Stability Analysis Of Horizontal Directional Drilling Hole-wall And Application In Engineering

Drilling technology is widely used in geological prospecting, drilling engineering, oil and gas exploration and development, tunnel advanced detection, pipe shed support, gas drainage, non excavation laying and other engineering fields. Drilling in the process of use and drilling hole-wall stability problem is drilling engineering and technical personnel of most concern. Hole-wall instability hinders the boring construction, and extend the boring construction period and increase the project cost. Serious hole accidents often causes serious consequences: On the one hand, drilling instability will be forced to scrap drilling and drilling tools, causing human, material and the waste of time, On the other hand, drilling instability will lead to cannot get the real geologic data of underground gas resources, also can cause leakage and resource waste and environmental pollution. At present, most drilling hole-wall stability study in the vertical drilling for research object. Many experts and scholars in the vertical drilling hole-wall stability, get a thorough study of the results have value. However, with the drilling technology in tunnel advanced detection, pipe shed support, gas drainage, trenchless laid and other engineering application fields are increasing. Horizontal directional drilling hole-wall stability problem has become urgent research topic.This article takes horizontal directional drilling hole-wall stability problems as the main research object. Complete the following main research work:⑴According to the theory of elasticity and establish a primitive geostress and drilling fluid pressure effect of horizontal directional drilling hole-wall stability problem of mechanics model.⑵Influence of horizontal directional drilling hole-wall stress distribution with drilling fluid pressure,drilling depth and lateral pressure coefficient was analyzed.⑶According to the Coulomb criterion and maximum normal stress theory derived the calculation formula of caving pressure and formation fracture pressure under different lateral pressure coefficient.⑷Drilling fluid pressure was to determine by the collapse pressure and fracture pressure. Put forward the concept about optimal drilling fluid pressure, and the calculation formula is deduced.⑸More research will be used during the advanced detection of the Mingyazi extra-long tunnel and Wulan coal gas drainage engineering, through calculation and analysis to determine the optimal drilling fluid pressure.This research project for the horizontal directional drilling holes in the fluid pressure selection provides a scientific reference.