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Wang, Wenjun (Petrochina Co. Ltd.) | Guo, Hongyan (Petrochina Co. Ltd.) | Huang, Youquan (Petrochina Daqing Oilfield Co. Ltd.) | Yu, Ying (Petrochina Daqing Oilfield Co. Ltd.) | Li, Donggang (Petrochina Daqing Oilfield Co. Ltd.) | Li, Qinggang (Petrochina Daqing Oilfield Co. Ltd.) | Sui, Hongyu (Petrochina Daqing Oilfield Co. Ltd.)
This paper introduces the first successful refracturing example of horizontal well in a tight volcanic gas reservoir of Xushen gas field. The well was fractured and put into production in 2008, with the accumulated gas production of 0.64×108 m3. Due to the limited technical conditions of the horizontal well-stage fracturing process at that time, only four fracturing stages have been carried out. the horizontal section of the volcanic gas reservoirs with more than 600 meters of the well was not fractured, leaving a large potential for increasing production. In 2017, based on the fine research of gas reservoirs, the refracturing optimization design, multi-stage perforation, fracturing and commissioning integrated tubular completion and the diagnosis control of complex fractures in fracturing construction, the refracturing job of the well is implemented successfully with a good result.
Elastomer is the core component of progressing cavity pump (PCP) which influences the running life of PCP considerably. Conventional elastomer performance tests only show basic mechanical and physical properties mainly simulate the static mechanic performance of elastomer. Numerical simulation indicates that dynamic performance is much more valuable in evaluating PCP's running life, while elastomer's dynamic test has not common criteria in the industry, especially for dynamic fatigue property test. This paper presents a novel simulated experimental design which could effectively evaluate dynamic fatigue properties of PCP elastomer.
Based on the operating conditions of PCP lifting system, a special experiment system has been designed and tested. It consists of power transmission system, friction pair system, and temperature control system. After implementing a series of contrasted tests, a special structure of elastomer sample and testing process were designed which showed best performance in accelerating dynamic fatigue process of elastomer as well as to simplify simulated test principle.
In order to verify the evaluation result of this fatigue testing system, three candidate elastomer formula (sample A, B, C) were evaluated. Experiments showed that dynamic fatigue properties of sample C were better than A and B. The fatigue properties of sample A was the worst. Statistics indicated that average running life of elastomer A was about 550 days, while running life of Elastomer B was 590 days and Elastomer C was 670 days. The application results had the same principle with experimental results. Experiments indicated that this simulated experimental system could describe the dynamic fatigue performance directly and clearly.
This paper presented a new experimental design which could evaluate the dynamic fatigue properties of PCP elasomer based on simulating PCP's operating conditions in practice. This experimental system has been applied to guide the design of elastomer formula and showed good results. This experimental system and testing process are of great significance in evaluating PCP elastomer's performance and developing high performance PCP elastomer in various operating conditions.
Chen, Mingzhan (Daqing Oilfield Co., Ltd. Northeast Petroleum University) | Cheng, Jiecheng (Daqing Oilfield Co., Ltd.) | Zhou, Wanfu (Daqing Oilfield Co., Ltd.) | Huang, Youquan (Daqing Oilfield Co., Ltd.) | Sun, Xiaoming (Daqing Oilfield Co., Ltd.) | Cao, Gang (Research Inst. Petroleum Exploration and Development, PetroChina) | Han, Song (Daqing Oilfield Co., Ltd.) | Wang, Guoqing (Daqing Oilfield Co., Ltd.) | Jiang, Tao (Daqing Oilfield Co., Ltd.) | Li, Ping (Daqing Oilfield Co., Ltd.) | Wang, Yanyan (Daqing Oilfield Co., Ltd.)
Scaling issue of artificial lift systems is the main bottleneck for ASP flooding, and has considerably negative influence in commercial stage. In the past decade, different anti-scaling technologies have been developed and applied in Daqing Oilfield. However, high pump failure still exists in severely scaling producers. This paper presents an innovative artificial lift method – a patented bailing pumping unit production system, which has been applied successfully in field test stage in Daqing Oilfield.
The system consists of soft plunger, special designed wire line, winch system and surface control. Produced liquid mixed with large quantity of scale particles is lifted to surface by the soft plunger connected to wire line. The plunger is made of high molecular materials and steel skeleton support which ensures good flexibility and reliability after long term of operation in abrasive environment. The wire line is specified designed and processed to enhance operation life. It connects downhole gauge and surface control. Down hole pressure can be monitored in real time, which provides references for adjustment.
This innovative bailing pumping unit production system has been applied in 80 wells in 3 ASP flooding blocks with severe scaling issue in Daqing Oilfield. The average running life was improved from several weeks to 710 days. Considerable benefits have been achieved by the 60% operation cost decline. It has been the premier artificial lift method for the severely scaling producers. Additionally, there is no need for flushing or acidizing treatment to deal with scale deposited in downhole pump, rod string, and tubing string compared with pumping unit production system in ASP flooding, which significantly reduces normal management intensity and cost.
Field test showed that this innovative bailing pumping unit production system has outstanding scale resistance capability for severe scaling wells in ASP flooding. It also provides a great reference for other oilfields in worldwide with similar issues both in ASP flooding and high salinity conditions.