Hierarchical Workflows for Realistic Facies Modeling: A Case Study

Summary A common problem with 3D modeling workflows is a lack of geological realism which limits the predictive behavior of the model. A key component of geological realism is to represent facies at the appropriate scale in a hierarchical stratigraphic framework. The majority of 3D geological models treat correlation as a rudimentary process to separate the interval of interest into major stratigraphic units, and bodies are distributed using stochastic techniques.Therefore resulting models are inherently disorganized and rarely produce geologically realistic framework which have any predictive power. In the proposed surface-based deterministic approach to facies modeling, every sediment body that occurs within the succession, down to the level of its component facies, is correlated and mapped using its top and base surfaces from a well tops file. This modeling approach results in a number of high-resolution framework models each based on realistic geological concepts. As facies are modeled deterministically, there is no requirement for a detailed geostatistical facies modeling step. Because reservoir properties are closely related to facies type, the property modeling step requires only the application of simple estimation techniques. The proposed workflow has been applied on a case study from a deepwater reservoir in the Gulf of Mexico.