Accurate Saturation Modelling on a 3D Structurally Complex Reservoir

Reserve estimates are often inaccurate as a result of poor representation of the reservoir structure (by means of a 3D grid), that in combination with the use of traditional saturation calculation methods, lead to wrong hydrocarbon volumes, poor investment decisions, and inefficient field development.

Traditionally a reservoir model is represented with a 3D grid, in a complex setting such as fault intersections and stacked reservoirs. A pillar grid is often used, which has limitations to represent this complexity. Further, the hydrocarbon saturations are then derived on a cell by cell basis on that 3D grid using simple averaging techniques of saturation height functions. The poor structure representation on the pillar grid in addition to the simplistic averaging methods lead to inaccuracies of the in place volumes especially where a prominent transition zone is present.

This paper presents a novel approach to accurately model the reservoir structure using a patented gridding approach in combination with advanced saturation averaging methods. This approach gives accurate hydrocarbon saturations irrespective of the size or complexity of the 3D grid.