Reducing Dry Hole Risk with 3D Seismic Data

Marc A. Lawrence, Hugh T. Logue, Don A. Grimm

New discoveries and wildcat well success rates have historically increased following the commercial application of significant new exploration technology. This was evidenced by the introduction of seismic reflection techniques in the 1930's, digital CDP seismic methods in the 1960's and now 3D seismic. Success rates examined in the Gulf of Mexico offshore Louisiana since 1938 indicate the wildcat success rate has averaged approximately 22%. The wildcat success rate for 1994 is approaching 44%. The present success rate is double the historical average rate despite the new drilling targets being areally smaller and having been overlooked all these years. This is attributed to 3D seismic data and its increasing availability at lower costs. However, during the same periods th success rate of field wells only increased from 73% to 76%. Despite the early reputation for being a development tool, 3D seismic seems to be having a stronger impact on exploration.

Operators exploring shallow waters offshore Louisiana were surveyed to determine which wildcat prospects were based on 2D or 3D seismic and the corresponding success rates. Dry holes based on 2D data are re-examined on 3D data and brief case histories illustrate two situations - dry holes where 3D reveals no evident prospect and dry holes where the prospect was simply missed. New 3D does not ensure 100% success and dry holes based on 3D data are also presented. The increased wildcat success rate has produced new major discoveries; several are presented.

AAPG Search and Discovery Article #91020©1995 AAPG Annual Convention, Houston, Texas, May 5-8, 1995