was brought up on a single sealift and started in the same year.

Relative to most domestic reservoirs the Lisburne is a substantial reservoir with three billion barrels of oil in place. From primary recovery supplemented by produced gas re-injection we expect to produce between 250 to 350 million barrels of oil. Ultimate recovery, including both primary and secondary, could range up to 500 million barrels. Primary development includes the drilling of up to 200 wells with initial well rates varying between 1000 to 3000 barrels of oil per day. Development cost at start-up was approximately 850 million dollars; ultimate cost is anticipated at 1.5 billion dollars. The field is being operated by ARCO Alaska, Inc. on behalf of the three owner companies, ARCO Alaska, Inc., Exxon Company, U. S. A., and Standard Alaska Production Company.
Oil Prices: Can We Predict Where They Are Going?
Authors: Dougherty E. L.
Published: December 2007

Earlier explorations of how to predict oil prices led, in 1978, to my being named project director of a contract between USC and the OPEC Secretariat in Vienna to develop a world energy model. OPEC wanted a tool to help devise rational oil production and pricing policies. Late in 1981, we installed the model on OPEC's computers in Vienna. It is unknown how effectively OPEC was able to use the model, but it did foretell the shape of recent events in world oil markets. In Jan, 1981, we gave our sponsors the results of a study of what would happen if OPEC raised its production rate back to 20 million barrels per day, a study they requested after their production rate fell to around 18 million B/D. The model predicted that if OPEC's rate were to be raised as proposed, oil price would fall $20/bbl within a year. Although not spot on, the prediction is certainly indicative of what was to come. (For this study all price elasticities were arbitrarily increased by 10 percent from their base levels, the medians of estimates reported in the literature. In hindsight, this adjustment was conservative. The past decade's price-induced, reduced growth rate in energy consumption, so-called conservation, corresponds to even larger values of price elasticity.) There is no indication that OPEC paid attention to this or other model predictions; they were still whistling their favorite high-price tune when the market forced their first official price cut late in 1982.

This paper presents some rules of thumb that my experience suggests may help to understand the evolution of oil prices. The intent is to identify factors to consider in deciding on the credibility of an oil price forecast (yours or another's), rather than to prophesize future oil price. The presentation is professorial in style; a series of questions penetrating different aspects of the dynamics of oil prices are asked, and answers to these queries are advanced. This interrogatory is targeted to broaden the reader's perspective on what makes the oil market tick. We also examine how individuals have responded in the past to signals from the marketplace. This examination's purpose is to call to attention the impact of emotions on the subjective weightings applied in reaching an economic decision. In the oil patch expectations about highly uncertain outcomes, both economic (mostly prices and taxes) and physical, exert a major influence on investment decisions. Being aware of how emotions can slant these expectations is a key consideration for a decision maker.
Evaluation of Reserves for a Number of Small, Partially Shut-in Gas Fields in Northern Tennessee
Authors: Blasingame T. A. , Poston S. W. , Hedberg W. H.
Published: December 2007

This paper presents analysis techniques for post-transient gas flow at a constant flowing bottomhole pressure. Reservoir parameters can be estimated from production decline curve analysis using analytical solutions which are formulated in terms of real gas pseudopressure analysis.

These techniques were applied to a field study of two small, low productivity gas reservoirs in Northern Tennessee. The production data for this field study was analyzed using decline curve analysis. The types of decline curve analysis used were: rate-time graphical, rate-time and cumulative-time non-linear least squares. Decline curve analysis by the use of type curves was attempted, but data scatter caused significant deviation of results when compared to the other types of decline curve analysis.

The decline curve analysis results were then interpreted using an analytic reservoir model which did include pseudopressure analysis. This analysis was verified by a simulated real gas example which attempted to model producing conditions similar to those encountered in the field.

