bluuebunny/crossref_metadata_2025 huggingface dataset:
New Control for Completing Multizone Steam Injectors Utilizing Limited/Metered Entry Techniques
Authors: Schwab C. M. , Mitchell III R. F.
Published: December 2007

Steam mass placement can be controlled by utilizing new tubing limited entry systems and procedures when completing multizone single string injectors.

A metered entry steam injection system that has been field tested is described. The system incorporates two phase flow control, limited entry devices and special completion design and analysis techniques.
Solvent and Acid Stimulation Increase Production in Los Angeles Basin Waterflood
Authors: Dayvault G. P. , Patterson D. E.
Published: December 2007

A detailed review of 69 acid stimulation jobs completed from 1984 through 1986 in the Inglewood field, California led to mechanical and chemical improvements that dramatically increased production response to acidizing. Average peak oil production gain from stimulation has increased from 22 to 45 bopd using the improved system. Significant procedure changes introduced in late 1987 included using a 40 foot circulation wash tool, overflushing acid immediately and modifying the stimulation chemicals. Damage mechanisms being treated are: 1) calcium carbonate scale; 2) asphaltenes and paraffins; 3) migrating clays and formation fines, and 4) drilling and completion fluid damage caused while gravel packing.
An Engineering Approach to Gas Anchor Design
Authors: Campbell J. H. , Brimhall R. M.
Published: December 2007

Free gas is the most common cause for low pump efficiency in sucker rod pumping wells. The installation of a gas anchor on the bottom of the downhole pump is a method used to help combat this problem. This paper describes improved gas anchor design for sucker rod pumping wells with gas problems. A computer program is described which will aid in the design of a gas anchor system and which evaluates pressure drops to determine the efficiency of the gas anchor.

The major parameters in gas anchor design are gas bubble velocity, diameter of the mud anchor, length of the dip tube, and the pressure drops associated with the gas anchor system. Validation of rules of thumb used in the past for gas anchor design is made. Gas bubble velocity of 0.5 ft/sec is a valid assumption if the API gravity of the liquid is greater than 300, the flow is turbulent and the temperature is greater than 100 OF. The principles behind the operation of an efficient gas anchor are presented with suggestions on how more efficient gas anchors may be designed by production engineers.
Engineered Perforation Design and Evaluat
Authors: Morris C. W. , Ayoub J. A
Published: December 2007

Underbalanced perforating has become accepted as one of the best methods for creating open, undamaged perforations.1’2 However, the magnitude of the underbalanced pressure which can safely be used to complete the well is a major uncertainty, especially in unconsolidated or poorly consolidated sands. This paper describes an integrated well data analysis procedure to estimate the safe underbalance perforating pressure and the well response to a short ‘cleanup’ flow period. The design procedure utilizes open-hole logs, fluid data, and reservoir data to determine the formation mechanical properties and to build a reservoir fluid flow model. The design results can then be compared to the actual well performance. This is evaluated using transient pressure analysis of the data acquired in conjunction with the underbalance perforating. A field example is used to illustrate the design and evaluation of a tubing-conveyed perforating well completion.
An Effective Completion Method Utilizing the Tubing Stability Latch
Authors: Gonzalez M. E. , Rubbo R. P. , Moody W. D.
Published: December 2007

The successful design of a cost effective oil or gas well completion system depends on the efficient use and integrity of the production tubing and related equipment. A tubing to packer landing technique made possible through the use of the Tubing Stability Latch (TSL) is described which can reduce the chance of catastrophic equipment failure and allow the use of lower cost production tubing when compared with traditional techniques. The characteristics of several tubing to packer sealing arrangements including the TSL are compared.
Predicting Horizontal/Slanted Well Production by Mathematical Modeling
Authors: Chang M-M. , Tomutsa L. , Tham M. K.
Published: December 2007

A horizontal and slanted well model was developed and incorporated into BOAST, a black oil simulator, to predict potential production rates for such wells. The slanted/horizontal well model can be used to calculate the productivity index, based on the length and location of the wellbore within the block, for each reservoir grid block penetrated by the slanted/horizontal wellbore. The well model can be run under either pressure or rate constraints in which wellbore pressures can be calculated as an option of infinite-conductivity. The model is easy to use and can simulate the performance of multiple horizontal/slanted wells in any geometric combination within reservoirs.

The model was checked against the analytical formulas of transient wellbore pressure in an infinite slab reservoir. A close match having an average deviation of only ±4% was found between the analytical formula and the fully penetrating slanted well model after a production period of early radial flow. A good agreement was also obtained between the simulation results of the horizontal well model and published analytical curves. This is the first reported mathematical model that has been validated for slanted well simulation.

