bluuebunny/crossref_metadata_2025_split huggingface dataset:
A Focused Current Resistivity Logging System for MWD
Authors: Evans H. B. , Brooks A. G. , Meisner J. E. , Squire R. E. 
Published: December 2007

ABSTRACT
An MWD focused current resistivity system has been developed for well conditions under which neither the short normal nor the electromagnetic device operates well; that is, in wells where highly conductive drilling fluids are used, where relatively high formation resistivities are encountered, and where large resistivity contrasts are expected. The focused current system employs a guarded electrode design; the dynamic measurement range is 0.1 to 1000 ohm-m at ±5 percent of the resistivity value. The response characteristics of the MWD focused current device compare well to some published responses for equivalent wireline systems.
The focused current system offers superior performance in logging high-angle holes where excellent thin-bed resolution is required, in high-salinity muds where other systems do not perform well, and in fresh muds where the short normal is typically run. It provides exceptional resistivity measurements in all conductive borehole fluids.
A limited number of MWD focused current logs, the system correction charts and comparisons of focused current log responses to wireline log responses in the same wells are shown.
Interference Pressure Behavior in Multilayered Composite Reservoirs
Authors: Hatzignatiou D. G. , Ogbe D. O. , Dehghani K. , Economides M. J. 
Published: December 2007

ABSTRACT
Analytical solutions are presented for studying the interference pressure behavior in a multi-layered, composite reservoir. The model considers an infinitely large reservoir with two partially or fully completed wells. Fluid interlayer crossflow is included. Each layer consists of two concentric zones, an inner and an outer region of uniform reservoir rock and fluid properties, separated by a mobility discontinuity.
The solutions are validated by comparison with the results obtained from several limiting models for interference testing, specifically the homogeneous single layer reservoir, the single layer composite system, and the two-layered systems with and without crossflow.
A sensitivity study is presented to examine the influence on pressure response of wellbore storage and skin effects at the active well, inter-layer crossflow, diffusivity ratio, mobility ratio, and permeability ratio.
Dimensionless pressure type curves are developed for estimating valuable formation characteristics of transmissibility and storativity from interference test data.
Pressure Drawdown in a Layered Reservoir With Linear Boundaries
Authors: Chen T. 
Published: December 2007

ABSTRACT
An analysis of pressure drawdown has been conducted for a layered reservoir in which each layer is pinched-out by a linear boundary. It was found that if all the pinch-out distances were finite, then the bottom-hole pressure behavior of such a system could not be distinguished from that of a single-layered reservoir with an equivalent pinch-out distance. Consequently, only a single distance can be estimated from a drawdown or a buildup test. If, however, one of the layers is infinite in extent, then there is sufficient character in the pressure response to enable the use of the test data for estimating the pinch-out distance of the finite layer as well as the transmissibilities of each layer.
High-Resolution Logging: The Key to Accurate Formation Evaluation
Authors: McCall D. C. , Allen D. F. , Culbertson J. S. 
Published: December 2007

ABSTRACT
Homogeneous geological zones, even 1-ft thick, are rarely seen in nature. The wireline logs that are used to evaluate reservoirs typically have bed resolutions ranging from 2 to 10 ft and cannot detect sudden changes in porosity, lithology or saturation. Now, however, log analysts can accurately evaluate formations that are less than 1-ft thick through new wireline measurements and enhancements of older measurements.
The Sources of Errors in Slowness Measurements and an Evaluation of Full Waveform Compensation Techniques
Authors: Liu O. Y. 
Published: December 2007

