Discussion on the Reasonable Time of Polymer Flooding to Subsequent Water Flooding

Abstract

Polymer flooding to enhance oil recovery technology of stop polymer solution injection timing is the key to affect the overall development effect and economic benefit, due to different in the tertiary oil recovery Wells, reservoir water cut and polymer concentration has the asynchronism and complex factors, there has been no systematic method to determine the time limit of stopping injection both at home and abroad. In this paper, based on the comprehensive variation law of water cut and polymerization concentration in polymer flooding development, the influence degree of whether to stop injection of polymer solution on water cut rise rate and polymerization concentration under different water cut levels and different polymer dosage is compared, and the decision model of stopping injection timing is established innovatively by using the principle of break-even. Combined with the actual field development parameters, the application results show that the optimum water cut level of stopping polymer injection increases with the increase of oil price. When the crude oil price is 2000 yuan, 2500 yuan and 3000 yuan/ton, the corresponding water cut at the time of injection stop is 95.2%, 96% and 96.8%, respectively. By setting the reasonable limit of stopping polymer injection, a total of 36 thousand tons of dry powder consumption is saved during the 13th Five-Year Plan period, which not only ensures the maximum enhanced oil recovery effect, but also optimizes the economic benefits of tertiary oil recovery, providing theoretical basis and technical support for polymer flooding reservoir engineering program and development adjustment.