A New Well Pattern for Enhancing Waterflood Performance of Ultra-low Permeability Reservoir in Changqing Oilfield

摘要

Because the development of ultra-low permeability reservoir is relative to fracture system, suitable well pattern arrangement is very significant for effective flooding management. There were three kinds of well pattern used to waterflood in Changqing oilfield: square inverted nine-spot, rhombus inverted nine-spot and rectangular five-spot pattern, according to the degree of fracture growth. In view of the defects of these well patterns in the development of ultra-low permeability reservoirs, a new well spacing concept is developed. Numerical simulations are carried out to illustrate the adaptability and strong points of this new well pattern. For this well pattern, on the one hand, the distance between producers and injectors along the fracture direction is widened and thus massive fracturing can be conducted to enhance oil productivity and water injection, and on the other hand, a high producer/injector ratio ensures high oil recovery rate in early stage. Besides, this new well pattern has a great ability of adjustment. Field application showed a remarkably well producing performance.