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Research program on fractured petroleum reservoirs. Second quarterly, April 1--June 30, 1995

Description: Very large compositional variation both areally and vertically has been observed in some hydrocarbon reservoirs. Several mechanisms are believed to contribute to such variations: gravitational segregation, molecular diffusion, thermal diffusion, and thermal convection. At isothermal conditions only gravitational segregation and molecular diffusion contribute to vertical compositional grading. The Gibbs segregation concept can properly account for this process. Under nonisothermal conditions, which is often the case, the process is thermodynamically irreversible and therefore Gibbs criteria of equilibrium cannot be invoked. The current literature often combines the Gibbs segregation concept and the natural convection process to formulate the interaction of convection and gravity segregation for multicomponent systems at nonisothermal conditions. The Dary law is also used without the modification of the velocity weighing for multicomponent systems. Such a formulation may not describe the process properly. This report formulates compositional variation in hydrocarbon reservoirs at nonisothermal condition. Results for the special case of gravity and thermal diffusion are also presented.
Date: July 31, 1995
Creator: Firoozabadi, A.
Partner: UNT Libraries Government Documents Department

Strategies for gas production from hydrate accumulations under various geologic conditions

Description: In this paper we classify hydrate deposits in three classes according to their geologic and reservoir conditions, and discuss the corresponding production strategies. Simple depressurization appears promising in Class 1 hydrates, but its appeal decreases in Class 2 and Class 3 hydrates. The most promising production strategy in Class 2 hydrates involves combinations of depressurization and thermal stimulation, and is clearly enhanced by multi-well production-injection systems. The effectiveness of simple depressurization in Class 3 hydrates is limited, and thermal stimulation (alone or in combination with depressurization) through single well systems seems to be the strategy of choice in such deposits.
Date: April 29, 2003
Creator: Moridis, G. & Collett, T.
Partner: UNT Libraries Government Documents Department

Riverton Dome Gas Exploration and Stimulation Technology Demonstration, Wind River Basin, Wyoming

Description: This project will provide a full demonstration of an entirely new package of exploration technologies that will result in the discovery and development of significant new gas reserves now trapped in unconventional low-permeability reservoirs. This demonstration includes the field application of these technologies, prospect definition and well siting, and a test of this new strategy through wildcat drilling. In addition this project includes a demonstration of a new stimulation technology that will improve completion success in these unconventional low permeability reservoirs which are sensitive to drilling and completion damage. The work includes two test wells to be drilled by Snyder Oil Company on the Shoshone/Arapahoe Tribal Lands in the Wind River Basin. This basin is a foreland basin whose petroleum systems include Paleozoic and Cretaceous source beds and reservoirs which were buried, folded by Laramide compressional folding, and subsequently uplifted asymmetrically. The anomalous pressure boundary is also asymmetric, following differential uplift trends. The Institute for Energy Research has taken a unique approach to building a new exploration strategy for low-permeability gas accumulations in basins characterized by anomalously pressured, compartmentalized gas accumulations. Key to this approach is the determination and three-dimensional evaluation of the pressure boundary between normal and anomalous pressure regimes, and the detection and delineation of areas of enhanced storage capacity and deliverability below this boundary. This new exploration strategy will be demonstrated in the Riverton Dome´┐Ż Emigrant Demonstration Project (RDEDP) by completing the following tasks: 1) detect and delineate the anomalous pressure boundaries, 2) delineate surface lineaments, fracture and fault distribution, spacing, and orientation through remote sensing investigations, 3) characterize the internal structure of the anomalous pressured volume in the RDEDP and determine the scale of compartmentalization using produced water chemistry, 4) define the prospects and well locations as a result on this new exploration technology, and 5) ...
Date: November 15, 1998
Creator: Surdam, Ronald C.
Partner: UNT Libraries Government Documents Department