The overall objective of the field study was to find correlations of reservoir parameters to measured production data. Several rate-reserve, rate-permeability/porosity-агеа ko A, and rate-permeability-thickness (kh) correlations were obtained from the results of the decline curve analysis. The best correlations were based on an average rate, q¯3, calculated from a well's first three months of production.
The Engineering Approach to Sand Production Prediction
Authors: Weissenburger K. W. , Morita N. , Martin A. J. , Whitfill D. L.
Published: December 2007

An engineering system has been developed for sand production prediction. The system synergistically uses geological reservoir characterization, log analysis, and core rock strength testing to forecast perforation cavity stability. Coupling the system with a reservoir simulator permits the modeling of cavity stability at initial conditions and throughout the life of a well. Three examples are given of applications of the engineering system to sand problems in North Sea reservoirs.
Study of the Effects of Fluid Rheology on Minifrac Analysis
Authors: Lee W. S.
Published: December 2007

Incorporation of a energy balance equation into the pressure decline analysis (minifrac) greatly improves the effectiveness of this analysis.

Minifrac analysis currently being employed by most petroleum industry operators does not consider the rheological properties of the fracturing fluid. The most severe consequence of this omission is that the geometry determined by minifrac analysis often differs from that of the fracture design programs based on the same model.

Inclusion of the energy balance equation developed by Biot, Masse, and Medlin enhances the analysis as described below. Rheological properties are considered, therefore geometry determined from pressure decline analysis is in agreement with geometry determined from fracture design programs. Because of the close agreement, one can better predict fracture fluid volume required in a full scale treatment.This method does not require the assumption that created fracture width is proportional to the pressure difference between instantaneous shut-in pressure and formation closure pressure. When this difference is on the order of 1000 psi, calculated widths can be several times as great as the width found by the fracture design program based on the same model.

Subject presents: (1) discussion of theoretical aspects of new analysis method, (2) case histories of jobs performed with this analytical method as a planning tool, and (3) a comparison of calculated parameters with those used for job design.
Determination Of Formation Properties From Long-Term Gas Well Production Affected By Non-Darcy Flow
Authors: Fraim M.L. , Lee W.J.
Published: December 2007

SPE Members

This paper presents new type curves to estimate formation and well properties such as gas in p lace, drainage area, and hydraulic fracture half length for fractured gas wells with finiteconductivity fractures. We model non-Darcy flow in the fractures or in the formation in unfractured wells with our type curves. Application of the curves allows rigorous modeling of gas property variation with pressure even after the boundary-dominated flow regime is reached. For wells with finite-conductivity fractures in bounded reservoirs, we generated a new analytical solution using Green's Functions.

Introduction

The purpose of this paper is to present new constant pressure type curves to analyze short-term and long-term production data for the following two physical situations:Wells with finite-conductivity fractures in bounded reservoirs having conductivity, CfD' varying from 0.1 to 100.Wells in homogeneous formations.

In addition, the paper presents a method to account for gas property variation with pressure, even after the boundary-dominated flow regime is reached. The paper presents methods to use the type curves to model non-Darcy flow in the fractures or in homogeneous formations.

Data required for the type curves include rate vs. time and either surface or bottom-hole pressures which, if not constant, can be treated using superposition.

In this paper, we present (1) back-ground on solutions for fractured wells and for handling variable gas properties; (2) a description of our mathematical model for a well with a finite-conductivity fracture; (3) a discussion of the deliverability equations for a homogeneous reservoir and for a vertically fractured well and of how we created the non-Darcy flow correlations; (4) an explanation of the non-Darcy correlations ; (5) an explanation of normalized time and normalized rate which are needed to use the type curves for gas wells; (6) an explanation of the new type curves that includes a description of the dimensionless variables and the relationship between the cumulative production-time match point and the rate-time match point; (7) a detailed description of the algorithms for history matching and predicting future performance with the type curves; (8) a discussion on superposition with normalized time and rate; (9) a discussion of the cumulative production type curve with an explanation of possible characteristic shapes; (10) a description of the numerical model used to generate data for the correlations and to validate the type curves; (11) a validation of the type curves with other published work; and finally (12) examples of application of the type curves to two field cases and one simulated case.

Background

Gringarten et al. in 1973 and 1974 developed analytical type curves for vertically fractured wells with infinite-conductivity fractures and with uniform flux into the fractures.
The Well Data System (WDS): An Advanced Formation Evaluation Concept in a Microcomputer Environment
Authors: Ball S.M. , Chace D.M. , Fertl W.H.
Published: December 2007

As processing capabilities of microcomputers Continue to increase in today's accelerated development climate, advanced formation evaluation, previously considered unsuitable for smaller processing environments, has now become both technically feasible and economically attractive.

