bluuebunny/crossref_metadata_2025 huggingface dataset:
A Progress Report on Polymer-Augmented Waterflooding in Wyoming's North Oregon Basin and Byron Fields
Authors: DeHekker T. G. , Bowzer J. L. , Coleman R. V. , Bartos W. B.
Published: December 2007

Marathon Oil Company has implemented two large full-field polymer augmented waterflood (PAW) projects in Wyoming's mature Rig Horn Basin oil producing area. These projects are well under way and are designed to improve the waterflood sweep efficiency in the Embar and Tensleep Reservoirs of the Byron and North Oregon Basin Fields. The observed production response of the two projects has resulted in the expansion of the PAW projects to other Big Horn Basin fields where further significant contributions to increased incremental tertiary production and reserves are expected.

This paper discusses historical secondary and recent tertiary production performance along with operations of the injection, production, and treating systems since commencing PAW operations. Also, laboratory work, field testing, PAW implementation and certification are presented.
Design and Analysis of a 30-in., 3,000-psi Blowout Preventer
Authors: Allen M. B. , Preston J. P.
Published: December 2007

Subject

This paper describes stress analysis methods and results used to evaluate and improve the design of a new blowout preventer. A 30 inch, 3000 psi blowout preventer had not been previously manufactured and the design procedures involved extrapolation of experience with smaller designs. To evaluate the new design and eliminate the need for testing prototypes, finite element stress analysis was performed on the original design and subsequent design modifications. The stress analysis ensures that stresses and deformations in the BOP under expected test and service conditions are within generally accepted values and conform to standards of the ASME Boiler and Pressure Vessel Code.

A coarse finite element model is used to determine nominal stresses in the BOP and identify high stress regions. Refined models are used to determine stresses in critical areas. Results of the analysis were used to reduce the overall weight by removing steel from low stress areas and adding steel to regions that required additional strength to satisfy fatigue life design criteria. The size of the BOP and the pressures it must withstand result in deformations larger than those typical of smaller designs. Accurate calculations of these deformations were important to determine if a particular seal design is sufficient. The large span also results in greater variations in flange bolt loads and contact stress around the ring gasket than what occurs in other designs.

Significance

Most existing blowout preventers have been designed with hand calculations and prototype testing, before finite element analysis techniques became widely available or accepted. The subject of this paper is unique because of the size and pressure rating of the BOP and because computer models were used to thoroughly evaluate the design prior to any physical testing.
Risk Reduction Through Quality Management of Critical Service Well Equipment
Authors: Armstrong G. M. , Brown D. H. , Reynolds W. W.
Published: December 2007

High strength, heavy wall, controlled yield or corrosion resistant alloy pipe and equipment are normally required for the complex operations and higher risks associated with deep, high pressure or corrosive environment wells. They may also be specified for wells in environmentally sensitive areas and wells with other critical circumstances. These components frequently require a level of quality assurance which can be provided only through execution of a centralized, integrated quality assurance program. This type of program, using a systematic approach to overall quality assurance, ensures that the appropriate items are ordered, manufactured, inspected, tested and delivered in compliance with the required specifications and schedules.

This paper discusses Quality Assurance Project Management (QM) as a means of planning and executing a quality assurance program from initial procurement specifications through final installation. The basic QM Elements are defined and explained. Typical examples, showing the application of QM to critical service well components, are included. Additionally, the effectiveness of the Quality Management approach is demonstrated through specific examples of failure prevention and cost avoidance.
Dehydration of Heavy Crudes by Electrical Means
Authors: Lucas Roy N.
Published: December 2007

This paper was prepared for the 41st Annual Fall Meeting of the Society of Petroleum Engineers of AIME, to be held in Dallas, Texas, Oct. 2–5, 1966. Permission to copy is restricted to an abstract of not more than 300 words. Illustrations may not be copied. The abstract should contain conspicuous acknowledgment of where and by whom the paper is presented. Publication elsewhere after publication in the JOURNAL OF PETROLEUM TECHNOLOGY or the SOCIETY OF PETROLEUM ENGINEERS JOURNAL is usually granted upon request to the Editor of the appropriate journal provided agreement to give proper credit is made.

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

Operating data and results from a number of commercial installations employing chemically-aided electrical dehydration to purify low gravity (less than 18 degrees API) crude oils (including those produced by thermal recovery methods) are reported. The influence of certain physical properties of the crude oils - including API gravity, viscosity, and particle size distribution of the water droplets in the emulsion - on the results achieved by commercial units has been investigated and is described in detail. Similarly, the influence of certain operating conditions - including temperature, pressure, and electrical potential - is reported.