Production rates from vertical wells, horizontal wells, and slanted wells of variable well lengths in a field of 40-acre well spacing were compared. During the pressure-depletion phase, about the same improvements in production rates over those of vertical wells were observed for horizontal and slanted wells which extended the same length from the plan view.

Horizontal/slanted wells showed more advantage over vertical wells at lower formation permeability (≤ 1 md) than at higher permeability (≥ 100 md). The effects of eccentricity on horizontal well performance were examined. The effects of vertical permeability on the production rates of horizontal and slanted wells were also studied. As expected, the vertical discontinuity of reservoirs showed insignificant effects on the production from slanted wells.

Field simulations of a horizontal well and of multiple slanted/horizontal wells demonstrated the application of the developed well model.
Second Law Analysis of Petroleum Reservoirs for Optimized Performance
Authors: Civan F. , Tiab D.
Published: December 2007

The second law of thermodynamics determines the practical limits of operating systems. However, within these limits, conditions leading to optimum performance can be found.

In reservoir analyses the conditions or variables which are controllable are somewhat limited. These include well head pressure, production or injection rate, number of wells and their locations and the recovery technique. The efficiency of reservoir exploitation decreases as the entropy generation increases. Since entropy generation translates into irreversible loss of fluid energy, the operating conditions of a reservoir should be selected to minimize the entropy generation over the productive life of the reservoir.

In this paper, it is shown how entropy generation function is calculated and used as a guideline for selecting the conditions leading to high ultimate recovery. This is accomplished by calculating the cumulative entropy generation over the reservoir volume and the production period and by determining the conditions minimizing the entropy generation.
Detection of Interlayer Communication at a Fault Using Type Curves
Authors: Tiefenthal S. A. , Wattenbarger R. A.
Published: December 2007

Previous work has shown that it is possible to detect the distance to a sealing fault. Recent work by several authors has been directed towards analyzing the effect of partially communicating faults on pressure transient responses. This current work concerns itself with a formation that has a fault which, rather than partially sealing the producing formation, allows influx from an adjacent formation (such as underlying aquifer). The goal is to determine the distance to this interlayer communication and the degree of communication by the use of type curve analysis.

The response caused by the producing zone alone can be filtered out using desuperposition. The remaining response is the "deviation function" caused by the "leaking" fault. Type curves were developed based on this deviation function response using dimensionless times and pressures and a dimensionless fault transmissibility as a matching parameter. The development of these type curves was based on numerical simulation.

The analysis technique is straightforward. The actual pressure response is subtracted from the extrapolated initial semi-log straight line and plotted. The resulting plot, which is the deviation function caused by the leaking fault, is compared to the type curve. The time match point provides the wel1-to-fault distance, while the matching parameter reveals the transmissibility of the interlayer communication.

A field example from a North Sea oil field illustrates the geological conditions under which the analysis technique is applicable, and how it is applied. The pressure transient data from an actual well test were first corrected for tidal effects and then analyzed using the above technique. As suspected from seismic and geologic interpretations, communication between the reservoir and an underlying aquifer could be detected. The distance to the leaking fault and its transmissibility were found. In this example case, the new analysis technique was able to provide input data essential to the reservoir description.
A New Approach for Decline-Curve Analysis
Authors: Duong A. N.
Published: December 2007

This paper presents a new approach which can be used for the computer-automated curve fitting for decline curve analysis. Arps' empirical-decline-curve equations for the exponential, hyperbolic and harmonic solutions are manipulated to produce a single relation which is a linear combination of variables: q, Np and qt. A linear multiple regression is performed for these variables to obtain optimal coefficients of the relation which are related to qi, Di and b in Arps' equations. Once qi, Di and b are known, the future production rate can be determined. Thus, the type-curve matching is not needed.

The proposed approach is, therefore, useful in application of the computer-aided analysis for the production forecast for oil and gas wells.
Current Trends in the Placement of Proppant During Fracture Stimulation in Southern Oklahoma
Authors: Freeman E. R. , Worley H. W. , Marple G. T.
Published: December 2007

Fracture stimulations in Southern Oklahoma over the last few years, that utilize sand as proppant, have undergone a marked change toward more aggressive sand placement. Since initial development of ‘modified fracturing treatments’ in Carter County was reported in 19871, the number of jobs employing higher sand concentrations has continued to wise. This manifestation may be supported by post frac well performance data, which in Carter county indicates that the more aggressive or higher sand concentration treatment is the economically preferable stimulation. The progressive placement of higher sand concentrations has since become more frequent in other counties (e.g. Stephens), and producing formations (e.g. Tussy and Deese).
The Progressing Cavity Pump: Principle and Capabilities
Authors: Saveth K. J. , Klein S. T.
Published: December 2007

