Laboratory evaluation on oil-soluble resin as selective water shut-off agent in water control fracturing for low-permeability hydrocarbon reservoirs with bottom aquifer

Abstract

During the development of low-permeability hydrocarbon reservoirs with bottom aquifer, hydraulic fracturing is essentially employed for commercial oil flow while increasing the potential risk of serious water production, thus water control hydraulic fracturing technology plays important role on addressing this challenge. In this work, a water control fracturing technique is developed to integrate fracture height containment with selective water shut-off. Specifically, oil-soluble resin is used as selective water shut-off agent and is injected with sinking agent simultaneously, carried by fracturing fluid at the fracture generation stage, to establish an improved artificial barrier. Afterwards, a modified fracture conductivity test equipment is designed and manufactured to measure the selective conductivity of the artificial barrier, its sensitivity to temperature, ratio of oil-soluble resin to sinking agent, two-phase flow are studied to evaluate the capability of selective water shut-off.The results demonstrated that 1) the occupation in porous space of sinking agent (0.212–0.425 mm) and the status change from glassy state to high elastic state of oil-soluble resin are mainly responsible for water shut-off; 2) The ratio of oil-soluble resin to sinking agent in 10 g: 70 g and temperature at 75 °C are two critical value to significantly reduce water conductivity in our experiments; 3) Fast dissolution of resin in oil results in oil conductivity over 5 to 100 times higher than water conductivity to achieve selective water shut-off. The results presented herein will provide important guidance on water control in low permeability reservoirs with active bottom aquifer and will promote the unconventional hydrocarbon recovery.