Print this pageSequence Stratigraphic Correlation and Reservoir Analysis of the Dakota Formation, San Juan Basin, Northwestern New Mexico
KOHLES, KEVIN M., CHARLES F. HEAD, and PAUL M. BASINSKI
In the San Juan Basin, the lower Cretaceous Dakota Formation consists of an intertonguing sequence of marine and non-marine sediments deposited during several transgressive/regressive cycles. The sandstone members of this sequence, particularly those of marine origin, form important San Juan gas reservoirs with estimated ultimate recoveries of over 6 TCF. Deciphering the complex sequence stratigraphic relationships and facies architecture of the Dakota interval across the basin provides an essential key to unlocking untapped and underdeveloped reserves.
A comprehensive subsurface database was constructed from geophysical logs for approximately 3,000 wells which penetrate the Dakota interval. Tops for the sandstone members of the Dakota, in descending order, Two Wells, Paguate, Cubero, Oak Canyon, Encinal Canyon, and Burro Canyon, were correlated by tying to a tight loop-tied cross-section network based on sequence stratigraphy.
The subsurface database was used to construct interval isopach maps for each Dakota sand member. In addition, the tops were merged with digital log data and engineering data to quantify reservoir potential and to evaluate completion efficiency for each zone. Depositional environments were derived from all available Dakota core and also integrated.
Comparison of the resulting maps with Dakota production data provides considerable insight into the geometry of producing trends, and delineates prospective areas for drilling and recompletion work.