Abstract:In recent 10 years, the shale gas revolution in the United States has changed the energy structure, which is attracting more and more countries devoting themselves to the development of shale gas. Firstly, this paper introduces the process of the shale gas revolution in the United States and its achievement. Secondly, the paper describes the process and status of shale gas revolution in China. Finally, some development proposals are presented about the shale gas exploration of China based on the experience of the United States and the characteristic of shale gas in China. It is of great benefit to the shale gas revolution in China.

Abstract:In order to improve ROP and efficiency in drilling in the Fuling Phase II complex structure, the rotary steering tool was introduced and the integrated operation mode of directional drilling, logging and rotary steering was applied. The integrated technology of directional drilling, logging and rotary steering was developed by selecting the rotary steering tool, matching formation characteristics with drilling bits, optimizing the trajectory control method, improving the existing information platform and rotary steering software. Field test in 8 wells in Fuling Shale Gas Field demonstrated that the reservoir intersection rate was obviously increased, the trajectory control was smooth, and ROP was obviously increased, which achieved the goal of “crossdisciplinary combination, innovation and development”, and has strong popularization and applicability.

Abstract:With the construction of Fuling Shale Gas Field annual production capacity of 10 billion square meters and the efficient exploration and development of Changning-Weiyuan National Shale Gas Industry Demonstration Zone, the Chinese energy structure is constantly changing. The commercial development of shale gas depends on the continuous progress of cluster horizontal well drilling technology and large-scale fracturing technology. Efficient complete technology for drilling and completion provides a powerful guarantee for improving the shale gas exploration and development. Sinopec Zhongyuan Petroleum Engineering Co., Ltd. has made a series of technological breakthroughs in drilling practice via independent R & D on and integration of new drilling techniques and tools. It has developed three-dimensional large offset long reach horizontal well trajectory control technology, oil-based emulsification/soil-free oil-based drilling fluid technology, leakage prevention and plugging technology, shale gas interpretation and evaluation-while-drilling technology, oil-based drilling fluid high-efficiency flushing technology, zipper fracturing technology in pad drilling and high-voltage electrical network supporting technology etc. The above technologies were adopted in more than 140 wells in Fuling, ChangningWeiyuan, Yongchuan and other Sichuan-Chongqing work sites, which effectively supported the shale gas productivity construction in China. This paper is a comprehensive summary of complete shale gas drilling and completion technologies based on Zhongyuan shale gas technical research and field experiences, providing good guiding for drilling and completion projects in other shale gas exploration and development blocks.

Abstract:The Well Qianpudi-1 is a shale gas geological survey well deployed in the Qingshan syncline in Southwest Guizhou Sag. This paper describes the outline of the project and the basic geology with focus on the drilling and construction technology of the well. In addition, the drilling quality is analyzed in light of drilling formation and logging data. With proper drilling equipment selection, well structure optimization, core drilling technology, drilling fluid system optimization and proper drilling parameters, drilling efficiency has been improved, and drilling quality met the geological requirements, resulting in effective completion of the drilling work. It may provide technical reference for drilling and construction of similar shale gas survey wells.

Abstract:In order to solve the problems of wellbore instability and wellbore cleaning in shale formation in the WeiyuanChangning area, the treatment agents such as emulsifiers, organic soils and filtration reducers suitable for high-density oil-based drilling fluid systems were selected through experiments. A high-density oil-based drilling fluid system suitable for use in both long and short shale gas horizontal wells in the WeiyuanChangning area was determined by orthogonal design. The final formulation ratio is: 5% primary emulsifier + 2.0% co-emulsifier + 2.0% wetting agent + 5% filtration reducer + 2% organic soil + 3% CaO, oil to water ratio 80∶20 (25% CaCl2 aqueous solution). Evaluation on its performance shows that the system can increase the density to 2.2g/cm3, and the performance is stable after addition of weighting material. It can resist water pollution up to 9%, anti-cutting pollution to 18%, providing good anti-pollution performance with shale recovery up to 95.11%, and good inhibition performance, as well as stable emulsification performance. The field application showed that the high-density oil-based drilling fluid met the drilling requirements of the shale gas horizontal well Wei 204H378. The performance of the whole well was good: there was no well leakage, the well diameter was regular, there was no abnormities in logging, and well completing was smooth.

Abstract:In view of some issues such as the lack of basic criteria and basis for 5000m geological core drilling, the great difference between oil and gas drilling and core drilling in drilling technology and equipment, this paper summarizes and systematically analyses the diameter size and tubing string specifications in deep geological core drilling at home and abroad. On this basis， basic external conditions and interrelated requirements are defined with calculation of annular hydraulics and design of the wire-line drill string strength for ultra-deep hole core drilling. The diameter size, drill string and casing string specification for 5000m ultra-deep hole drilling are preliminarily set up with the wire-line drilling process as the main part.

Abstract:The geological survey drilling project in the Keping area of the Tarim Basin-Well Xinsudi1 is located on the Shajingzi tectonic belt of the Awati depression in the Tarim Basin. The structural belt is featured of a large inclination, poor cementation, serious breakage and the stability of the borehole wall is poor. The lithology encountered during drilling was mainly mudstone, sandstone, argillaceous siltstone, limestone, dolomite, mud-bearing dolomitic rock, quartz schist and so on. There were many collapses and circulation loss. Use of the polymer anti-collapse drilling fluid system on the site has solved the complex problems such as broken formation, collapse, falling stones. The system provided strong inhibition and good cementation, and achieved good performance in borehole wall protection leakage plugging, ensuring successful implementation of the project.

