Modeling commingled reservoirs with pressure-dependent properties and unequal initial pressure in different layers

This paper introduces a new approach to model the performance of commingled reservoirs with pressure dependent fluid properties in each layer. With this approach, reservoir engineers can readily modify an analytical model for slightly compressible liquids to model commingled gas systems. We used a numerical simulator to verify this approach. Based on the analytical model and this approach, we developed an analytical computer simulator which reservoir engineers can use to model the performance of commingled reservoirs with unequal initial pressures in different layers and which allows each layer to be homogeneous or dual porosity, hydraulically fractured or have radial flow (with skin), and to be finite or infinite in extent. This analytical simulator can be used to predict future performance, match past performance, and to assist in the analysis of pressure transient tests. A major advantage of this simulator is that it requires far less computer time than conventional finite-difference simulators to solve the same problem. Using the new analytical simulator, we can model several important reservoir situations with different inner and outer boundary conditions and reservoir rock types. Most importantly, in this paper we present a new technique to model pressure buildup performance of a commingled reservoir following constant pressure production.

Modeling commingled reservoirs with pressure-dependent properties and unequal initial pressure in different layers Conference Paper