The progressing cavity.(PC) pump has been. used, as a fluid transfer pump for many years. From various industrial applications to surface transfer of oilfield fluids. Within the last several years the progressing cavity pump has been widely used as a method of artificial lift for the oil and gas industry. The use of progressing cavity pumps as a means of artificial lift has numerous advantages over other artificial lift methods. Through years of research and development in progressing cavity pump design, the production and lift capabilities are expanding to cover a wide range of applications. With various elastomeric materials available, a wide range of well fluids can be handled efficiently using the progressing cavity pump. The ability to pump abrasive fluids lends itself well to many of the viscous sand laden crudes found throughout the world. With present lift capabilities from 4000 feet and capacities to 1000 BFPD, the progressing cavity pump is ever expanding and becoming a viable alternative for wells utilizing artificial lift.
Design of Acid Fracturing Treatment with Double Fluid System
Authors: Wang Hong Xun , Zhou Yun Xu
Published: December 2007

A new acid fracturing design model called double fluid system model is presented in this paper. In this model the difference in the ability to create fracture geometry between acid and pad fluids is considered. The fracture width during acid fluid injection period does not increase, nor remains constant as some papers stated, but decrease. This may be inportant because many design aspects, such as acid concentration along the fracture, effective fracture length and acid–etched fracture conductivity etc., depend on fracture width. According to this new idea the concentration in the fracture is lower, and the effective length is shorter because the fracture width is narrower than the data published previously.
Desirability Quotients Help Screen Investment Opportunities
Authors: Randall B. L.
Published: December 2007

This paper defines two new economic valuation criteria, or desirability quotients, that are shown to be especially useful in screening potential oil and gas producing property acquisitions candidates. Both quotients have been derived to provide comprehensive measures of the quality of the reserves production stream, in that they are direct functions of both the magnitude and time-distribution of reserves recovery. In addition, both quotients are unique to any previously defined valuation criteria in that they are direct, quantitative functions of simple payout time. It is demonstrated that, given a value for either desirability quotient and a value for maximum payout time, a preliminary estimate of a potential project's present worth can be generated without computing a cash flow projection.

The development of the desirability quotients parallels that of the deferment factor introduced by Brons and McGarry in the late 1950's. However, several differences have been incorporated into the derivation of the desirability quotients; namely, (1) whereas the deferment factors of Brons and McGarry were to be applied to declining rates of income, the desirability quotients are functions of production stream characteristics, thus precluding the necessity for predicting future product prices, and (2) specifically, the desirability quotients are functions of the after payout production stream; thus, opposite of most common economic valuation criteria, they are independent of the time distribution of reserves recovery during the pre-payout years, and (3) the two desirability quotients introduced in this paper, DQA and DQT, have as their denominators the acquisition cost and the total (acquisition plus lifting) cost, respectively. Hence, the desirability quotients are direct measures of the acquisition's magnitude and time distribution of after-payout reserves recovery per acquisition (or per total) dollar invested.

The application of the desirability quotients to a field of twenty hypothetical acquisitions is presented and discussed, as well as a comparison of the investment ranking behaviors of the desirability quotients to those of commonly used economic criteria. Specifically, it is shown that in the evaluation of certain types of projects under certain economic assumptions, the ranking behaviors of both desirability quotients will be virtually identical to that of the discounted profit to investment ratio, DPR. In addition, discussion of how the desirability quotients can be utilized as investment screening criteria (without the requirement of a cash flow projection) is presented.
Well Test Analysis of Dual-Porosity Systems Intercepted by Hydraulic Vertical Fractures of Finite Conductivity
Authors: Aguilera R.
Published: December 2007

Analytical solutions are presented for the analysis of dual-porosity systems intercepted by hydraulic vertical fractures of finite conductivity. The well can be in an infinite or a bounded dual-porosity system. The outer boundary can be sealed or it can be at constant pressures.

The following flow periods have been identified:

A bilinear flow period typical of finite conductivity fractures. This is recognized by a quarter slope in a conventional log-log crossplot of pressure differential vs. time. A transition period due to flow from the matrix into the natural fractures. A pseudo radial flow period recognized by a straight line in a conventional semilograthmic plot. Boundary effects which can be due to a sealed boundary or an outer boundary at constant pressure.

