Using 3-D Property Models to Optimize Infill Drilling in from East Texas Tight Gas Play
The Lower Cretaceous Travis Peak Formation is a tight gas sandstone reservoir that occurs in Carthage field at depths between 6000ft and 10000ft. The Travis Peak Formation in Carthage field (study area) largely consists of fluvial continental to coastal siliciclastic facies. It is a micro Darcy reservoir with low porosities (3 - 18%); the product of multiple regimes of diagenesis. Since discovery in 1968, it’s been through periods of intense development; corresponding to drilling densities of 640, 320, 160 and now about 80 acres (some operators are even drilling at denser well spacing). The development paradigm has mainly been; drill wells (vertical), do hydraulic fracturing across multiple intervals then hookup for production but not all wells have been a commercial success.
This study area (a part of Carthage field) contains about 250 wells (all have log data). The area lacks 3D seismic coverage so well log and performance-based data was used to model the 3D distribution of rock properties using geostatistical methods. Sequential Indicator Simulation and Sequential Gaussian Simulation methods were used in building 3D property models (porosity and pay) which were then used to predict fairway continuity (a basis for quasi ‘sweet spot’ delineation). The modeling of pay (a composite variable) was designed to discount the impact of the pervasive and ‘difficult to predict’ diagenesis observed in Travis Peak Formation Sands. Comparisons of pseudo (pre drill) to actual (post drill) porosity and pay logs along with interval ‘predicted pay’ thicknesses (gross and trended) were all used to validate ‘best fits’ from a number of equiprobable realizations.
The results show that this method can be used to predict pay connectivity especially in facies that are relatively extensive (laterally) or connected (laterally or stacked) and is useful as an additional tool in planning future Travis Peak infill development.
AAPG Search and Discovery Article #90090©2009 AAPG Annual Convention and Exhibition, Denver, Colorado, June 7-10, 2009