RESERVOIR SIMULATION STUDY ON THE PERMEABILITY JAIL'S EFFECT DURING TIGHT GAS PRODUCTION

Abstract

Permeability jails in tight rocks can lead to severe impacts on hydrocarbon production. Although this is a significant problem, the understanding of the influence of the permeability jail on tight gas production is limited. Few methods to avoid the permeability jail's effect have been reported. In this work, the permeability jail's effect on tight gas production was studied using the reservoir simulation method based on two real tight gas wells. First, the gas−water flow resistance in porous media was analyzed to calculate the critical pressure drop, which can be used to find the location of the permeability jail in tight gas reservoirs. Then, the location of the permeability jail was investigated using a reservoir pressure profile. Finally, two real wells were modeled to study the influence of the permeability jail on tight gas production by: (1) analyzing the location of the permeability jail; (2) evaluating the permeability jail's effect and well performance; and (3) optimizing the bottomhole pressure to reduce the permeability jail's effect. The results indicate that the permeability jail is located in the zone away from the wellbore and hydraulic fracture faces. About 64.5% of the gas production rate is lost due to the permeability jail at the beginning of production. However, this effect starts to be relieved when production lasts for 182 days. A low bottomhole pressure tends to reduce the impact of the permeability jail. To avoid loss of well productivity, the value of the bottomhole pressure necessitates careful optimization.