Recognition of these flow periods allow calculation of parameters such as omega, lambda, distance between natural fractures, permeability, fracture conductivity and half-fracture length. This is illustrated with an example.
Characterization and Significance of Natural Fractures in Mesaverde Reservoirs at the Multiwell Experiment Site
Authors: Finley S. J. , Lorenz J. C.
Published: December 2007

Natural fractures dominate the permeability of tight gas reservoirs in the Mesaverde Formation of the Piceance Creek Basin, northwestern Colorado. Roughly 450 natural fractures have been detected in reservoir sandstones and siltstones in 4200 ft of core from the U.S. Department of Energy's Multiwell Experiment (MWX). Sixty percent of the fractures are calcite-mineralized, vertical extension fractures that are probably the greatest contributors to reservoir permeability. However, the contribution of the other mineralized fractures should not be discounted.
Devonian Shale Gas Development Through Multiple Completions Minimizes the Finding Cost of New Reserves
Authors: Koziar G.
Published: December 2007

Multi zone completion opportunities in the Appalachian basin are being investigated by Columbia Gas under contract to DOE to encourage exploitation of Devonian shale gas reserves into regions extending beyond the borders of historic shale production. Data presented within this paper show that Devonian shale gas potential can be economically exploited in areas removed from historic shale production through: (1) dual or multiple completion of wells targeting nonshale formations, and (2) recompletion of existing nonshale producing wells to the Devonian shale.
Combustion System Technology and Application Assessment
Authors: Williams S. J.
Published: December 2007

Detailed technical and market assessments are being conducted of five advanced industrial burner technologies: radiant, pulse combustion, catalytic, oxygen/gas, and plasma burners. Using a computer simulation model, advanced and conventional technologies are being compared in thirteen process heating applications to develop ten-year market estimates of installed heating capacity and to assess changes in natural gas consumption. Preliminary results project that with advanced technologies natural gas consumption in these applications will increase 50 percent to 3,000 trillion Btu/yr by 1997 and natural gas market share will increase from 45 to 60 percent. Without the advanced technologies, natural gas consumption is projected to be 280 trillion Btu/year lower.
Multiflex Method: Innovative Approach To Meeting Tomorrow’s Consumer Gas Needs
Authors: Torbin R. N.
Published: December 2007

GRI-sponsored research indicates that semirigid tubing systems are more cost-effective than conventional steel pipe systems for distributing natural gas inside residential dwellings. The combination of semirigid tubing and a hybrid pressure design provides the distribution system with several enhanced use features which will benefit the occupants of both single and multifamily homes. The MULTIFLEX approach makes the gas system more analogous to the household electric system. This translates into a more flexible system with three essential characteristics: expandability; accessibility; and adaptability.
Use of Gas-Infrared Hoods for Improved Quality and Productivity in the Paper and Textile Industries
Authors: Turbet C.
Published: December 2007

The recent introduction of gas-fired infrared heaters for use in the textile and papermaking industries has led to significant upgrading of the quality of the manufactured product and an often marked increase in machine productivity.

Three concrete examples are given, two in papermaking and one in the textile industry. In all three cases, users noted a clear energy savings (as high as 30%), but appreciated above all the possibility of higher machine operating speeds (5 to 10%) and the distinct improvement in quality, due to faster binding of deposited substances.
Automated Analysis of Gas Reservoirs With Edgewater and Bottomwater Drives
Authors: Olarewaju J. S.
Published: December 2007

A combination of the gas material balance equation and an analytical water influx model is presented in this paper for the analysis of gas reservoirs with edgewater and bottomwater drives. The paper presents some application of an automatic parameter estimation technique coupled with the material balance and water influx model for analyzing production data from water drive gas reservoirs. This automatic history matching technique has made it possible to accurately determine gas-in-place, aquifer radius and aquifer permeability.

A forecast of the reservoir performance can then be made using the parameters estimated from the history matching process.
Review of Methods for Measurement of Natural Gas Specific Gravity
Authors: Civan F.
Published: December 2007

Specific gravity is one of the basic properties used for characterization and measurement of natural gases. Many instruments and methods are available for measurement of specific gravity of natural gases. These devices vary in their operating principles, efficiency and accuracy. However, there are not readily available references and guidelines for the user to choose between various options for specific applications.

The present paper critically evaluates and compares the frequently used gravity measurement methods in various terms. Specifically, each method is described and its operating principle and the governing equations are analyzed, Then, an assessment of the measurement error is carried out.

The confidence limits for the random error are determined. Error analysis is presented for typical data. Finally, a comparison of various methods is presented in a systematic manner for reference.
Investigation of the Error Sources While Measuring Air Flow Rate by an Orifice Meter
Authors: Bouhroum A. , Saleh A. , Marx C.
Published: December 2007

The accuracy of differential pressure flowmeters can be strongly affected by gas flow rates obtained from a pulsating source. This work discusses the error sources present when air flows through an orifice flowmeter which is installed downstream of a positive displacement rotary compressor in a gas-processing plant. Air velocity profiles were used successfully to identify the error sources, which indicate pulsation interference in a specific frequency band. This came in addition to an acoustic resonance caused by an installed pressure regulator in the flow system.

