【摘要】 诱导裂缝性井漏是钻井过程中常见的井漏类型,控制此类漏失的关键是阻止裂缝的延伸。应用岩石断裂力学的理论与方法,揭示了钻井液堵漏阻止诱导裂缝延伸的作用机理。分析了堵漏后裂缝内压力分布,提出人工隔墙对裂缝壁面的支撑应力应与钻井液的液压相等的新观点;建立了诱导裂缝性漏失堵漏的断裂力学模型,推导了裂缝尖端应力强度因子的计算公式;研究了堵漏材料不同封堵位置形式对阻止诱导裂缝延伸的影响,提出堵漏材料在裂缝入口后较短距离内的封堵为封堵诱导裂缝的最佳位置形式,堵漏评价装置必须能反映这种封堵形式;给出了堵漏阻止诱导裂缝延伸的必要条件,即裂缝尖端部分流体压力必须低于水平最小主应力,增加缝内流动压降或加速缝尖段内流体压力耗散有利于裂缝的阻裂。更多还原

【Abstract】 Induced fracture lost circulation during the drilling process is a common type of lost circulation,the key to control it is to stop the propagation of the fracture.Aided by the rock fracture mechanics,the mechanism of preventing an induced fracture from propagating was proposed.On the basis of analyzing the pressure distribution in the facture after plugging,the viewpoint that the support stress of the plug in the induced fracture should be equal to the drilling fluid′s pressure is presented.The fracture mechanics model and the formula for calculating are developed.The effect of blocking location on preventing the extension of an induced fracture was studied,the results demonstrated that the best type of plugging location is certain distance near the facture mouth;the evaluation device must reflect this plugging location form.The requirements of preventing the induced fracture are presented,that′s to say the fluid′s pressure in the isolated fracture tip part must be lower than the horizontal minimum principal stress,it will help stop the propagation of the induced fracture to accelerate the pressure drop.更多还原