The U.S. on-shore Gulf Coast Basin is one of the most prolific oil & gas producing provinces in North America with many fields having already been exploited via secondary or tertiary enhanced recovery methods. Our focus is to build a comprehensive geology model suitable for assessing remaining hydrocarbon resources. It includes a 3D geologic model for the entire stratigraphic section across 162,379 SqMi (420,561 SqKm), extending from the Mexico/Texas border to the Florida Panhandle. This 3D model permits the isolation of rock volumes for individual producing formations. Finally, OOIP and OGIP (Original In-Place Oil and Gas) volumes were contrasted against historical production volumes to determine remaining resources.
Three years in the making, the study involves over half a million historical well records containing production data, interpreted formation tops, digital logs and various test data. The main objective was to build a geologically consistent 3D model from economic basement to the ground surface across the entire study area. The 3D geological model is used in identification of hydrocarbon productive formations which are classified as either, Continuous Shale or, Non-Continuous Strati-Structural play types.
The Continuous Shale Play is defined as a self-sourcing formation or reservoir that is filled during expulsion. It is also referred to as a source-rock-reservoir-system implying that part of the generated hydrocarbons remains trapped within the source rock itself with minimal or no migration. The Non-Continuous Strati-Structural play is defined as a non-self-sourced reservoir, disconnected from a mature source rock, filled during secondary and tertiary migration, and spatially confined by a conventional trap mechanism.
A total of 92 formations were mapped, of which, 89 were found to be hydrocarbon productive, and are classified as 15 Continuous Shale and 74 Non-Continuous Strati-Structural play types. For each play, OOIP (Original Oil in Place) and OGIP (Original Gas in Place) resources were estimated using mass balance volumetric methods. By subtracting out historical produced volumes and applying a conservative realistic RF (Recovery Factor) to the in-place resources, Technically Recoverable Remaining Resources are determined for each play. A roll up of all the 89 plays indicates total Technically Recoverable Resources in excess of 40 billion barrels of oil and 300 trillion cubic feet of gas in the study area.