| In recent years, China’s economic construction makes great strides forwards and the need of energy increases rapidly, because the development of oil and gas resources is hard in our country and cost too much, Our country is very dependent on imported oil. To ensure the sustainable and healthy development of our country’s economic, we must develop our own oil industry vigorously. However, the very low international oil price makes our oil industry development harder, which is not conducive to our country’s energy security. In the long term, it will bring hidden trouble to China’s economic take-off in the future. With the transformation of economic structure, China’s oil industry has begun to explore the demand for the diversification of energy structure. These years the successful application of shale gas development in the United States lowers prices for oil and gas resources and realizes its own energy security, so enhancing the grope for the development of shale gas is conducive to the healthy and sustainable development of our country’s petroleum industry and helps to improve the structure of energy supply and demand in our country.This paper begins with the reference of horizontal multi-stage fracturing technology at home and abroad, summarizes their respective characteristics and corresponding working condition, for some technologies with especially potential applications in the shale gas development, we do comparative analysis on them.The main way for shale gas development in our country is pumping drillable bridge plug perforating technology for staged fracturing, this technology has achieved good results, but its cost is very expensive for a lot of the consumption of bridge plugs and it needs a long construction time. The cementing sliding sleeve technology for multi-stage fracturing has obvious advantages in the fracturing effect and construction time compared with pumping drillable bridge plug perforating technology for staged fracturing. So in this paper we mainly consider using the cementing sliding sleeve technology to apply shale gas fracturing operation. In the cementing sliding sleeve technology for multi-stage fracturing, the most important part is the study of the sliding sleeve and its supporting tools. We take the the corresponding process of different ways of opening the sliding sleeve as the breakthrough point, to study the technology in the application of the shale gas development.For two ways to open the sliding sleeves, one is releasing the ball of different sizes in proper order,the other is using the downhole sliding sleeve switch tools, the author has given their corresponding basic principle, the structure of the operation string, the specific construction process, the characteristics of this process and mainly optimized and improved the process of using the downhole sliding sleeve switch tools. The pressure drop of fracturing process has been analyzed in theory. Aiming at the main problem in technological application of the process by releasing the ball of different sizes in proper order, too much pressure drop caused by ball seats leads to the failure of fracturing, the author analyzed the corresponding theoretical calculation model and used the simulation software to verify and correct the theoretical calculation model. Considering China’s shale gas fracturing Series in general more than 15, the results show that the pitch needed to open the sliding sleeve fracturing mode of pump pressure is too large, so the fracturing operation is not suitable for shale gas. For the process by using the downhole sliding sleeve switch tools, the author get the required flow’s theoretical calculation model when switch tools work and used the simulation software to verify and correct that. The author made economic analysis on the processes of different ways to open the sliding sleeves. It is concluded that when the number of segments is small, selection of open type sliding sleeve has a good economic effect, when the number of segments is a long time, selecting switch type sliding sleeve has economic effect.The author has carried on the design research to the accessory tools of the switch type sliding sleeve sectional fracturing string, The research and development of the six-opening-degree fracturing sliding sleeve and the hydraulic sliding sleeve switch tool are mainly included in the research. The six-opening-degree fracturing sliding sleeve has the conventional switchable sliding sleeve’s technology advantages, besides, it realizes the function of adjusting the jet-flow rate when sandblast perforation is taken in the case of a combination of an open-hole packer and a sliding sleeve and solves the problem of gas cone effectively in the late stage of production when it is used with casing for cementing completion, it also has unique buckles to prevent the error operation to the sliding sleeve In downhole operation. The hydraulic sliding sleeve switch tool is the supporting tools for the six-opening-degree fracturing sliding sleeve, they don’t require precision location technology, have reliable performance and can be reused many times, which reduce the construction cost and improve the construction reliability. Then the author analyzed and designed on how to realize the sliding sleeve’s function of adjusting jet-flow’s kinetic energy in blasting perforation and solving the problem of gas and oil cone by finite element calculation and flow analysis. After determining the structure of the switch tool, the parts are designed and calculated, and the finite element analysis is carried out. The results verify the reliability of the switch.In the end, according to the results of the previous process model, the engineering calculation software for the well-cementing sliding sleeve fracturing technique is developed. The author firstly introduced the program of basic function and the running environment, and then explained the the preparation process of data and structure, then described software instructions, lastly, combined with the actual data of shale gas wells The author has carried on a calculation for an example. |
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