--> Abstract: Role Of Gas Generation In Fracturing And Compartmentation, by D. F. Payne, K. Tuncay, A. J. Park, J. B. Comer, and P. J. Ortoleva; #90928 (1999).

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PAYNE, DOROTHY F., KAGAN TUNCAY, ANTHONY J. PARK, JOHN B. COMER, and PETER J. ORTOLEVA
Laboratory for Computational Geodynamics, Indiana University, Bloomington, IN

Abstract: Role of Gas Generation in Fracturing and Compartmentation

Gas generation in the Piceance Basin and other basins has been suggested to cause overpressuring and to contribute to fracturing. To evaluate its role, we have simulated these dynamical petroleum systems using the CIRFB reaction-transport-mechanical simulator, which accounts for compaction, fracturing, hydrocarbon generation, and multi-phase flow. As input, the simulator uses burial and thermal histories, stratigraphy, and lithologic properties. Gas speciation and the timing of gas generation are functions of the composition of the sedimentary organic matter, and the reaction rates of thermal maturation processes, as well as the thermal history. Gas saturation is a function of gas solubilities, stresses, and flow path characteristics.

Comparisons of predicted and observed present-day reservoir characteristics show that the simulation generally captures the patterns and scales of observed phenomena. The results suggest: 1) gas generation and resulting gas saturations increase the magnitude of overpressure, although significant overpressure can occur in the absence of gas generation; 2) gas saturation in one unit affects fracturing in other units, thereby contributing to the creation of flow conduits through which gas may migrate; and 3) gas saturation helps sustain overpressure during uplift and erosion, allowing fractures to remain open. Although gas generation is not always a dominant cause of fracturing, it can play an important role in the dynamics and geometry of fracture compartmentation.

AAPG Search and Discovery Article #90928©1999 AAPG Annual Convention, San Antonio, Texas