ABSTRACT
The sources of errors in slowness, or ∆t, measurements are analyzed in this paper. Using synthetic waveforms generated by the finite difference method and a scaled model, the slownesses of compressional, shear and Stoneley waves are evaluated for examples of bedding, cave-in, fractured formation, eccentered and tilted tools. The depth-derived borehole compensation (DDBHC) and other means of improving the accuracy of slowness estimation are applied to the full waveform slowness estimation.
The effect of washouts on slowness estimates is extremely large if borehole compensation is not applied. Bed boundaries cause moderate error in slowness measurements and can be minimized by compensation. Simulation shows that the tool eccentering and tilting have only minor effect on compressional and shear slownesses, and no effect on the Stoneley wave. The shear slowness is disturbed more by discontinuities than compressional and Stoneley waves. The slowness is most affected when the receiver array is straddling the discontinuity and relatively more affected after the array passes the discontinuity than before entering it.
The conventional DDBHC method produces fairly good results for full waveform slowness estimation. Better results can be obtained, especially for shear slowness estimates, if some preprocessing is done on the waveforms and if the weighting on the receiver and transmitter slownesses used in the conventional DDBHC method is modified according to the results of model simulations and earlier studies. For borehole washouts, more scaled model and simulation work is needed for developing better compensation algorithms.
Behavior of Wells With Low-Conductivity Vertical Fractures
Authors: Cinco-Ley H. , Ramey H. J. , Samaniego F. , Rodriguez F. 
Published: December 2007

ABSTRACT
This paper presents the transient pressure behavior for a well with a low conductivity vertical fracture, (kfbf)D ≤ 0.1; these cases include low kfbf fractures, long fractures or wells in relatively high permeability formations.
It appears that this type of systems exhibits two flow periods only: bilinear flow and pseudo-radial flow. It is demonstrated that for these fracture conductivities the effective wellbore radius is given by rw′=0.28(kfbf/k); that means that there is a maximum value of the effective wellbore radius achieved by hydraulic fracturing for a given value of (kfbf/k).
A new single line type curve is presented for analysis of pressure transient tests.
A Unified Type Curve Approach for Pressure Transient Analysis of Naturally Fractured Reservoirs
Authors: Jalali Younes , Ershaghi Iraj 
Published: December 2007

ABSTRACT
A comprehensive treatment of pressure transient analysis of naturally fractured reservoirs is presented. Parameter estimation is based on pattern recognition, type curve matching, and auxiliary correlations. Pattern recognition verifies the amenability of data to analysis as well as the applicability of the model to observed behavior. Conditions under which a variety of pressure response patterns develop, are rigorously established. For each pattern, the applicable analysis procedure is specified.
A type curve is developed that incorporates interporosity flow response ranging from unsteady state to pseudo-steady state. Thus, type curve analysis determines the governing mode of interporosity flow and yields the reservoir parameters accordingly.
Auxiliary correlations are based on a thorough analysis of the transition curve. The correlations independently determine the reservoir parameters and thereby assist type curve analysis. In certain cases, the correlations can determine the proportion of matrix that contributes under "restricted" and "unrestricted" conditions.
The developed procedure is readily amenable to computer aided analysis of pressure transient data in naturally fractured reservoirs.
Acquisition Techniques in Cross-Hole Seismic Surveys
Authors: Delvaux J. , Nicoletis L. , Noual G. , Dutzer J. F. 
Published: December 2007

SUMMARY
The key to cross-hole seismic measurements is actually to dispose of appropriate sources and receivers. Most of the cross-hole seismic experiments have been done with hydrophone receivers and air gun or sparker types of sources. We have experimented these tools and compared them to other solutions like a coupled weight drop source and 3 component geophones. These equipments have been tested on a same site, a shallow reservoir in the Paris Basin. The hydrophone streamer enables a fast collection of the data but requires an energetic source (around 10 000 Joules) in order to counterbalance the lack of preamplifiers in the streamer, and to increase signal/noise ratio. The conventional 3 component borehole tool is more sensitive but does not record the full spectrum transmitted by the source (currently up to 500 Hz). Our results corroborate theoretical investigation on the radiation pattern of down-hole sources.
Electrochemical Origin of Conduction in Shaly Formations
Authors: Sen P. N. 
Published: December 2007

