Seismic Exploration in the Dalhart Basin, Western Texas Panhandle
WALKER, P. DAVID, Society of Exploration Geophysicists, Amarillo, TX
The Dalhart basin, the Texas panhandle's "other" basin if one does not count the Palo Duro basin and recognizes the prolific Anadarko, is accountable for over 16 million bbl of oil production since the 1954 discovery of Rehm field by Standard Oil of Texas in Hartley County, Texas. Since that time, the basin has been the target of extensive exploration plays performed by such entities as Shell, Exxon, and Baker and Taylor Drilling Company, which notably has been the most successful company having produced nearly 9 million bbl of the total to date. The primary objective in all seismic exploration has been Pennsylvanian-Missourian granite washes, one of several sequences of wash deposition that occurred in the basin.
These granite washes, sourced from the Bravo dome of the extreme western Texas panhandle and eastern New Mexico, have been distributed into the Dalhart basin in both deltaic and longshore patterns across and along carbonate shelf margins of Missourian-Virgilian age. In some cases, this carbonate bank has been productive and should be considered as prospective in any exploration program in the basin. More recently, the potential for production from Permian-Wolfcampian granite exists in more of a stratigraphic play adjacent to Bravo dome. Such a play is exemplified by encouraging oil shows and drill-stem tests in this interval. In most cases, the application of seismic in the Dalhart basin appears to reflect the concrete data, which subsurface geology represents.
Generally, it has been the use of seismic to delineate structure that has prompted the majority of penetrations throughout the Dalhart basin. This has resulted in the acquisition of an estimated 6000+ mi of seismic data in the basin to date. Whereas anomalies may be uncovered in most seismic surveys, a careful coupling of subsurface stratigraphic information to determine fairways of clean Missourian or Wolfcampian granite washes, along with detailed, high-quality seismic grips is a necessity. Such high-quality data require careful acquisition and processing. Field operations should seek to minimize data skips as well as maintaining close group intervals and the recording of far offsets. Processing should employ comprehensive refraction static corrections to minimize surface distortion effects on the data in light of mapping critical structural closures. Careful migration of seismic data is paramount and proper display and scaling parameters must be applied to enable the interpreter to verify these subtle closures and recognize stratigraphic changes with confidence. The combination of these factors hopefully would increase success significantly and thus may help the Dalhart basin become somewhat less of a frontier area.
AAPG Search and Discovery Article #91011©1991 AAPG Southwest Section Meeting, Abilene, Texas, February 9-12, 1991 (2009)