Reach About Well Pattern And Injection-production Parameter Boundaries Of Reservoir In Extra-high Watercut Stage

With the nationwide oilfield development of water drive, a considerable part of Chineseoilfield has entered high water cut stage, or even extra high water cut stage. The high watercut stage is very meaningful in the entire life cycle of reservoir development. Compared withthe low water cut stage, high water cut stage has characterizes as low oil recovery rate, largequantity of water injection, more dispersed residual oil, declining economic benift, and so on.But theoretical studies have shown that, even in extra high water cut stage, there still areconsiderable reserves in the reservoir. Therefore, it’s worth exploring how to economicallyand efficiently exploit high water cut stage reservoir.Baseing on the summary of the existing high water cut stage reservoir developmentmethods and evaluation system, the water flood experiments under different displacementpressure gradient were carried out. These experients pointed out the main factors that affectthe reservoir recovery of high water cut stage, and a new set of well pattern evaluation indexwas built according to the analysis, which is PG、PV、and Gr. The affects on well spacingfrom geological and productional parameters such permeability, water cut, thickness, residualoil saturation, were qualitatively analyzed with the newly built index. A mathematical modelfor the establishment of well spacing under multi-parameter influence was built withcomprehensive application of reservoir engineering method and economic calculation.The reservoir fluid production rate variation under the influence of multiple parameterswas also qualitatively analysis with the evaluation indexs, and a model to calculate maximumreasonable fluid production rate was establish using reservoir engineering method. Withactual data from the field, the maximum fluid production rate, reasonable reservoir pressure,reasonable injection and production well ratio, and other major production parameters can bequickly and easily calculated. After the calculation of well spacing, scattered small sand bodies that couldn’t be takeninto account before were also studied. And well pattern optimization and adjustment wascarried out in order to better develop those small sand bodies. These sand bodies wereclassified into different kinds according to their shape and area, and then well pattern wasoptimized by using evaluation indicators. In order to combine the optimization results withbasic wellnet, adjustment principles were published to guide the actual production.