Abstract
Solving equations of motions for cations and anions in the presence of a double layer we show that rock conductivity σ is a nonlinear function of water conductivity σw. Both the observed bend for low salinity and the simple linear form at high salinity, similar to the empirical rules of Waxman – Smits (W-S) or Dual Water (D-W) model of Clavier et. al., are obtained. This provides a fundamental basis for these widely and repeatedly used empirical rules. We find additional geometrical factors multiplying the "clay" term which can explain the experimentally observed variation of conductivity intercept, from sample to sample, as a function of charge Qv. Most importantly, we show that the conductivity depends on the micro-geometry and a key dimensionless parameter ξ = Ω+r+/(N0a). The surface ion number density is Ω+, r+ is the ratio of average diffusion coefficient of the counter ions in the double layer divided by that outside, N0 is the bulk ion density far from the double layer and the particle radius is a. Dependence on r+ explains why exchanging with less mobile ions like Ca++ reduces the conductivity.
Closed Chamber Testing: The Effects of Wellbore Friction and Fluids Compression
Authors: Salas B. , Sageev A. 
Published: December 2007

ABSTRACT
Closed chamber tests are commonly performed as back surge perforation cleaning in wells where high surface pressures are not desired. Typical of closed chamber tests are high fluid velocities in the wellbore, and a variable wellbore storage caused by the rapid gas compression as the liquid column approaches the upper surge assembly. In this paper, we examine the effects of wellbore friction and variable wellbore storage including liquid and vapor compressibilities on pressure responses on closed chamber tests.
The bottom hole pressure builds up more rapidly at early time when frictional effects are present. This rapid build up is associated with high liquid velocities in the wellbore. However, at late time the liquid velocity decreases, and frictional effects diminish. Wellbore frictional effects are dampened significantly in the presence of positive wellbore skin.
The effects of liquid and gas compressibilities in the wellbore on the pressure build up during a closed chamber test are significant. Allowing the liquid to expand in the wellbore causes the rapid gas compression to occur earlier, but results in a slower final build up. This delay in the final build up is caused by the additional late time wellbore storage that depends on the compressibility of the liquid and the vapor columns. The final wellbore storage is a combination of a large volume of a low compressibility liquid, and a small volume of a high compressibility gas.
The closed chamber tests responses including frictional effects and wellbore fluids compression were generated by coupling a superposition reservoir model with a wellbore fluid flow model.
Petroleum Engineering: An Emerging Discipline for the 21st Century
Authors: Miller M. A. , Pope G. A. 
Published: December 2007

ABSTRACT
Petroleum engineering as a discipline has historically been intimately allied with a single industry. As such, the discipline is often viewed as being more of a technical specialty than as a fundamental discipline in the same sense as chemical, civil, electrical, or mechanical engineering. However, there are distinctive factors that make petroleum engineering fundamentally different from other engineering disciplines, much in the same way that mechanical engineering is different from chemical engineering. These differences make petroleum engineers best qualified to deal with the general class of engineering problems involving fluid movement within the earth, even in such non-energy related areas as hydrology and underground waste disposal. In addition to the need for petroleum engineers for hydrocarbon extraction, it is likely that as we move into the next century, many natural resource problems will require increasing reliance on technical expertise that can and should be supplied by what are currently called petroleum engineers.
Nomenclature has forced petroleum engineering into being a narrowly-perceived discipline, when in reality it possesses as much or more breadth as any other engineering discipline. The time is at hand for the discipline of petroleum engineering to stake out a claim to address all engineering problems involving fluid transport in the earth. No other engineering discipline provides a more appropriate base of knowledge and methodology. An example undergraduate curriculum is proposed for the education of petroleum engineers for the 21 st century. It is further proposed that the term "petroleum engineering" may not be entirely appropriate to fully describe this more fundamental emerging discipline.
The Effects of Current Low Drilling Levels on Lower 48 Oil and Gas Production
Authors: Woods T. J. 
Published: December 2007

