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31 October 2017, Volume 36 Issue 5 Previous Issue    Next Issue

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2017, 36(5): 1-1.  DOI: 10.3969/j.issn.1002-302x.2017.05.00 Abstract ( )   PDF (606KB) ( )

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Review and Outlook of Promotion Project for Coiled Tubing Service Technology Zhao Ming, Shi Lin, Liu Guanghua, Li Xuehui, Tan Duohong, Hu Qiangfa 2017, 36(5): 2-6.  DOI: 10.3969/j.issn.1002-302x.2017.05.01 Abstract ( )   PDF (1658KB) ( )   China National Petroleum Corporation has launched a special campaign for promotion of coiled tubing service technology since 2011 and made remarkable achievements in this area. Coiled tubing unit has played an important role as “universal service unit.” Coiled tubing service technology is used to solve the production bottlenecks in operation of shale gas horizontal wells. “Qinghai Experiences” were developed in using coiled tubing technology for conventional service to substantially raise speed and efficiency. Coiled tubing service equipment and tools as well as dedicated tubular are independently development in different families. The specialized standards and engineering service capability of coiled tubing crews are fully improved at the same time. Against the background of continual low oil prices on the international market and increasingly stern requirements on the environment at home, CNPC has accelerated the process of promoting CT technology and expanded application areas in its special campaign for CT technological promotion. Those efforts are helpful to conversion of downhole service pattern and operational cost-effectiveness.

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Research and Application of Coiled Tubing Service Technology and Equipment Hu Qiangfa, Fu Yue, Gai Zhiliang, Xu Yunxi, Liu Shoujun, Tan Duohong, Jia Xia 2017, 36(5): 7-11.  DOI: 10.3969/j.issn.1002-302x.2017.05.02 Abstract ( )   PDF (1657KB) ( )   China’s coiled tubing technological development has experienced three stages – introduction of technology, independent development and promotion of application. Jianghan Machinery Research Institute of CNPC Drilling Research Institute has always committed itself to the study in this area during this period of time. As the organizer unit of projects, Jianghan Machinery Research Institute has been in charge of a series of research, experiment and promotion projects for the State and CNPC since 2006, independently developing a number of coiled tubing service technologies and equipment. First of all, the key technology of coiled tubing unit has been developed to entirely replace the imported equipment so that the domestic families of coiled tubing equipment can be used in the mountainous areas and complicated conditions. Secondly, a total of 24 coiled tubing service tools in four families and 35 processes were independently developed to facilitate integrity of tools and workover process, effectively improving the CT service efficiency. Thirdly, the process technology was developed for coiled tubing fracturing and well completion, thus increasing oil production cost-effectively by means of coiled tubing service. Fourthly, the research institute, as an organizer of projects, was involved in formulation of a series of relative technological standards, specification of products and service. The coiled tubing technological industrial chain was preliminarily established in the efforts to provide after-sales service, personnel training and on-the-site demonstration of technology, thus leading to a wider application of coiled tubing technology. Independent technological development substantially raised China’s coiled tubing service technological level and widened its application areas, promoting continual conversion of downhole service technological pattern.

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China’s Research and Production of Coiled Tubing Zhang Xiaofeng, Xue Qiwei, Zhang Peng, Gao Fei 2017, 36(5): 12-15.  DOI: 10.3969/j.issn.1002-302x.2017.05.03 Abstract ( )   PDF (1697KB) ( )   In 2009, the first domestic coiled tubing product of CT80 Grade was successfully turned out in Baoji Petroleum Steel Pipe Co Ltd. As the sole manufacturer in China, a perfect quality control system was established on the basis of high quality policy. The company has continued to center on the research and development of new CT products, perfect the specifications for care and maintenance of coiled tubing and actively improve the standard of technological service. Driven by CNPC’s Promotion program, the company demonstrated and promoted popularization and application of the coiled tubing banded with research institute, equipment manufacturing industry, engineering service company and the related oil and gas fields. The sales volume increase progressively year after year, climbing to 4000 tons per year in 2014 from 300 tons per year in 2011, which has fully guaranteed the domestic demand for the of coil tubing service.

