Seismic Detection and Analysis of Underground Laboratory Facilities

An abandoned underground tunnel complex at Fort Hood, Texas, was made available for project study. The physical size and depth of this tunnel system were similar to the physical dimensions and burial depths of underground laboratory (UGL) targets that are the subject of this UGL Countermeasures program. The first seismic field test objective at the Fort Hood tunnel system was to determine if cultural activity within a tunnel can be detected with seismic sensors deployed on the surface near an underground facility. The second objective was to try to identify a tunnel target with these same surface-positioned sensors using reflected and refracted seismic wavefields generated by a weight-drop source stationed at locations around the tunnel target. Seismic test data were recorded with three-component (3-C) geophones to allow vector extrapolation of event arrivals to their subsurface points of origin. The recording system had only 24 active recording channels, which limited the number of 3-D geophones that could be used for target detection and analysis to eight. Test results verified that cultural activity within a tunnel can be detected by surface-positioned seismic sensors. Point-source disturbances, such as hammering at a fixed location within the tunnel, yielded more interpretable data than did disturbances from a distributed source, such as the movement of airwaves along the entire 1000-ft length of the study tunnel when the entry doors were opened and closed. These data show that passive seismic monitoring of a UGL site will provide valuable information about UGL structure and geometry. The weight-drop source produced sufficient seismic illumination of the chosen tunnel target and other near-surface discontinuities in the tunnel area. These data demonstrate that UGL targets can be illuminated appropriately for target analysis purposes with seismic wavefields if an adequate number of moderate-energy source stations are distributed across a target area. The results shown here are qualitative in nature. Quantitative analysis of the data will be done during the next funding period.Bureau of Economic Geolog

An Investigation to Document Morrow Reservoirs That Can Be Better Detected with Seismic Shear (S) Waves Than With Compressional (P) Waves

Pennsylvanian-age Morrow reservoirs are a key component of a large fluvial-deltaic system that extends across portions of Colorado, Kansas, Oklahoma, and Texas. A problem that operators have to solve in some Morrow plays in this multi-state area is that many of the fluvial channels within the Morrow interval are invisible to seismic compressional (P) waves. This P-wave imaging problem forces operators in such situations to site infill, field-extension, and exploration wells without the aid of 3-D seismic technology. The objective of this project was to develop and demonstrate seismic technology that can improve drilling success in Morrow plays. Current P-wave technology commonly results in 8 percent of Morrow exploration wells not penetrating economic reservoir facies. Studies at Colorado School of Mines have shown that some of the Morrow channels that are elusive as P wave targets create robust shear (S) wave reflections (Rampton, 1995). These findings caused Isos Energy to conclude that exploration and field development of Morrow prospects should be done by a combination of P-wave and S-wave seismic imaging. To obtain expanded information about the P and S reflectivity of Morrow facies, 9-component vertical seismic profile (9-C VSP) data were recorded at three locations along the Morrow trend. These data were processed to create P and S images of Morrow stratigraphy. These images were then analyzed to determine if S waves offer an alternative to P waves, or perhaps even an advantage over P waves, in imaging Morrow reservoir targets. The study areas where these field demonstrations were done are defined in Figure 1. Well A was in Sherman County, Texas; well B in Clark County, Kansas; and well C in Cheyenne County, Colorado. Technology demonstrated at these sites can be applied over a wide geographical area and influence operators across the multi-state region spanned by Morrow channel plays. The scope of the investigation described here is significant on the basis of the geographical extent of Morrow reservoirs, the number of operators that can be affected, and the importance of Morrow hydrocarbon reserves to the nation's economy.Bureau of Economic Geolog

Extracting and Applying SV-SV Shear Modes from Vertical Vibrator Data Across Geothermal Prospects Final Report