Formation evaluation packages on microcomputers have typically been restricted to simple processing routines, including data entry either by hand or through digitization of a particular zone of interest. With microcomputers now having larger memory capacities, disk storage, and faster processing speeds, advanced log evaluation may often be performed at data rates exceeding the capabilities of minicomputer systems. With appropriate peripherals, a workstation can be established that allows true advanced log interpretation on microcomputer systems.

The Well Data System (WDS), an advanced log evaluation system operational on a microcomputer, increases the productivity of formation evaluation specialists in single and multi-well reservoir descriptions. WDS incorporates software packages for both open and cased hole well log analysis, advanced dip log evaluation (including stratigraphic analysis), statistical analysis in complex reservoir rocks, formation pressure evaluation, and completion flow systems nodal-type analysis.

Performance is oriented toward high volume operation and incorporates batch and interactive processing modes, datailfile portability, tape processing, digitizing, plotting, and data communications.

This paper highlights the multidisciplinary approach of WDS, facilitating cost-effective and comprehensive evaluation of well logging and related petrophysicaI and production data over the entire life of a well.

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Wettability Alteration Induced by Oil-Based Drilling Fluid
Authors: Ballard T. J. , Dawe R. A.
Published: December 2007

Invert emulsion oil based drilling fluids rely on surfactants and emulsifiers to maintain the stability of the invert emulsion. An excess of oil wetting agents in the system is usually necessary in order to oil wet the drilled solids. This excess of surfactants causes wettability alteration in the drilled formation. This is recognised as one of the mechanisms of formation damage.

A study has been carried out to assess the influence of the surfactant concentration in oil based mud filtrates on the wettablility alteration of glass surfaces. Micromodel work has shown that oil based mud filtrate can cause emulsification and migration of connate water, thus reducing the water saturation as well as the alteration of the wettability of the pore walls. Results of contact angle studies suggest the surfactants in oil-based mud filtrates adsorb on to silica surfaces to build up a monolayer, Thus changing the initailly strongly water-wet surface to one of intermediate wetting.

This paper reports in detail the experiments carried out to demonstrate the wettability alteration caused by an oil based mud filtrate. A detailed investigation carried out to discover any correlation between the concentration of oil-wetting agent in the filtrate and the magnitude of the change in wettability produced on glass surfaces.

The studies of contact angle variation as a function of surfactant concencentration show that even very small concentrations of surfactants are potentially damaging to reservoir formations.
Formation Damage During Gravel-Pack Completions
Authors: Houchin L. R. , Dunlap D. D. , Hutchinson J. E.
Published: December 2007

Most gravel packed completions are considered successful if the well produces sand free. However, many successfully gravel packed wells suffer reduced productivity as a result of formation damage induced by current gravel pack completion practices. Gravel packing even a slightly damaged formation can result in long term detrimental effects on production. The most predominate problem is that dehydration of the gravel carrier fluid will be restricted and perforation tunnels will not tightly pack.

The areas of interest in which formation damage can be limited during a gravel pack completion include perforating, filtration, gravel carrier fluid selection, lost circulation control, and workstring hygiene. In addition, fluid leak-off during gravel packing may be optimized by proceeding the gravel pack slurry with low strength acid.
Discussion of Intermediate Casing Design Parameters
Authors: Curry W. E.
Published: December 2007

Design procedures used to establish burst requirements for surface and intermediate casing are extremely different and are nearly as numerous as the companies that design casing. This paper briefly discusses the differences in design philosophies, but primarily examines the historical performance of the entire design spectrum and the explanation of why so many widely varying design procedures have succeeded equally well. From this examination, a list of key design considerations is developed which will hopefully assist designers who may now (or in future) struggle with surface and intermediate casing burst design.
Performance Evaluation of a New Rock Bit Bearing Seal
Authors: Kelly J. L. , Ledgerwood L. W.
Published: December 2007

Reliability functions derived from field performance data are used to measure the effectiveness of a new rock bit bearing seal. The new seal is a metal face seal and its performance is compared to the standard O-ring seal. The results show a significant increase in bit life measured in cone revolutions under typical operating conditions. This increase in cone revolutions may be utilized to increase rotating time, rotary speed or both. An example comparing various alternatives is provided. Data are also provided which show a much improved tolerance to high bottom hole temperatures.
Applications of a Computerized Bit Record Database
Authors: Steinke S. C. , Watson J. A. , Bremner D. C.
Published: December 2007

