Improved Oil Recovery in Fractured Carbonate Reservoirs: Don’t Give InducedFractures a Chance!

摘要

In a naturally fractured carbonate reservoir in Oman, threerninjector-producer pairs were identified for fracture shut-offrntreatments to improve on their oil production. For these wellrnpairs, the oil production process was inefficient due to shortcircuitingrnof injection water to production wells along fracturernpaths.rnThe field-observed response on fracture shut-off by gelrninjection into the water injectors provided a good opportunityrnto learn more on the fracture geometry, aiming for thernformulation of general guidelines for an efficient water floodrnin naturally fractured reservoirs. The fracture shut-off job wasrnanalysed by the combined use of a fracture growth simulatorrnand a reservoir simulator.rnThe response was explained by the combination of anrninduced fracture in the water injector in the direction of thernmain fracture trend, in which the gel is destroyed afterrnresumption of water injection and a natural fracture in therndirection of a secondary fracture trend, which remains shut-offrnby the gel. For such fracture geometries water floods can bernoptimized by minimization of the risk of short-circuitsrnbetween injectors and producers. This can be achieved byrnusing injection and production patterns, aligned with therndominating fracturing direction and by keeping inducedrnfractures small to prevent or minimise intersections withrnnatural fracture corridors by proper management of injectionrnrate and water quality.rnThe analysis of the fracture shut-off treatmentrndemonstrates the technical potential of analysis of fieldrnperformance by combination of fracture growth models andrnreservoir simulation.