Research On Reaming Technology Of Small Borehole While Drilling

Slim-hole sidetracking, is one of the important measures taken by every oil field to cut the cost and increase the production, and is mainly used to help some oil-field’s old blocks to recover the productive capacity of deepen wells, deformed wells and accident wells which have certain value for exploitation. One of the critical technologies of slim-hole sidetracking is Reaming while drilling(RWD). This RWD technology could solve the hole diameter’s reduction or borehole wall’s collapse that caused by stratum’s creeping or instability, and also works to the poor cementing quality of slim-hole. For the aspect of borehole wall’s strain, there are obvious differences between conventional well and stepped well formed by reaming. Therefor, it is necessary to design a kind of reaming blade that could stick to the sidewall efficiently and cut the rock steadily according to the characters and demands of project. On the basis of investigations and studying for both domestic and foreign reaming blade’s structure, this article tries to design the reaming blade’s structure and it’s placement of tooth referring to the way how PDC bit goes. With the finite element analysis(FEA) software, this article analyzes the flow field of blade’s flow channel. Through the sidewall’s rock breaking simulation considering multi-environment load situation, interaction characteristics are acquired, during different processes that bit’s tooth breaking rock under overlying strata pressure, horizontal crustal stress and well bore pressure. Ultimately, the tooth placement parameters of reamer blade get adjusted and optimized effectually. Under below are the works done in this article:(1) Investigated both domestic and foreign status quo for reamer’s structure, and researched the reamer’s developing process as well as it’s current representative structure and function axiom, providing the guidance to later design.(2) After gaining the existing great reamer’s design principle, to satisfy the enlarging hole demand of open hole section in the stage of comprehensive drilling after slim-hole sidetracking, here designed a RWD reamer with hard supporting capacity and advanced function, which has a big and stable ratio of expanding diameter.(3) Referring to the PDC bit, here are some works did to the reamer blade’s structure and tooth placement. Aiming at the situation that reamer blade always brings about bit balling, there is an improving design by broadening the watershed and reducing the depth. Through the flow field analysis by ANSYS, studied how the drilling fluid’s displacement, viscosity, density and dip of ejector affect the tooth surface’s flow velocity on the cutting edge.(4) Made a simulation about how single tooth breaking the stepped sidewall rock, and also optimized the reamer’s parameters for tooth placement.In a word, these works done in the article would be helpful to understand the axiom that how reamer breaks annular sidewall, and would be guidance for the design of reamer and its blade also the implementation of RWD.