DEVELOPMENT OF A 400 LEVEL 3C CLAMPED DOWNHOLE SEISMIC RECEIVER ARRAY FOR 3D BOREHOLE SEISMIC IMAGING OF GAS RESERVOIRS

Description: Borehole seismology is the highest resolution geophysical imaging technique available to the oil and gas industry for characterization and monitoring of oil and gas reservoirs. However, the industry's ability to economically do high resolution 3D imaging of deep and complex gas reservoirs using borehole seismology is currently frustrated by the lack of the acquisition technology necessary to record the large volumes of the high frequency, high signal-to-noise-ratio borehole seismic data needed to do 3D imaging. This proposal takes direct aim at this shortcoming. P/GSI is developing a 400 level 3C clamped downhole seismic receiver array for borehole seismic 3D imaging. This array will remove the acquisition barrier to record the necessary volumes of data to do high resolution 3D VSP or 3D cross well seismic imaging. 3D VSP and long range Cross-Well Seismology (CWS) are two of the borehole seismic techniques that will allow the Gas industry to take the next step in their quest for higher resolution images of the gas reservoirs. Today only a fraction of the original Oil or Gas in place is produced when reservoirs are considered depleted. This is primarily due to our lack of understanding of the detailed compartmentalization of the oil and gas reservoirs. The 400 level 3C borehole seismic receiver array will allow for economic use of 3D borehole seismic imaging for reservoir characterization and monitoring. By using 3C surface seismic or 3C borehole seismic sources the 400 level receiver array will furthermore facilitate 9C reservoir imaging. The 9C borehole seismic data will provide P, SH and SV information for imaging of the complex deep gas reservoirs and allow quantitative prediction of the rock and the fluid types. The data quality and the data volumes from a 400 level 3C array will allow us to develop the data processing technology necessary for ...
Date: September 1, 2002
Creator: Paulsson, Bjorn N.P.
Partner: UNT Libraries Government Documents Department

RIVERTON DOME GAS EXPLORATION AND STIMULATION TECHNOLOGY DEMONSTRATION, WIND RIVER BASIN, WYOMING

Description: A primary objective of the Institute for Energy Research (IER)-Santa Fe Snyder Corporation DOE Riverton Dome project is to test the validity of a new conceptual model and resultant exploration paradigm for so-called ''basin center'' gas accumulations. This paradigm and derivative exploration strategy suggest that the two most important elements crucial to the development of prospects in the deep, gas-saturated portions of Rocky Mountain Laramide Basins (RMLB) are (1) the determination and, if possible, three-dimensional evaluation of the pressure boundary between normal and anomalous pressure regimes (i.e., this boundary is typically expressed as a significant inversion in both sonic and seismic velocity-depth profiles) , and (2) the detection and delineation of porosity/permeability ''sweet spots'' (i.e., areas of enhanced storage capacity and deliverability) in potential reservoir targets below this boundary. There are other critical aspects in searching for basin center gas accumulations, but completion of these two tasks is essential to the successful exploration for the unconventional gas resources present in anomalously pressured rock/fluid systems in the Rocky Mountain Laramide Basins. The southern Wind River Basin, in particular the Riverton Dome and Emigrant areas, is a neat location for testing this exploration paradigm. Preliminary work within the Wind River Basin has demonstrated that there is a regionally prominent pressure surface boundary that can be detected by inversions in sonic velocity depth gradients in individual well log profiles and that can be seen as a velocity inversion on seismic lines. Also, the Wind River Basin in general--and the Riverton Dome area specially--is characterized by a significant number of anomalously pressured gas accumulations. Most importantly, Santa Fe Snyder Corporation has provided the study with sonic logs, two 3-D seismic studies (40 mi{sup 2} and 30 mi {sup 2}) and a variety of other necessary geological and geophysical information.
Date: August 1, 1999
Creator: Surdam, Dr. Ronald C.
Partner: UNT Libraries Government Documents Department

Stresses and fractures in the Frontier Formation, Green River Basin, predicted from basin-margin tectonic element interactions

Description: Natural fractures and in situ stresses commonly dictate subsurface reservoir permeability and permeability anisotropy, as well as the effectiveness of stimulation techniques in low-permeability, natural gas reservoirs. This paper offers an initial prediction for the orientations of the fracture and stress systems in the tight gas reservoirs of the Frontier Formation, in the Green River basin of southwestern Wyoming. It builds on a previous report that addressed fractures and stresses in the western part of the basin and on ideas developed for the rest of the basin, using the principle that thrust faults are capable of affecting the stress magnitudes and orientations in little-deformed strata several hundreds of kilometers in front of a thrust. The prediction of subsurface stresses and natural fracture orientations is an undertaking that requires the willingness to revise models as definitive data are acquired during drilling. The predictions made in this paper are offered with the caveat that geology in the subsurface is always full of surprises.
Date: January 1, 1996
Creator: Lorenz, J.C.
Partner: UNT Libraries Government Documents Department

Assessment and Forecasting Natural Gas Reserve Appreciation in the Gulf Coast Basin

