Oyvind Sylta1, Wenche Krokstad1
(1) Sintef Petroleum Research, Trondheim, Norway
ABSTRACT: Prediction of Oil and Gas Column Heights in Prospects Using Probabilistic Basin Modelling Methods
Source and reservoir properties are often poorly constrained in frontier basins. Geologic analogoues may be used to create source and reservoir rock models in these areas with very sparse well data coverage. Exploration will frequently need to account for two or more rock facies models (interpretations). This presentation outlines a methodology for assessing the consequences of two or more source and/or reservoir models on hydrocarbon phase distributions in prospects and leads.
Each reservoir and source rock scenario is represented by computerised maps (grids) of thicknesses, porosities etc. The uncertainties of each scenario is described as probabilistic properties, e.g. the reservoir thickness may be represented by a gaussian distribution with the mean described as a map (grid) and with a standard deviation of 50m. A Monte Carlo simulation of hydrocarbon generation and migration is carried out, and the resulting probabilities of oil and gas in prospects and leads are compiled. The results can be plotted as maps of most likely oil and gas column heights. Uncertainty maps can also be plotted. These maps can be used to rank the optimum drilling locations. The ranking criteria may use weighting of large oil columns and larger uncertainties against each other. The risk of each planned well location can be estimated.
As (more) wells are drilled in the basin, the best match simulations are used to further refine the predictions as well as creating a posteriori source and reservoir rock models.
AAPG Search and Discovery Article #90906©2001 AAPG Annual Convention, Denver, Colorado