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ABSTRACT: West Chalkley Field: A Significant Discovery in a Mature Area

J. R. Bedingfield, Forrest E. Hand, Richard J. Powell

In August 1989 the Exxon #1 Sweet Lake FARO 21.9 MMCF/D with 384 BC/D ushered in a significant discovery in the Oligocene Frio Miogyp sand of South Louisiana. The West Chalkley discovery is located within the Miogyp Embayment of South Louisiana, 20 mi west of nearest equivalent production at South Lake Arthur field. The trap is a buried lowside rollover anticline downthrown to the embayment fault. The Miogyp sequence is an expanded lowstand deltaic system with porosities averaging 17-20% and permeabilities up to several hundred millidarcies. The test was from a 66 ft interval at the base of this deltaic system in an overall pay section between 14,000 ft and 14,860 ft. Development drilling in West Chalkley field began in late 1989.

The Miogyp Embayment exemplifies the nature of exploration in a mature basin where new, deeper-resolution seismic is imaging high-potential buried structures. West Chalkley field is located beneath the 400 BCFG Chalkley field discovered in 1938, where five tests had unsuccessfully attempted to explore deeper targets. Until recently, seismic data in the West Chalkley field area was not of high enough resolution to adequately image structures at the depths drilled by the #1 Sweet Lake.

Two reasons the Miogyp trend has become very active over the last several years are the growing realization of world-class reserves at South Lake Arthur field and the ability to structurally image this relatively unexplored trend via new and improved seismic data. West Chalkley is the first discovery resulting from this increased level of activity and exemplifies the potential for future discoveries.

AAPG Search and Discovery Article #90999©1990 GCAGS and Gulf Coast Section SEPM Meeting, Lafayette, Louisiana, October 17-19, 1990