8th Annual 3-D Seismic a Success

Title: 8th Annual 3-D Seismic a Success

Author: by Ron Pritchett, 3-D Seismic Planning Committee 2002

Publication: The Outcrop, April 2002, p. 10-13

The 8th Annual 3-D Seismic Symposium on Feb. 22 was well attended, with 422 participants. The symposium, sponsored by RMAG and the Denver Geophysical Society, showcased abundant links between 3-D seismic technology and value-creation.

“Maps and cross sections are obsolete,” said kickoff-speaker Michael Zeitlin (President and CEO of Magic Earth, a Halliburton company), noting that business-drivers include cycle-time (cycle value), data volume (which is ever-increasing), and the demographics of older workers (who are decreasing in number). The biggest problem for the petroleum industry now, said Zeitlin, is attracting capital away from “dot-coms” and service-based companies to asset-based entities like oil and gas companies.

Enhanced technical tools improve speed and accuracy in the search for real value. For example, Central Processing Unit (CPU) speeds are increasing, leading to more flexibility in interpretation and powerful systems that support human-like pattern recognition. Because the human eye is sensitive to motion and pattern recognition, managers can use “immersion” to take advantage of the brain’s cognitive ability. Managers can use immersive data environments for selecting multiple attributes, for prospect sales, and for achieving partner consensus. “Remember what business you are in–the oil and gas finding business, not the technology business, ” said Zeitlin.

Keynote speaker Bill Keach, Volume and Interpretation Manager for Landmark Graphics illustrated “smart (Denver) systems” that integrate production data, economics, and advanced imagery for rapid decision-making. Noting efficiencies in workflows from the technology, Keach showed how business decisions (Net Present Value comparisons) are made from seismic imagery, comparing costs and potential revenue in a range of drilling choices. Keach showed how one company used “volume interpretation” to strip away unnecessary data in the interpretation volume, for well planning and an efficient combination of producer and injection wells. Decision flexibility for business is the driver for advanced software and imaging techniques applied to 3-D seismic data.

Tom Davis, Professor of Geophysics at Colorado School of Mines, described how multicomponent seismic is used to improve oil recovery in the world’s largest horizontal secondary recovery (carbon-dioxide miscible flood) field, Weyburn Field, Saskatchewan, in the northeastern Williston Basin. “We can monitor the field for reservoir-access,” said Davis, meaning that sweep fluids can be monitored, highlighting those field areas not reached by the flood. Using multicomponent sensors (9C and triaxial vibrators), velocity-changes due to the presence of carbon dioxide allow mapping of fluid-flow “fingering” in space and time. Davis’s case history is an example of how to improve oil-field performance in mature fields.

David Gray, research geophysicist with Veritas (Calgary), showed an analytic technique that has great potential for finding gas in the Rockies – AVAZ (Amplitude vs. Angle and Azimuth) applied to fractured rock volumes. Gray showed the Pinedale Anticline example (Sublette County, Wyoming), a feature with huge gas reserves in place in upper Cretaceous Lance sandstones. Operators are taking advantage of this 3-D seismic application to image the orientation and abundance of fluid-filled fractures via changes in amplitudes from long-offset receivers. Practical applications include calibrating gassy fracture reservoirs to wellbores, gas shows and stimulation results, identifying trend and size of fracture volumes or “swarms,” and designing wells to infill and intersect promising volumes.

Paul Favret, President of Aspect Energy, LLC (Denver), described how his company has achieved market success with “3-D dominance” strategy in a targeted onshore area extending more than 300 miles by 50 miles along along the coast of Texas and Louisiana. Aspect built company value rapidly (40% per year) after committing to a large, competitive acreage position, a big 3-D and digital-log data-base ($130 million), identifying numerous gas prospects resolved to low-risk with careful 3-D processing and interpretation, then drilling more than 200 wildcat wells. With this integrated strategy, Aspect achieved a 63% commercial success rate. Aspect also shot seismic near towns and homes, building a safety record that will be important in public relations for industry geophysical operations. The audience liked Favret’s talk about company success and regional success with 3-D seismic, voting his the Best Presentation of the non-keynote speakers.

Stuart Wright of WesternGeco (Denver) addressed the access problem for geophysical operations of onshore USA. Every 3-D seismic program begins with an effort to obtain formal and informal permission from landowners and from state authorities. Through the years, this process has become more complicated with respect to environmental and cultural regulations. A typical survey requires more than 6 months from start to end of acquisition on federal land. Stuart’s advice: “Plan well in advance.”

