摘要
重复压裂井中新裂缝重定向的主要影响因素有人工裂缝、孔隙压力变化、地层温度变化。应用弹性力学、孔隙弹性理论以及热弹性理论建立三者相应的诱导应力场数学模型,并用ANSYS软件进行诱导应力的计算。结果表明:诱导应力在最大水平主应力方向和最小水平主应力方向的改变量不同,在最大水平主应力方向上应力变化值高于最小水平主应力方向上的变化值;如果诱导应力差大于初始水平应力差,则初始最大水平应力方向将变为目前最小水平应力方向,重复压裂新裂缝将垂直于初始裂缝方向起裂。
Reorientation of new fractures in a refracturingw ell is mainly controlled by artificial fracture,pore-pressure andf ormation-temperature variation.In this study,a mathematicalm odel of stress-induced field is developed based on elastic mechanics,porous and thermal elastic theory;and induced stress isc alculated by ANSYS software.Results show that(1)for induceds tress,the rescale is different at the direction of both maximuma nd minimum horizontal major stress;(2)in a direction of maximum horizontal major stress,stress change is much higher;and(3)a direction of primary maximum horizontal stress will change to another direction of current minimum horizontal stress if stress-induced difference is larger than primary horizontal stress difference,as a result,new fractures may be cracked vertically to primary direction of fracture.
出处
《天然气技术》
2010年第1期30-32,共3页
NATURAL GAS TECHNOLOGY
基金
国家自然科学基金项目(编号:50604022)的资助
