水平井裂缝诱导应力场影响因素分析

Impacting Factor Analysis of Horizontal Well Fracture Induced Stress Field

为了进一步探究裂缝周围应力场的分布规律,确定不同因素对诱导应力影响程度的强弱,利用单因素法对其进行了敏感性分析。基于传统诱导应力数学模型,推导出了多条裂缝叠加的水平诱导应力差数学模型,以裂缝水平诱导应力差为评价指标,经过无量纲化处理,建立了各参数敏感度函数,进而采用单因素敏感性分析方法,选定参数平均值和频次集中值作为基准值,定量评价了不同影响参数对裂缝水平诱导应力差的敏感性。结果显示裂缝净压力为最敏感因素,裂缝条数、裂缝高度、水平距离较为敏感,裂缝间距和地层泊松比最不敏感,从而确定了水平井压裂过程中调控参数的主次顺序,为优化设计水平井分段压裂的裂缝布置提供了有效依据。

To further study on stress field distribution pattern around fractures, determine impacting intensity from different factors on induced stress, the single factor method has been used to carry out sensitivity analysis. Based on traditional induced stress mathematical model, deduced multiple fractures stacked horizontal induced stress difference mathematical model. Taking the fracture horizontal induced stress difference as assessment index, through nondimensionalization process, established sensitivity function for each factor.Then using single factor sensitivity analysis, to select mean parameter and frequency concentration value as reference values, have quantitatively evaluated sensitivity of different impacting factors on fracture horizontal induced stress difference. The result has shown that the fracture net pressure is the most sensitive factor; fracture number, height and horizontal distance more sensitive factors; fracture spacing and stratum Poisson ration are least sensitive factors. Thus have determined the sequence of controlling parameters in horizontal well fracturing process, and provided effective basis for optimal design of horizontal well staged fracturing arrangement.