Testing results evaluation on water flooding with horizontal wells in Chang-8 ultra low permeability oil reservoirs of Honghe oilfield

In Chang-8 ultra-low permeability reservoir of Honghe oilfield,the multi-stage fracturing technology with horizontal well has been adopted for natural energy development,and there were prominent problems of fast decline and low recovery ratio.In order to make reasonable technology,the evaluation on well pattern,well spacing,injection-production parameters of water flooding development in the testing area has been carried out.In combination with the theoretical calculation,the similar reservoir simulation and field test,the research on avoiding rapid water channeling and ensuring effective water flooding has been conducted.The optimized principles for present well pattern,well spacing and reservoir engineering parameters have been made clear:(1)flat injection flat production is superior to direct injection flat production;(2)the injection-production well spacing should be generally greater than 700 m;(3)moderate water injection should be adopted,the water injection pressure for single well should be less than 15 MPa,and water injection for single well should be controlled among 15 ~ 20 m3.Based on this research results,thinning well pattern and appropriately enlarged the present well spacing have been adopted in Chang-8 oil reservoirs of Honghe oilfield,and the suggestion on optimizing reservoir engineering parameters for other 6 well groups has been put forward.