承压封堵裂缝止裂条件影响因素分析  

Key Factors for Inhibiting Fracture Propagation during Leakage Control under Pressure

作　　者：贾利春 陈勉[2] 谭清明 孙振[3] 吴嗣跃[4] 

机构地区：[1]中国石油川庆钻探工程有限公司钻采工程技术研究院,四川广汉618300 [2]油气资源与探测国家重点实验室(中国石油大学(北京)),北京102249 [3]中国石化江苏油田分公司石油工程技术研究院,江苏扬州225009 [4]中国石油西南油气田分公司川东北气矿,四川达州635000

出　　处：《石油钻探技术》2016年第1期49-56,共8页Petroleum Drilling Techniques

摘　　要：对于裂缝性地层中发生的井漏问题,通常采用堵漏材料承压封堵阻止裂缝扩大,但到目前为止对裂缝止裂条件的影响因素缺乏深入分析,为此,通过分析承压封堵后缝内的压力变化,应用叠加原理推导了缝内压力引起的缝尖应力强度因子分量公式,并在此基础上分析了其随不同影响因素的变化规律。分析表明,随着封堵长度增长、钻井液黏度增大或封堵渗透率降低,应力强度因子分量减小,裂缝逐渐满足止裂条件;裂缝长度越长或井内压力越高,应力强度因子分量越大,裂缝越不容易止裂;封堵位置越靠近缝尖处,应力强度因子分量越大,越不利于裂缝止裂。缝内压力引起的缝尖应力强度因子分量与封堵长度、封堵位置均近似满足三次函数关系,与钻井液黏度、井内压力均满足线性函数关系,与封堵渗透率近似满足对数函数关系,与裂缝长度满足幂函数关系。研究认为,承压堵漏过程中,在裂缝长度和井内压力不变或无法控制时,通过优化调整堵漏液配方和钻井液性能可实现裂缝止裂。In order to minimize lost circulation time while drilling through fractured formations,lost circulation plugging materials are generally used to prevent fracture propagation under pressure.So far,however,no further analysis has been performed on the key factors that arrest or inhibit fracturing.In this paper,a related study was conducted.First,analysis was conducted on fracture pressure variation after leakage control.Second,a formula for the fracture terminations and a stress intensity factor induced by fracture pressure was derived using the principle of superposition.And third,the influencing factors of the stress intensity factor were analyzed.It is shown that the stress intensity factor decreases with the increase of plugging length,drilling fluid viscosity,and the decrease of the plugging permeability,and consequently arrest/inhibition of propagation conditions are gradually satisfied.The stress intensity factor increases as fracture length or subsurface pressure increases or plugging location gradually approaching fracture terminations.The higher the stress intensity factor is,the more difficult the fracture inhibition.The functional relationships between the stress intensity factor induced by fracture pressure and other parameters are as follows.The formula shows approximately a cubic relationship with plugging length and location,linear relationship with drilling fluid viscosity and subsurface pressure,approximately a logarithmic relationship with plugging permeability,and power relationship with fracture length.In summary,fracture propagation can be stopped through optimizing circulation lost materials and improving drilling fluid properties if the fracture length and subsurface pressure are constant or out of control during pressured leakage control.

关 键 词：裂缝性储层 井漏 承压堵漏 止裂 应力强度因子 影响因素 

分 类 号：TE21[石油与天然气工程—油气井工程] TE283