Cathy Farmer has 22 years of experience as an exploration and development geologist for Amoco and BP. She has worked the thrust belt of Montana and Wyoming, Alaska's North Slope, California, the United Arab Emirates (Sharjah), Oman, Jordan, Congo, Angola, Norway, Trinidad, and is currently working Venezuela. The Red Mango discovery in Trinidad is the largest discovery of her career to date. Farmer was the lead exploration geologist for the prospect and followed the discovery into the new field development group to facilitate fast-tracking of the project.

The Red Mango Area—Discovery and Delineation of a 3 Tcf Gas Field
Columbus Basin, Offshore Trinidad

C. L. Farmer¹, E. R. Shaw², and T. K. Burch¹

ABSTRACT
The Columbus Basin of Trinidad is one of the largest emerging gas provinces in the western hemisphere. Major gas fields include Immortelle (1967), Cassia (1983), Mahogany (1994), Flamboyant (1994), Amherstia (1995), Corallita (1996), and Kapok (1997–1998) together totaling over 15 Tcf of recoverable reserves. The most recent Red Mango discovery (2000) adds another 3 TCF 

Recent gas discoveries in Trinidad result from several extensive 3-D seismic surveys which image complex, faulted, stacked reservoirs. Conformance of bright amplitude anomalies to structural closure and “flat spot” detection are key techniques for mapping gas reservoirs. All of the Red Mango reservoirs exhibit bright amplitude anomalies that conform to structure. Flat spots in the thicker horizons correspond to fluid contacts. Excellent seismic resolution of mapped reservoir horizons yielded a 90% pre-drill chance of success for Red Mango.  

The discovery is located in a graben between a major east dipping listric normal fault and a west dipping antithetic normal fault. Strike closure is related to a deep transpressional ridge that predates normal faulting. The anticlinal crest is cross-cut by normal faults. Reservoirs are laterally extensive Pliocene sands deposited in a shallow marine shelf environment. Depths range from 6400 to 13400 feet. Porosities ranging from 20–33% can be predicted predominantly as a function of depth. Petrophysical analysis emphasizes laminated pay and calibrates porosity to cores.  

Trinidadian gas is an economic reality following the 1999 completion of a liquefied natural gas plant. Continued exploration is planned to expand the natural gas resource base.  

¹Trinidad East Business Unit, BP, P. O. Box 3092, Houston, TX 77253; phone: 281-366-3037; E-mail: farmercl@bp.com.

² BP Trinidad, Port of Spain, Trinidad and Tobago.