A description of the design procedure by which the electrical requirements, capacity, and product quality expected of field installations are calculated from laboratory pilot tests is included, as is a discussion of the means by which appropriate chemical aids are selected. A brief discussion of the role of chemical aids in electrical dehydration is also provided.

The data and results presented indicate that field installations can be satisfactorily designed on the basis of the physical properties of the crude oils and pilot plant tests when these elements are combined with appropriate empirical data. Both field data from operating units and laboratory tests also demonstrate that, with suitable equipment and operating conditions, the electrical dehydration characteristics of thermally produced oils do not differ significantly from those of other heavy oils.

Introduction

Background. Electrical dehydration was one of the earliest commercial means of dehydrating the heavy viscous crudes produced in California.
Laboratory and Field Applications of the Strain Relaxation Method
Authors: El Rabaa A. W. M. , Meadows D. L.
Published: December 2007

Over the past few years, the Strain Relaxation (SR) method (or the anelastic strain recovery) has been used for predicting the orientation of induced hydraulic fractures in oil wells. Reliability of the method requires a sensitive measuring device and cores free of natural cracks.

A SR device that uses DC displacement transducers was developed and tested in laboratory and field conditions.

An extended version of the SR method is suggested for laboratory use to predict directions and magnitudes of the in-situ stresses. In the laboratory, effects of pore pressure and natural fractures on SR data are investigated. It is observed that jacketed cores that have been subjected to hydrostatic pressure, expand in all directions on the release of the pressure, and that unjacketed porous cores subjected to the same pressure contracted in all directions during their relaxation period. Agreement between the laboratory azimuth predicted by both type of tests is observed.

The calculated fracture direction suggested by SR data collected through testing cores which contain natural fractures is likely to be perpendicular to the maximum horizontal in-situ stress, thus the calculated direction will be 90° away from the true direction. On-site, the SR method is applied in three different wells. Results from two wells are in a fair agreement with predictions of other fracture orientation detection techniques.
Blending Alkaline and Polymer Solutions Together into a Single Slug Improves EOR
Authors: Mihcakan I. M. , Van Kirk C. W.
Published: December 2007

Polymer augmented alkaline flooding (PAAF) is a relatively new EOR process, and its first version has been defined as injecting an alkaline slug chased by a polymer slug. During the early 1980's the second version of PAAF was introduced, being composed of a single slug of alkaline and polymer blended together, followed by a polymer slug.

A series of corefloods was conducted with alkaline solution, polymer solution, and a blend solution of alkaline and polymer in linear and radial Berea sandstone cores for studying the mechanisms of the second-version PAAF process. Sodium hydroxide was used as the alkaline agent, and the polymer was 30-percent hydrolyzed polyacrylamide. The efficiency of the second-version PAAF was compared with that of both alkaline flooding and polymer flooding alone.

Results showed that the synergistic effect of the second-version PAAF provides better efficiency than either alkaline or polymer alone for enhancing oil recovery. This chemical system of alkaline and polymer blended together yielded more oil recovery with increasing blend slug size.

Also, a phenomenon never before reported was observed. It is a visible residual oil saturation ring next to the region cleaned of oil adjacent to the injection sand face, and it was observed in both linear and radial cores after the application of the second version PAAF process. The size of this oil ring is similar to the size of the blend slug of alkaline and polymer.
The Role of Screening and Laboratory Flow Studies in EOR Process Evaluation
Authors: Goodlett G. O. , Honarpour M. M. , Chung F. T. , Sarathi P. S.
Published: December 2007

Numerous steps are involved in evaluating enhanced oil recovery (EOR) methods for field application. Technical screening guides are consulted for initial determination of applicability. This is followed by a comprehensive analysis of fluid, rock, and rockfluid interactions. Prior to displacement studies, decisions concerning type of core, core size, and experimental apparatus are made considering scaling laws, dispersive effects, duplication of reservoir conditions, and the unique parameters of the particular process being utilized. Experimental flooding techniques and interpretation of subsequent results are discussed for each type of EOR method. These tests are based on those found in the published literature and experience at this laboratory.

EOR methods discussed include polymer, surfactant-polymer, alkaline flooding, thermal, and miscible and immiscible gas displacement. The critical flow study parameters are considered for each method. What can be learned from each type of coreflood experiment is described and limitations are given. Specific techniques used in carrying out each type of coreflood experiment are presented. The coreflooding aspects of emerging EOR technologies, such as microbial methods and emulsion blocking in steamflooding, are examined.

