--> ABSTRACT: Probabilistic Quantitative Estimation of Coexisting Liquid and Gas Phases in a Play, by Pulak K. Ray, John G. Buffington; #91020 (1995).

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Probabilistic Quantitative Estimation of Coexisting Liquid and Gas Phases in a Play

Pulak K. Ray, John G. Buffington

In the last three decades, numerous methods have been proposed for the estimation of oil and gas in a play. The models, whether deterministic or subjective, require the play to be either an oil or a gas play, and estimate the resources as only oil or gas for a play. In basins like the Gulf of Mexico, majority of the plays consist of both oil and gas pools and these pools contain significant amount of solution gas and condensates. In the determination of the economic viability of a play, quantitative estimates of both the liquid and the gas phases is essential.

The Geologic Resource Assessment Program (GRASP) described in this paper is derived from the Petroleum Exploration and Resource Evaluation System (PETRIMES) model of the Canadian Geological Survey. In GRASP, a finite probabilistic pool size distribution for a play is established from a superpopulation of hydrocarbon-occupied-pore-volumes. Based on input oil, gas or mixed pool probabilities, each pool is determined to be an oil, a gas or a mixed pool. The liquid phase (oil and condensates) and the gas phase (non-associated gas and solution gas) volumes are calculated as distributions for each pool and are reported with their associated uncertainties. The play level aggregation of resources utilizes the joint probability of a pool's occurrence and its rank in the pool size distribution. It is possible to formulate an appropriate engineering and development scenario for the economic evaluation of plays because oil and gas distributions are available separately for each pool in this methodology.

AAPG Search and Discovery Article #91020©1995 AAPG Annual Convention, Houston, Texas, May 5-8, 1995