The Bit Record Database and analysis program discussed in this paper were developed to provide rapid access to and analysis of bit run information. The system was developed in three phases:

Bit Record Database construction Analytical programs that also access Engineering, Manufacturing, and Sales databases Computer-assisted well programming

The Bit Record Database resides on an IBM mainframe and provides rapid on-line access as well as a down load facility to floppy disks for microcomputer applications. The system contains over 100,000 bit records which represent over 700 million feet of drilling hole. Data accuracy and confidentiality are strictly controlled through stringent data validation, access codes, and flagging of tight holes.

Programs have been written to evaluate bit performance data in relation to various engineering and manufacturing parameters. This data enables both product engineers and manufacturing process engineers to set specifications that will result in consistently high bit performance.

The microcomputer is used in various field offices to assist technical personnel in preparing recommended bit programs and rapidly summarizing the drilling history for a selected area. The computer quickly identifies offset wells and then accesses programs which optimize hydraulics, evaluate bit run efficiency, and determine overall cost effectiveness. The result is a well program that allows field technicians to combine their knowledge of an area with the computer's ability to quickly locate wells and then precisely calculate needed values. This helps produce accurate and timely well programs which result in the lowest cost per foot.
Effect of Shock Absorber on Drag Bit Chatter
Authors: Zamudio C. A. , Tlusty J. , Dareing D. W.
Published: December 2007

This paper first reviews the theory of self excited vibrations in oil drilling which was presented in a previous paper. It then concentrates on the methods of developing an efficient vibration absorber.
Spudding a Vertical Hole in Deep Water Using MWD Surveys
Authors: Belaskie J. P.
Published: December 2007

Spudding a well in deep water can be complicated as the presence of large currents may cause the bottom hole assembly (BHA) to be inclined up to ten degrees at the bit. A desirable hole inclination would be less than 0.5 degrees for setting surface casing. A method of taking Measurements While Drilling (MWD) surveys and repositioning the rig until the drill collars are vertical has been developed and tested on two wells.
The Drilling and Testing of High-Pressure Gas Condensate Wells in the North Sea
Authors: Low E. , Seymour K. P.
Published: December 2007

During the 1980's exploration activity in the North Sea turned towards deep, high pressure, Jurassic gas condensate reservoirs. These reservoirs occur at 16 – 18,000 ft, are abnormally pressured with pore pressures of approximately 15,500 psi, and temperatures approaching 400 deg F. This presented a new challenge to the drilling industry which required the development of new techniques, equipment and philosophies.

By 1985 considerable experience had been gained in the drilling and testing of these wells. In mid 1985 Ranger Oil drilled Well 29/5b-4 to a depth of 17,930 ft using their own semi-submersible drilling unit, the SEDCO 714. Electric logging indicated that the Upper Jurassic objective at 17,080 ft had a pore pressure of 15,800 psi. The presence of H2S and CO2 were detected and calculations showed that the maximum anticipated tubing head pressure was 13,500 psi. By following the concepts developed from past experience that wells of this type cannot safely be tested from a floating drilling unit, the well was suspended. Procedures were established to permit the safe testing of this well using engineering innovation to develop new equipment and techniques. Re-entry and testing took place in August 1986 using the jack-up GLOMAR MORAY FIRTH and produced a total of 54 mmscf/d and 4,500 BOPD. Maximum wellhead pressure was 12,500 psi, surface temperatures reached 300 deg F and reservoir temperatures of 406 deg F were recorded.

By examining the operational procedures, equipment and techniques used to overcome the problems encountered, a drilling and testing philosophy is developed, which provides a field proven basis for the economic exploitation for reservoirs of this type.
Certification of Electrical Instrumentation for Use on Drilling Rigs
Authors: Dolphin J. R.
Published: December 2007

Certification is the documented, independent third-party determination of compliance with a prescribed set of requirements. The procedure for obtaining a certification is typically quite simple. However, the process for obtaining certification is frequently complicated by confusion over the numerous variables associated with certification. Understanding these variables is a prerequisite to the preparation of a meaningful specification, and defining these variables facilitates the process of certification.