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Specialization of Coiled Tubing Service Crew Sun Hu, Ren Bin, Fei Jiegao, Yang Hongbin, Lan Jianping 2017, 36(5): 16-21.  DOI: 10.3969/j.issn.1002-302x.2017.05.04 Abstract ( )   PDF (2740KB) ( )   CNPC oilfield engineering technological service enterprises have made significant progress in quantity of coiled tubing equipment, auxiliary tools and application of coiled tubing technology in recent years. To promote application of coiled tubing process technology for safe and high-efficiency service as well as cost-effectiveness, Changqing Downhole Technology Company of CNPC Chuanqing Drilling Engineering Company Limited put coiled tubing service personnel under specialized training in the light of the process demand by Changing Oilfield. The efforts were focused on four areas – specialization of organizational structure and personnel, characterization of equipment families, perfection of supporting system, and standardization of on-the-site service. The company has established four demonstration crews specialized in coiled tubing fracturing service and two demonstration crews for speed string service. As of August 2017, a total of 84 wells, with 242 intervals (sections), had been cumulatively fractured by means of coiled tubing to move bottom packer, while 241 wells were cumulatively completed for speed string service. Application of the two processes on a large scale has made remarkable economic performance and promoted development of coiled tubing service technology.

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Experiences of Qinghai Oilfield in Application of Coiled Tubing Service Technology Lu Mingchun, Zhao Ming, Lu Yansen, Chen Weixi, Li Lianxi, Luan Zhou 2017, 36(5): 22-26.  DOI: 10.3969/j.issn.1002-302x.2017.05.05 Abstract ( )   PDF (1809KB) ( )   Qinghai Oilfield urgently needs the latest equipment and process technology to offset the harsh natural environment and poor social logistic conditions. With the help of the special platform provided by CNPC to extend new technology of coiled tubing, Qinghai Oilfield actively combined a series of advantages of coiled tubing – short service period, low accident rate, small formation damage and easy tripping-in – with its own actual conditions and conversed development pattern for continual technological innovation and application on a larger scale. The oilfield established a high-quality specialized technological service crew and developed a series of characteristic processes, such as low-pressure gas well coiled tubing nitrogen foam flushing service process, coiled tubing flushing well integrated service process and coiled tubing injecting well scale-removing process. With the annual service amount leading the nation for four consecutive years, the scale application has reached the advanced international standards, Qinghai Oilfield brought about conversion of plateau downhole service from low-end labor service to modern downhole operational technological service, achieving remarkable integrated economic performance and promoting oil and gas engineering technological development. Extension of coiled tubing service technology allowed Qinghai Oilfield to put high-end technological results into wide application, improve its independent creating ability and engineering technological service level, and make a satisfactory economic performance.

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Experiences in Promotion and Operational Management of Coiled Tubing Service Technology Li Xuehui, Tan Duohong, Liu Guanghua, Liu Hongjun, Song Zhiguo, Hu Qiangfa 2017, 36(5): 27-33.  DOI: 10.3969/j.issn.1002-302x.2017.05.06 Abstract ( )   PDF (3159KB) ( )   CNPC has made special efforts for promotion of coiled tubing operation technology. Fruitful results have been achieved in CT equipment and its auxiliary tools, demonstration and extension of process, expansion of application area and development of industrial chain. Application of CT equipment, tools and process is on the rise year by year. With the annual amount of services climbing significantly, large-scale application led to remarkable economic performance. This article elaborates the managerial experiences in organization and operation of the CT application project and the main factors for effective application including perspective design at top level, regional bottlenecks oriented and effective execution, focusing on collaboration and organizational management, adherence to continual innovation, cultivation of talents and specialization of professional crews, and development of complete industrial chain. The experiences can be borrowed and worth being extended.