ABSTRACT
The severe drop in oil and gas drilling activity since 1985 has led to growing concerns about the near-term oil and gas production outlook in the lower-48 states. The Gas Research Institute has developed a detailed representation of the lower-48 oil and gas resource base and the activities necessary to explore and develop that resource base. Combined with a highly detailed assessment of gas well completions, the analysis indicates that lower-48 oil and gas production could be maintained at their 1986–87 levels through the year 2000 without a return to the peak drilling activity levels of the 1981–85 period and with little increase in real oil prices above the 1985 level. The development of new technology and improved production practices to improve the recovery of hydrocarbons-in-place in known oil and gas fields will play a critical role in sustaining lower-48 oil and gas production at their 1986–87 levels through the year 2000.
Unique Subsea Completions in the Kepiting Field, Indonesia
Authors: Coates R. L. , Kadi I. 
Published: December 2007

ABSTRACT
The Kepiting Field development demonstrates an economical way of producing marginal reservoirs using a floating production facility and seafloor completed wells.
Unique to the Kepiting completions is a method for re-entering the wells to perform wireline operations. The system consists of steel tubular risers permanently connected to the seafloor trees which are terminated at the top by tensioning buoys located approximately 50 feet below the water. A buoyed platform/ginpole structure that extends the riser to the surface is temporarily attached to the top of the riser buoy and provides a dry working area from which to support operations using a wireline unit mounted on a workboat.
The success of the Kepiting project, which presently is used as a testing model for future deepwater projects, has increased Conoco's interest in developing marginal reservoirs using similar production/completion systems.
Economic Evaluation of Thermal Recovery Projects
Authors: Ramage W. E. , Castanier L. M. , Ramey H. J. 
Published: December 2007

ABSTRACT
This paper presents a technique of economic evaluation of enhanced oil recovery projects for steam injection and in-situ combustion. In 1980, Williams and Ramey1 presented a model for the economic evaluation of steamfloods and in-situ combustion projects. Our study revises and updates then-work.
The oil recovery schedules for steam injection were generated using a modified Marx and Langenheim2 model and the recovery for in-situ combustion was computed using the Gates and Ramey3 technique. These models allow the determination of oil recovery versus fluid injected for a given reservoir or pilot providing that the main reservoir parameters such as porosity, thickness and saturations are known.
Some of the parameters needed for economic evaluation are not well known, and other parameters such as the recent price of oil may vary rapidly. A classic economic analysis is bound to be uncertain at best. In order to partially alleviate this problem our economic evaluation method includes a spreadsheet approach and a Monte Carlo simulation. A discounted net present value was obtained for each of the processes at different injection rates, and pattern sizes. The results are presented as a probability for a given net present value instead of a single value.
An example using published data from the Belridge field is shown. For this field both in-situ combustion and steam injection were found to be economically competitive.
The above mentioned technique can easily be modified for application to other fields or even other enhanced oil recovery processes. The models and economic calculations can easily be run on a microcomputer (IBM PC in our case).
The Tax Reform Act of 1986: Impact on Oil and Gas Tax
Authors: Kells R. B. 
Published: December 2007

ABSTRACT
The Tax Reform Act of 1986 has created numerous changes in the tax laws which affect oil and gas investors, producers, royalty owners and the oil and gas industry in general.
Tax changes have been implemented with respect to intangible drilling costs, prepayment of intangible drilling costs, depletion, depreciation of oil, and gas equipment, the investment tax credit and the alternative minimum tax.
An Analysis of Field Development Strategies for Methane Production From Coal Seams
Authors: Sung W. , Ertekin T. 
Published: December 2007