Classic scaling criteria and dispersive constraints indicate core lengths of about 4-ft are necessary to linearly scale reservoir conditions. Composite cores are often constructed from available field material to meet scaling constraints. In immiscible displacements, the introduction of multiple capillary discontinuities significantly alters oil saturation distribution. Berea sandstone and sandpacks, widely used in petroleum research, are found to be more heterogeneous than is commonly believed. To accurately address the problems of laboratory evaluation of individual EOR methods, appropriate laboratory apparatus and techniques should be designed and utilized. Concurrently, a realization of the limitations of the laboratory model is necessary for accurate interpretation of results obtained.
Drilling Engineering and Database Applications on Microcomputers Using Pascal
Authors: Zamora M. , Wilson C. D.
Published: December 2007

FORTRAN and BASIC may not be the microcomputer languages of choice for many engineering applications. We have developed a complete suite of engineering programs using Turbo Pascal and have found the new language provides superior benefits for the user, programmer and software manager. The applications range from user-friendly input screens to complex calculations, from memory-resident utilities to sophisticated database managers, from real-time simulations to artificial intelligence, from high-quality graphics to laboratory data acquisition. In this paper, we describe these developments and show how Turbo Pascal and its extensions can form the core of a very powerful and cost-effective software system.
Reduced Computing Time in Cash Flow Risk Analysis for Microcomputers
Authors: Crout L. E. , Startzman R. A. , Wattenbarger R. A.
Published: December 2007

A recent development in Monte Carlo methods makes a significant reduction in the number of simulations needed to converge. This development is the Latin Hypercube Sampling (LHS) method. This paper shows the results of numerical experiments, conducted on a microcomputer, which examined this computing problem using a cash flow model.

It was found that the computing speed of the LHS method is greatly affected by the design of the random sampling procedure. There appears to be an optimum sampling approach which results in a minimum run time. This run time is a small fraction of the time required for conventional Monte Carlo simulation. We believe this reduced run time allows fairly complex cash flow problems to be simulated on a microcomputer, as well as, reducing the costs of runs on mainframes as well.
What Are We Talking About?
Authors: Thompson Craig
Published: December 2007

This paper was prepared for the 41st Annual Fall Meeting of the Society of Petroleum Engineers of AIME, to be held in Dallas, Tex., Oct. 2–5, 1966. Permission to copy is restricted to an abstract of not more than 300 words. Illustrations may not be copied. The abstract should contain conspicuous acknowledgment of where and by whom the paper is presented. publication elsewhere after publication in the JOURNAL OF PETROLEUM TECHNOLOGY or the SOCIETY OF PETROLEUM ENGINEERS JOURNAL is usually granted upon request to the Editor of the appropriate journal provided agreement to give proper credit is made.

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

During the early and mid-30s business managers began to recognize the need for improving the public acceptance of their companies. This, they reasoned, could best be done by speaking out in their own defense.

Reasons that lead to the birth of public relations programs and activities were various. Among them were the gains of trade unions in obtaining greater public sympathy and support; the effects in the market place felt by companies whose labor policies were unpopular; a determined drive to extend Federal authority over corporations; and an increase in the number of persons and institutions owning stocks which made desirable the enlarged flow of information about companies, their policies, plans, and operations.

Early Public Relations practitioners usually were men with experience in writing politics or finance men of maturity and judgement who proved capable of contributing useful and valuable services to all levels of management.

Over the years, a new concept of public relations began to take shape and public relations became a total corporate concern and responsibility. Under this concept, every officer, every employee, every dealer who sells the product is sort of a goodwill ambassador with local managers in every community encouraged to take part in local projects even to the point of running for public office if his talents are in that direction.
Reservoir and Production Engineering Application Programs
Authors: Boone D. M. , Terril T. A.
Published: December 2007

This paper discusses the use of Lotus 123 spreadsheet software to design reservoir and production engineering applications that are easy to use and understand. Several of these applications have been created using a series of spreadsheet templates or subroutines that function as building blocks in developing larger petroleum engineering programs. These building blocks are based upon the algorithms available in industry publications that estimate properties of petroleum fluids. The design philosophy was to use algorithms whenever possible and to reduce the amount of input required by the engineer. It is hoped that demostrating this programming techniques, demonstrated in this paper, will lead to the development and exchange of application programs.
Hydrate Predictions on a Microcomputer
Authors: Berge B. K.
Published: December 2007

This paper describes the formulation and basis of the microcomputer program, HYDRATE.BAS, which calculates hydrate formation conditions of natural gases. The program is based on the Carson and Katz method for hydrate predictions. It is designed for pressures in the range 100 to 2000 psia (700 to 14000 kPa), and temperatures between 32 and 80 °F (0 and 26 °C). Comparisons with published experimental data indicate average pressure deviations of +/− 30 psi (200 kPa) and temperature deviations of +/− 2 °F (1 °C). The program is written in BASIC, and will be available for Osborne 1*, IBM PC** and compatibles.
The Use of Microcomputers in Well Test Data Acquisition and Analysis
Authors: Home R. N. , Perrick J. L. , Barua J.
Published: December 2007

The advent of small and portable microcomputers provides interesting new possibilities for the acquisition and analysis of well test data. In particular, there is a considerable saving in time if the data is transferred directly (or remotely using a modem link) to the computer for scaling, filtering and plotting. In addition, since present day microcomputers have considerable processing power, it is possible to perform all of the interpretation using the same portable microcomputer.

