Kenneth C. Hood1, F. Dennis Walton1
(1) ExxonMobil Exploration Co, Houston, TX
Play assessment is a process in which undiscovered hydrocarbon potential is estimated for geologically defined exploration plays. Our approach incorporates four components: 1) chance that a potential play exists, 2) number of future fields, 3) size distribution of future fields, and 4) hydrocarbon type (oil, gas, and condensate). Geographic Information Systems (GIS) enable more rigorous play assessments while automating key aspects of the process.
Chance that a potential play exists is evaluated using play element maps for reservoir, trap/seal, source/maturation, and migration/timing in a standard GIS format. Individual play elements incorporate multiple geologic maps. GIS spatial overlay capabilities combine play elements into geologic subplays and associate fields and known prospects with subplays. Number of future fields is estimated by applying future success ratio to prospects, including known prospects and prospects postulated in areas with limited mapping. Future success ratio is calibrated to the play element maps. Size of future fields is determined through analysis of historical discovery data or evaluation of undrilled prospects. Interactive query and display capabilities of GIS can be used to select representative subsets of fields and prospects. Hydrocarbon type is determined from historical data or estimated from source properties and migration effects.
The GIS assessment framework provides an unparalleled capability for opportunity analyses. The combination of undiscovered potential with discovered undeveloped and remaining or enhanced recovery possibilities increases the business focus of an evaluation. GIS enables stacked potential in multiple stratigraphically defined plays or within individual closures to be analyzed in three dimensions.
AAPG Search and Discovery Article #90906©2001 AAPG Annual Convention, Denver, Colorado