Suitability of the Wolfcamp Series as a High Volume Disposal Zone in the Palo Duro Basin

R. Gibson¹ and S. Ritter^2
1Xcel Energy, Amarillo, TX ([email protected])
²G.S.M., Inc., Amarillo, TX

The PermianWolfcamp Series has served as an oil and gas producing reservoir as well as a disposal zone for several low capacity (<15,000 barrels/day) injection wells in the Palo Duro Basin. Recently, changes in wastewater disposal practices at a power plant facility near Amarillo, Texas necessitated a high-volume disposal option. Historically, cooling tower blowdown from the two power plants, which generate approximately 1,616 megawatts, was utilized as irrigation water. A shift away from land application constituted the need for approximately 36 barrels/minute (1,500 gallons/min.) of injection well capacity. The Brown Dolomite of the Wolfcamp Series was evaluated to serve the requirements of this electric utility.

Preliminary investigation of injection zone suitability originated with core data and openhole logs from an on-site abandoned gas storage test well. The temporarily abandoned test well had been drilled into the Lower Clearfork, with continuous 2 1/2 in. core obtained from 1,403 to 3,263 ft in the San Andres, Glorieta, and Clearfork Formations. This test well was re-entered and deepened to 5,140 ft. Openhole logs and injectivity testing indicated that the porosity, permeability, and thickness of the reservoir made for a likely candidate for high volume wastewater disposal. Additionally, the targeted Brown Dolomite was known to have a large aerial extent covering several counties, further enhancing the suitability of large capacity injection. After a two-year Texas Natural Resource Conservation Commission (TNRCC) permitting process, the Class I well was drilled to a total depth of 5,185 ft. Four-inch cores were taken in the Tubb Formation (confining interval), the Panhandle Lime Formation, and the Wolfcamp interval. Openhole logs and drill stem tests indicated receptive injection intervals in the Panhandle Lime (Wichita), Brown Dolomite andWolfcamp Limestones. Actual injection testing accommodated rates of approximately 35 barrels/min. (1500 gal/ min) or volume in excess of 40,000 barrels per day.

AAPG Search and Discovery Article #90903©2001 AAPG Mid-Continent Meeting, Amarillo, Texas