bluuebunny/crossref_metadata_2025 huggingface dataset:
Comparison of WAG and Continuous Enriched-Gas Injection as Miscible Processes in Sadlerochit Core
Authors: Spence A. P. , Ostrander J. F.
Published: December 2007

Short core displacements were conducted to evaluate miscible condensing-gas drive for the Sadlerochit reservoir of the Prudhoe Bay field. The cores were from well DS 14-5. The enriched gas was a 60-40 blend on a mole basis of rich Sadlerochit gas and the liquids from the Field Fuel Gas Unit (FFGU) and the separators at Flow Station 3. The experimental program consisted of four floods conducted in each of four cores for a total of sixteen displacements. Each set of floods consisted of: a gravity-stabilized continuous gas injection displacement with the core at connate water saturation;a gravity-stabilized continuous gas injection displacement with the core at waterflood residual oil saturation;a simultaneous injection brine enrichedgas flood at a 4 to 1 brine-to-gas ratio (as determined at reservoir conditions) with the core at connate water saturation;a simultaneous injection brine enrichedgas flood at a 4 to 1 brine-to-gas ratio with the core at waterflood residual oil saturation.

All displacements yielded approximately the same residual oil saturation averaging 2.26% STPV (i.e., stock tank pore volume). The range of values was 0.88 to 3.74% STPV.

The gravity stabilized displacements were piston-like, consistent with the experimental design. The piston-like displacement coupled with the high recoveries indicated rock pore structure did not adversely affect the displacement.

In the simultaneous injection displacements with brine, the oil production was dispersed due to the high fractional flow of brine. However, mobile brine did not affect the ultimate recovery. Trapping or bypassing of oil was not observed. Trapping was observed in a simultaneous injection displacement conducted in strongly water-wet Berea using the same fluids at a 4 to 1 brine-to-enriched-gas ratio. For this flood, the residual oil saturation was 19.4% STPV.

Oil production curves for the simultaneous injection displacements before and after waterflooding were identical except for the early production of the waterflood oil saturation in the non-waterflooded cores. Thus for this linear system, the timing of oil recovery is better for the WAG (i.e., water-alternating-gas ) process operated in the secondary mode as opposed to the tertiary mode.
Interference Analysis of an Anisotropic Reservoir Using Five-Spot Data
Authors: Chen H. G. , Lescarboura J. A.
Published: December 2007

A CO2 miscible flood is being studied in the San Andres 9th Massive formation of the Maljamar Field in New Mexico with a five-acre inverted five-spot pilot. Single-well tests in the five pattern wells and a production interference test with the center well as source and the four corner wells as observers were run to characterize the reservoir prior to the start of the pilot test.

The results of the analyses indicate that the reservoir is anisotropic with the two principal kh's approximately 3,000 and 30 md-ft, and the direction of maximum permeability 77° west of north. The large difference in major and minor axis flow capacities led to a postulate of natural fractures, oriented toward the direction determined by the interference test. The results of the single-well tests reflect the fracture density in their radius of investigation. The proposed reservoir description is consistent with core data and currently available tracer results.
Salem Unit Micellar/Polymer Project
Authors: Ware J. W.
Published: December 2007

Texaco, as operator of the Salem Unit, Marion County, Illinois, is conducting a 60 acre semi-commercial tertiary recovery project in the watered out Benoist sandstone. This paper discusses field design and implementation of the project as well as results to date. An extensive field testing program preceeded initial injection.

The process used is the Texaco developed brine tolerant surfactant system followed by a biopolymer. Application of this process field-wide in the Benoist reservoir at Salem is anticipated to have a tertiary oil target of 50 million barrels. The project demonstrates a process which extends greatly the reservoir salinity range for which surfactant systems have application.

The surfactant system was successful in mobilizing waterflood residual oil. More importantly, the project demonstrates the capability of designing surfactant systems for use in high brine reservoirs without expensive time consuming pre-flushing or reservoir pre-treatment. Field results indicate problem areas to be: Contacting the reservoir with injected fluids (Volumetric Sweep Efficiency), handling and mixing of viscous injectants, treating produced emulsions, obtaining accurate well tests, and bacteria control in biopolymer solutions.
Control of Xanthan-Degrading Organisms in the Loudon Pilot: Approach, Methodology, and Results
Authors: Bragg J. R. , Maruca S. D. , Gale W. W. , Gall L. S. , Wernau W. C. , Beck D. , Goldman I. M. , Laskin A. I. , Naslund L. A.
Published: December 2007

An investigation of loss of mobility control in Exxon's Loudon micellar/polymer pilot test has confirmed that loss was caused by microbial degradation of the xanthan biopolymer used to viscosify the micro-emulsion and polymer drive banks. This paper describes techniques which were used to sample and culture bacteria from the Loudon pilot and demonstrate that these mixed cultures are able to degrade xanthan rapidly under reservoir conditions. Laboratory studies show that, under anaerobic conditions, bacteria cultured from the Loudon pilot can cause over 90% loss of xanthan viscosity in micellar/polymer fluids within seven days.