The variables associated with certification are listed below.

Applicant Object of certification Nature of object History of object Certifying agency Hazardous locations Scope of investigation Applicable standards Grade of certification Inspections Follow up service Updates in requirements Identification of certified products Destination of equipment Type of platform Flag of vessel

Some of these variables are not applicable in every case.

This paper discusses the aforementioned variables, explains how the variables affect certification of electrical instrumentation used on drilling rigs, and describes the procedures for obtaining certification on components, products, systems, installations, and rigs. Certification for both new and old rigs is included, as well as modifications to rigs subsequent to certification. Examples of specifications for certification are given at the end of the paper.
A Combination of Logging Measurements for Quantitative Monitoring of CO2 Floods
Authors: Schwanitz B. J.
Published: December 2007

The need for monitoring miscible and immiscible CO2 gas floods has become increasingly apparent to operators engaged in these often expensive, yet potentially rewarding projects. By combining logging measurements, a new 3-phase approach can be obtained and used as a tool to quantitatively monitor a CO2 flood on injection, observation, or producing wells.
Mathematical Modeling and Testing of Hydraulically Driven Pumping Jack
Authors: Luo F. , Miska S.
Published: December 2007

A hydraulically driven walking beam pumping jack* is introduced which differs from the conventional pumping jack in that the walking beam is activated by two telescopic joints. To analyze the performance of sucker rod pumping systems (both standard and hydraulic), a mathematical model and a numerical simulation were developed. Seven performance criteria were used to characterize the pumping systems. Full scale laboratory type experiments were performed to verity the mathematical model. Both computer generated and experimental results indicate that the hydraulic pumping jack consumes less energy at the polished rod than does the conventional pumping jack.
State of the Art Installation of CO2 Injection Equipment: A Case Study
Authors: Collier T. S.
Published: December 2007

Corrosion of injection equipment is a common problem in CO2 miscible injection operations. The two basic mechanisms by which this corrosion occurs are from internal corrosion caused by holidays in the injection tubing coating as well as from external corrosion caused by CO2 invading the tubing-casing annulus through minute seepages in the downhole injection equipment.

Unfortunately, these problems are both common and costly.

In one West Texas CO2 injection project, Unocal Corporation, using state of the art connection and testing procedures has developed a method of installing downhole CO2 injection equipment which virtually eliminates this tubing-casing communication. In addition, the internal plastic coating of the tubulars remains intact and holiday free during field handling procedures. The system involves the use of a helium connection test combined with meticulous attention to detail in the field handling and connection of the tubulars.

The following is a discussion of the development of these procedures.
Novel Workover Treatment Proves Effective in Permian Basin: Laboratory and Field Results
Authors: Harms S. D. , Smith J. M. , King G. E. , Posey K.
Published: December 2007

A novel foamed acid treatment has proven effective in the workover of more than 20 wells in the Permian Basin Delaware, Grayburg, and Upper Clearfork formations. The treatment described uses a foaming mutual solvent/acid system. This system provides the desirable wetting and solubilization properties of a mutual solvent and acid along with the inherent advantages of foam. The uniqueness of this treatment is derived from the prolonged stability of the foam, a property not characteristic of foamed mutual solvent systems.

Data is presented from both laboratory and field tests comparing this procedure to conventional foamed acid techniques. Detailed treatment designs are presented which are applicable in coiled tubing and workover strings. These procedures have been used in treatment of injection and producing wells. The treatment described is especially effective in low pressure wells where previous workovers have resulted in poor performance.
Controlling Rod Body Corrosion Failures With Spray-Metal Plastic-Coated Sucker Rods
Authors: Ryan R. A.
Published: December 2007

This paper presents the results of an investigation into the benefits of spray metal plastic coated (SMPC) sucker rods for reducing rod body corrosion failures. The operating histories of over 650 bare steel and SMPC rod strings that were installed in several West Texas producing locations since 1977 are reviewed. Over 9000 failure and installation records have been summarized. Comparisons have been made in the performance (runtime and failures) of sucker rod strings before and after the installation of SMPC rods. Major operating practices have not significantly changed during the time period studied.