The advantages of doing this are several. Computerized analysis using automated techniques can provide good estimates from much shorter test data than is required for standard graphical analysis. Thus it is possible to analyze the test at the same time data is being collected, and to terminate the test when the data are sufficient for interpretation. Examples given in the paper demonstrate that the well test can sometimes be shortened by an order of magnitude in this way. The cost saving could therefore easily pay for the computer itself.

The advents of compact and powerful microcomputers, of computerized data acquisition and control, and of automated interpretation software represent major advances in the field of well test analysis.
The Fragmentation of Brittle Media by Concentrated Loadings
Authors: Simon Ralph
Published: December 2007

A study is made of the fragmentation of some brittle media by the loadings of wedge- and cone-shaped tools onto the surfaces of effectively semi-infinite specimens. The ratio of the work done in loading with a particular tool to the mean volume of material broken out, averaged over a number of loadings, is found to be constant over the ranges of experimental conditions investigated, which agrees with a result previously obtained in an investigation of the fundamentals of rock drilling. The value of this ratio, termed the fragmentation strength, varies with the included angle of the wedge or cone in a different manner for brittle media of different porosities. The mechanisms of energy dissipation in concentrated loadings on brittle media are discussed, particularly in regard to the energy requirements for rock drilling.

Introduction

Concentrated loadings are defined as loadings of such localized nature on an essentially plane surface of a specimen of a medium that the patterns of deformation and damage are independent of the linear dimensions or of the geometric shape of the specimen. The deformation of ductile media by concentrated loadings has received considerable attention in view of the importance of indentation testing for measuring hardness, principally of metals. However, little work of this nature has been done with materials that exhibit predominantly brittle behavior under concentrated loadings. Notable exceptions are the studies that have been made of the flow and fracture behavior of glass when loaded with pyramidal and spherical indenters as reviewed by Douglas. Work has also been recently reported on the forces required to push wedges into coal and into mixtures of pitch and sand.

The effects of concentrated loadings on rock were investigated in a study of the fundamentals of rock drilling conducted at Battelle Memorial Institute for Drilling Research, Inc., which is an organization formed by a group of companies engaged in various phases of oil production to investigate novel methods of drilling. The basic action of most mechanical means of drilling into rock consists of indexed and repeated, concentrated loadings on the bottom of the hole. Of primary interest in this previous investigation was the relationship between the volume of rock broken out per impact and the pertinent variables associated with the loadings and with the characteristics of the rock. The conclusions from this study proved to be of value in analyzing and comparing conventional and new methods of rock drilling.
Meeting the Consulting Needs of a Changing Industry
Authors: Hartsock J. H. , Root P. J.
Published: December 2007

Recent declines in oil and gas prices have forced consultants to re-examine their mode of doing business. In the future, consultants will strive to reduce the costs of completing any assignment. This can only be accomplished by using the most current technology in the form of computer hardware and software (including interactive graphics and reservoir modeling). Although consultants will be performing tasks similar to those in the past, they will have better technology and be more cost effective. In addition, the reduction in technical staff by all producing companies will result in an increased demand for consultants to do reserve estimates, detailed reservoir studies and training.
Analysis of Oil and Gas Reserve Acquisition Costs in Corporate and Property Purchases
Authors: Horn S. R.
Published: December 2007

This paper will analyze the purchase of domestic U.S. oil and gas reserves in corporate and property acquisitions during the past five years. This topic has occupied the attention of industry, financial press and investing public who have wanted to know the price at which oil properties are selling, and more specifically, the price at which oil has "sold for on Wall Street."

The specific questions to be considered in this paper are: –What has been the "average " price paid for oil and gas reserves over this period of time?–How do the prices paid in corporate acquisitions compare to those for property acquisitions?–Is it cheaper to buy properties in larger transactions than in smaller transactions?–Has there been a premium paid by non-industry or foreign buyers to acquire domestic oil and gas reserves?