To remedy this problem, an extensive laboratory screening program was conducted to identify biocides that are effective against the offending organisms. Complete kill of the organisms under repeated laboratory challenge tests was the chief screening criterion. Biocide compatibility (with biopolymer, formation rock, field brines, and microemulsion), cost effectiveness, and chemical stability were also judged key parameters for effectiveness in field applications.

Of the biocides tested against the Loudon organisms, formaldehyde was found to be the most consistently effective, providing complete kill and persistence at levels of 500 to 2000 ppm. Formaldehyde was shown to reduce bacteria below detectable levels in the formation and permit propagation of xanthan in a follow-up test conducted within the highly contaminated pilot zone. Therefore, formaldehyde should be an effective biocide for future floods at Loudon.
Response-Time Testing for Subsea Controls in the Cadlao Field
Authors: Manuel W. S. , Hall J. E.
Published: December 2007

This paper describes the response time properties of the direct hydraulic control system for the subsea Christmas trees installed in the Cadlao Field, offshore Philippines. Experimental testing simulated 29 different operating conditions to verify analytical predictions, to demonstrate the effectiveness of applying a common boost pressure to the spring chambers of the gate valve actuators, and to collect data for future applications. Actual data are presented and various relationships defined. With the use of boost, direct, closed hydraulic circuits with ganged functions offer a viable control method for distances up to 3 miles.
Pressure Buildup Analysis for a Well Produced at a Constant Pressure in a Naturally Fractured Reservoir
Authors: Ohaeri C. U.
Published: December 2007

The objective of this study is to present the pressure build-up behavior of a well located in a naturally fractured reservoir and produced at a constant well bore pressure. The flow period response is presented to preserve continuity. By a fractured reservoir we mean a reservoir con-sisting of two systems of porosity and perme-ability: a primary system which is the rock matrix, and whose properties were determined by the depositional environment, and a secondary system of fissures of induced properties. The latter is usually assumed to be the result of post depositional geologic events. Furthermore, the properties of a naturally fractured reservoir are such that the storage properties are associated with the matrix while the conducting properties are due largely to the fracture network. In this study, we consider the model with unsteady state fluid transfer from matrix to fracture. The matrix elements are assumed to be cylindrical in shape. We present analytical solutions for the flowing period and also for the build-up period. It is shown that a plot of the wellbore shut-in pressure divided by the flowing rate at the time of shut-in versus the shut in time on semi-log paper may have up to three straight line segments with character-istic slopes. However, all three straight line segments will be evident only for certain combi-nations of reservoir properties and flowing time. These slopes can be used to obtain reservoir (matrix and fracture) properties.
Impact of Rapidly Changing Economic Environment on Petroleum Exploration and Acquisition
Authors: Schaefer G. T. , Powers L. W.
Published: December 2007

In the last decade, the petroleum industry has experienced the most strenuous growth cycle in recent memory. Beginning in 1973, it enjoyed a period of unprecedented growth until late 1981 when a precipitous decline was initiated. This downturn, which was unforeseen by most organizations and individuals, has adversely affected many including investors, operators, equipment suppliers, and the financial community.

This paper will put this rapidly changing environment into perspective by illustrating the historical relationships between price changes in actual and real terms, activity levels, energy supply/demand and petroleum reserves in U.S.A., all of which have had significant impact on the investment outlook of the petroleum industry. It will demonstrate that rapidly rising prices in last decade elevated expectations of return on investments in the oil and gas industry. For the investor, this became a seller's market where the investor generally took what the operator offered with marginal room for negotiations. High activity levels often resulted in higher than anticipated costs and when complemented with sudden downturn in prices, caused many programs to generate less than desired results. By relating average 1980–81 industry finding and acquisition costs to after-tax rate of return on investment based on actual exploration and acquisition programs, this paper will illustrate why many investors became disappointed with these programs. This explanation will take into account economic factors such as federal income tax changes, excise tax (windfall profits tax), price and market changes as well as exploration and development costs.

Based on this actual data and information, the relationships between after-tax return on investment and both finding and development costs and acquisition costs will be graphically illustrated for several future oil and gas pricing scenarios. Comparisons are provided to illustrate the tax benefits associated with exploration and development vis-a-vis acquisition. In addition, examples will be given to demonstrate the various factors which result in different rates of return for similar acquisition costs. In effect, using this information, analysts will be able to do a better job of screening future programs without doing a tedious, detailed analysis. This information should be useful to anyone involved in economic decisions within the petroleum business, especially management, consultants, bankers and investors.
Acquisition and Enhancement of Mature Producing Properties: A Case History
Authors: Artus D. S. , Solmonson D. W.
Published: December 2007

This paper describes the three year history of an independent oil company formed to purchase and enhance producing properties. The application of detailed field studies and conventional enhancement techniques has resulted in increased proven reserves and substantially increased cash flow from the properties in spite of the decline in oil prices.

