川西南部灰岩地层取心层裂机理

发布时间：2018-04-24 08:19

本文选题：高地应力 + 损伤尺寸　；参考：《科学技术与工程》2017年34期

【摘要】：在深部高地应力地层中取心,岩心层裂(饼化)是一种常见的工程现象。岩心层裂和岩体的物性、力学性质以及原地应力密切相关。为研究钻井取心过程中岩心层裂现象的机理,结合川西南部地区A井和B井取心过程中的岩心层裂现象,考虑岩石矿物组分与岩石脆性指数的关系,基于应力集中的非均匀岩石拉伸破坏模型,给出了岩心层裂现象产生的判据,采用理论计算对饼化现象进行了验证。研究结果表明:脆性矿物含量越高,岩石脆性越强,越易生成裂缝;岩心套取是一个卸载水平方向最大主应力的过程,卸载速度越快,损伤处的附加拉应力越大,且对应被激活损伤的尺寸就越小,当附加拉应力大于岩石抗拉强度时,会出现岩心层裂现象,随着取心的继续此过程将重复地发生下去。
[Abstract]:Core spallation is a common engineering phenomenon in deep high ground stress strata. Core spallation is closely related to physical properties, mechanical properties and in-situ stress of rock mass. In order to study the mechanism of core spallation during coring drilling, the relationship between rock mineral composition and rock brittleness index is considered in combination with the core spallation in well A and well B in southern Sichuan. Based on the tensile failure model of inhomogeneous rock with stress concentration, the criterion of spallation of core is given, and the theoretical calculation is used to verify the phenomenon of pancake. The results show that the higher the content of brittle minerals, the stronger the brittleness of rock and the easier it is to form cracks, and the higher the unloading speed is, the greater the additional tensile stress is at the damage site. When the additional tensile stress is greater than the rock tensile strength, the core spallation will occur, and this process will be repeated as the coring continues.
【作者单位】：西南石油大学油气藏地质及开发工程国家重点实验室;
【分类号】：P634

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