BEG Friday Seminar Series: Dr. Osareni Ogiesoba, BEG
||December 7, 2012 at 9:00 am
||December 7, 2012 at 10:00 am|
| ||Location:||J.J. Pickle Research Campus, Bldg. 130, room #1.202|
Video Streaming: Not available for this seminar
SEISMIC INVERSION FOR SHALE GAS/OIL IN THE AUSTIN CHALK AND EAGLE FORD SHALE IN A SUBMARINE VOLCANIC TERRAIN, MAVERICK BASIN, SOUTH TEXAS
Osareni (Chris) Ogiesoba
Bureau of Economic Geology (STARR)
Hydrocarbon exploration in the Austin Chalk began in 1916 with the discovery of hydrocarbon traps located in and around volcanic centers (serpentine plugs) encased by Austin Chalk. Owing to the occurrence of hydrocarbons around these serpentine plugs, exploration efforts were focused on identifying surface as well as subsurface locations of volcanic centers within the Austin Chalk. However, with the realization of the existence of fault-related, fractured reservoirs within the Austin Chalk in the 1980’s, fault zones became the main target of exploration—and the drilling spree started. To date, more than 2,000 horizontal wells have been drilled within the Austin Chalk.
Although some of these wells were successful, many others failed either because they did not penetrate hydrocarbon sweet spots, or hydrocarbon-source-rock distribution within and outside the Austin Chalk was unknown. In this project, seismic inversion studies was conducted by combining seismic data with wireline logs to determine sweet spots and predict resistivity distribution (using the deep-induction log) within the Austin Chalk and Eagle Ford Shale in South Texas.
Results show that >90% of productive zones are in the lower part of the Austin Chalk and are associated with Eagle Ford vertical-subvertical en echelon faults, suggesting hydrocarbon migration from the Eagle Ford Shale. Furthermore, the lower Austin Chalk and upper Eagle Ford Shale together appear to constitute a continuous (unconventional) hydrocarbon play.
In addition, local accumulations within the Austin Chalk may be related to Austin TOC-rich zones or migration from the Eagle Ford through fractures. The quality-factor attribute (Q) can serve as a tool for detecting high-water saturated zones. Although Q was not selected as one of the primary attributes for predicting resistivity, it nevertheless can serve as a good reconnaissance tool for predicting resistivity and brittle zones. Wells that have high water production do so because the water-bearing middle Austin Chalk that sits on the downthrown side of Eagle Ford regional faults constitutes a large section of the horizontal well, as evidenced by the Q attribute. Finally, based on the seismic stratigraphic positions of identified submarine volcanic mounds within the Austin Chalk, volcanic activity probably continued up middle Campanian time.