Uniform Acid Cleaning Technology and Its Application in Horizontal Wells with Open Hole Screen Tube

Abstract

After the completion of the open hole sieve tube in a horizontal well, it is necessary to replace the slurry and put it into production. Generally, circulating acid outside the tube cannot fully remove mud pollution. The acidification process needs to fully consider the heel effect of horizontal wells. Based on the horizontal pipe flow model and the characteristics of foam diversion, a mathematical model of acid washing suitable for open hole screen horizontal wells is established. Analysis suggests that lower flow rates and higher fluid viscosity during the acid washing process are more conducive to the uniform entry of the plugging solution into the formation. We have designed a uniform liquid mixing equipment with a flow blocking mechanism, and improved the acid washing construction process to achieve negative pressure reverse discharge of acid solution. This process can achieve uniform entry of the unblocking fluid into the formation after passing through the screen gap, and remove the blockage of the mud layer inside and outside the near screen tube. The horizontal wells using this process have a 30% increase in production capacity compared to oil wells in the same block, and the high yield validity period has been extended by 680 days.