Total investment in the properties to through 1982 was $41.3 million with an additional $16 million remaining to be spent if all identified enhancement projects are implemented. Pre-tax rates of return for the total acquisition program are expected to be in the 24 to 28 percent range.
Foam Fracturing Laboratory
Authors: Wendorff C. L. , Earl R. B.
Published: December 2007

A new laboratory has been constructed with test equipment designed to expose foam fracturing fluids to test conditions simulating treatment conditions of shear, time, temperature and pressure during the tests. The goal for designing this laboratory was to simulate treating and downhole conditions as closely as possible and to determine fracturing foam properties under these conditions. This paper describes the design parameters and equipment in this unique laboratory.
A New Crosslinked Foamed Fracturing Fluid
Authors: Watkins E. K. , Wendorff C. L. , Ainley B. R.
Published: December 2007

The technology of stabilizing foamed fracturing fluids has been extended to include the use of cross-linked gels as foam stabilizers. Gasified treating fluids prepared from these gels have unique properties which differentiate them from both traditional foams and gels. Traditional foams require that the gas/volume ratio be greater than 0.52 in order to obtain a stable foam structure. Such high gas ratios produce foams with low fluid densities and low proppant concentrations. Using crosslinked gelled fluid as the stabilizer for foams, very stable dispersions of gas in liquid can be prepared with almost any gas content. Stable foams having a gas/volume ratio (GVR) greater than 0.52 as well as stable energized fluids having a GVR of less than 0.52 can be prepared. Stable energized fluids containing less gas can have appreciably higher fluid densities and proppant concentrations. This paper describes the properties of foams stabilized with crosslinked gels, their broadened uses in stimulating wells and the results of treatments.
Optimizing Surfactant Molecular Weight Distribution I. Sulfonate Phase Behavior and Physical Properties
Authors: Salter Stephen J.
Published: December 2007

In this paper experimental results are presented in an investigation of surfactant-oil-brine phase behavior and physical properties. The question of whether single-component surfactants are preferable to diverse mixtures is addressed both from the stand-point of oil and brine solubilization, as well as surfactant component fractionation. This investigation includes a detailed study of the phase behavior of a monoisomerically pure sulfonate, a pure hydrocarbon, water, and sodium chloride. Conclusions are reached regarding both the complexity of the global phase behavior of this system and the number of components necessary to describe this phase behavior.

The phase behavior for mixtures of nonoisomerically pure surfactants is then compared to the single-component results. The degree of sensitivity to the composition of these mixtures is shown to be very high. An hypothesis is presented, and supported by experimental data, in which the mechanism that controls surfactant component fractionation is proposed. This mechanism relates the importance of structure formation to surfactant fractionation. Results are presented for five component systems (oil, brine, and two surfactants) that illustrate the shape of the three-phase region in phase-space, and the movement and alteration of this region with changes in salinity.
Observation, Prediction, and Analysis of a Laboratory Two-Well Chemical Flood
Authors: Haskin H. K.
Published: December 2007

The concept of volumetric linear scaling was developed to provide a simple oil recovery prediction procedure that adequately described the important aspects of chemical flooding for single and multiple slug systems. This approach has been used successfully to model several chemical flood systems in both field cores and synthetic rock.1,2 When coupled with a flow description, linear flood oil saturation data have also been used to predict oil recovery performance of laboratory pattern floods.3,4

This simple scaling approach will be used here to describe chemical flood performance in a novel unconfined laboratory flood monitored by a microwave saturation scanner. An unconfined two-well geometry was chosen for study because it provided a severe test of the simple streamtube flow description employed. A two-well pattern also represents the simplest of the class of small isolated patterns sometimes employed in field pilot tests. Interpretation and modeling of these isolated patterns has historically been difficult. Extension of the scaling theory to a two-well pattern would provide the engineer with another tool for analysis of such floods.

Ten curvilinear unit mobility streamtubes were employed to describe flow in the laboratory experiment. Predictions of 2-propanol saturations measured during miscible injections in the two-well model were compared to observations to check the validity of the streamtube net. Expected effects of the two-well geometry on oil recovery from the laboratory model are discussed in light of the large variation in size of the individual streamtubes in the flow description.

