Stress release mechanism of deep bottom hole rock by ultra-high-pressure water jet slotting  

作　　者：Hua-jian Wang Hua-Lin Liao Jun Wei Jian-Sheng Liu Wen-Long Niu Yong-Wang Liu Zhi-Chuan Guan Hedi Sllami John-Paul Latham 

机构地区：[1]School of Petroleum Engineering at China University of Petroleum East China,Qingdao,Shandong,266580,China [2]Key Laboratory of Unconventional oil and Gas Development,Ministry of Education,Qingdao,Shandong,266580,China [3]Shandong Ultra-deep Drilling Process Control Tech R&D Center,Qingdao,Shandong,266580,China [4]MINES Paris Tech,PSLResearch Universty Geociences Rearch Center,bd Saint Miche,Paris,France VAEL Euroe,2 rue Johannes Keple 64000,Pau,France [5]Earth Science and Engineering,Imperial College London,London,SW72Az,United Kingdom

出　　处：《Petroleum Science》2023年第3期1828-1842,共15页石油科学（英文版）

基　　金：support of the National Key Research and Development Program of China(2021YFE0111400);the Shandong provincial natural science foundation(No.ZR2019MEE120);the horizon programme of the EU's funding of the ORCH YD project,EU-H2020(101006752-ORCHYD).

摘　　要：To solve the problems of rock strength increase caused by high in-situ stress,the stress release method with rock slot in the bottom hole by an ultra-high-pressure water jet is proposed.The stress conditions of bottom hole rock,before and after slotting are analyzed and the stress release mechanism of slotting is clarified.The results show that the stress release by slotting is due to the coupling of three factors:the relief of horizontal stress,the stress concentration zone distancing away from the cutting face,and the increase of pore pressure caused by rock mass expansion;The stress concentration increases the effective stress of rock along the radial distance from O.6R to 1R(R is the radius of the well),and the presence of groove completely releases the stress,it also allows the stress concentration zone to be pushed away from the cutting face,while significantly lowering the value of stresses in the area the drilling bit acting,the maximum stress release efficiency can reach 80%.The effect of slotting characteristics on release efficiency is obvious when the groove location is near the borehole wall.With the increase of groove depth,the stress release efficiency is significantly increased,and the release range of effective stress is enlarged along the axial direction.Therefore,the stress release method and results of simulations in this paper have a guiding significance for best-improving rock-breaking efficiency and further understanding the technique.

关 键 词：Hard rock SLOTTING Stress release Down hole pressures Poroelastic mechanics Fluid-structure Interaction Ultra-high-pressure water jet 

分 类 号：P631.4[天文地球—地质矿产勘探]