径向井压裂激活天然裂缝模型研究

径向井压裂技术是在主井眼钻出径向井的基础上再实施压裂,是一种新型的非常规储层改造技术.针对径向井穿过天然裂缝后,天然裂缝对裂缝起裂的影响开展研究,建立径向井压裂激活天然裂缝解析模型,分析天然裂缝位置、倾角、方位角以及储层地应力状态对裂缝起裂的影响.结果表明:随天然裂缝与主井筒距离增大,天然裂缝拉伸激活压力显著增大,剪切激活压力变化较小;随天然裂缝倾角增大,天然裂缝激活压力增大,方位角对激活压力无影响;正断层和逆断层地应力状态下,天然裂缝容易激活;走滑断层地应力状态下,天然裂缝较难激活.研究成果为径向井压裂技术在含天然裂缝储层推广应用打下了基础.

Research on Activation Model of Natural Fracture by Radial Wellbore Fracturing

Radial wellbore fracturing technology is a new unconventional reservoir reconstruction technology, which is based on the radial wellbore drilled from the main wellbore. The influence of natural fracture on fracture initiation is studied after radial wellbore intersect with natural fracture. The analytical model of natural fracture activation by radial wellbore fracturing is established. The influence of natural fracture location, natural fracture dip angle, azimuth angle and reservoir in-situ stress state on fracture initiation is analyzed. The results show that: with the increase of the distance between the natural fracture and the main wellbore, the tensile activation pressure of the natural fracture increases significantly, while the shear activation pressure changes slightly.With the increase of the natural fracture dip angle, the natural fracture activation pressure increases, and the azimuth angle has no effect on the activation pressure.Under the normal fault and reverse fault stress state, the natural fracture is easy to activate; under the strike slip fault stress state, the natural fracture is difficult to activate. This study lays a foundation for the application of radial well fracturing technology in reservoirs with natural fractures.