Oil saturation profiles were measured during a linear chemical flood involving injection of a small surfactant slug followed by a small polymer slug and continuous drive brine. These So profiles were then scaled along the unit mobility streamtube net. Oil saturation contours, endpoint conditions, oil breakthrough time, and oil production history predictions were made. Comparison of these predictions to the observed performance of the eight day chemical flood carried out in the large two-well model indicate that the scaling concept can be used to model this type of flood. The fixed streamtube description served as a useful first approximation for the unconfined pattern geometry even in the presence of observable crossflow between stream-tubes.
The Flow Of Foam: I. Rheology And Streaming Potential
Authors: Raza S.H. , Marsden S.S.
Published: December 2007

This, paper presents an experimental study of the flow behavior of foam through capillary tubes as well as a theoretical and experimental study of the streaming potentials generated during the flow. Important parameters such as the pressure differential, the quality of foam, the electrochemical nature of the surface active agent and the dimensions of the capillary tube have been investigated and a physical model describing the experimental results is presented. Foams were produced from aqueous solutions of various surface active agents in a foam generator of novel design. The flow media studied were:

capillary tubes of several diameters, a capillary tube packed with glass beads slightly smaller in diameter than the capillary tube, and a capillary tube filled with crushed pyrex glass.

The quantities measured were foam flow rate, foam quality (ratio of gas volume to total volume of foam), streaming potential and streaming current. As indicated by the general overall shape of the pressure differential versus flow rate plots, the flow of foam in capillary tubes is quite similar to that of pseudo-plastic substances.
The Real-Time Calculation of Accurate Bottomhole Fracturing Pressure From Surface Measurements Using Measured Pressures as a Base
Authors: Hannah R. R. , Harrington L. J. , Lance L. C.
Published: December 2007

Several papers written since 1978 have addressed the inportance of an accurate knowledge of bottom hole fracturing pressure. Nolte and Smith1 in 1979 focused industry attention on the value of this information in predicting fracturing conditions. By the proper interpretation of the slope of log net fracture pressure versus log time, they showed that normal extension with confined height, fracture height growth with extension, loss of fluid loss control due to hairline fracture openings, and runaway growth of fracture height could be interpreted for fractures conforming to the fracture geometry of Perkins and Kern2 and Nordgren3. Nolte4, in another paper, demonstrated that post-fracturing pressure decline data could be used to predict certain other fracturing parameters such as fracture height, leak-off coefficient, length, width, and closure time. Papers dealing with this technique include those of Veatch and Crowell5, Schlottman, et al6, Dobkins7, Smith8 and Smith9. Nolte, in 1982, wrote an excellent paper summarizing these techniques in SPE paper 10911, "Fracture Design Considerations Based on Pressure Analysis."10 Novotny11 also proposed a fracture closure model based on fracture geometry and leak off. Erdle12, et al, discussed the results of an experimental program conducted in Peru that addressed the same topics.

The authors here will not attempt to review or expand on the interpretive techniques given in the literature cited above. This approach has been generally accepted by the industry and dealt with in an excellent manner by the authors listed.

In the cited literature a reference string, either the tubing or the tubing casing annulus, was available to act as a monitor for bottom hole pressure behavior, that is the sum of the indicated surface pressure plus the pressure exerted by the hydrostatic head in the reference string is an accurate reflection of the true bottom hole fracturing pressure. The reference string, while desirable in terms of pressure measurement, presents some problems from both an operational and economic standpoint. In many cases the strength of the tubular goods is insufficient to allow the well to be fractured at meaningful rates with a reference string in the well. For higher pressured wells, treatment down tubing without a packer is many times impossible without casing rupture. In addition, unless the well can be placed in its final production configuration, the expense of tubing trips must also be borne. Where annular treatments are performed there is concern that the presence of the tubing may contribute significantly to shear degradation of the crosslinked gels and that injection rates using this configuration may be limited.10
A Computer Database System Designed for Drilling Information Analysis
Authors: Lacy K. D. , Gill B. B. , Buras K. F.
Published: December 2007

This paper describes a data base system used by Chevron USA's Eastern Region which allows in depth analysis and comparisons of any of the recently drilled Chevron Wells. Compared to previous methods of record keeping, the new system is much more timely and accurate and has reduced the time spent in gathering information when more than one well is reviewed.

Drilling information is input into the data base for each well as the well is drilled. This information is used on a daily basis to produce a drilling morning report for management. Once the well is finished the daily information is compiled and used to prepare a final well report. This report is designed to provide a brief summary of all the highlights and problems encountered along with final costs and performance curves for each new well. Not all of the information entered into the data base is used in the final well report. This information however remains in the data base where it can be accessed to help in planning offset wells, evaluating drilling problems, and making special studies.

This paper covers the development of the data base and gives information useful to those who may want to set up a similar system. The format of the daily drilling report and the final well report is given along with examples of the reports that can be generated using information from the data base. A system similar to the one developed by Chevron should be very useful to anyone involved in drilling operations. The system need not be limited to drilling information and can easily be changed to include information others feel is relevant to the well file.
New Methods for Locating the Moving Gas/Water Boundary in Underground Storage Reservoirs
Authors: Udegbunam E. O. , Tek M. R.
Published: December 2007

Methods have been developed which permit the calculation of the approximate position of the moving gas-water boundary in underground gas storage reservoirs from data on storage pressures and distant observation well liquid levels.

