Abstract:

A double media mathematical model is established according to the feature of the Xinjiang carboniferous volcanic rock gas reservoir; the cross flow among the matrix pore-fracture-borehole is studied by means of the numerical simulation; and how the interporosity flow coefficient λ influenced on the rate maintenance capability is analyzed quantitatively. Results indicate that there are two periods in the process of cross flow: transition period and stabilization period. In the transition period, the cross flow amount is smaller than the bottom hole inflow, and the bottom hole pressure drops quickly; in the stabilization period, the cross flow amount is equivalent to the bottom hole inflow, and the bottom hole pressure flattens out. The time needed from transition period to stabilization period is depended on the interporosity flow coefficient ?; the greater the ? , the shorter the time is need. If ? >10-7, interporosity flow has little influence on gas well production. If ? <10-8, stable yields is greatly influenced by the interporosity flow, and it is important to fix production according to the interporosity flow coefficient ?. Finally, an example is given to verify the correctness of these results.

Key words: volcanic rock, dual media gas reservoir, interfacial flow coefficient, supplying and draining mechanism, numerical simulation