低渗气藏水平井分段压裂间距优化设计方法

The Optimal Design Method of Stage Interval for Horizontal Well Fracturing in Low-Permeability Gas Reservoirs

水平井分段压裂已经成为低渗透气藏开发的必需手段,其中分段间距对压裂施工和压后效果具有较大影响。不同于以往采用数值模拟的手段,在总结了直井压后生产效果和经验后,综合考虑水平井分段压裂后的产能和应力干扰两方面的因素,给出水平井分段间距优化的计算方法。在水平井压裂后的产能至少应大于裸眼产能的前提条件下,假设地层内气体线性流进裂缝后,径向流进井筒,推导出计算压裂最大分段间距的计算公式。同时,利用压裂时裂缝周围产生的应力干扰理论,可确定出水平井压裂时的最小分段间距。运用这两种计算方法,最终确定出水平井分段压裂间距的最大和最小范围。通过计算实例进一步表明所提出的方法比较适用于现场压裂的快速设计。

Staged fracturing of horizontal wells is an essential development technology for low-permeability gas reservoirs, and the stage interval will affect fracturing treatment and production rate greatly. Different from the previous reservoir simulation method, the optimal design method in this paper is based on the production of frac-tured vertical well and experience to determine the stage spacing, and considers both production and stress distur-bance. As a prerequisite, the productivity of horizontal well should be equal to the open well＇s at the least, at the meaning while, assuming that gas flows linearly from formation into fractures, and enters the wellbore radially, the calculation equation is derived to determine the max stage interval. The minimum stage interval can be calculated by stress disturbance theory around fractures. At last, the two calculation methods are combined to define the maximum and minimum scope of stage interval. A computation case shows that the optimal method is optional for on-site rapid fracturing design.