In using publicly available information to analyze corporate and property transactions, the traditional rule of thumb of dollars per barrel equivalent ("$/BOE") was considered. In addition, several new measures of value. Percentage of SEC Value and Percentage of Operating Margin – were developed to better analyze the transactions. These new methods were designed to address several of the factors -- different product prices, different reserve lives, the time value of money and differences in operating costs and required capital investments -- which cause difficulties in comparing transactions using traditional rules of thumb.
Improved Coring and Core-Handling Procedures for the Unconsolidated Sands of the Green Canyon Area, Gulf of Mexico
Authors: Whitebay L. E.
Published: December 2007

The development of a full-closure core catcher coring system has greatly improved the chances for successfully sampling the very soft, unconsolidated sands of the Gulf of Mexico. Designed as an alternative to the rubber-sleeve core barrel, the new coring system cuts a larger diameter, 3 1/2-in versus 3-in, and longer, 30-ft versus 20-ft, core. The full-closure core catcher completely seals the bottom of the barrel trapping the unconsolidated sands inside. Core handling is simplified through the use of a rigid PVC liner which encases and supports the loose sand. Freezing the unconsolidated sand in the liner at the rig and keeping it frozen throughout the entire core analysis program preserves the quality of the samples. Whole core X-ray analysis of the material encased in the liner reveals bedding planes, fractures, rock type, and the degree of sample disturbance. Slabbed cores can easily be preserved for ongoing studies by packaging them in a new core preservation system, ProtecCore®.
The Interrelationships of Tubing Strings, Flow Lines, and Compressors Their Effect on Gas Well Deliverability
Authors: Nauck George S.
Published: December 2007

This paper was prepared for the 41st Annual Fall Meeting of the Society of Petroleum Engineers of AIME, to be held in Dallas, Tex., Oct. 2–5, 1966. Permission to copy is restricted to an abstract of not more than 300 words. Illustrations may not be copied. The abstract should contain conspicuous acknowledgment of where and by whom the paper is presented. Publication elsewhere after publication in the JOURNAL OF PETROLEUM TECHNOLOGY or the SOCIETY OF PETROLEUM ENGINEERS JOURNAL is usually granted upon request to the Editor of the appropriate journal provided agreement to give proper credit is made.

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

When dealing with a high-volume gas well, the size of the tubing string and flow line can have significant effects on the deliverability of the well. If compression is used to increase the deliverability of the well, the size of the tubing string and flow line can also have significant effects on the amount of compression required.

This discussion deals with the interrelationships of tubing strings, flow lines and compressors as applied to gas well deliverability. The principles and relationships involved are not new nor are they very complicated, but they are important from an economic standpoint. Since the calculations involved are relatively basic, the discussion will be primarily concerned with illustrations of the results.

Introduction

In the operation of a gas field from, which we are obligated to maintain a given total deliverability, we are often faced with the decision of how to maintain deliverability as reservoir pressure declines. In a case where the wells have been previously completed and the gathering system installed, it is necessary to determine whether to install larger tubing in the wells, enlarge or loop existing flowlines, install compressors in the gathering system, or attempt to choose an optimum combination of these methods. There is no cut-and-dried answer to this problem that would apply to every situation and the answer may be determined only after careful evaluation of any specific case.

In some cases it may be known that compression will eventually be required for depletion of a field. This knowledge might lead to the assumption that the best thing to do when additional deliverability is required is to proceed with compression. Installation as required and in the amount necessary to maintain required deliverability. Such an assumption may or may not be legitimate, depending on the specific case in question. To arrive at the answer it is necessary to understand the interrelationships of tubing strings, flow lines and compressors, and their effect on gas well deliverability.
Engineering Salary Trends in the Petroleum Industry
Authors: Brown D. C. , Tarrant L. E.
Published: December 2007

To understand the changes that occur cyclically in engineering manpower supply/demand trends in the petroleum industry, it is desirable to have an awareness of some of the major activities and factors affecting such trends; of starting Petroleum Engineering salaries relating to that background; of the on-going engineering salary status which developed from these activities; and of the large effect that high starting and on-going salaries do have in attracting and retaining engineers within the petroleum industry. It is important to realize that changes in industry trends can be brought about both by economic and political decisions, in both domestic and international activities.

There is no single entity or group, which by itself sets the climate for engineering manpower trends in all of the parts of the petroleum industry. Rather, it is set by the political and economic decisions of nations affecting the industry, and by the interactions of a very large number of companies and individuals, from the diverse and multiple parts of the industry, in creating demand for engineers of the various types and levels needed by their organizations.

