A geological model of a typical Austin Chalk fracture system has been constructed. The geological model is composed of a major and at least one minor fracture system dividing the rock matrix into small sized blocks. Type curves representing the expected producing characteristics for a reservoir possessing at least two different permeability fracture systems and a matrix block system have been developed. These curves represent a combination of flow through a major fracture system with infinite conductivity, linear flow through a set of lesser, subsidiary micro-fractures, and flow from the matrix block system. The mathematical model replicating these expected conditions and providing the foundation for the type curves is discussed.

A field case study of an Austin Chalk lease shows the utility of the new, dual fracture-matrix concept to determine the variation of productive capacity and the degree of connectivity of offsetting wells. The six wells penetrating the 640 acre lease appear to have encountered four different producing systems.

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