Alternate Completion Methods Lead to Success in Tight Upper Atoka Sandstones, Black Ranch Area, Hood County, Texas: ABSTRACT

Abstract

Part of the Pennsylvanian System in northern Hood and southern Parker Counties, Texas, is represented by siliciclastic sediments assigned to the Atoka Series. These sandstones, deposited in a fluvial deltaic environment, produce gas and associated condensate in several fields with recoverable reserves ranging from 200 mmcf to 1.0 bcf/well. Stratigraphic and structural cross sections within the study area allow correlation of the more persistent sand bodies and are useful in delineating prospective areas for drilling. Although five or six depositional cycles or units of sand are distinguished in the depth range of 2,000-5,000 ft (610-1,524 m), the uppermost (A-1) sandstones render the most profitable production to date and have been studied in greatest detail. Conventional cores of the A-1 sandstones have been taken in two wells and examined as slabbed core, thin sections, and by scanning electron microscopy. Porosity and permeability data from conventional core analyses were compared to electric log responses across the sandstone intervals. Economically successful completions in this area require hydraulic fracturing. A fracturing technique has been developed that increased deliverability by an average of more than eightfold on 12 field wells. This stimulation procedure differs substantially from conventional techniques applied in the area.