Geologic Expansion of the Eagle Ford

Abstract

Approaching 10,000 total horizontal wells, the Eagle Ford play in South Texas is one of the most mature unconventional fields in the US. However, recent developments have the Eagle Ford geologic targets growing both spatially and vertically, with identification of the viable "Easter Eagle Ford" (or Eaglebine), multi-lateral development of the Upper and Lower Eagle Ford and vertical-well exploitation of the underlying Buda limestone. Each of these expansions of the traditional Eagle Ford play illustrate an expanding understanding of the geology and fluid characteristics of the rocks underlying the Austin Chalk. Mapping of fluid characteristics in the form of oil API gravity or gas-oil-ratio (GOR) have consistently delineated the Eagle Ford "sweetspots" for optimal production of oil, condensate, natural gas liquids and dry gas. Extension of this technique beyond the San Marcos Arch to Burleson and Brazos Counties exhibits similar characteristics to Karnes, Gonzales and other liquids-rich parts of the play. Early well results are promising and provide economic opportunities that increase the overall Eagle Ford extents. Heavy well coverage is providing well log data that are also enhancing understanding of the distinct character and thickness of the Upper and Lower Eagle Ford. Regional mapping of geologic tops, coupled with detailed directional survey data and validated reported reservoir data provides insights into targeted zones and corresponding production. Sufficient thickness in both the Upper and Lower Eagle Ford is also providing opportunities for staggered multi-lateral development of both formations, in certain areas. Improved understanding of the Upper and Lower Eagle Ford, coupled with older and recent deeper vertical wells, is identifying targeted development opportunities for the Buda limestone. Impressive initial liquids production is being reported with vertical wells with relatively high-intensity completions. Against this backdrop of improved geologic understanding of the Austin/Eagle Ford/Buda/Eaglebine is a method increasing of the size of hydraulic fractures. With a historic average of 4 million pounds of sand per well, recent completions are ranging two to more than four times this value, with impressive geologic and fluid flow responses. Time will tell with respect to decline rates and sustainability, but indications are that the geology and fluid characteristics of the "old" and "new" Eagle Ford are amenable to high-intensity completions.

AAPG Datapages/Search and Discovery Article #90216 ©2015 AAPG Annual Convention and Exhibition, Denver, CO., May 31 - June 3, 2015