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Study and Application of Coiled Tubing for Workover in Daqing Oilfield Liu Yan, Wang Lin, Nan Zhixue, Tang Qingchun, Hou Jinglong, Jia Yanxue, Zhao Haowei 2017, 36(5): 34-38.  DOI: 10.3969/j.issn.1002-302x.2017.05.07 Abstract ( )   PDF (2300KB) ( )   Daqing Oilfield tested coiled tubing for rapid workover service to improve the efficiency of paraffin removal from oil well and blocking removal from water well. Based on the principle of using hydraulic power for paraffin removal and scale removal, high-efficiency rapid coiled tubing workover service process technology was developed by means of optimizing hydraulic parameters of high-pressure rotary spraying jet flow and high-pressure flushing tools, reasonably matching parameters with operation, and perfecting the relative surface process. Field application and experiment indicated that use of coiled tubing for paraffin removal, scale removal and blocking removal services had the advantages of snubbing service, environmental protection and high efficiency. The process technology can effectively remove paraffin and scales from oil tubing and casing and substantially improve the operational efficiency as compared to conventional oil tubing service. In addition, it can solve some special service bottlenecks in the conventional service, such as blocking of tubing or casing leading to failure of pipe string trip-out and lack of circulation of tubing or casing making well killing job impossible. The process has changed the service pattern and helped the oilfield bring about rapid workover service.

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Application of Coiled Tubing Salt Flushing and Plug Removing Process in Yingxi Area Chen Kehua, Sheng Guoqing, Lu Yansen, Zhu Feng, Xu Huijun, Chen Weixi 2017, 36(5): 39-43.  DOI: 10.3969/j.issn.1002-302x.2017.05.08 Abstract ( )   PDF (1942KB) ( )   Yingxi area was a key block for Qinghai Oilfield to increase reserves and production in recent years. However, the formation of this area has a high content of salt. In addition, salt is rapidly crystallized. Production from a lot of oil wells dropped quickly owing to plugging of production channels, causing great difficulties for exploration and development. To solve this bottleneck, the plug removing scheme was designed on the basis of various coiled tubing processes and under the principles of “tripping-in, tripping-out and small damage.” The scheme was mainly focused on rotary spraying jet tools for salt flushing + rotary spraying jet for reaming +hot water for dissolution of salt, with the help of using screw drill for drilling and abrasion as well as stabilizing the spraying jet. Meanwhile, a variety of salt flushing tools were designed and processed, such as rotary flow jet tool, rotary spraying jet tool and sharp point tool, whose process parameters were continually optimized in the service. A series of coiled tubing salt flushing and plug removing process technologies was developed and successfully used at nearly 50 times in the well service, providing effective support for normal production of high-pressure and high-yield oil wells.

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Promotion and Application of Domestic Coiled Tubing in Oil and Gas Fields in Sichuan-Chongqing Area Zou Xianxiong, Lu Xiude, Li Zongqi, Fei Jiegao 2017, 36(5): 44-48.  DOI: 10.3969/j.issn.1002-302x.2017.05.09 Abstract ( )   PDF (1710KB) ( )   The oil and gas fields in the Sichuan-Chongqing region take the lead in use of coiled tubing equipment in China. However, development in this area used to be sluggish for long time owing to the cost for import of coiled tubing equipment and the related services. With China’s first set of coiled tubing unit and coiled tubing developed successfully, the domestic equipment found wide applications in the oil and gas fields in the Sichuan-Chongqing region, thus breaking foreign technological monopoly, reducing the purchase cost, solving the production bottlenecks, improving service ability and achieving remarkable economic performance. This article reviews the process for application of domestic coiled tubing in the Sichuan-Chongqing oil and gas fields and summarizes and analyzes a series of adopted effective measures. They include combination of production with research, cooperation between research institutes and enterprises, reciprocation of each other’s advantages, putting safety first and sharing risks, optimization step by step, market-oriented, guided by technological research, characteristic tailored service and standardized development. The article also analyzes the issues and challenges for the business development and comes up with the related suggestions on further application of domestic coiled tubing in the oil and gas fields in the Sichuan-Chongqing area.

