Stratigraphy, Structure, and Reservoir Characteristics
of the Block 889 Area, Offshore Texas

Ramón Treviño

The State of Texas Advanced Resource Recovery (STARR) team recently completed a detailed studied of the State Lease Block 889 area, offshore Mustang Island, Texas.  The study was conducted in keeping with STARR’s mission to increase royalty income to the Permanent School Fund through the drilling of profitable wells on State Lands. The data used in the study includes a ten-square-mile 3-D seismic survey provided by Sabco Oil and Gas Corporation, which currently holds the lease to Block 889. The data set also includes 27 wells in and around the area of seismic coverage, as well as engineer data from the productive wells.

  The area of interest is bounded by two growth faults. Hydrocarbon production (gas and condensate) is from the crest of an asymmetrical anticline, which is highly compartmentalized by synthetic and antithetic faults. The full stratigraphic section in the area of interest consists of parts of a second-order sequence set in the Upper Oligocene and Lower Miocene. This sequence set is composed of nine third-order sequences. The major flooding surface of the second-order sequence is in the middle of the Anáhuac Formation. Most of the production is from third- and fourth-order lowstand systems tract sands within the second-order lowstand, which, along with the second-order transgressive systems tract units, comprise the lithostratigraphic unit designated the Frío Formation. There has also been some production from a fourth-order incised valley stand within the second-order transgressive systems tract. Our study confirms one previous Sabco lead (as a prospect) and identifies several other prospects.  These include both untested compartments and compartments that are not fully drained within the Block 889 lease.