Abstract: An Assessment of Undiscovered Hydrocarbon Resources of the Offshore U.S.

Pulak K. Ray

Any assessment methodology for basinwide petroleum resources estimation consists of two basic components: defining and evaluating the geologic potential of plays--a geologic formation or group of formations having commonality in terms of source-reservoir-trap controls, and probabilistic statistical modeling for the estimation of expected volume. The success of the second component is dependent upon the proper geologic modeling of the plays. The Minerals Management Service (MMS) is in the process of evaluating the petroleum potential of the offshore U.S. The results will be published at the end of 1995.

For the purpose of the 1995 assessment, the plays have been grouped into three types: Established Plays, Frontier Plays, and Conceptual Plays, based on the geological and geophysical data availability for a play. Over 74 oil and gas plays in Alaska, more than 64 plays in the Pacific, 16 plays in the Atlantic, and 7 plays in the Eastern Gulf of Mexico have been tentatively identified and evaluated in terms of their source, timing, and trapping potential. The major plays are highlighted in this paper.

The assessment of technically recoverable undiscovered hydrocarbon volumes is being done with a statistical model that is based on a super-population concept which assumes that pools in a play are derived from an infinite population with a continuous probability distribution. Based on the probability distribution of input reservoir variables, number of prospects and an average prospect risk, the pool size distributions in a play are established. The resource volume aggregation for plays is done through a Monte Carlo method, having the interplay dependency evaluated as an additional risk or through other statistical methods. Unlike earlier National Assessments, the results will be reported as a full range of resource values for plays in graphical form and ranked pool size distribution howing the position of discovered pools (including reserves growth). The play endowment will be reported as price supply curves. Pertinent input data will be made available, so that the users can make their own interpretation based on their favored model.

AAPG Search and Discovery Article #90986©1994 AAPG Annual Convention, Denver, Colorado, June 12-15, 1994