In order to improve the system the installation of the following devices were suggested:–a diffuser downstream of the orifice plate–an inline silencer to control valve noise–a pulsation damper to damp pulsation wavelengths of 7.83 and 7.33 m (23.86-23.34 ft) corresponding to frequencies of 38.67 and 41.33 Hz respectively.
LTX: Reapplication of Proven Technology
Authors: Dorsett L. R.
Published: December 2007

This paper resurrects a proven technology which saw its zenith in the 1960s, but which, due to changes in gas contract terms, became less common. It is now virtually unknown to engineers new to the field. This is unfortunate because circumstances have changed again, allowing this field-proven process to improve economics in some areas of gas production.

Engineers familiar with modern gas plant operation, particularly cryogenic plants, are acutely aware of the need for gas dehydration. This concern for hydrate prevention carries over into low temperature separation in the field. Although thousands of low temperature wellhead gas processing units have been placed in operation, most gas engineers have not experienced the sound of intentionally formed hydrates as they ricochet around the LTX spinner chamber, nor have they seen performance data which demonstrate the significant cost effectiveness of LTX processing in the field.

The purpose of this paper is to present such data and to reintroduce this proven technology to a new generation of gas engineers. The theory and practical application of LTX processing will be explained, along with the conjunctive effects of condensate stabilization and overhead vapor recompression. In summary, the paper will demonstrate that the road to increased profits is not paved solely by new technology.
Status of Gas Storage in Salt Caverns in West Germany
Authors: Gomm H. , Quast P.
Published: December 2007

In recent years the climb in demand for gas storage space has led to the expansion of existing and construction of new cavern storage facilities. More projects are currently under discussion.

The planning and construction of gas caverns in West Germany has been the state of the art for many years. This is becoming reflected on an international scale, as evidenced by the increasing foreign orders for planning and construction work.

This paper deals in some detail with certain innovative technical developments, including newly developed methods for testing correct makeup torque as well as the tightness of pipe joints from the inside to the outside with a test gas.

Moreover, insitu large-scale tests in the areas of "stability and convergence behaviour" as well as "cavern sump sealing" and their results to date are presented.

Operational experience with gas caverns is now available for up to 2 0 years. During this period of time, some repair work to subsurface technical installations was necessary. The planning and execution of this work is described.
Differential Sensing Direct-Control Gas Storage Well Safety Valve
Authors: Gano J. C.
Published: December 2007

A pneumatically governed, wireline-retrievable subsurface safety valve directly operated by local tubing pressure change at the valve has been developed for natural gas storage wells. This paper provides a detailed operating theory and description of the valve, which utilizes a control chamber volume of well-effluent to maintain a history of well bore pressure. The "memorized" pressure is constantly compared to current flowing tubing pressure via a sensing piston. When an established differential pressure value is exceeded, the sensing piston allows valve closure and control of the well. A "flapper-type" closure valve with an automatic reset mechanism allows the tool to be placed back in service with manipulation of tubing pressure.

Application of this technology is best suited to gas storage wells with a routine flow rate change caused by seasonal variation in gas demand. In these wells a fixed-rate flow sensing valve is not preferred.

The viability of this technology has been demonstrated by prototype testing in a producing gas storage well.

This new concept will be of particular interest to gas storage well operators seeking simple, subsurface-controlled well protection.
Production of Inert Gas for Partial Replacement of Natural Gas Trapped in an Underground Aquifer Storage Reservoir
Authors: Berger L. C. , Amoult J. P.
Published: December 2007

In seasonal modulation storages of natural gas In an aquifer, a varying fraction of the injected gas, the cushion gas, cannot be recovered. This cushion gas may represent more than half the total gas volume, and up to 70 % of the initial investment for the storage facility. Experimental studies, backed up by field experience, have shown that at least 20 % of the cushion gas can be replaced by a less expensive inert gas.

Different methods are available to produce an inert gas which meets the specifications required. Recovery of natural gas air combustion products (mixture of 88 % N2 and 12 % CO2) and physical separation of air components (more or less pure N2) have been selected. For the specific needs of France inert-gas injection program, the production facilities must satisfy requirements of autonomy, operating flexibility and transportability.

