FRACTURE CONNECTIVITY AND RESERVOIR CHARACTERIZATION OF THE AUSTIN CHALK
Nine oil and gas fields were grouped into low, moderate, and high reservoir communication, based on correlation values of produced water vs. hydrocarbons. Most fields in the historic trend (e.g., Giddings) display low correlation values, potentially indicating that the reservoirs are poorly-connected and thus continuous. Continuous reservoirs contain dominantly vertical, strike-parallel fractures due to local structures or movement along nearby faults, which lead to little reservoir connectivity. Masters Creek, Luling-Branyon, and Buchanan fields, however, display very high correlation values. These fields are probably conventional, because the reservoirs are well-connected and likely have oil-water contacts. In hybrid reservoirs, connected fractures are localized, and the reservoir may act as either continuous or conventional. Much of the Austin Chalk trend probably contains hybrid reservoirs, where a single fracture system type does not dominate across an entire field. In hybrid reservoirs, fracture studies would be beneficial in determining whether to drill vertical or horizontal wells. Additional research is necessary to better characterize hybrid reservoirs in the Austin Chalk and to distinguish between conventional and continuous accumulations.