Experience with bare steel and SMPC rod strings in one major West Texas producing unit is reviewed in detail. The runtime and failure histories for all rod strings (both bare steel and SMPC) in this unit are summarized. The economics of SMPC sucker rod string installation are also reviewed.
Engineers And The Oil Industry Today And Tomorrow
Authors: Mims C.D.
Published: December 2007

Mims, C.D., president Standard Oil Company of California Western Operations, Inc.

Any industry as vast as ours will necessarily encounter problems—-occasionally serious ones—-but I think all of us here would agree that the oil business has a long and prosperous future ahead of it.

I know that the industry's engineers will be able to meet the developing problems of the future just as able and successfully as they have in the past, with even more sophisticated techniques and tools.

One of the best examples of how the industry has managed to handle its problems is the outstanding success that petroleum engineers have had in the areas of development well programs and assisted recovery projects. There are other examples, such as offshore production and recovery from beneath heavily populated areas.
The Use of Inert Gas Radioactive Tracers for Steam Injection Profiling
Authors: Nguyen T. V. , Stevens C. E.
Published: December 2007

This paper presents a study on the use of radioactive tracers for steam vapor phase injection profiling. Field data show that methyl and ethyl iodide are not reliable vapor phase tracers because they decompose into water soluble tracers at steam conditions. Vapor phase injection profiles obtained with methyl and ethyl iodide are therefore incorrect. Radioactive inert gases (krypton, xenon, or argon) are recommended as vapor phase tracers. Field data using inert gases to trace the vapor phase identify gravity segregation problems in the wellbore. Techniques to measure downhole steam quality are discussed and field data presented.
Analysis of Production and Reservoir Performance, Casa Diablo Geothermal Project
Authors: Miller R. J. , Vasquez R.
Published: December 2007

The Mammoth-Pacific geothermal project at Casa Diablo has been in production since January, 1985. The plant generates 7-8 MW of electric power using a binary system supplied by geothermal fluid production from four wells that produce about 3500 GPM of 340° F, low salinity geothermal fluid. The wells produce from a fault/fracture system that is apparently continually recharged from a deep "reservoir" with no significant drawdown in pressure or decline in flow rate over the 2 year period.

Prior to the start of production a series of well tests were conducted to determine the pumped flow capacity of the original four wells and to determine reservoir properties from pressured drawdown and build-up analysis. Since the start of operations a continuous record of production rate, flowing bottom-hole pressure, and temperature has been maintained. The well tests and production records have been evaluated to determine the nature of the reservoir and reservoir permeability and other properties. This paper presents the results of that evaluation.
A Model for Development, Sensitivity Analysis, and Optimization of Gas Reservoirs with or without Aquifer: Part I-The Model and Solution Technique
Authors: Alcocer C. F. , Ghalambor A. , Hayatdavoudi A. , Tussaneyakul S.
Published: December 2007

This work is a study for the development and optimization of gas reservoirs that depend upon the effect of water drive mechanism and production demand schedule. The objectives are to determine the optimum number of wells and time for these wells to be drilled for the gas reservoirs without or with water influx for steady state and unsteady state for linear and radial system, the effect on gas production by water influx, and to perform a sensitivity analysis to study the effect for unsteady state water drive reservoir due to: production rate, permeability, water viscosity, porosity, water compressibility, rock compressibility, and encroachment angle and rock and water compressibility term in material balance equation for volumetric, steady state, and unsteady state water drive reservoir. To solve this problem, an analytical mathematical computer program was designed and implemented. The model is separated into three parts: Volumetric; Steady state water influx, and Unsteady state water influx. The computer program was written by using the volumetric and material balance equation that include Van Everdingen-Hurst unsteady state water influx equation or Schilthuis steady state water influx equation and the latest correlations available in the technical literature, modified and adapted for this work. From the result, it shows that the model can be used to analyze gas reservoir, predict the drilling period for that reservoir and rebuild pressure history of a reservoir from production data. This paper is only concerned with the development of the model computer program and solution techniques. The remaining material will be presented in part II of this series of two papers.
The Effect of Steep Temperature Gradient on Relative Permeability Measurements
Authors: Watson R. W. , Ertekin T.
Published: December 2007

