深水浅层破裂压力计算方法  

Calculation method for fracture pressure of deep sea shallow formation

作　　者：孙清华[1] 邓金根[1] 闫传梁[1] 蔚宝华[1] 刘书杰 刘正礼 肖坤[1] 

机构地区：[1]中国石油大学(北京)油气资源与探测国家重点实验室,北京102249 [2]中海石油研究总院,北京100027 [3]中海石油(中国)有限公司深圳分公司,广东深圳518067

出　　处：《中南大学学报（自然科学版）》2015年第4期1402-1408,共7页Journal of Central South University:Science and Technology

基　　金：国家自然科学基金创新研究群体项目(51221003);国家自然科学基金资助项目(51174219);国家科技重大专项(2011ZX05026-001-01)~~

摘　　要：假设深水浅部地层为均质、各向同性的理想弹塑性材料,将井眼周围的地层分为弹性区和塑性区两部分,地层屈服后服从Mohr-Coulomb强度准则,推导出深水浅层不排水时的塑性区半径和井周应力场的理论解答,引入土力学中的超孔隙压力理论,得出井眼钻开引起的超孔隙压力在井眼周围的分布规律,结合水力压裂理论分析了深水浅部地层的破裂机理并推导出破裂压力的理论公式。该理论的计算结果与工程实测结果接近,证明该理论的可靠性的。深水浅部地层未成岩,在分析深水浅部地层的地质力学问题时,应当考虑引入土力学中的相关理论进行分析。Assuming the shallow formation is a homogeneous, isotropic and ideally elastoplastic material, the formation around a borehole was divided into elastic zone and plastic zone. Formation in the plastic zone followed the Mohr-Coulomb criterion. The theoretical solution of the radius of plastic zone and stress distribution in two zones were derived in undrained condition. With the introduction of excess pore pressure theory in soil mechanics, the distribution rule of excess pore pressure around a borehole induced by drilling was obtained. Combined with hydraulic fracturing theory, the fracture mechanism of shallow formation in deep sea field was analyzed and the theoretical formula of fracture pressure was provided. The theoretical calculation results are quite close to the measured results of engineering practice, so the reliability of the theory is initially confirmed. As deep sea shallow formation is unconsolidated, the relevant theory of soil mechanics analysis should be taken into account when the geological mechanics problems of deep sea shallow formation are analyzed.

关 键 词：深水钻井 理想弹塑性 井周应力 超孔隙压力 破裂压力 

分 类 号：TE21[石油与天然气工程—油气井工程]