隔层厚度与第二胶结面抗剪切强度关系研究  

Study of Relationship Between Interlayer Thickness and Shearing Strength at Cement-Formation Interface

作　　者：顾军[1] 陈雪峰[1] 

机构地区：[1]中国地质大学构造与油气资源教育部重点实验室,湖北武汉430074

出　　处：《中国矿业大学学报》2010年第2期219-222,258,共5页Journal of China University of Mining & Technology

基　　金：国家自然科学基金项目(40972103,50774071);国家高技术研究发展计划(863)项目(2007AA06Z205)

摘　　要：水力压裂是高效开发低渗透油气田的主要工艺,而导致压裂失败或爆性水淹的主要原因是层间发生窜流,层间窜流的位置在隔层处的第二胶结面,因此研究隔层厚度与第二胶结面抗剪切强度之间的关系具有重要意义.基于提出的第二胶结面仿真试验方法,定量验证了当隔层厚度<1m时,第二胶结面抗剪切强度随隔层厚度减小而降低.提出了隔层界面窜流系数ξ的概念,并建立了相关数学模型,即ξ越趋近于0,隔层界面的抗窜能力越强;仅当ξ>1时,第二胶结面才会发生窜流;当隔层厚度<1m时,隔层厚度对第二胶结面抗剪切强度无明显影响.薄隔层压裂时第二胶结面是否会发生窜流取决于压裂压力、泥饼厚度、井筒尺寸和第二胶结面抗剪切应力,与隔层厚度无关.Hydraulic fracturing is a main process for ty oilfield. The interlayer channeling located at the an efficient development of low permeabili-cement-formation interface in the interlayer is the main cause of the fracturing failure or the sudden water flooding. So, it is very important to study the relationship between the interlayer thickness and the shearing strength at cementformation interface. Based on the proposed simulation experimental method, the numerical simulation results show that the shearing strength decreased with the decreasing of the interlayer thickness which is less than 1 m. The concept of channeling coefficient of interlayer interface ξ： and related mathematical model were proposed. When ξ is close to 0, the channeling resistance ability of interlayer interface become higher. Only when ξ is more than 1, the channeling at cement-formation interface will occurs. The interlayer thickness has no significant effect on the shearing strength when the interlayer thickness is less than 1 m. Whether the channeling of the thin interlayer occur is determined by the fracturing pressure, thickness of mud cake, hole size and shearing force at cement-formation interface, and has no correlation with the interlayer thickness.

关 键 词：薄隔层压裂 层间窜流 第二胶结面抗剪切强度 隔层厚度 隔层界面窜流系数 

分 类 号：TU432[建筑科学—岩土工程]