Inter-well flow during polymer injection for offshore oilfields and preventing methods

Systematic monitoring and testing are conducted for the process of polymer injection for offshore oilfields, in order to ensure the quality of “one-pump-multi-well” polymer injection for offshore oilfields. Through the adjustment test, the mechanism of inter-well flow caused by the inconsistency between “well pump pressure” and “inter-well pressure” is proved. A method for judgment of inter-well flow and the correlation between the direction of inter-well flow and the number of one-pump wells are presented in this paper. According to the mechanism of “inter-well flow”, measures for preventing inter-well flow are given. Field test shows that “inter-well flow” occurs during polymer injection. On the basis of the characteristics of polymer injection technology for “one-pump-multi-well” in offshore oilfields, the occurrence of “inter-well flow” may lead to the change of injection ways of polymer injection wells, i.e. the change from “continuous polymer injection” into “water alternating polymer injection”. As a result, the polymer injection quality may be affected seriously. It is suggested that the number of one-pump wells be less than three. It is necessary to optimize the pump-well combination while conducting technology design.