The technique of recovering natural gas air combustion products has been experienced in two facilities. A nitrogen production unit using the Pressure Swing Adsorption (PSA) technology will be put into service in July 1989. This paper discusses the principles of these two methods and reviews the operating characteristics of each facility.
A New Analytical Model of Finite-Conductivity Hydraulic Fracture in a Finite Reservoir
Authors: Olarewaju J. S. , Lee W. J.
Published: December 2007

A new analytical solution for the pressure response of a well intercepting a finite-conductivity fracture is presented. We examine the effects of fracture conductivity, fracture height, drainage boundary size, wellbore storage and phase segregation on the pressure response of such wells. Example applications of the model for history matching of actual buildup examples are presented. We demonstrate that fracture length will be underestimated significantly if a type curve for an infinite-conductivity fracture with wellbore storage is used to analyze wellbore storage distorted data from a well with a finite-conductivity hydraulic fracture.
Design of Fracturing Treatments for Gas Wells Considering Gel Filter Cake Residue and Non-Darcy Flow Effects
Authors: McDaniel B. W.
Published: December 2007

When an operator designs a hydraulic fracturing stimulation treatment, two basic design tools are available: fracture design simulators and reservoir production simulators. Essentially all other information obtained will be intended as "enhancements" to one or both of these simulators. Minifrac tests will help identify formation pressure response and fluid loss coefficients used by the desigh simulator. If a 3-D design simulator is used, stress data from microfrac tests or mechaftical properties logs will be needed. Information from previous stimulation treatments such as production results, treating pressure response, pre-frac and post-frac pressure build-ups and post-frac tracer surveys are also used to improve modeling with the simulators.

The most recently available "enhancements" for the design and production simulators are the development of more accurate and realistic data bases for fracture conductivity and non-darcy flow effects. Data are now available that were generated under test environments that better simulate in situ reservoir conditions.

This paper illustrates how treatment designs are altered when the design simulator and the reservoir simulator use the new data for conductivity and consider non-darcy flow effects. It is clear that many treatment designs have beeii too conservative as to volume of proppant considered adequate. Also, the criteria for choosing a more costly proppant than sand require conductivity data and consideration of non-darcy flow effects. By incorporating the use of computerized economic analyses, the effect of using a more accurate data base for fracture conductivity values is studied.

The use of total stimulation cost considerations in the selection process gives a more accurate assessment of the economics than previously published studies, which often have considered only one variable (such as proppant cost) in their economic analysis.

In this paper, examples are included for shallow, intermediate depth, and deeply buried gas reservoirs, with several well conditions and treatment conditions varied to broaden the application of the resulting economic analyses.
Self-Erection of Offshore Platform Workover Rigs
Authors: Huthnance W.B.
Published: December 2007

American Institute of Mining, Metallurgical, and Petroleum Engineers, Inc.

This paper was prepared for the 42nd Annual Fall Meeting of the Society of Petroleum Engineers of AIME, to be held in Houston, Tex., Oct. 1–4, 1967. 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.

The heavy-duty offshore platform workover rig must be capable of working efficiently with tubing and drill pipe. It must be capable of jarring with substantial hook loads and performing drilling as well as drilling operations of all sorts in high angle directional holes.

To evaluate rig mobilization using the light lift, self-erection (platform crane) technique, Walker-Huthnance offshore Workover Company's Rig # 1 was used. This heavy-duty platform workover rig has been in operation in the Gulf of Mexico, Offshore Louisiana, since January, 1967 and has made three locational moves to date. Erection procedure, using the rig's crane, was analyzed on a recent locational move.

Cost studies reflect that considerable savings can be effected using the self-erection technique as compared with derrick barge handling. On many platforms rig layout flexibility of the multi-component, self-erected workover rig offers a decided advantage over the large component, derrick barge handled rig.

Using the self-erection technique, a rig comprised of light lift packages can be geared for a rougher sea mobilization operation than can a heavier lift rig. Although the light packaged rig has more lifts, these lifts can be handled and positioned faster than can the lifts which comprise the heavier packaged rig.

The light lift, self-erection method is an extremely versatile, safe and economical method of platform workover rig mobilization.

Introduction

Basically, there are four types of offshore well servicing units: The heavy duty platform workover rig; concentric tubing (sand wash) platform workover rig; vessel equipped with a heavy duty workover rig for small jacket type well structures; vessel equipped for concentric tubing (sand wash) work on small jacket type well structures. Although a single offshore servicing unit may be capable of functioning in more than one of these categories, economics is the limiting factor.
Pressure Transient Analysis of Coal Seams in the Presence of Multi-Mechanistic Flow and Sorption Phenomena
Authors: Ertekin T. , Sung W.
Published: December 2007

Coal seam reservoirs are characterized by their dualporosity nature. This dual-porosity reservoirs are composed of well-defined macropore and micropore structures. In contrast with conventional natural gas reservoirs where gas is stored in the internal pore structure of the reservoir rock in free state, methane gas in coal is subject to sorption phenomena. This mechanism of storage results in an adsorbed monolayer film on the coal grain surface. The dual-porosity characteristics of coal seams together with time dependent sorption phenomena make the mathematical description of methane flow in coal seams a relatively complex problem. Accordingly, analytical solution to the coalbed methane transport problem is also challenging.