Description: Reserve appreciation, also called reserve growth, is the increase in the estimated ultimate recovery (the sum of year end reserves and cumulative production) from fields subsequent to discovery from extensions, infield drilling, improved recovery of in-place resources, new pools, and intrapool completions. In recent years, reserve appreciation has become a major component of total U.S. annual natural gas reserve additions. Over the past 15 years, reserve appreciation has accounted for more than 80 percent of all annual natural gas reserve additions in the U.S. lower 48 states (Figure 1). The rise of natural gas reserve appreciation basically came with the judgment that reservoirs were much more geologically complex than generally thought, and they hold substantial quantities of natural gas in conventionally movable states that are not recovered by typical well spacing and vertical completion practices. Considerable evidence indicates that many reservoirs show significant geological variations and compartmentalization, and that uniform spacing, unless very dense, does not efficiently tap and drain a sizable volume of the reservoir (Figure 2). Further, by adding reserves within existing infrastructure and commonly by inexpensive recompletion technology in existing wells, reserve appreciation has become the dominant factor in ample, low-cost natural gas supply. Although there is a wide range in natural gas reserve appreciation potential by play and that potential is a function of drilling and technology applied, current natural gas reserve appreciation studies are gross, averaging wide ranges, disaggregated by broad natural gas provinces, and calculated mainly as a function of time. A much more detailed analysis of natural gas reserve appreciation aimed at assessing long-term sustainability, technological amenability, and economic factors, however, is necessary. The key to such analysis is a disaggregation to the play level. Plays are the geologically homogeneous subdivision of the universe of hydrocarbon pools within a basin. Typically, fields within ...
Date: October 1, 1997
Creator: Kim, E.M. & Fisher, W.L.
Partner: UNT Libraries Government Documents Department

Comprehensive Geostatistical Technology on PC Platform

Description: Geostatistics has attracted the attention of many earth scientist and engineers who need better modeling tools for natural gas reservoirs. Two years ago Correlations Company responded to this need through the peer reviewed, DOE Small Business Innovative Research program to develop a fractal algorithm for interpolating between measurements and mapping the consequences. During the two years research period Correlations Company has combined geostatistical modeling with high quality graphics to produce Gviz. This software provides accurate 3D reservoir modeling tools and high quality 3D graphics for PC platforms enabling engineers and geologists to better comprehend reservoirs and consequently improve their decisions. Until recently geostatistical modeling was only available to the limited number of earth scientist familiar with UNIX based platforms. Gviz runs on any PC with Windows 95 or Windows NT operating system. The Gviz pre- processing module reads LAS and ASCII files. The pre-processing module facilitates selection of the stratigraphic units prior to processing by a nearest neighbor, kriging and co-kriging, conditional simulation, or fractal module. A user friendly GUI simplifies the examination of the statistical data and the geostatistical analyses using isotropic and anisotropic variograms. After completing the analyses, the post-processing unit can generate ID models of well logs, 2D models such as cross-sections, or a 3D model of any petrophysical property. Post- processing includes the display of reservoir slices, multiple cross-sections, rotation along any axis, and identification of geobodies (visually inspect the effect of porosity cutoffs on connected pore volume). The post-processor includes an up-scaling module to transform a fine scale grid into a reservoir simulation grid which can then be exported in an Eclipse format. Gviz emphasizes a self-explanatory GUI and visually oriented help pages which guides even a novice through the process of generating realistic, two to five million cell, 3D reservoir models. Beta testing of ...
Date: October 1, 1997
Creator: Stevenson, C.
Partner: UNT Libraries Government Documents Department

Naturally fractured tight gas reservoir detection optimization. Annual report, August 1994--July 1995

Description: This report details the field work undertaken Blackhawk Geosciences and Lynn, Inc. during August 1994 to July 1995 at a gas field in the Wind River Basin in central Wyoming. The work described herein consisted of four parts: 9C VSP in a well at the site; additional processing of the previously recorded 3D P-wave survey on the site and Minivibrator testing; and planning and acquisition of a 3-D, 3-C seismic survey. The objectives of all four parts were to characterize the nature of anisotropy in the reservoir. With the 9C VSP, established practices were used to achieve this objective in the immediate vicinity of the well. The additional processing of the 3-D uses developmental techniques to determine areas of fractures in 3-D surveys. With the multicomponent studies, tests were conducted to establish the feasibility of surface recording of the anisotropic reservoir rocks. The 3-D, 3-C survey will provide both compressional and shear wave data sets over areas of known fracturing to verify the research.
Date: September 1, 1995
Partner: UNT Libraries Government Documents Department

