Erendi, Alex¹, Joao V. A. Keller²
(1) ChevronTexaco, San Ramon, CA
(2) Chevron Petroleum Technology Company, San Ramon, CA

ABSTRACT: Leveraging Capabilities of Gocad for Assessing Hydrocarbon Migration

This talk presents how Gocad is used for secondary hydrocarbon migration assessment. Similar tools exist and are commonly referred to as 2.5D models. However, having this functionality present in environments like Gocad, which is available to most earth scientists, will allow them to run quick what-if scenarios at such an early stage as seismic interpretation, before full 3D basin models are run. Moreover, different velocity models for time-depth conversion will result in different realizations of the migration pathways and will allow us to assign probabilities to traps and fetch areas. The added information of migration pathways will also aid us while using geostatistical methods to populate oil fingerprinting information etc.
In this model, buoyancy is the main driving force by which hydrocarbons migrate through a carrier bed to a trap. The Gocad surface objects are well suited for such calculations where they can carry additional information such as capillary forces that resist migration and sealing capacity of the carrying horizon which may cause the hydrocarbons to exit vertically. The horizon selected for the source rock will have its temperature history estimated by bottom hole temperature measurements. Custom kinetics can be delivered by XML format to the maturation engine.
One limitation is the lack of a pressure solver for estimating overpressures and the impact they may have on horizontal flow. It also does not currently provide a structural history of the basin. Although simple back-stripping is useful the addition of restoration directly from 3D seismic will make Gocad even more complete.

AAPG Search and Discovery Article #90026©2004 AAPG Annual Meeting, Dallas, Texas, April 18-21, 2004.