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Abstract: A Hybrid Streamtube Simulator Using A Semianalytical Method

BAEK, MUNSEOK, Korea Gas Corp.

A hybrid streamtube simulator is developed using a semianalytical method. This hybrid simulator applies to steady-state, incompressible, two-phase, field-scale problems, where the effects of gravity can be neglected. The underlying idea of the hybrid streamtube method is to decouple a large 3-D problem into multiple cross-sections along areal streamtube bundles. Using the calculations of cross-sections, the areal recovery is computed.This method is based on the assumption that the effects of a changing mobility field can be accounted for by using fixed streamtube geometries with updated flowrates. In each cross-section the semi-analytical method is applied, which uses the single-phase pressure distribution and the 1-D Buckley-Leverett solution along the streamtube. The distribution of pore volume along each streamtube is calculated by using the Time-Of-Flight method. This information and the pressure solution are used to calculate oil recovery by the semi-analytical method.Unlike previous hybrid methods, the simulator developed uses a streamtube method in each cross-section. Due to the simple calculations and small arrays the method developed shows a very fast calculation speed compared to a conventional finite difference simulator(ECLIPSE), a streamline simulator (3DSL) and another streamtube simulator (STUB3D). The simulator developed shows good agreement with other methods for an end-point mobility ratio range from 1 to 50. The hybrid streamtube method(HST) was faster than the updated streamline method(3DSL) by factors of 1 to 3 orders of magnitude, and the conventional finite difference method(ECLIPSE) by factors of more than 3 orders of magnitude.

AAPG Search and Discovery Article #90911©2000 AAPG Pacific Section and Western Region Society of Petroleum Engineers, Long Beach, California