ABSTRACT
Natural gas production from conventional gas reservoirs and methane production from coal seams are different not only because of the different physical characteristics of the producing horizons but also because of the existence of different gas storage mechanisms. In the design of an optimum development plan for a coal seam degasification process, as it is the case in conventional reservoirs, it will be necessary to have a good knowledge of the field parameters such as total reserves, well productivity and formation characteristics. One of the more significant planning concerns in the development of a coal seam is the determination of the most efficient geometric arrangement of drainage wells for the purpose of establishing a uniform pressure decline throughout the coal seam. Since most of the methane gas in the coal seams is in the adsorbed stage, achievement of a uniform pressure distribution will assure the continuity of the free gas phase in the system. Existence of a pronounced permeability contrast in two principal directions coupled with the sorption characteristics necessitates the identification of certain criteria that will infer the optimum pattern configuration for coal seams.
In this paper we present the results of a series of numerical exercises targeted for a better understanding of the effectiveness of several drainage patterns. Along these lines, the effects of coal seam properties such as porosity, permeability, and permeability contrast have been isolated to understand the role of each individual parameter in the selection of optimum vertical and horizontal drainage well configurations. In the case of sparsely drilled well configurations, several infill drilling scenarios have been considered in an effort to maximize the ultimate recovery.
Evolution of Prudhoe Bay Automation
Authors: Davis Guy E. 
Published: December 2007

Abstract
The Standard Alaska Production Company (SAPC) was faced with a need to upgrade four major digital control systems used for oil production at Prudhoe Bay, Alaska. This equipment directly controls production of a 850,000 BPD facility. The changes were necessitated because of continuing plant expansions and resolution of control system debottlenecking problems. This paper describes the distributed control systems, methods used, technical complexity of the work, team organization, scheduling, installation coordination and duration of plant shutdown to perform the actual cutovers. The bottom line—the job of replacing four major computer systems was completed using a six-day outage for each facility. Impact to production was held to a minimum through advanced personnel training. Control system availability and plant operation improved considerably when the work was completed.
As production facility equipment ages, these techniques will become more important to other plant owners.
Diagnosis and Removal of Microbial/Fines Plugging in Water Injection Wells
Authors: Cusack F. , McKinley V. L. , Lappin-Scott H. M. , Brown D. R. , Clementz D. M. , Costerton J. W. 
Published: December 2007

SUMMARY
Because bacteria are naturally present in the water12 used in water injection for secondary oil recovery, these organisms adhere to available surfaces and produce biofilms3 just as they do in all aquatic ecosystems examined to date4. The bacterial biofilms in individual water injection wells develop to an extent dependent on the nutrient supply in the injection water. Organic contaminants are converted to bacterial biomass, and to bacterial exopolysaccharide slimes. Some organic compounds (notably lactate and acetate) are oxidized by anaerobic bacteria that use sulphur compounds as hydrogen acceptors and produce H2S. This souring process is dependent on the input of organic nutrients and it is the function of a heterotrophic bacterial population that is concentrated very close (&lt;3 meters) to the well bore. The generation of H2S in the bulk of the water-flooded formation is severely limited by the very low levels of available bacterial nutrients in these areas and most H2S production is limited to the immediate viscinity of water injection and production wells. Injection well back flow data12 and injection well cleaning data2 both demonstrate, unequivocally, that heterotrophic bacterial growth in a waterflood operation is limited to areas very close to injection and production well bore holes. These areas are readily accessible to biocide treatment.
Bacterial biofilms develop very rapidly on the extensive surfaces of artificial and natural rock cores14, and these slime-enclosed adherent bacterial populations can reduce permeability by direct plugging. Treatment with 5-12% sodium hypochlorite (bleach) is sufficient to remove these bacterial accretions in both field2 and laboratory5 experiments, and treatment with sufficient bleach (3-4 tubing volumes) is regularly used to clean injection wells plugged by bacterial growth. We have recently shown6 that the bleach concentration used to remove bacterial biofilms can be reduced to ±1% without loss of efficacy. Bacterial biofilms trap particulate material8 and injection wells in systems with large amounts of particulate material in the injection water become plugged with biofilms impregnated with these particles. Bleach alone is not effective in cleaning these microbial/fines plugged wells but a combination of bleach and acid (in that order, with a water "spacer") is very effective5 because bleach removes the biofilm and allows access of acid to acid-soluble fines. Our developing general understanding of the nature of injection well plugging allows us to custom-design a cleaning protocol to remove this damaging material and restore original levels of water injectivity.