ABSTRACT

High Island 140 Field was discovered in1958 by the Standard Oil Company of Texas' Federal Block 140-L #1 well. The field has been producing since 1967, and to date has produced in excess of 210 billion cubic feet (Bcf) of gas and 1,167,000 stock tank barrels (Stb) of oil. The primary producing horizons are lower Miocene Robulus L (M-20 Sand) and Robulus M (M-40 Sand) in age. Pennzoil acquired a 3-D seismic survey over the field in 1993.

High Island 140 Field is a large domal feature associated with a major northwest-southeast down-to-the-south fault system. This fault system divides the field into upthrown and downthrown reservoirs and is responsible for some growth between the M-20 and M-40 producing intervals. The M-20 through M-40 interval comprises interbedded thick prodelta mudstones and sandy progradational sequences deposited near the margin of a large delta complex. A series of smaller down-to-the-southeast faults further subdivides the field into a number of separate fault blocks.

Interpretation of the 3-D data volume showed that the fault pattern was more complex than previously mapped using subsurface data and the available 2-D seismic data. The 3-D data significantly reduced risk by providing the ability to accurately map smaller fault blocks and targets. To date, two successful wells have been drilled based on the 3-D interpretation giving new life to this declining field. On the basis of geological subsurface data and 2-D seismic, it is doubtful that these results would have been obtained.