Critical parameters of horizontal well influenced by semi-permeable barrier in bottom water reservoir

YUE Ping(乐平), DU Zhi-min(杜志敏), CHEN Xiao-fan(陈小凡), ZHU Su-yang(朱苏阳), JIA Hu(贾虎)

(State Key Laboratory of Oil & Gas Reservoir Geology and Exploitation Engineering
(Southwest Petroleum University), Chengdu 610500, China)

Abstract:It is well-known that barriers have a significant impact on the production performance of horizontal wells developed in a bottom water drive reservoir. In most cases, reservoir barriers are semi-permeable. Based on previous research on impermeable reservoir barrier, a mathematical flow model was derived for a horizontal well of a bottom water drive reservoir with a semi-permeable barrier. Besides, analytical equations were also presented to calculate critical parameters, such as production rate, pressure and potential difference. The effects of barrier, well and reservoir parameters on our model results were further investigated. The results show that the larger the barrier size is or the higher the barrier location is, the higher the critical production rate and potential difference of a horizontal well are. when the barrier permeability equals the formation permeability or the barrier width equals zero, the critical production rates converge to the values same to that of the case with no barrier. When the barrier permeability equals zero, the problem is regarded as a case of impermeable barrier. This model can be applied to predicting horizontal wells’ critical production parameters in reservoirs with semi-permeable barriers.

Key words:horizontal well; bottom water reservoir; semi-permeable barrier; critical rate; cresting