Naturally fractured tight gas reservoir detection optimization. Quarterly technical progress report, April 1995--June 1995

Description: Research continued on methods to detect naturally fractured tight gas reservoirs. This report contains a seismic survey map, and reports on efforts towards a source test to select the source parameters for a 37 square mile compressional wave 3-D seismic survey. Considerations of the source tests are discussed.
Date: August 1, 1995
Partner: UNT Libraries Government Documents Department

In-Situ Sampling and Characterization of Naturally Occuring Marine Methane Hydrate Using the D/V JOIDES Resolution

Description: The primary accomplishments of the JOI Cooperative Agreement with DOE/NETL in this quarter were that: (1) Leg 204 scientific party members presented preliminary results and operational outcomes of ODP Leg 204 at the American Geophysical Union Fall meeting, which was held in San Francisco, CA; and, (2) a report was prepared by Dr. Gilles Guerin and David Goldberg from Lamont-Doherty Earth Observatory of Columbia University on their postcruise evaluation of the data, tools and measurement systems that were used for vertical seismic profiling (VSP) experiments during ODP Leg 204. The VSP report is provided herein. Intermediate in scale and resolution between the borehole data and the 3-D seismic surveys, the Vertical Seismic Profiles (VSP) carried during Leg 204 were aimed at defining the gas hydrate distribution on hydrate ridge, and refining the signature of gas hydrate in the seismic data. VSP surveys were attempted at five sites, following completion of the conventional logging operations. Bad hole conditions and operational difficulties did not allow to record any data in hole 1245E, but vertical and constant offset VSP were successful in holes 1244E, 1247B and 1250F, and walk-away VSP were successfully completed in holes 1244E, 1250F and 1251H. Three different tools were used for these surveys. The vertical VSP provided the opportunity to calculate interval velocity that could be compared and validated with the sonic logs in the same wells. The interval velocity profiles in Holes 1244E and 1247B are in very good agreement with the sonic logs. Information about the Leg 204 presentations at the AGU meeting are included in a separate Topical Report, which has been provided to DOE/NETL in addition to this Quarterly Report. Work continued on analyzing data collected during ODP Leg 204 and preparing reports on the outcomes of Phase 1 projects as well as developing plans ...
Date: December 31, 2003
Creator: Rack, Frank; Guerin, Gilles; Goldberg, David & Party, ODP Leg 204 Shipboard Scientific
Partner: UNT Libraries Government Documents Department

In-Situ Sampling and Characterization of Naturally Occurring Marine Methane Hydrate Using the D/V JOIDES Resolution

Description: The primary accomplishments of the JOI Cooperative Agreement with DOE/NETL in this quarter were (1) the preliminary postcruise evaluation of the tools and measurement systems that were used during ODP Leg 204 to study hydrate deposits on Hydrate Ridge, offshore Oregon from July through September 2002; and (2) the preliminary study of the hydrate-bearing core samples preserved in pressure vessels and in liquid nitrogen cryofreezers, which are now stored at the ODP Gulf Coast Repository in College Station, TX. During ODP Leg 204, several newly modified downhole tools were deployed to better characterize the subsurface lithologies and environments hosting microbial populations and gas hydrates. A preliminary review of the use of these tools is provided herein. The DVTP, DVTP-P, APC-methane, and APC-Temperature tools (ODP memory tools) were used extensively and successfully during ODP Leg 204 aboard the D/V JOIDES Resolution. These systems provided a strong operational capability for characterizing the in situ properties of methane hydrates in subsurface environments on Hydrate Ridge during ODP Leg 204. Pressure was also measured during a trial run of the Fugro piezoprobe, which operates on similar principles as the DVTP-P. The final report describing the deployments of the Fugro Piezoprobe is provided in Appendix A of this report. A preliminary analysis and comparison between the piezoprobe and DVTP-P tools is provided in Appendix B of this report. Finally, a series of additional holes were cored at the crest of Hydrate Ridge (Site 1249) specifically geared toward the rapid recovery and preservation of hydrate samples as part of a hydrate geriatric study partially funded by the Department of Energy (DOE). In addition, the preliminary results from gamma density non-invasive imaging of the cores preserved in pressure vessels are provided in Appendix C of this report. An initial visual inspection of the samples stored in liquid ...
Date: December 31, 2002
Creator: Rack, Frank; Storms, Michael; Schroeder, Derryl; Dugan, Brandon; Schultheiss, Peter & Party, ODP Leg 204 Shipboard Scientific
Partner: UNT Libraries Government Documents Department