The development of a pressure transient analysis technique for coalbed methane is the primary focus of this paper. As a first step toward solving this problem, a single-phase mathematical model in radial-cylindrical coordinates is formulated to describe both unsteady state sorption phenomena in the coal matrix and laminar gas transport in the fracture network. The analytical diffusion expression which is obtained from the bounded matrix cylinder is imposed as a non-uniformly distributed source function over the macropore formulation. The subsequent solution of the macropore formulation, then, represents the solution to the composite macropore/micropore coal seam reservoir.

The constant terminal rate solution is first obtained in Laplacian space for an infinite acting coal seam reservoir. This solution is, then, brought to the real time domain with the aid of a numerical Laplace inverter. The proposed semi-analytical solution is validated by collapsing the solution to continuous point source solution which is applicable for conventional natural gas reservoirs. Also, comparisons are made against available numerical solutions. A series of example problems is presented to further demonstrate the validity of the proposed solution. Along these lines, field data compiled from Mary Lee/Blue Creek Seam in Warrior Basin, Alabama and from Deep Coal Seams in Piceance Basin, Colorado are analyzed using the solution procedure presented in the paper, and good matches have been obtained.
Prediction of Flowing Bottomhole Pressures in Gas Wells
Authors: Takacs G. , Guffey C. G.
Published: December 2007

The measurement of flowing bottom-hole pressures in gas wells is a frequently incurred and costly operation in natural gas production. The calculation of this pressure from surface data is complex involving a trial and error solution of Bernoulli's differential equation. A number of methods have been used previously for this solution - usually requiring computer methods. A new procedure for calculating flowing bottom-hole pressures using only simple algebraic equations has been developed.

The new procedure uses factorial design analysis from statistical experimental theory to determine the parameters in an algebraic equation which best fit the "experimental" data for the bottom-hole pressures for a given field. However, instead of actual field data, bottom hole pressures are calculated with a computer using any of several methods (Aziz, Cullender-Smith, Gray, etc.). These calculated "experimental" values are used to determine an algebraic equation which best fits the data. The day-to-day use of the resulting algebraic equation is very simple and can be performed by field personnel using a hand-held calculator for any wellhead pressure for the particular field.

Actual flowing bottom-hole pressure measurements for three gas fields containing 55 wells were used to test the accuracy of the procedure developed. Corrections for condensate flow and sour gas components were required in the calculations. The calculated bottom-hole pressures agreed with measured ones with an average absolute accuracy of 1.9%.
Production Strategies for Tight Gas Sands: A Case Study of the Upper Cozzette Blanket Sand
Authors: Bezilla M. , Adewumi M. A. , Ertekin T. , Sung W. , Frohne K-H.
Published: December 2007

The importance of the role that natural gas from tight formations would play in achieving energy self-sufficiency for the United States cannot be over-emphasized. One reliable source estimates the natural gas reserves of the tight sands of the Western United States alone to be more than 5700 trillion cubic feet. However, the technology for recovering this resource remains elusive, primarily due to lack of adequate understanding of the physics of fluid flow dynamics within this type of porous media. The fluid flow in tight formations does not subscribe to that normally associated with conventional reservoirs. It is believed that tight formations frequently possess dual porosity, and the flow field in these formations may be governed by more than one mechanism. The model utilized in this study possesses proven predictive capabilities, an essential ingredient to production forecasting, and hence is used as a framework for the development of optimal production strategies for the Upper Cozzette blanket sand. The model has multi-well capabilities and has options for either vertically or horizontally fractured wells and horizontal boreholes. Simulation results from a variety of production schemes are presented. The results provide some insight into production strategies involving horizontal boreholes and hydraulic fractures.
The Underwater Power Package
Authors: Johnson F.C. Pat
Published: December 2007

American Institute of Mining, Metallurgical, and Petroleum Engineers, Inc.

This paper was prepared for the 42nd Annual Fall Meeting of the Society of Petroleum Engineers of AIME, to be held in Houston, Tex., Oct. 1–4, 1967. 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.

Many professional articles and technical papers have been written on the numerous power sources available for oceanographic work, yet none have been specifically oriented to the problems of underwater drilling and completion. This paper will investigate and report on the various types of independent power sources which may be used by the petroleum industry for an underwater operation.

There is little doubt that as the drilling platform moves into deeper water, a power package, independent of the surface rig, will become a necessity. Power to operate the blowout preventer is the initial step; power for the entire drilling operation is the final goal.