This 3-year project was terminated at the end of Year 1 because the DOE Geothermal project-evaluation committee decided one Milestone was not met and also concluded that our technology would not be successful. The Review Panel recommended a ?no-go? decision be implemented by DOE. The Principal Investigator and his research team disagreed with the conclusions reached by the DOE evaluation committee and wrote a scientifically based rebuttal to the erroneous claims made by the evaluators. We were not told if our arguments were presented to the people who evaluated our work and made the ?no-go? decision. Whatever the case regarding the information we supplied in rebuttal, we received an official letter from Laura Merrick, Contracting Officer at the Golden Field Office, dated June 11, 2013 in which we were informed that project funding would cease and instructed us to prepare a final report before September 5, 2013. In spite of the rebuttal arguments we presented to DOE, this official letter repeated the conclusions of the Review Panel that we had already proven to be incorrect. This is the final report that we are expected to deliver. The theme of this report will be another rebuttal of the technical deficiencies claimed by the DOE Geothermal Review Panel about the value and accomplishments of the work we did in Phase 1 of the project. The material in this report will present images made from direct-S modes produced by vertical-force sources using the software and research findings we developed in Phase 1 that the DOE Review Panel said would not be successful. We made these images in great haste when we were informed that DOE Geothermal rejected our rebuttal arguments and still regarded our technical work to be substandard. We thought it was more important to respond quickly rather than to take additional time to create better quality images than what we present in this Final Report

Shear Wave Seismic Study Comparing 9C3D SV and SH Images with 3C3D C-Wave Images

The objective of this study was to compare the relative merits of shear-wave (S-wave) seismic data acquired with nine-component (9-C) technology and with three-component (3-C) technology. The original proposal was written as if the investigation would be restricted to a single 9-C seismic survey in southwest Kansas (the Ashland survey), on the basis of the assumption that both 9-C and 3-C S-wave images could be created from that one dataset. The Ashland survey was designed as a 9-C seismic program. We found that although the acquisition geometry was adequate for 9-C data analysis, the source-receiver geometry did not allow 3-C data to be extracted on an equitable and competitive basis with 9-C data. To do a fair assessment of the relative value of 9-C and 3-C seismic S-wave data, we expanded the study beyond the Ashland survey and included multicomponent seismic data from surveys done in a variety of basins. These additional data were made available through the Bureau of Economic Geology, our research subcontractor. Bureau scientists have added theoretical analyses to this report that provide valuable insights into several key distinctions between 9-C and 3-C seismic data. These theoretical considerations about distinctions between 3-C and 9-C S-wave data are presented first, followed by a discussion of differences between processing 9-C common-midpoint data and 3-C common-conversion-point data. Examples of 9-C and 3-C data are illustrated and discussed in the last part of the report. The key findings of this study are that each S-wave mode (SH-SH, SV-SV, or PSV) involves a different subsurface illumination pattern and a different reflectivity behavior and that each mode senses a different Earth fabric along its propagation path because of the unique orientation of its particle-displacement vector. As a result of the distinct orientation of each mode's particle-displacement vector, one mode may react to a critical geologic condition in a more optimal way than do the other modes. A conclusion of the study is that 9-C seismic data contain more rock and fluid information and more sequence and facies information than do 3-C seismic data; 9-C data should therefore be acquired in multicomponent seismic programs whenever possible.Bureau of Economic Geolog

Hypervelocity Impact with Flow and Shock Penetration Through Fluid, Plastic, and Elastic Zones

Physic

Elastic-Wavefield Seismic Stratigraphy: A New Seismic Imaging Technology

We have developed a numerical technique that will adjust 3-D S-wave seismic images so that they are depth equivalent to 3-D P-wave seismic images. The ability to make this type of P-SV to P-P depth registration is critical to our elastic wavefield seismic stratigraphy research because we now have higher confidence that depth-equivalent data windows are being used in the P-SV to P-P comparisons that we are making

Design and Construction of a Helium Gas Gun and a Numerical Solution of a Hypervelocity Impact of a Thin Plate

Physic

Secondary Natural Gas Recovery: Targeted Technology Applications for Infield Reserve Growth in Fluvial Reservoirs, Stratton Field, South Texas

