基于统一强度理论的牙齿侵入井底岩石的机理分析  

Mechanism Analysis of Tooth Sink into Rock Based on Unified Strength Theory

作　　者：李玮[1] 闫铁[1] 陈世春 丛长江 

机构地区：[1]东北石油大学石油工程学院,黑龙江大庆163318 [2]中国石油渤海钻探工程有限公司塔里木第四勘探公司,新疆库尔勒841000 [3]中国石油渤海钻探工程有限公司塔里木钻井分公司,新疆库尔勒841000

出　　处：《石油钻探技术》2013年第4期32-36,共5页Petroleum Drilling Techniques

基　　金：国家重点基础研究发展计划("973"计划)项目"深井复杂地层破岩机理与高效破岩方法"(编号:2010CB226703);国家自然科学基金项目"钻头谐振激励下岩石的响应机制及破碎机理研究"(编号:51274072);国家科技重大专项"碳酸盐岩;火成岩及酸性气藏高效安全钻完井技术"(编号:2011ZX05021-002)部分研究内容

摘　　要：为了弄清深部地层复杂钻进条件下的牙轮钻头破岩机理,研究了牙轮钻头牙齿侵入井底岩石问题。在考虑井底压力的条件下,基于统一强度理论对牙齿侵入岩石的力学过程进行了分析,建立了含有统一强度参数的井底岩石侵入方程,并给出了不受轴向载荷、侵入深度和刃尖角影响的侵入系数。该方程考虑中间应力对井底岩石侵入系数的影响,在中间主剪应力的效应系数为0时,方程计算结果与Mohr-Coulomb强度理论所得结果完全相同。根据侵入方程,分析了内摩擦角、液柱压力、孔隙压力和刃尖角对侵入系数的影响。结果表明,侵入系数随中间主剪应力的效应系数的增大而增大,随内摩擦角和刃尖角的增大呈指数增大,随液柱压力的增大呈线性增大,随孔隙压力的增大呈线性减小。研究结果为牙轮钻头的现场应用提供了理论指导。In order to figure out the rock breaking mechanism in complex formation conditions, the teeth cutting into rock in bottom was studied. Considering the condition of the bottom hole pressure, based on unified strength theory, the mechanical process of teeth cutting into rock was analyzed, bottomhole rock sinking equation with unified strength parameters was established and sinking coefficient without the im- pact of axial load, invasion depth and bit angle have been worked out. The equation considers the impact of intermediate stress on sinking coefficient. The results of the equation and Mohr-Coulomb strength theory are identical when the effect coefficient of intermediate principal shear stress equals 0. The impact of angle of internal friction, fluid column pressure, pore pressure and bit tooth angle on sinking coefficient were ana- lyzed based on sinking equation. The results show that the sinking coefficient increases with the increase of effect coefficient of intermediate principal shear stress, increases exponentially with the increase of angle of internal friction and bit tooth angle, increases linearly with the increase of fluid column pressure, and de- creases linearly with the increase of pore pressure. The analysis of rock breaking mechanism of teeth can provide further theory guidance for cone bit onsite application.

关 键 词：统一强度理论 钻头牙齿 牙轮钻头 侵入系数 

分 类 号：TE21[石油与天然气工程—油气井工程]