Marcus Countiss of Pogo Producing (Houston) showed how extracting higher-frequency data helped resolve thin-bed (20 to 40 ft.) targets leading to new pay and new reserves in a mature offshore Gulf of Mexico field. Countiss found a way to boost high-frequency signal with less increase in noise. Frequency-enhanced images were compared to payzones identified in wells, showing new, unexploited reservoir intervals. Countiss showed an excellent case history for wealth generated by integrating field data, careful high-frequency 3-D seismic processing, and commitment to testing the ideas.

Geoffrey Dorn, Ph.D, Executive Director of the BP Center for Visualization (University of Colorado, Boulder), showed how “immersive visualization” ties with human abilities for pattern recognition in larger data-display habitats. Immersed in a data-display, an interpreter can move “through the data” and gain different perspectives by walking through the fields of view. Dorn described newer, larger visual systems, noting possible advantages for team collaboration, training, prospect evaluation, and improved communications in ongoing (real-time) drilling operations. Dorn extended an invitation to all RIMAG and DGS members to see firsthand the new University of Colorado immersive visualization center at an open house on April 12, 2002.

Tim Berge, Chief Geo-physicist with Forest Oil (Houston), described how 3-D seismic led to identifying an 8.5 TCF gas accumulation in Forest’s concession in offshore Western Cape South Africa (Ihbubesi Field). Berge identified ways to derive “inverse” data from seismic: modeling reservoir porosity from acoustics, fluid types (gas and water) from elastic data, and shapes from neural-network statistics. In addition to pay and reserve estimates, Berge showed how the inverse process led to features fitting a deltaic model for reservoirs styles and gas traps. From inverse conclusions based on 3-D seismic data, Forest has greater confidence for drilling other features across the concession.

Nancy J. House, Ph.D candidate at Colorado School of Mines (Golden), described her experience in defining dimensions of a large (3 TCF) gas target in the Amazon rain forest of Peru on a project for ExxonMobil Exploration Company. Seismic design for the conditions and budget led to acquiring 128 square-kilometers (49.4 square miles) of limited (low fold) 3-D seismic in cross or “X-spread” patterns. The data provided limited aperture and illumination, but defined the structure well enough to resolve fault patterns, drilling targets, and potential reserves. Results from the limited program proved its worth despite the minimum criteria for a 3-D seismic program.

Ed Jenner, Product Development Geophycist with AXIS Geophysics (Denver) described azimuthal analysis of 3-D seismic data. Sonic energy in any survey will usually arrive at detectors in a range of velocities depending on travel direction through anisotropic strata; the velocity range can be modeled with an elliptical function. Identifying the orientation of velocities and correcting for the differences can lead to a number of uses, like a reduced 3-D footprint, better frequency content, more accurate 4-D (3-D and time) maps, fracture analysis, and horizontal well planning.

Bill Lyons, geologist/geophysical interpreter with Chevron/Texaco (Denver) showed how 2D seismic is applied to the developing coalbed methane Drunkards Wash/Buzzards Bench trend in north-central Utah. The trend is now about 65 miles long and 10 miles wide. The gassy coal and carbonaceous interval of the Upper Cretaceous Ferron Formation is found at about 3,000 feet, and reprocessing was guided by comparing amplitudes that relate to facies changes and differences in gas production. With reprocessed lines, coaly intervals and limits were identified, together with faults and folds that influence CBM production “fairways.” Water disposal is generally key to commercial CBM production, and seismic helped identify potential disposal reservoirs. The reprocessed seismic helped explain the gas and water production patterns throughout the trend. More gas and less water will result.

Ed Blott, Ph.D., co-founder and principal of ExplorTech, LLC (Littleton, CO), described a high-resolution case applying 3-D seismic to a long-wall coalmine near Farmington, New Mexico. Exposed coal, sandstones, and faults in the active mine were calibrated to seismic data; resulting maps were useful for mine planning. Seismic data were acquired in a 1.6 square-mile area, and the Fruitland coal interval is about 300 feet in depth across the future mine area. The seismic revealed coal splits and at least one area of potential roof weakness due to faults, information valuable to mine planners.

Participants had positive comments about the new hotel setting in the downtown Denver Hyatt Regency for 2002. The layout favored energized discussions near exhibitors outside the conference hall. This year sponsors were key to event success. Sponsors generously support the Denver Geophysical Society and Rocky Mountain Association of Geologists and the volunteer assembly of key ideas and case histories vitally important to building value in petroleum exploration in the Rockies. The 3-D Seismic Planning Committee extends sincere thanks to the speakers, sponsors, exhibitors, RMAG staff and volunteers, and enthusiastic participants of the 8th Annual Symposium.

 

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