The Role of Petroleum Systems Modeling in Petroleum Resource Assessments

Abstract

Petroleum resource assessments are used to quantify discovered and undiscovered petroleum that is technically and economically recoverable within a certain time frame. It is understood that what is technically recoverable can change significantly due to new technical developments, and that what is economically recoverable can also change due to production costs and/or market prices. Rapid changes in markets are also possible, due for example to the development of new resource types and plays such as biogenic gas, shale gas/oil, coal-bed methane and gas hydrates. Unlike petroleum reserves which must be discovered by drilling and are then assessed according to generally accepted standards (e.g. SPE), petroleum resources are less well defined. Regardless of whether the assessments are performed by National Hydrocarbon Agencies or Geological Surveys, or by E&P companies and consultants, all resource assessments show deficiencies. Not only are they not based on a rigorously applied methodology, but they are mostly proprietary and therefore confidential, which is often only used to conceal the fact that the assessments are arbitrary and that they do not directly take the underlying geoscience data into account. However, their main deficiency is the lack of auditability, i.e. that exact information is not available on which data and methodologies have been used to perform the assessment. While it is generally accepted that petroleum systems modeling provides essential input for resource assessments, it cannot support full resource assessment workflows on its own. Missing elements include assessments of production-related factors to determine recoverable resources, and combined deterministic and statistical methods which both play an essential role. We present an approach that provides a rigorous connection from the underlying geoscience data that is used for the assessment, to the petroleum systems modeling that is essential to determine process-based factors, and then to the statistical analysis which is essential due to the uncertainties in the data and which provides the final assessment results. The workflow will be demonstrated for an assessment of unconventional petroleum resources. While resource assessments will continue to have large uncertainties, the proposed approach will help to make the process and the resulting assessments more efficient, transparent and auditable.

AAPG Datapages/Search and Discovery Article #90189 © 2014 AAPG Annual Convention and Exhibition, Houston, Texas, USA, April 6–9, 2014