Quick assessment to ascertain technical rational well spacing density in artificial water flooding oilfield

Optimization of technical rational well spacing density (TRWSD) is a crucial part of the study of oilfield development. However, the methods widely used previously have some disadvantages as followings: (1) Some quoted theories and formulas for algorithms are intractable. (2) Some are incompatible with the reality as they assumed too many conditions which are more ideal. (3) The influence factors considered by other algorithms are not comprehensive and irrational. (4) In applications, the applicable conditions are ignored by some algorithms. Aiming at the problems above, this paper has built a quick estimation model of TRWSD and proposed a new optimizing method of TRWSD, based on the comprehensive investigation of pressure distribution and the theoretical model of rational ratio of oil to water wells (RROWW) in artificial water flooding oilfield. Verification by reservoir numerical simulation model and actual data of the field implementation shows that the TRWSD model is reliable, and practical. It is revealed from the studies that the injection-production pressure system factors are the main ones to control TRWSD except water cut, such as the oil-bearing area of producing geological reserves, liquid productivity index, injection-production ratio and number of injection-production wells, and so on. And compared with the previous ones, the TRWSD method comprehensively takes into account such the factors as injection-production unbalance, density difference between oil and water, volume factor, start-up pressure gradient of injection wells, start-up pressure gradient of production wells and so on. Hereinafter, the new model can be applied for the calculation of the TRWSD and related parameters at any injection-production development stages, reservoir types and reservoir pressure distributions in artificial water flooding oilfield, all of which means that the new method has a strong promising adaptabilities and prospects in the water flooding oilfield with close well spacings or during high water cut stage.