Abstract:In order to prevent the support crushing disaster, a technique is presented for pressure relieve blasting of concentrated coal pillars with the super long upward hole through analysis of the theory of disaster prevention by pressure relief and loosening blasting with super long upward holes. Three technical difficulties have been solved through field practices and some experiments. First, an explosive charging device was developed by ourselves for quick explosive charging even to 110m hole depth with the angle to 30°. Second, the optimal spacing of blasting holes was found through theoretical calculation. Third, the explosive safety detonation and elimination of plugging of the super long upward hole was achieved through the explosive test and the cement-silicate grouting’s setting properties test. Successful field blasting practices proved the technique can provide engineering reference and be promoted.

Abstract:An MP-1000 portable drill was used to drill a 45° inclined hole in Erdaokan village of Nenjiang County, Heilongjiang Province during survey of silver polymetallic mines. The drill occupies a small area and is easy to move, so it is suitable for inclined hole drilling. In view of drill hole leakage, collapse, falling stones, deviation in inclined hole drilling, the modified rigid cement plugging agent was used to plug the leakage section of the drill hole with good plugging effect achieved; the drilling fluid with proper wall protection performance has been selected to reduce the collapse and falling stones in the drill hole; and the anchor bolt has been adopted to fix the drill to prevent hole deviation. The high body drill bit was used to reduce the number of trips and avoid hole deviation due to squeezing drill tools by falling stones. By choosing the appropriate flushing fluid and optimizing the drilling technology, good results has been achieved in drilling of the 45° inclined hole.

Abstract:Continuous solution mining of underground salt minerals through drilling technology is the most common and economical method for development of well and rock salt resources. The development of well and rock salt resources with boreholes in China has a long history, and it is the origin of human drilling activities. It is the fastest growing raw salt resource in recent years. Due to the characteristics of water solubility, rheology and modes of occurrence of salt minerals, drilling and mining technology for well and rock salt is very different from that for oil and gas resources. After absorbing modern drilling technology (directional wells and horizontal wells, etc.) and logging technology, the key application technologies such as anti-collision and bypassing, multi-branch wells, Under-pressure drilling, intersection drilling has been developed for well and rock salt mining.

Abstract:There are some difficulties in drilling in Pengzhou Gas Field in Longmen Piedmont. In the upper strata, gas drilling technology is limited and prone to deviation. The middle part of the Xujiahe Formation and the Xiaotangzi Formation is featured of strong abrasiveness and poor drillability. In the lower Leikoupo Formation, the strata are relatively broken, prone to bit sticking and easy to leak. ROP is low and the drilling duration is long. Based on the analysis of geological data and formation characteristics in Pengzhou Gas Field, the research and application of complete technologies for ROP improvement, such as optimizing the well bore structure, hydraulic WOB, vertical drilling technology, PDC bit optimization technology, high-efficiency drilling fluid technology and torsion impactor, were carried out in Well PZ115. Safe and fast drilling was achieved with the average drilling speed at 2.62m/h and the drilling duration 265.75d. Compared with the shortest drilling duration of Well YS1 in the same block, the drilling depth and the ROP increased by 454m and 24.17% respectively, creating the record of the deepest drilling depth and the shortest drilling duration in the fourth member of the Leikoupo gas reservoir in the West Sichuan area. Research results show that the proposed high-speed drilling techniques for Well PZ115 can provide references for coming operations to enhance the ROP and efficiencies in Pengzhou Gas Field.

Abstract:The insert-type cementation technology was performed for the surface casing of Well Mengazuodi1, which eliminated the difficuties such as high risk of unstable formation in the long well section, large annulus inside and outside the casing, long operation time. The corresponding technical measures and management measures were formulated according to the characteristics of the insert-type cementation process, which resulted in better cementation quality, construction efficiency increase by 42% and construction cost reduction by 30%. The surface casing cementation over the large-diameter and long-section unstable strata in Yin’e Basin can provides valuable experience for cementation in this area.

Abstract:In order to ensure safe drilling and shorten the drilling period of the first bedrock risk exploration horizontal well in Songliao Basin, optimum design of the borehole trajectory, casing program, drilling speed increase and prevention of complex incidents were carried out, calculation methods of internal compressive strength of casing at different well sections were established, and effective technical measures were determined. Geological targets were determined through the seismic profile. According to the statistics of actual drilling in the adjacent wells where 1.5° motor was used in the well drilling design, and the build rate was controlled at (5°～7°)/30m, the borehole trajectory was accordingly designed. Based on the difference in compressibility coefficients of gas and fluid, the compressive strength of casings with different spud was studied, and it was found that the bottom of production casing was the weak point, while for the other casing the weak point was at the wellhead. On the basis of geological prediction, the drilling speed was increased by 13.38% over adjacent wells by adopting the composite bit and strengthening drilling parameters, and circulation loss was reduced by 247m3 by using compound plugging technology and complete process. Through the research and application of the above technology, the drilling time of Well Longping1 was shortened by 21.16 days compared with the adjacent wells, which provides technical support for the exploration and development of bedrock weathered crust in Songliao Basin and provides a basis for the implementation of similar wells in the future.

Abstract:In order to solve the sampling problem in special shallow overburden formation, the CBQ30A portable sampling drill was developed. This paper introduces the main modular components of CBQ30A in turn: lightweight power engine, brake block clutch, gear shifting mechanism with the independent patent, simplified swivel and quick-disconnect transmission mechanism. This rig has been verified by production trials in many fields, which basically meets the needs of green exploration, and has a good effect on the promotion of shallow sampling technology.