Each organization must continually monitor and find ways to meet its needs for engineers for the present and foreseeable future, as to the various engineering subfunctions which must be filled in drilling, production, reservoir, process, mechanical, electrical, and other engineering activities.
Sondes for Big Hole Logging
Authors: Gianzero S. C. , Konen C. E. , Chemali R. E. , Strickland R. W.
Published: December 2007

Offshore drilling costs are affected by the need to drill a borehole for logging purposes, then ream the hole for deeper drilling. The introduction of an entirely new suite of logging tools designed to operate in an 18 inch (or larger) borehole significantly reduces these drilling costs.

The induction and resistivity tools are totally new designs based on mathematical simulations which were verified by experiment. On the other hand, the pad type Big Hole tools are similar to their conventional counterparts except for a redesign of the caliper assemblies.

The induction design measures a signal of 1 mmho from a 24 inch borehole with mud resistivity of 1Ω · m. The depth of investigation of 65 inches is comparable to the ILd but the new design has a reduced shoulder effect. A focused resistivity log specifically designed for large boreholes is also run in combination. For Rm = 0.1Ω · m, Rt ≤ 100Ω · m and borehole diameters between 8 and 20 inches, the error due to borehole effect is less than ± 17%. The nominal bed definition of the focused resistivity log is 2 1/2 feet.

The proposed suite of tools were successfully tested under controlled field conditions. Log examples comparing the conventional and Big Hole tools indicate the improved performance characteristics in big holes.
A Method for Determining Recovery Factors in Low Permeability Gas Reservoirs
Authors: Harlan L.E.
Published: December 2007

This paper was prepared for the 41st Annual Fall Meeting of the Society of Petroleum Engineers of AIME, to be held in Dallas, Tex.,Oct. 2–5, 1966. Permission to copy is restricted to an abstract of not more than 300 words. Illustrations may not be copied. The abstract should contain conspicuous acknowledgment of where and by whom the paper is presented. Publication elsewhere after publication in the JOURNAL OF PETROLEUM TECHNOLOGY or the SOCIETY OF PETROLEUM ENGINEERS JOURNAL is usually granted upon request to the Editor of the appropriate journal provided agreement to give proper credit is made.

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

Recovery factors for low permeability depletion gas reservoirs are usually difficult to estimate. It is characteristic of many reservoir appraisal engineers to over estimate these recovery factors, especially for newly completed wells when the only data available are potential tests and well logs. Recovery factors in such reservoirs are likely to be less than 50 percent.

This paper presents a method for estimating recovery factors that departs from the more familiar approach of using back pressure curves. It was developed primarily for the appraisal of new wells when information is limited and often of poor quality. The complexity of the method is kept from outreaching the amount and quality of this information. No new theory is introduced and it is not a computer solution.

The basis for the approach used is to provide a method for determining reservoir rock properties and then to calculate a reservoir abandonment pressure from a form of Darcy's equation. It has been tested on 23 wells with complete data and histories which represent a variety of rock types and geological age groups in three basin areas. The method is empirical to the extent that it uses facts obtained from field testing and from the laboratory which relate the reservoir's flow properties to its rock properties. It recognizes the problems that make the study of low permeability gas reservoirs difficult, including those of turbulence, skin effect, and transient flow.

Introduction

This is a method which can be used to estimate recovery factors for depletion-type gas reservoirs with low permeability. No new theory is introduced.
The Role of Objective and Subjective Data in Predicting Undiscovered Amounts of Oil and Gas in Virgin or Immature Basins
Authors: Snow S. E. , Gangwar A.
Published: December 2007

Discovery process models are used to predict drilling success rates and field sizes for a developing basin. The earliest attempts at these predictions relied either on historical data (objective models) or on the development team's "feel" for the basin (subjective models). Recently models have been developed which are more rigorous than these earlier models. However, these models have not found general usage because they are not applicable during the early life of the basin and because they are highly data intensive. A new model has been developed which is based on these newer models but which is applicable during the entire life of the basin and which is more flexible in its data requirements. The model is applied to both a mature and an immature horizon in the Greater Green River Basin.
Simulation Approach in Risk-Weighted Cash Flow Rate of Return Determination
Authors: Yu J. P.
Published: December 2007

Discounted cash flow rate of return polynomial equations sometimes result in several values of the roots. Only one of these values can be used to accurately characterize the venture, and concern about this prompts a new approach to the problem. Simulation approach evaluates the risk-weighted rate of return which determines the proper range of values. The range of values is then used to estimate the cash flow with probabilistic sensitivity analysis. This analytical technique will determine a valid rate for high risk oil ventures. Simulation method is very easily applied with a microcomputer, and the computer speed has made this approach possible. In addition, spreadsheet and graphic application programs can be used to display the cash flow rate of return and help the decision-making procedure.
Performance Testing of Shock Absorbers
Authors: Skaugen E. , Kyllingstad A.
Published: December 2007