Locating the gas-water boundary in underground storage is important in control of gas bubble growth and in monitoring against possible migration away from storage horizon. The mathematical procedures developed permit calculation of gas-water interface location as a function of time as it moves laterally in response to storage operations. Reasonable results and agreement with observations were obtained from the model using reservoir data from a large storage field. The sensitivity of results to possible errors in the reservoir data and the effect of location of the available key storage well are shown to provide practical guidelines defining limitations of the mathematical technique.
A Study of Caustic Consumption in a High-Temperature Reservoir
Authors: Simlote V. M. , Zapata V. J. , Belveal L. A.
Published: December 2007

This paper describes a procedure used for evaluating a high temperature reservoir for caustic flooding. A comprehensive feasibility study included reservoir rock and fluid characterization, laboratory measurements of parameters controlling caustic consumption and a process evaluation by simulation with a finite difference chemical model. A two phase, six component finite difference chemical model was modified to include the long term caustic consumption based on first order reaction kinetics. The model produced a satisfactory match of a laboratory experiment conducted for determining caustic consumption. The influence of ion exchange, slug size and flow rates on the propogation of an effective caustic concentration through the reservoir was also investigated.

The study indicated that caustic flooding of a high temperature reservoir can be successful only if the reservoir has sufficient flow capacity. To overcome the large caustic consumption due to high temperature, a high velocity must be maintained. Concentration of the caustic is also critical. However, if the fluid cannot be propogated fast enough, the concentration becomes insignificant.
Recent Changes in the Natural Gas Industry and the Potential Shape of its Future: A Regulatory Perspective
Authors: Essley P. L.
Published: December 2007

From 1954 through 1981 the retail price of most natural gas in the interstate market was equal to the sum of a regulated wellhead price, a regulated transportation cost, and a regulated distribution cost. The profits of each segment of the natural gas industry were controlled by regulators and were essentially independent of the profits of the other two segments. Currently, the sum of the prices allowed by regulators exceeds the price the marketplace will allow. The various sectors of industry must now compete against each other for a share of the consumer's dollar. The industry practices that developed during the past regulated environment are proving to be inefficient in the new competitive environment of the 1980s. As a consequence, the industry structure and practices will change.
Multiphase Flow in Porous Media: III. Oil Mobilization, Transverse Dispersion, and Wettability
Authors: Mohanty Kishore K. , Salter Stephen J.
Published: December 2007

A pore-level, three-dimensional network model is presented in this paper to calculate transverse dispersion and residual oil saturation at high capillary number floods in strongly wet media and many transport properties in mixed wet media. These transport properties are capillary pressure, relative permeability, and mixing parameters. A technique has been developed to generate well controlled mixed wettability in sandstones. Model predictions are compared with experimentally obtained values of transport coefficients. Our results illustrate the effect of wettability on transport properties of a rock.
Multiphase Relative Permeability Measurements Using an Automated Centrifuge
Authors: O'Meara D. J. , Lease W. O.
Published: December 2007

The automated centrifuge uses a linear photodiode array in conjunction with a microcomputer to image and identify liquids recovered from centrifuged rock samples. Compared to previous centrifuge measuring techniques this new system Obtains and analyzes production data electronically, thus requiring little human intervention.reduces inaccuracies in measurementsallows for collecting initial data when liquid levels are changing rapidlyprovides for easy corrective action if problems occur during an experiment.

Typical raw data along with calculated realtive permeabilities are shown for both two-phase and three-phase experiments.
Enhanced Load Water-Recovery Technique Improves Stimulation Results
Authors: Penny G. S. , Soliman M. Y. , Conway M. W. , Briscoe J. E.
Published: December 2007

The roles of capillary pressure, wettability and relative permeability in controlling load water recovery following hydraulic fracturing treatments have been examined. It has been found in laboratory studies that the judicious alteration of wettability to control capillary pressure and/or relative permeability can promote a rapid thorough cleanup of injected water. Field applications employing these concepts have resulted in enhanced load water recoveries and higher production due to longer effective frac lengths and/or higher fracture conductivities following cleanup.
The Simulation of Water-Injection Performance for a Well with a Propagating Fracture
Authors: Cottrell C. W. , Al Baker S. A.
Published: December 2007

A method of numerically simulating the water injection performance of a well with a propagating fracture has been developed. The fracture propagation is modelled by adjusting the well completion to include grid blocks laterally displaced from the centre of the well. For a multilayered system any required fracture shape and development with time can be accommodated.
Pore Pressure Detection From the MWD Gamma Ray
Authors: Zoeller W. A.
Published: December 2007

Formation pore pressure abnormalities can be detected and evaluated by many known methods1. These abnormalities may be identified by drilling parameters, formation log properties, mud analyses, etc. The natural gamma ray intensity, a formation property, can also be used for pressure detection and evaluation. Using the Measurements While Drilling Gamma Ray Log, pore pressure can be interpreted at the well-site, thus providing a real-time pressure detection tool for better well control.