The injection of a fluid with a temperature either higher or lower than the in situ reservoir temperature results in a temperature gradient between the injected fluids and the in situ rock and fluids. Relative permeability is a means of characterizing the flow of immiscible fluids through a porous media. The objective of this study is to consider the effect of the steep temperature gradient upon relative permeability. Along these lines, we present a series of imbibition cycle relative permeability measurements which were conducted in 12-inch and 24-inch Berea sandstone fired and unfired cores using Soltrol 170 and CaCl2 brine. The temperature gradient in the 12-inch core was made equal to the temperature gradient in the first 12-inches of the 24-inch core by injecting the fluids at a constant temperature. Four injection temperatures varying from ambient to 300°F were used to conduct the experiments. Variations in the relative permeability curves from the 12-inch core to the 24-inch core were indicative of the effects of the temperature gradient. Experimental results indicate that the irreducible water saturation increased and the residual oil saturation decreased with average temperature. As the injection temperature increased, the computed values of oil and water relative permeability decreased. The difference in the temperature gradient resulted in variations in both the irreducible water saturation and residual oil saturation and suggested that changes in wettability occurred. Both oil and water relative permeabilities decreased at a larger rate with an increasing temperature gradient.
New Methods for Evaluation of Shaly Formations by Well Logs
Authors: Aguilera R.
Published: December 2007

New methods are presented for analyzing (1) laminated, (2) dispersed, and (3) total shale models. The techniques involve the use of log-log crossplots of effective porosity vs. true resistivity as 'affected by a shale group (As h).

Response equations for the above models have been written in such a way as to allow the generation of log-log plots from which values of water saturation can be readily calculated.

Three key advantages of the proposed methods are: (1) the value of m does not have to be assumed equal to 2.0; in fact, it can be determined from this analysis by trial and error, (2) water resistivity does not have to be known in advance provided that the reservoir contains some water-bearing intervals, and (3) all shaly intervals being analyzed can be displayed in a single log-log plot that includes porosity and water saturation even if shale volumes are changing continuously. An application is presented in detail.

It is concluded that log-log crossplots provide powerful evaluation techniques for the analysis of laminated, dispersed and total shale models. These methods can be readily extended to the analysis of naturally fractured reservoirs.
Real-Time Optimization of Fracturing Fluid Viscosity to Meet Changing Fracture Conditions
Authors: Olsen T. N. , Debonis M. P.
Published: December 2007

Materials such as crosslinked guar-gum derivatives have had widespread applications as viscosifying agents for water-base hydraulic fracturing fluids. Laboratory tests have demonstrated that the crosslinked gelled water viscosity will degrade with increasing temperature.

Heat-transfer simulators indicate that when there is a temperature difference between the formation temperature and the surface fluid temperature, a significant cooldown will occur across a portion of the length of the fracture. However, because of operational limitations, most treatments are designed for a worst-case temperature with, at most, two fluids of different viscosity to compensate for fluid temperature variance. Therefore, the result is a fracturing fluid with varying viscosity throughout the fracture.

Now, with the emergence of on-site microprocessors and new, accurate, continuous-mix gelling equipment, the gel loading can be varied to compensate for time and temperature effects, thus yielding a fracturing fluid with a more consistent downhole viscosity while using less gelling agent.

On-site adjustment of polymer loading gains even more utility when the net fracturing pressure is monitored for changing fracture conditions1-3

This paper presents many of the advantages of real-time viscosity control, and several field examples that apply these features.
The Evaluation of Oil and Gas Plays
Authors: Warren J. E.
Published: December 2007

A play is a group of exploration prospects or potential fields with geologically similar source, trap and reservoir characteristics contained within a continuous stratigraphic interval. The total economic reserves for an untested play can be estimated via a straightforward, albeit subjective, procedure; and, its net present-worth value can be approximated in an analogous manner.

First, assume that the play exists and model it in accordance with the following estimates: (1) the underlying prospect-size distribution-assumed to be equivalent to the field-size distribution (2) the distribution of the number of prospects in the play and the conditional probability that any prospect in the play will contain hydrocarbons - or, more simply, the distribution of the number of fields in the play (3) the practical truncation points for the prospect-size distribution - the minimum (economic) and maximum field sizes for the play. All of these estimates can be based on the analysis of all geochemical, geologic and geophysical data pertinent to the play and/or information collected from one or more similar (look-alike) plays.