For a better understanding and evaluation of shock absorber performance, detailed data upon their relevant physical parameters, such as spring characteristics and energy dissipation properties, have been measured in a test jig. Down hole tests where well defined sinusoidal vibrations are generated in a 1000 m vertical drill string by means of a down hole exciter were also performed. The drill string response above the shock absorber is measured by a hard wired MWD tool giving high frequency data on accelerations, WOB, torque and pressures. Examples of test results for different types of absorbers are presented and discussed for both laboratory and downhole tests.
Offshore Adriatic Marginal Gas Fields: An Approach to the Technique of Reservoir Development
Authors: Montanari A. , Bolelli V. , Piccoli G.
Published: December 2007

The application of accelerated gas blowdown and wire line techniques in reservoir development and exploitation is presented for an off-shore Adriatic marginal gas field. The approach discussed in this paper utilizes selective completion, very low reserves/production ratio, sequential production, Through Tubing Bridge Plug and Through Tubing Perforation techniques to avoid the use of costly workover rigs and to allow economically convenient exploitation of a structure which otherwise would have been abandoned.
Quantitative Interpretation of Electric Logs in Oil-Wet Rocks Proposed Procedure and Example Applications
Authors: Pirson S.J. , Fraser Charles D.
Published: December 2007

Quantitative evaluation of electrical surveys recorded in oil wells often provides the best and many times the only means for determining the reservoir parameters used in reserve estimates, well productivity predictions and other aspects of formation evaluation. Should the zone of interest be oil-wet, standard procedures for interpretation will not apply, and a revised method must be employed.

Laboratory data and fundamental reasoning were used as a foundation for deriving an "oil-wet interpretation procedure". The purpose of this paper is to present the premises upon which the revised procedure is based, to explain how an oil-wet zone may be recognized from logging surveys and to test the interpretation method through application to field examples. Also, the scope of quantitative log interpretation is extended to include estimates of absolute and relative permeability and predictions of well productivity in terms of the expected water-oil ratio and initial flow potential.

Logs from the Springer sand of Southern Oklahoma were used to test the proposed technique, and results of the work provide further evidence that this sand is at least partially oil-wet in certain areas. From the study of these logs, it is concluded that use of the proposed method derives values which are much more reasonable than those calculated with standard techniques; furthermore, predicted well productivities were in reasonable agreement with reported performance in most cases. Although there is as yet little known about the actual conditions of in situ rock wettability, it is believed that the interpretation method proposed in this paper is presently the best available for analyzing zones possessing characteristics such as those exhibited by the Springer sand.

Introduction

Quantitative interpretation of electrical, radioactivity, acoustic velocity and other types of logging surveys provides a practical and often quite accurate means for evaluating the prospective formations penetrated by wells drilled in the search for oil.
The Effects of Viscosity and Wettability on Oil and Water Relative Permeabilities
Authors: Donaldson Erle C. , Lorenz Philip B. , Thomas Rex D.
Published: December 2007

This paper was prepared for the 41st Annual Fall Meeting of the Society of Petroleum Engineers of AIME, to be held in Dallas, Tex., Oct. 2–5, 1966. Permission to copy is restricted to an abstract of not more than 300 words. Illustrations may not be copied. The abstract should contain conspicuous acknowledgment of where and by whom the paper is presented. Publication elsewhere after publication in the JOURNAL OF PETROLEUM TECHNOLOGY or the SOCIETY OF PETROLEUM ENGINEERS JOURNAL is usually granted upon request to the Editor of the appropriate journal provided agreement to give proper credit is made.

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

Outcrop cores and crude oils were used to examine the effects of viscosity and wettability on relative permeabilities. Wetting was evaluated from capillary pressure curves. Changes in wettability were produced by using different crude oils and additives. As the system became less waterwet, k(ro) decreased, but k(rw) was not affected. Cores cleaned with solvents were less waterwet than natural cores. Apparent values of k(ro) exceeding unity are due to capillary end effects.

Introduction

It is well established that waterflooding is the most important method of secondary recovery but leaves large quantities of unrecoverable oil. It is possible that specific additives may effect changes in wettability that will bring about improvements in the displacement efficiency of waterfloods. Although previous investigators have studied the effects of floodwater additives, many of these studies were conducted with refined oils and artificial cores. Crude oils and outcrop core samples were used to secure better representation of natural systems.

Gatenby and Marsden have shown that wettability tests determined by capillary pressure measurements agree qualitatively with those determined by imbibition tests. Imbibition tests with crude oils are complicated by an induction period as well as viscosity and permeability. The centrifugal method of determining capillary pressures was used because it yields results in a few hours that may require several days by the imbibition method.

