Giddings Wells Produce Both Oil and Natural Gas GIDDINGS OIL AND GAS FIELD, Daryl Mazzanti, Anadarko Petroleum Company One of the major's cumulative production from the Central Texas Giddings field is 461 MMboe (barrels of oil equivalent) out of a total field production of 1,279 MMboe. The major's 461 MMboe equals 36% of the field total. This 461 MMboe comprises 200 MMbbl oil and 1.6 Tcf natural gas ( 44% oil; 56% natural gas ). The company's Central Texas production is 168 MMcfd of natural gas, 16,738 bopd and 27,500 bwpd. Total well count is 1,210 (810 oil and 400 natural gas wells). Giddings field, the largest field in a 10- to 20-mile-wide trend (figs. 1, 16), extends from Mexico through Central Texas and into northwest Louisiana. The primary producing reservoir is the Austin Chalk (Upper Cretaceous, 85-90 million years old), with secondary production from the Taylor (Upper Cretaceous) and deeper Buda and Georgetown Formations (Lower Cretaceous, 98-105 million years old). Today the Austin Chalk outcrops at the surface along a belt that runs from Del Rio on the Texas-Mexico border, northeast through San Antonio, then north through Austin, Waco, and Dallas. The Chalk then dips gently (2°) to the southeast into the subsurface. In Giddings field, the Austin Chalk reservoir ranges in burial from 5,500 ft TVD in Milam County to over 15,000 ft TVD in Austin County. The Austin Chalk in Giddings field, ranging from 150 to 750 ft in thickness, consists of interbedded chalk and marl (limestone with shale). It was deposited in a low-energy, openmarine setting, where very fine calcium carbonate debris could settle slowly to the seafloor. Most hydrocarbon production in the Austin Chalk comes from an extensive network of fractures. Localization of these fracture networks is controlled by bending of the formation in areas with a gentle southeast dip. Clean chalk beds fracture when bent, whereas the marl/shale beds will not. Local disturbance by salt domes also influences fracture development. Top of Page