Integrated evaluations of geology, geophysics, reservoir engineering, and petrophysics were conducted for mid-Oligocene-age fluvial reservoirs in Stratton field as part of this study. Located in South Texas within the Frio Fluvial-Deltaic Sandstone along the Vicksburg Fault Zone play (FR-4), Stratton field represents a mature gas field with significant opportunities for natural gas reserve appreciation. These fluvial reservoirs exhibit heterogeneity and often contain multiple compartments. The study identifies a considerable potential for reserve appreciation, with documented opportunities for a 100 percent increase in reserves within a large contiguous area of Stratton field, despite 40 years of prior development. Remaining natural gas reserves can be accessed through recompletion of existing wells that have bypassed reservoir compartments or by drilling infield wells to target compartments not effectively drained at current well spacing. Exploration efforts to discover new reservoirs, identify incompletely drained compartments, or tap bypassed gas zones in old fields can benefit from detailed geological studies integrating engineering, petrophysical, and geophysical methodologies. Various geophysical techniques, including 3-D surface seismic, vertical seismic profiling, amplitude versus offset, and 2-D seismic inversion, were utilized to visualize subtle changes in reservoir topology and compartment boundaries at depths as low as 6,800 ft. The study delineates three classes of compartment sizes based on analysis of ten groups of Frio reservoirs. Forward stochastic modeling of maximum gas recovery suggests that well spacings of 340, 200, and 60 acres (or less) offer optimal gas-contact efficiency in large, medium, and small compartment size reservoirs, respectively.Bureau of Economic Geolog

State of Texas Advanced Oil and Gas Resource Recovery

The objective of the State of Texas Advanced Resource Recovery program, Project STARR, is to increase royalty income to the Permanent School Fund through the drilling of profitable wells on State lands. The Bureau of Economic Geology (Bureau) receives $450,000 per year from the State to pay salaries of Bureau researchers involved in Project STARR who analyze State lands properties and databases and then advise operators how to increase production. The State requires the STARR program to be revenue-positive; that is, the Bureau has to cause an amount of new royalty revenue to flow into the Permanent School Fund that exceeds the$900,000 that is appropriated to the program every 2 years by the Legislature. This report summarizes the STARR studies that have been done since the inception of the program and documents that in the 2-year period since the last STARR report, the program is revenue-positive by a factor of 2.7. The term proved oil reserves refers to oil that will be produced using currently deployed technology. On State Lands, proved oil reserves total 270 million barrels (MMbbl), which is only 8 percent of the 3.43 billion barrels (Bbbl) of oil that is projected to remain across these properties at reservoir abandonment (Holtz and Garrett, 1997). Of this 3.43 Bbbl, 1.6 Bbbl is mobile oil that will not be recovered unless advanced geological, geophysical, and engineering technologies are applied to State Lands reservoirs. This potentially recoverable amount (1.6 Bbbl) nearly equals the cumulative production on State Lands.Bureau of Economic Geolog

Development of Active Seimic Vector Wavefield Imaging Technology for Geothermal Applications

This manuscript is the final report for the research project conducted under grant no. DE-FG07-97ID 13573, Development of Active Seismic Vector-Wavefield Imaging Technology for Geothermal Applications, funded by the U.S. Department of Energy, Idaho Operations Office. The report is structured as two parts. The first, and major, portion describes the development and testing of new vector-wavefield seismic sources that can generate shear (S) waves that may be valuable in geothermal exploration and reservoir characterization. The second part describes a 3-D seismic data-processing effort to create images of Rye Patch geothermal reservoir from 3-D sign-bit data recorded over that geothermal prospect. Vector-wavefield illumination of subsurface targets with S-waves is essential for interpreting anisotropic rock systems, particularly systems that are dominated by fractures, as many geothermal reservoirs are. Two new seismic sources were developed and tested in this study that can be used to illuminate geothermal reservoirs with S-waves. The first source was an explosive package that generates a strong, azimuth-oriented, horizontal force vector when deployed in a conventional shot hole. This vector-explosive source has never been available to industry before. The second source was a dipole formed by operating two vertical vibrators in either a force or phase imbalance. Field data are shown that document the strong S-wave modes generated by these sources. Three-dimensional (3-D) seismic technology has had a tremendous economic influence on oil and gas exploration. Thus applications of 3-D seismic techniques may also have an economic impact on geothermal exploration and must be evaluated. One such 3-D seismic evaluation was done as the final phase of this study. Tape copies of a 3-D P-wave seismic survey (not a vector-wavefield survey) recorded in sign-bit format over Rye Patch geothermal field in northwest Nevada were received from Subsurface Exploration Company. These data were reprocessed, and the results of the data-processing research were coordinated with Lawrence Berkeley Laboratory. The sign-bit data recorded at Rye Patch had low signal-to-noise character, and the final migrated data volume had limited interpretation value. Recommendations for improving 3-D seismic data quality in future geothermal surveys are provided.Bureau of Economic Geolog