The ultimate answer is nuclear power, but a proven design is not available today. Battery power and the fuel cell are possibilities for intermediate power sources. The evolution through batteries and fuel cells to the nuclear power plant will provide an orderly development such that the underwater nuclear power package may be phased in with a thoroughly tested, operational plant as soon as it becomes available to industry.

Introduction

The oil industry has been drilling offshore for about 25 years. Initially, drilling was done with land based equipment adapted (often poorly) for usage underwater. In the last ten years, industry has developed more sophisticated equipment designed specifically to cope with the unique problems of drilling underwater.

One area obviously in need of greater improvement is the power supply to remote underwater tools. The blowout preventer stack and christmas tree require power sources independent of the drill string. These units are presently powered hydraulically from the surface. This method is cumbersome and inefficient.
Intriguing Aspects of the 52-Mile Titas-Joydebpur Gas Line Project in Bangladesh
Authors: Bakht D.
Published: December 2007

This paper is based on experiences of implementing the project with application of labour intensive appropriate technology amidst extremely adverse climatic & terrain conditions within a short time frame and yet achieving a strikingly low inch mile cost. Discussion of different aspects of economic technical & mathematical considerations resulted from a close look of its execution & operation is also included to suggest a priority for over coming the limitations in future projects of similar nature & of equivalent or higher magnitude.
WAG Process Promises Improved Recovery in Cycling Gas Condensate Reservoirs: Part 1—Prototype Reservoir Simulation Studies
Authors: Jones L. G. , Cullick A. S. , Cohen M. F.
Published: December 2007

An unconventional method to improve sweep efficiency in highly stratified or naturally fractured gas condensate reservoirs has been explored through simulation studies. The alternating water and gas injection process (WAG) has not been heretofore seriously considered in gas cycling projects for fear of losing ultimate production. For the base case study presented here, however, WAG is shown to improve sweep efficiency and ultimate recovery by 862 at one pore volume injection over that of dry gas injection alone into a prototype gas condensate reservoir containing a single, high permeability thief zone. The increase in sweep efficiency occurs primarily because the high viscosity water tends to block the thief zone, thus forcing following injection gas to invade the reservoir matrix. The principal factors governing the process are the contrast between thief zone and matrix permeabilities, the viscosities of injected gas and water, and the residual gas saturation to water. Varying the relative permeability curves and water/gas slug sizes and ratios had smaller effects on the results. Since only relatively small amounts of water are required to obtain large increases in recovery, expected detrimental effects from gas trapping and premature abandonment are limited. An additional economic benefit arises because the water occupies space which must otherwise be occupied by make-up gas.
Low Temperature Phase and Volumetric Behavior of Natural Gases
Authors: Gore T.L. , Davis P.C. , Kurata F.
Published: December 2007

Published in Petroleum Transactions, AIME, Volume 195, 1952, pages 279–284.

An experimental method and apparatus for the study of the low-temperature phase and volumetric behavior of volatile mixtures are described. The phase diagrams, including the critical points, and the volumetric behavior of two natural gases at temperatures from -40°F to -200°F and pressures to 1200 lb/sq in are given.

Introduction

Knowledge of the phase and volumetric behavior of light hydrocarbon mixtures at low temperatures is becoming of increasing importance as interest in low-temperature separation processes increases. Ethane and ethylene are already being removed from natural and refinery gases by low-temperature distillation, and removal of nitrogen from natural gases by this process has been proposed as a means of increasing the transmission capacity of existing pipe lines. While existing correlations of equilibrium vaporization constants may be used to predict the vapor-liquid equilibrium behavior of such mixtures at lower pressures, high-pressure phase computations often require knowledge of the critical behavior of the system involved. Although correlations have been developed for the prediction of the critical temperature and pressure of certain types of hydrocarbon systems, they are not applicable to very volatile systems such as nitrogen-bearing natural gases. This paper describes the initial stages of an investigation which had as its main purpose the study of the low-temperature phase and volumetric behavior of such mixtures. The experimental phase diagrams, critical points, and volumetric behavior of two natural gases are presented here.

The published low-temperature vapor-liquid equilibrium data for hydrocarbons and mixtures of hydrocarbons with nitrogen and helium are summarized in Table 1. Most of these data are for binary systems, and the data of Stutzman and Brown, at 100 lb/sq in. are the only data on a natural gas. The data of Bloomer and Parent on the methane-nitrogen system, which have been published since this study was completed, are a valuable addition to the knowledge in this field. Prior to the publication of these data the only critical data on systems having critical temperatures below the ice point were those of Ruhemann, on the methane-ethane system, and those of Eilerts, et al, on a gas-condensate system. These data alone were not sufficient to allow accurate estimation of the critical behavior of the very volatile systems of engineering interest.