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Successful Application of Full Coiled Tubing Process for Dun-1 H Well Ren Yongqiang, Cui Shijie, Wu De, Zheng Zilong, Yi Zhongjian, Zeng Hao 2017, 36(5): 49-53.  DOI: 10.3969/j.issn.1002-302x.2017.05.10 Abstract ( )   PDF (2761KB) ( )   Coiled tubing service technology has a series of advantages, such as high automation, short operational period, high safety coefficient, snubbing service and protection of formation. This technology is especially suitable for complicated downhole services and handling emergence cases like horizontal well and slim-hole well. Taking Dun-1 H Well for instance, this article makes briefings about the complicated conditions of this well and the bottlenecks for downhole services. It also introduces the integrated coiled tubing service process based on combination of procedures, such as using f 50.8mm coiled tubing for flushing, logging depth correction, multi-cluster hydraulic jet and perforation, and gas lift displacement of liquid. Field application indicated that with the technological advantages of coiled tubing service and its multi-process assemblage superiorities, integration of well drifting and flushing and logging accurate depth correction were brought about in the complicated segment of the slim-hole horizontal well, thus competing one-trip string multi-cluster jet perforation service, which is difficult to be completed in the downhole service of conventional process. Coiled tubing process technology is high in operational efficiency and remarkable for service results, solving the on-the-site bottlenecks. This well was tested to produce two tons of crude oil per day in the wake of service, satisfying the follow-up fracturing conditions.

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Study and Application of Coiled Tubing Testing Service Wang Xinhe, Liao Weiyu, ZhengHui, Sun Guoqiang, Wei Liang, Chen Zhouyang 2017, 36(5): 54-59.  DOI: 10.3969/j.issn.1002-302x.2017.05.11 Abstract ( )   PDF (2910KB) ( )   Conventional oil tubing testing service has a long period of operation and a high intensity of labor. Coiled tugging service has a number of advantages, such as without moving the production string, snubbing, less service equipment, short service time and cost-effective. The company has developed a complete set of coiled tubing testing processes and equipment, including wellbore preparations for new wells.These preparations provide a clean and safe environment for lateron service. Cementing quality inspection after well completion provides technological support for perforation and layered fracturing services. Accurate perforation of straight well, channeling of horizons and perforation of the first segment of horizontal well provide channels for transmission by fracturing pump. The tested reservoir sealed with pressure is brought under layered fracturing stimulation. In the wake of fracturing service, the compound bridge plug is removed to restore the full path of wellbore and reduce flowing friction. In the process of production, the layers are tested one by one to acquire the relative data of each horizon, such as temperature, pressure, flow and water cut. Field application indicated that coiled tubing testing process can effectively reduce oil testing period, improve service efficiency, lower the risks for safety and the environment and accelerate the exploration and development process of low-permeability and non-conventional reservoirs.

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Pilot Experiment of Coiled Tubing Spraying Flow Radial Drilling Technology and Suggestions on Its Wide Application Hu Qiangfa, Zhang Youjun, Lu Yansen, Chen Zhi, Wan Youyu, Chen Kehua, Zhang Yan 2017, 36(5): 60-67.  DOI: 10.3969/j.issn.1002-302x.2017.05.12 Abstract ( )   PDF (3222KB) ( )   To better understand the special reservoirs like thin inter-layers and keep the production stable in the old oil areas, Qinghai Oilfield led the country in making pilot experiment of coiled tubing spraying flow radial drilling technology in an attempt to expand application area of coiled tubing technology and seek new methods for cost-effective increase of production. In the physical simulation of spraying jet drill ability on the surface, three typical drilling nozzles and spraying jet parameters of tested cores were brought under experiment for comparison. Three typical blocks were evaluated for their formation adaptability with the process parameters optimized. The field application was divided into two stages using a series of key technologies and relative equipment, such as depth correction while drilling and relative azimuth orientation technology, drilling pressure stabilizing and stuck prevention technology as well as jet drilling technique. A total of seven wells with 40 radial branches were completed for drilling, a breakthrough in this area and a high success rate of process. With a maximum drilled depth of 35.8 meters for a single hole, incremental production and injection were remarkable. Coiled tubing spraying flow radial drilling technology can be put into wide application in domestic oilfields as a new technology for reservoir transformation and increase of production.