Study On The Sidewall Coring Technical Proposal Of Scientific Drilling Superdeep Borehole

In the near future, our country will be bound to carry out a super-deep borehole with depth over 10000 m which is part of scientific drilling project. The sidewall coring technique, which is one of the important method of drilling and coring, should get attention and investment on research and development as soon as possible.By reading articles and collecting information and data, this author did some detailed investigation and in-depth research on the existing sidewall coring techniques at home and abroad; summed up almost all of the existing sidewall coring techniques; classified these techniques and divided them into five categories: (1)press-in; (2)perforating; (3)deflecting and drilling; (4) continuous-cutting; (5)rotary drilling. Then the coring principles of every coring category were analyzed; part of representative tools were selected and given detailed description; technical specifications of these sidewall coring tools were listed and compared in this paper. In addition, the feasibility of these techniques applied in super-deep borehole of scientific drilling was also discussed.The main factors and a few issues affecting sidewall coring of super-deep borehole on scientific drilling were then discussed. The effect of high temperature, high pressure environment, cable length and tension, mud and other factors on sidewall coring of super-deep borehole were given a brief analysis.On the basis of in-depth research on the existing sidewall coring techniques at home and abroad, three kinds of sidewall coring techniques suitable for super-deep borehole on scientific drilling were summed up: deflecting and drilling, continuous-cutting, rotary drilling. The advantages and disadvantages of the three methods applied to sidewall coring of super-deep borehole were analyzed and compared. On this basis, a recommendation that the more advanced rotary sidewall coring technique was used in super-deep borehole was presented.For some shortages of the existing Rotary Sidewall Coring Tools(RSCT), a initial design of a new type of RSCT was done. The initial design work was mainly on the structure component and mechanism of pushing bodies, drilling and coring bodies, and counting bodies. Then a brief mechanics analysis was made. Subsequently, a preliminary design of hydraulic system and security system of the RSCT was made.Finally, a prospect of future research content on the sidewall coring techniques applied in super-deep borehole on scientific drilling was made.