The gamma ray intensity, a natural radioactive property, has not been used as a primary pore pressure indicator; this paper provides a technique to use this formation property as a pore pressure detection tool. Analyses, primarily from the Gulf Coast, were made from both Measurements While Drilling and wireline gamma ray logs, demonstrating the flexibility of this method.
An Experimental Investigation of Fines Migration in Porous Media
Authors: Gabriel G. A. , Inamdar G. R.
Published: December 2007

Permeability decline in argillaceous sandstone formations has tendered a broad spectrum of explanations and related remedial treatments. This decline has often been attributed to the mobilization, migration, and plugging of fine particles in the formation pore spaces. While previous investigations have generally been directed toward either a chemical or a mechanical characterization of the damage mechanism, this experimental study was undertaken to comprehensively analyze both the chemical and the mechanical interactions.

In linear core tests, the flow of a chemically compatible, wetting fluid resulted in severe permeability loss when the fluid velocity exceeded a critical value. The flow of a chemically incompatible, wetting fluid resulted in a total loss of permeability which exhibited no dependency on fluid velocity or volumetric throughput. Pretreatment of the core with a cationic polymer (clay stabilizer) prevented permeability damage due to chemical incompatibility. However, a cationic polymer pretreatment could not protect the core against damage caused by exceeding the critical velocity.
Low Interfacial Tension Relative Permeability
Authors: Harbert L. W.
Published: December 2007

EOR processes that feature a near miscible process, CO2 injected below the minimum miscibility pressure or micellar fluids, require relative permeability data to calculate the flow behavior of the low interfacial tension (low IFT) fluids. The flow behavior of low IFT fluids differs from that of conventional gas and oil or water and oil; it depends upon IFT, viscosity, and flow rate as well as the rock properties of pore size distribution and wettability. The results of laboratory core tests using an alcohol, brine, and oil fluid system in outcrop and reservoir rock samples are presented. Both water and oil relative permeability curves were found to shift upward, indicating the two phases interfere less with each other as IFT is reduced. For a given reservoir rock type, the flow behavior is adequately characterized by a capillary number defined by combined (total) fluid velocity, average viscosity, and interfacial tension. It was also found that flow tests on representative reservoir rock samples are necessary to describe low interfacial tension relative permeability for field process performance calculations.
Analysis of Step-Pressure Tests
Authors: Sengul M. M.
Published: December 2007

A new technique has been developed for analyzing step-pressure test data. The technique yields formation permeability and skin factor.

Step-pressure tests involve flowing an oil or gas well at two successive constant pressures and recording the flow rates during the second constant-pressure flow period. Except for a limiting case where the first constant-pressure flow period is large compared to the second, there is no conventional analysis technique available in the literature for analyzing step-pressure test data. The technique presented in this paper is general and can be used regardless of the relative sizes of the constant-pressure flow periods.

The equations necessary for analyzing step-pressure tests were developed, and a new function, "production time function," was defined. Plotting the reciprocal of the rate data against the production time function results in a straight line. Formation permeability and skin factor are computed using the slope of this straight line. The paper includes sample application of the method to simulated step-pressure test data.

Step-pressure tests have two attractive features: (1) they do not require that the well be shut in if it is already producing against a constant pressure, such as a gas well producing against a constant pipeline pressure; and (2) wellbore-storage effects on the test data are short-lived. This paper presents a practical new technique for analyzing data from such tests.
An Analysis of Rate-Sensitive Skin in Gas Wells
Authors: Meehan D. N. , Schell E. J.
Published: December 2007

This paper documents the analysis of rate dependent skin in a gas well. Three build-up tests and an isochronal test are analyzed in some detail. The results indicates the rate dependent skin is due to non-darcy flow near the wellbore. Evidence is presented that suggest the non-darcy flow results from calcium carbonate scale partially plugging the perforations. Also, the summary of a pressure build-up study is included on the wells recently drilled in Champlin's Stratton-Agua Dulce Field.
Formation Dip Determination Using Digital Wellsite Processing Techniques
Authors: Easton Steven B.
Published: December 2007

Digital processing of recorded dip information at the wellsite can, provide detailed and accurate geological information in a time frame suitable for wellsite economic decisions. A new wellsite formation dip analysis program, Prodip*, has been implemented in the Dresser Atlas computerized logging units on a worldwide basis. The program is quite similar to the formation dip processing program currently used in regional computer centers and utilizes the same methods for pad correlation, quality assurance, and geometric solution of formation dip angle and direction. Prodip, however, is necessarily different due to the limited available memory within the computerized logging unit. Thus, the wellsite program is designed to approach the computer center program results as closely as possible under wellsite operating conditions.

