Study On Combination Displacement Mechanism Of Super Heavy Oil Reservoir

In terms of extra-heavy crude with viscosity above 100000mPa.s, no mature producing technology has been developed home and abroad. As the foreground of petroleum industry becomes severe and more and more extra-heavy crude reservoirs have been discovered, study of displacement mechanism for such kind of reservoirs are in urgent need in order to find reasonable producing technology. In this paper, based on thermal production engineering theories of heavy crude, related physical model has been constructed and displacement mechanism for extra-heavy oil reservoirs has been researched after laboratory experiments. Firstly, rheological behavior and displacement mechanism for thermal production has been studied based on special petrophysical properties of extra-heavy crude; Secondly, oil-soluble complexing dissolver has been combined with hydrocarbon chains, which have certain number of C, functional groups and additives and its visbreaking mechanism has been addressed—penetrating between colloid molecules and bitumen molecules by strong hydrogen bond energy and breaking up the molecules aggregate; Thirdly, the action mechanism of CO2 on super heavy oil reservoir has been studied—reducing viscosity through solving due to no miscible phase will be formed; Forthly,combination displacement mechanism by oil-soluble complexing dissolver, Carbon dioxide and Steam has been studied stressly. The injection of oil-soluble complexing dissolver and Carbon dioxide can reduce viscosity greatly through solving, dilution and disgregation by oil-soluble complexing dissolver and solving, visbreaking and deemulsification by Carbon dioxide. The actuating pressure can be knocked down by 2～3MPa and the steam injecting pressure can be knocked down by more than 1.5MPa. The combination displacement by oil-soluble complexing dissolver, Carbon dioxide and Steam is 10 percent more than that of conventional steam displacement. Combined these research achievements above with horizontal well technology, New EOR technique of HDCS has been developed, simulated and optimized—a way of exploiting ultra-heavy oil in horizontal well by injecting oil-soluble dissolver, CO2 and steam. HDCS technique has been applied successfully in Shengli oilfield and OOIP of 3,920,000 ton has been put into production with deliverability of 100,000 ton by this technique. It also brings promising for extra-heavy crude reservoirs of 70,000,000 tons in Shengli.