致密气藏压裂倾斜缝压力动态分析

针对致密气藏斜井筒压裂形成的倾斜缝，将裂缝离散为微元，推导了裂缝内部有限导流数值解；采用倾斜板
源函数及势叠加原理得到了气藏流动解析解，通过将缝内流动和气藏流动在裂缝面上进行压力及流量耦合，建立了压
裂倾斜缝不稳定流动模型。划分了流动阶段，给出了对应的拟压力或拟压力导数解析表达式，分析了储层及压裂参数
对压力动态的影响。结果表明：不考虑井筒储存效应时，压裂倾斜缝流动形态分为：裂缝与地层双线性流、地层线性
流、早期径向流、拟复合线性流和晚期拟径向流。井筒存储效应产生的井筒续流段会掩盖双线性流。裂缝倾斜角和储
层渗透率各向异性对井底压力动态影响时间最长，会一直延续到晚期拟径向流阶段。无因次裂缝导流能力唯一决定
了裂缝与地层双线性流和地层线性流的出现与否及持续时间。随着气藏厚度的增大，早期径向流的持续时间增加，拟
复合线性流的出现时间推迟。最后，利用苏里格气田一口压裂定向井实例证明了该模型的正确性。

Transient Pressure Analysis of Inclined Fracture in Tight Gas Reservoirs

In view of the inclined hydraulic fracture formed by slant well fracturing，the numerical model for fracture flow was
derived based on the discrete fracture segments and the analytical model for reservoir flow was established by combining slant
plane source function and the superposition principle. A semianalytical model for inclined fracture was developed by coupling
the numerical fracture flow model and the analytical reservoir flow model dynamically in this paper. The flow regimes were
defined，the corresponding pressure or derivate analytical equations were derived and the effect of reservoir and fracture parameters
on transient responses was investigated. The results show that there are five flow regimes including fracture/formation
bilinear flow，formation linear flow，early radial flow，pseudo-compound linear flow and later pseudo-radial flow for inclined
fracture in the absence of the effect of wellbore storage. The wellbore afterflow caused by wellbore storage may mask the fracture/
formation bilinear flow. The period of the effect of the inclination angle and permeability anisotropy on transient pressure
is very long，which will last to later pseudo-radial flow. The existence and duration of fracture/formation bilinear flow and
formation linear flow is only determined by dimensionless fracture conductivity. Finally，a field test in fractured directional
well from Suliger Gas Field verified the validity of the model.