高温高应力盐膏层弯曲井筒围岩失稳机理与控制理论研究

The part in the deep salt is the focus of China's oil and gas resource development, an effective way against low porosity and permeability of which is to introducing horizontal wells. Due to complexity of crooked wellbore wall rock deformation and failure on non-continuous and non-uniform salt cream layer, how to quantitatively describe the spatial and temporal evolution of it has been problems and the core issues of the international academic community. Starting from the regional salt-gypsum layer deposition, tectonic evolution, based on stress nonlinear prediction theory about the elastic-viscoplastic salt-gypsum layer, carrying out the experimental study on the salt cream creep under high temperature and pressure, building up a three-dimensional fabric modeling on dynamic evolution between interior salt cream and salt crystal micro-structure under different mineral composition - chemistry - temperature - stress coupling, establishing rheological model and failure criteria correspondingly, proposing the instability catastrophe theory on crooked wellbore wall rock, which have an comprehensive reflection of the physical properties - the degree of injury - chemical activity - factors of creep rate, analyzing the wellbore deformation law under different borehole curvature, physical properties, drilling fluid properties and temperatures and revealing a prediction mechanism on crooked wellbore wall rock destablization, and all above will provide a theoretical basis for a scientific guidance to parameter optimization of drilling fluid properties and drilling operation.

深层盐下油气藏是我国油气资源开发的重点。水平井是盐下低孔低渗油气藏开采的有效方式，由于非连续非均匀盐膏岩地层弯曲井筒围岩变形破坏的复杂性，如何定量描述盐膏层弯曲井筒变形的时空演化规律一直是国际学术界研究的难题和核心课题。从区域盐膏层沉积、构造演化角度出发，建立基于粘弹塑性的区域盐膏层地应力非线性预测理论。开展高温高压条件下盐膏层蠕变的实验研究，构建不同矿物组份-化学-温度-应力多场耦合下盐膏层内部及盐晶间微结构的动态演化三维组构模型，建立矿物成份、微结构、温度和应力条件下盐岩流变模型及破坏准则。提出综合反映盐膏层物理特性-损伤程度-化学活度-蠕变速率因素的弯曲井筒围岩失稳灾变理论，分析不同井眼曲率、盐膏层物理特性、钻井液性能和温度下井眼变形规律，揭示盐膏层弯曲井筒围岩失稳孕育发生机制，为科学指导钻井液性能和钻井作业参数优选提供理论基础。

深层盐下油气藏是我国油气资源开发的重点。水平井是盐下低孔低渗油气藏开采的有效方式，由于非连续非均匀盐膏岩地层弯曲井筒围岩变形破坏的复杂性，如何定量描述盐膏层弯曲井筒变形的时空演化规律一直是国际学术界研究的难题和核心课题。. 针对上述难题，结合盐膏层区域构造演化特征，建立了复合盐膏层三维地质力学预测模型，提出了采用 DRA 法和 Kaiser 效应法联合测定盐膏层地应力的新方法，确定了地应力场反演边界与实测标志层地应力之间的非线性映射关系，形成了基于粘弹塑性的区域盐膏层地应力非线性预测方法。基于微纳米表征技术，观察到流体作用下盐膏岩内部特征矿物引起微裂缝的差异性，考虑钻井液滤液与盐岩接触界面性质，建立了盐岩蠕变控制方程，分析了流体性质、围压对盐岩蠕变的影响规律。研制了大型物理模拟实验装置，发明了岩石大变形测量关键仪器和方法，系统模拟了不同井眼轨迹、地应力状态与温度下盐膏层弯曲井眼围岩变形特征的评价实验，在室内与现场发现了复合盐膏层界面开裂、井壁围岩变形与井眼轨迹的内在联系，揭示高陡、高应力、强水敏复合盐膏层井壁围岩的变形机理，提出了超深盐膏层变曲率变方位井壁稳定力学模型，建立井壁稳定安全钻井液密度图版，为复合盐膏层各类井型设计与安全钻井新理论提供了基础与方法。. 近三年来，相关研究成果在Journal of Petroleum Science and Engineering、Petroleum Science and Technology、Rock Mechanics and Rock Engineering和石油学报发表论文6篇（SCI论文1篇，EI论文2篇），参加The 8th Asian Rock Mechanics Symposium和SPE Asia Pacific Unconventional Resources Conference and Exhibition并作分组报告，授权国家发明专利2项，实用新型专利1项，获得中国石油与化学工业联合会科技进步奖一等奖2项。