Application of Intelligent Rodless Artificial Lift Technology in Shale Oil of Changqing Oilfield

Abstract

The shale oil reservoirs of Changqing Oilfield are generally developed by large well clusters, 3-D long horizontal wells and subdivision cutting volume fracturing. The wells have a high liquid rate initially and decline rapidly that causes pumping unit is difficult to adapt to full life cycle of the wells. Meanwhile, because the complex well trajectories cause serious eccentric wear of rod and oil pipe, and the wellbores environment containing waxing, sand, scaling, and gas are complex, the pumping units used in shale horizontal oil wells require frequent workover, which severely affect the production. According to the wellbore and production characteristics of shale oil horizontal wells, electric submersible progressive cavity pump (ESPCP) is selected as the main lifting technology. By optimizing the submersible motor, progressive cavity pump and wellbore matching technology, a rodless artificial lift technology is formed integrating ESPCP, “five prevention” wellbore matching technology, digital transmission and intelligent control system. An industrialized rapid putting into production mode in large platform and an intelligent closed-loop control system based on reasonable flow pressure is established, and the largest horizontal-well-platform of shale oil reservoirs with intelligent rodless artificial lift technology in China on land was built. The technical indicators of rodless lift are greatly improved compared with the pumping units used in Changqing shale oil reservoirs that the average pump efficiency increases from 43.5% to 66.0%, the system efficiency increases from 23.3% to 33.6% and the time used to put one well into production is reduced from 15 days to 1.5 days. Meanwhile, the intelligence of artificial lift system has a huge improvement that real-time transmission of underground parameters, remote instantaneous adjustment of the pumping system and unattended intelligent control of the well platform are achieved. It has been proved that the intelligent rodless artificial lift technology realizes a efficient and intelligent development of shale oil reservoirs, and has an extensive applications prospect.