Evaluation and Application of New Anti-expansion Unblocking Agent for Water-sensitive Oil Deposit

Abstract

In water-injection development, water-sensitive oil deposits are prone to water injection pressure increase and water injection volume decrease, which makes it difficult to complete production and injection allocation. To solve this problem, on the basis of screening traditional anti-expansion unblocking agents, and combined with the performance evaluation of the formula and core experiment, a reasonable improvement scheme was proposed in this paper to develop a new type water-sensitive oil reservoir anti-expansion unblocking agent. The performance evaluation experiment shows that it has an applicable dissolution rate for oil rock samples and can dissolve inorganic salt scale; the anti-expansion rate is up to 90%; the core dynamic evaluation experiment shows that the core permeability can be increased more than double after the injection of the anti-expansion unblocking agent. The new type water-sensitive anti-expansion unblocking agent were used in 7 wells of the site, and all of them have a good effect of water injection pressure decrease and water injection volume increase.

Effect Evaluation and Action Mechanism Analysis of “Profile Control + Plugging Removal” after Chemical Flooding

“…In the oilfield production practice, increasing the liquid suction pressure difference is the only way to increase the suction amount of plugging removal agents in the middle and low permeability parts and improve the plugging removal effect. Increasing the injection pressure is an important measure to increase the liquid suction pressure difference [ 17 , 18 , 19 , 20 , 21 , 22 ]. Increasing the injection pressure can be achieved by increasing the injection speed and increasing the seepage resistance at the high permeability part, i.e., the start-up pressure of liquid absorption.…”