IN-SITU SAMPLING AND CHARACTERIZATION OF NATURALLY OCCURRING MARINE METHANE HYDRATE USING THE D/V JOIDES RESOLUTION

Description: The primary accomplishments of the JOI Cooperative Agreement with DOE/NETL in this quarter were that: (1) Frank Rack presented preliminary results and operational outcomes of ODP Leg 204 at the DOE/NETL project review and two made two presentations at the ChevronTexaco Gulf of Mexico Hydrate JIP meeting, which were both held in Westminster, CO; and, (2) postcruise evaluation of the data, tools and measurement systems that were used during ODP Leg 204 continued in the preparation of deliverables under this agreement. Work continued on analyzing data collected during ODP Leg 204 and preparing reports on the outcomes of Phase 1 projects as well as developing plans for Phase 2.
Date: May 1, 2004
Creator: Rack, Frank R.
Partner: UNT Libraries Government Documents Department

SEISMIC ATTENUATION FOR RESERVOIR CHARACTERIZATION

Description: In this report we will show some new Q related seismic attributes on the Burlington-Seitel data set. One example will be called Energy Absorption Attribute (EAA) and is based on a spectral analysis. The EAA algorithm is designed to detect a sudden increase in the rate of exponential decay in the relatively higher frequency portion of the spectrum. In addition we will show results from a hybrid attribute that combines attenuation with relative acoustic impedance to give a better indication of commercial gas saturation.
Date: April 1, 2003
Creator: Walls, Joel; Taner, M.T.; Derzhi, Naum; Mavko, Gary & Dvorkin, Jack
Partner: UNT Libraries Government Documents Department

SEISMIC ATTENUATION FOR RESERVOIR CHARACTERIZATION

Description: In this report we will show the fundamental concepts of two different methods to compute seismic energy absorption. The first methods gives and absolute value of Q and is based on computation with minimum phase operators. The second method gives a relative energy loss compared to a background trend. This method is a rapid, qualitative indicator of anomalous absorption and can be combined with other attributes such as band limited acoustic impedance to indicate areas of likely gas saturation.
Date: October 1, 2003
Creator: Walls, Joel; Taner, M.T.; Derzhi, Naum; Mavko, Gary & Dvorkin, Jack
Partner: UNT Libraries Government Documents Department

Seismic-Scale Rock Physics of Methane Hydrate

Description: We quantify natural methane hydrate reservoirs by generating synthetic seismic traces and comparing them to real seismic data: if the synthetic matches the observed data, then the reservoir properties and conditions used in synthetic modeling might be the same as the actual, in-situ reservoir conditions. This approach is model-based: it uses rock physics equations that link the porosity and mineralogy of the host sediment, pressure, and hydrate saturation, and the resulting elastic-wave velocity and density. One result of such seismic forward modeling is a catalogue of seismic reflections of methane hydrate which can serve as a field guide to hydrate identification from real seismic data. We verify this approach using field data from known hydrate deposits.
Date: January 8, 2009
Creator: Nur, Amos
Partner: UNT Libraries Government Documents Department

Interdisciplinary study of reservoir compartments and heterogeneity. Progress report, January 1--March 31, 1996

Description: The major project objective is to help move small American businesses (oil and gas independent operators) from traditional practices in oil and gas reservoir management to an unproved integrated team approach making better use of information and the expertise of people. This objective is being accomplished in two ways: (1) Specific examples resulting from our field study, and (2) A general manual documenting the process of integrating data and people from the disciplines of geology, geophysics, and petroleum engineering. An actual oil field in the Denver Julesburg Basin in Colorado was selected to test the methods of integration. Efforts during this quarter were dedicated to history matching of the simulation model and to planning for various forecast runs. The geologic model and the engineering analysis resulted in a reservoir simulation model that is representative of the main features of the reservoir, such as the compartments and differing gas-oil contacts in each compartment. As a result of the history matching process, changes were made in the model. The economic significance of these changes, if any, will be addressed in the final report.
Date: April 30, 1996
Creator: Van Kirk, C.W.
Partner: UNT Libraries Government Documents Department