The use of new data handling hardware such as array processors has greatly decreased the timing between data aquisition and computed dip presentation at the wellsite. This new hardware, coupled with the continuing evolution of computer logging units, promises significant improvements in the speed, flexibility and accuracy of wellsite data processing capabilities in the near future.
A Case Study of Retrograde Behavior in a Gas Transmission Network
Authors: Ullah M. R.
Published: December 2007

The paper describes an analytical approach that effectively utilizes pressure gradient, transmission factor and effective roughness for identification of the problem area of an offshore gas transmission network suffering retrograde condensation.

The paper also investigates the causes of such behavior of the network in the light of the phase behavior of the gas stream flowing through the affected area.
Measurement of Suction and Discharge Pressure Pulsations in Waterflood Facilities
Authors: Wurzbach W. M. , Happel P. E.
Published: December 2007

Recent mechanical problems with reciprocating water injection pumps prompted a study of suction and discharge pressure conditions in the Red River Bull Bayou Unit, Red River Parish, Louisiana. Frequent failures in plunger pump components and discharge lines were occurring at several injection sites within the unit. Electronic surveillance equipment consisting of an oscilloscope and pressure transducers was utilized to locate and identify large suction and discharge pressure pulses. The severity of these pulses could not be identified with standard pressure gauges. The data obtained with the electronic equipment indicated that cavitation was occurring on the suction side of the pumps due to insufficient net positive suction head. The large pressure pulsations caused by this cavitation problem were carried through the pump and amplified on the discharge side. This resulted in excessive vibration and equipment overload. Subsequent changes in the suction and discharge piping design eliminated cavitation and effectively reduced the peak pressure pulses. These piping changes were done systematically to measure the effect of each change individually. The resulting measurements gave better insight to future piping design for both suction and discharge installations.
Thermal Synthesis Protection Relay Increases Pump and Motor Life
Authors: Dickson W. D. , Oxley G. A.
Published: December 2007

A solid-state relay using a method new to the petroleum industry has been applied to the protection of three-phase submersible pumps and motors. The method consists of a thermal synthesis model of heating that occurs in motors due to electrical abnormalities. Conventional relays monitor only line current magnitude or average magnitude of unbalance. The Thermal Synthesis Relay monitors and analyzes all electrical components that contribute to heating. The relay interrupts the motor on the basis of an inverse time-heat curve, not the conventional time-current curve.
An Engineering Simulator for Drilling: Part II
Authors: Millheim K. K. , Huggins R. L.
Published: December 2007

In Part 1, the Engineering Simulator for Drilling (ESD) is described, explaining the overall design, the engineering algorithms, the use of the interactive graphics, and the software and hardware used to create and operate any drilling system.

Part 2 presents how the ESD is designed as a tool for the drilling person, giving the person the flexibility to use the ESD as a drilling time and cost analysis tool, or for well planning, or a full engineering simulator. A stand alone capability to use parts of the ESD for real time drilling analysis is also possible.

An example of how a drilling person would use the ESD to build a drilling system is given. This includes logging onto the ESD, selecting the drilling location and geology, selecting the drilling rig, the initiation of the wellbore and the design of the mud system and the drill string.

A description is given of how the user can operate the newly created drilling system, describing some of the options available to him.

All Figures are actual photographs or plots of the various ESD graphic's pictures and menus.
Exploration in Andaman Forearc Basin its Evaluation, Facies Trend and Prospects – A Review
Authors: Misra P C , Roy T K
Published: December 2007

The paper reviews the exploration activities in the Andaman forearc basin. Structural analysis reveals various stages of evolution with corresponding sedimentation cycles. Subduction complex comprises accretionary prisms and forms the floor of the ponded Neogene sediments in the Upper trench slope and also the base of the young accretionary basins in the west of the Outer high. Unconformity overlying subduction complex is much younger in the Lower trench slope as compared to the east. Reliable and continuous reflections are absent within subduction complex. Favourable lithofacies trends vis-avis structural evolution of the area have been outlined. This has enabled to identify broadly the future hydrocarbon prospects in the region.
Analytical Study of Overpressured Area in Bombay Offshore Basin
Authors: Sahay Bhagwan
Published: December 2007

Occurrence and evaluation of overpressured sub-surface formations are critical to exploration concepts, drilling and production operation, involving hydrocarbon resources. It is therefore necessary that inter-disciplinary technical approach is required to optimise exploration efforts in such hostile sub-surface environments. In the search for hydrocarbon resources in many areas both onshore and offshore, abnormal formation pressures have been encountered. This paper is aimed on the analytical studies on such overpressures in the Bombay Offshore basin, which is a major oil/gas province in the country.