Oil and water relative permeability values are basic to the calculation of waterflood performance in the field as well as in the laboratory. The unsteady-state method of core analysis was used, because it is representative of the actual oil depletion process occurring in a field waterflood and is a rapid method of analysis.

LABORATORY PROCEDURES

Cores and Solutions

Outcrop core samples: The core samples were cut from an outcrop of the Torpedo sandstone using a portable drilling rig equipped with a 1 1/2" × 40" diamond bit. The cores were taken from the formation in a pattern that was as close together as possible for uniformity of the core samples.
Generalized Transmissibilities for Distorted Grids in Reservoir Simulation
Authors: Hegre T. M. , Dalen V. , Henriquez A.
Published: December 2007

Distorted grids or "corner point geometry" have received increased attention as a means of enhancing the modelling flexibility of finite difference type reservoir simulators. Non-rectangular grids permit better alignment with reservoir boundaries and faults and may lead to fewer grid blocks and therefore less computational efforts in simulation of complex reservoirs.

This paper shows that caution should be used as regards the transmissibility calculations for distorted grids. Specifically, it is demonstrated by simulation experiments that methods which try to maintain (for 2-D problems) the five-point connectivity of standard finite differences may lead to serious errors. A generalized nine-point scheme is constructed and shown to be more appropriate for distorted grids. For instance, the scheme seems to preserve the accuracy of a square nine-point scheme if the distortion is kept within certain limits. Although based on finite element techniques, the scheme is given a finite difference type form, and can therefore easily be implemented in more general-purpose finite difference type reservoir simulators.
Rheology and Molecular Structure of HPG Gels
Authors: Kramer J. , Chu A. , Prud'homme R. K.
Published: December 2007

Hydroxypropyl guar (HPG) polymer solutions crosslinked with titanates (Ti) are used in hydraulic fracturing operations. The rheology of these gels arise from the complex interaction of polymer chemistry, metal ion chemistry, and flow history. We have employed several techniques (steady shear viscosity, dynamic oscillatory shear. Laser Doppler Anemometry, and freeze fracture electron microscopy) to develop a consistent picture of the factors controlling gel rheology. An impingement mixing technique has been developed to prepare uniform HPG gels and reproducible rheological data has been obtained. Dynamic oscillatory rheological measurements have been used as diagnostic probes of gel structure, and are shown to be useful in understanding chemical effects on gel structure. Laser Doppler Anemometry, a non-invasive technique for measuring velocity distributions, has been used to measure velocity profiles for gels under flow. Classical wall slip is not observed, rather distortions of the velocity profiles are observed for gels that have gelled under quiescent conditions. For gels made with impingement mixing linear velocity profiles are observed. Freeze fracture electron microscopy has been used to image gel structure and the results show the fracture of gel structure by shear. These observations demonstrate the mechanism of temperature stabilization of the viscosity of cross-linked gels. Temperature stability measurements of gel viscosity have been made using a novel reciprocating capillary viscometer.
Field Analysis and Flow Loop Tests Diagnose Problems With Delayed Action Crosslinked Fracturing Fluid Systems
Authors: Zigrye J. L. , Osborne M. W. , Westbrook G. H.
Published: December 2007

This paper summarizes problems Conoco has experienced with delayed temperature activated crosslinked fracturing fluid systems since their inception in 1982, and how these problems have been diagnosed and resolved by the combined efforts of production personnel, production engineering services personnel and production research engineers.

A statistical analysis was made of forty-one fracturing treatments in Conoco wells in the Lobo Wilcox Trend, South Texas Area, performed since 1982. In this analysis, two crosslinked fluid systems had very few pressure increase problems while two other systems showed a high incidence. Pressure increases resulted in sand outs or required injection rate increases to complete the treatments.

A flow loop testing procedure was devised to closely simulate temperature and shear rate conditions of frac fluids from the wellbore at the surface to the fracture tip. Tests on all four systems involved in the statistical analysis were performed.

The agreement between the field analysis and the flow loop tests was remarkable. Both systems that showed up well in the statistical analysis had good early time viscosity development and good long term viscosity in the flow loop tests. One system that had performed poorly in the field showed poor early time viscosity development in the flow loop tests. The other system had poor long term viscosity in the flow loop tests.

As a result of the flow loop tests, one service company changed their crosslinking system which greatly improved their fluid's early time viscosity development.

After more testing, the problem with the other system was determined to be in the hydroxypropyl guar (HPG) polymer. A change in the polymer resulted in a vastly improved fluid system.