Next, these random variables - field size and number of fields - are combined probabilistically, without recourse to Monte Carlo simulation, to permit the approximation of the distribution for the total economic reserves associated with the play. Finally, estimate (4) the probability that the play really does exist - the chance that adequate source, trap and reservoir are present; and, approximate the distribution of the total, geologically-risked, economic reserves for the play.

For the economic assessment, the evaluation procedure used to determine the minimum (economic) field size is extended over the entire doubly-truncated field-size distribution; and, the same combinatorial process is employed to obtain the distribution of the total, unrisked, net present-worth value of the play. Risk is introduced via the probability that the play is valid and the expected cost of exploration; and, the distribution of the play’s total, geologically-risked, net present-worth value is approximated.

This paper discusses the theoretical bases for the proposed procedure and some practical considerations applicable to input information. It also presents a complete example that uses actual field data and compares the results with an independent evaluation of the same data.
A Typical Petroleum Engineering Curriculum in the U.S. and Curricula on Transcripts From the P.R.C.
Authors: Carlile R. E.
Published: December 2007

The 1980’s have seen an increasing number of students from the People’s Republic of China come to US petroleum schools for basic or advanced degree training. Dissimilar transcripts, courses taken, and degrees obtained make transcript analyses difficult and each candidate’s application a unique analysis.

This study analyzes 26 petroleum undergraduate programs in the US and presents a "typical US Petroleum Engineering undergraduate program." Twenty-seven transcripts from eight PRC petroleum institutes have been examined in an attempt to point out similarities and dissimilarities between the petroleum training common to both nations. From these comparisons, future student candidates traveling to either nation to study petroleum engineering can better determine what preparatory courses are applicable to the degree program in that nation.
A Fractured/Matrix Model for Estimating Water Saturations in Reservoir Rocks
Authors: Xiaokui Xu , Colpitts R. M. , Bretz R. E.
Published: December 2007

In this paper we present a model for calculating water saturations in clean, fine-grained, fractured rocks. The model, called the fracture/matrix (F/M) model, is used to calculate a composite porosity exponent, m, which is then used in Archie’s relationship to calculate water saturations. An application of the F/M model to wells located in S.E. New Mexico which penetrate the Bone Spring sands is presented.
Extended Reach Appraisal Well: A Case History
Authors: Locke H. A. , Johnson J. B. , Jewkes D. C.
Published: December 2007

The justification, planning, and implementation of a high angle, extended reach appraisal well for a newly discovered field is presented. This paper discusses the impact that the drilling of the well has on the feasibility of economic field development. Results of the drilled well and application of state-of-the-art techniques in steerable downhole motor technology, high angle hole maintenance, drilling fluids and hydraulics, plus high angle casing cementation are described.
Completion of Horizontal Drainholes
Authors: Lessi J. , Spreux A.
Published: December 2007

Horizontal drainholes, of which the aim is to collect the fluids over considerable lengths, may cross heterogenous zones of the reservoir. So as to turn to practical effect the advantages which in theory, ensue from horizontal drains, specific techniques must be made available providing solutions to the selective completion problems. Indeed, only a selective production method taking into account the geological heterogeneities of the reservoir will enable high production and recovery rates.

This paper presents results concerning three stages of the methodology of selective completion design, i.e., procedures and equipment for cementing or setting external casing packers, methods of reservoir evaluation in order to describe heterogeneities and models to optimize the flow rate distribution according to these heterogeneities.
Development Feasibility Study: Dong Sheng Pu Buried Hill Reservoir
Authors: Ullah S. , Shen Tse Yone , Mobarak S. A. , Carnes A. C. , Jiang Zhu Xue , Lin Wu Qi , Wen Hou Zhen , Mon Wan Zhong , Lin Zhao Cheng , Ding Feng
Published: December 2007

The Dong Sheng Pu Buried Hill reservoir in Liaoning Province is a fractured, metamorphic basement rock of generally low porosity which contains an undersaturated, 36° API oil. Production began in 1983. In late 1985 and early 1986, a detailed reservoir study was conducted to determine the most appropriate method of developing and operating the field. Water injection was predicted to yield the highest oil recovery and cash flow at an average oil price of $17/bbl. A water injection pilot was recommended. The operator has been developing the field according to recommendations put forth in the study.