Bombay Offshore basin which is the southern extension of Cambay basin, came into existence during Upper Cretaceous time as a result of faulting in the Deccan trap basement. Two prominent structural trends, one aligned N-S, while the other E-W, are present in the Offshore, similar to lend part of the basin.

The sedimentary section of this basin comprises mostly of shale and limestone, ranging from Paleocene/Cretaceous to Recent. Considerable facies changes has been observed in the different parts from north to south and east to west in this basin which has played a significant role in the generation of overpressure, specially in the North, North West and North East region, besides contributing to commercial/nen-commerciai hydrocarbon accumulations in different areas. Overpressured zones in this basin have been encountered in the structures, which are mostly aligned in east-west direction and are of late origin. They are also devoid of major commercial accumul tions of hydrocarbons.

The possible reason for the occurrence of such horizons which occur in the sediments of Eocene to Miocene in the Bombay Offshore basin falls in two broad categories.

Primarily Compaction and/or Diagenesis of limestone which might have created permeability barrier in the porous sequences, thus inhibiting expulsion of fluids from the rock.

As a result of work which has been done on the prediction of such overpressured horizons in the sediments with the help of DXC, Shale density, flow-line temperature and conductivity studies, etc, it has been possible to forewarn the occurrence of such overoressured horizons, in different areas in Offshore before they were uncovered by the bit and by devising Mud and Casing policies suitably, it has been thus possible to avoid many well hazords and there by achieve the objectives.

Field case histories from the area will highlight the presentation.
Some Structural Considerations in the Operation of Jack-Up Platforms
Authors: Edwards A. J.
Published: December 2007

Self-elevating mobile drilling or accommodation platforms, generally referred to as "jack-ups" have been on the offshore scene in some form or other for many years.

In recent years the range and capability of such structures has extended to enable them to operate in water depths of greater than 400 feet, and in areas with very severe meteorological conditions.

At the same time designers have made great efforts to avoid concomitant in-creases in costs by paying great attention to the structural design of legs, jack frame, jacking system, and hull. Whereas the aoplication of static design methods have been successful in water depths up to above 300 feet, increasing the allowable water depth above this necessitates the detailed consideration of dynamic effects and foundation behaviour.
Post Frac Pressure Analysis Tells a Story
Authors: Lee Byung , Mao Ming
Published: December 2007

Analysis of pressure data immediately subsequent to a fracturing stimulation treatment gives indications of the fracture length and representative conductivity. A comparison of these post-treatment values allows corrections to be incorpora ed into treatment design studies and thus improves design optimization.

As a first step, the calculations of fracture length and conductivity using two case histories of wells fracture stimulated are included in this study. Some analysis considerations for designing or evaluating post-frac test are also included.
Single Point Moorings: Options for Offshore Loading, Storage and Process
Authors: Gruy R. H. , Kiely W. L.
Published: December 2007

While the concept of offshore tanker loading has been around for many years, it was not until the early 1970's that the idea of employing a Single Point Mooring (SPM) terminal as an integral part of an offshore production facility achieved wide industry acceptance. In this application, the SPM provides both a permanent (or semi-permanent) mooring for the tanker and a means for transporting oil from the seafloor to the tanker. The SPM thus eliminates the requirement for a pipeline from the offshore field to the shore which often significantly reduces the overall project cost and may allow development of marginal fields which have insufficient recoverable reserves to justify a pipeline system.

A second economic consideration in the election to use offshore loading is that it makes it possible to ship crude and receive income as soon as oil is available for a relatively small investment and in a relatively short time frame. Thus, production from initial wells can be generating cash flow while the the drilling program continues with delineation of the reservoir. Even if the economics can support the cost of a pipeline, an offshore loading system ensures income during the sometimes lengthy design and construction period and is often retained subsequent to pipeline completion as a backup system in the event of pipeline outage.

Selection of an offshore loading scenario obviously will often require in-depth analysis of many economic considerations. However, the fact that viable concepts for offshore loading are available is of prime importance and offers a much greater flexibility to the operator in his planning than previously existed.
Current Cementing Practices in the Abnormal Pressure Zone Arun Field – Indonesia
Authors: Thibault Leo R. , Calvert D. Gerry
Published: December 2007

This paper presents the Mobil Oil Indonesia experience associated with cementing the 9-5/8 inch casing through the abnormally pressured and water sensitive sand/shale Baong formation in the Arun field. North Sumatra.

The paper will discuss how the cement slurries and cementing procedures for the 9-5/8 inch casing have been modified to overcome two major problems. The first being the inability to fully displace the cement due to swelling of sensitive shales, the second being severe annular flow after cementing.

This paper will further examine the changes made to slurry design after the recent discovery that circulating temperatures during 9-5/8 inch cementing operations are considerably lower than predicted by the API schedules. Because of these low temperatures, the slurries used in the past were greatly over retarded which contributed to the long and costly afterflow periods.