低渗透气藏产水压裂水平井产能评价

低渗气藏自然产能低，通常需要水力压裂等有效的储层改造手段才能正常见产，同时地层水的产出对气井产量的影响也不容忽视。基于对压裂水平井影响下流体的渗流规律分析，充分考虑流体渗流时产生的达西效应和非达西效应，划分流体的流动为地层内椭圆流以及裂缝到井筒间的线性流和径向流。引入椭圆坐标系下的标度因子和两相拟压力函数，对椭圆坐标系和直角坐标系进行换算，并利用当量井径理论和势的叠加原理，推导出地层内和裂缝内流动的综合产能方程。实例计算表明，该方程能较为准确地计算气井的无阻流量，具有较强的矿场实用性。从敏感性分析可知，裂缝的应力敏感和裂缝的技术参数对产能影响较大，其中裂缝参数存在一个最优设计值，在发挥气井产能同时也能带来最优的经济性；气井产水会严重影响气井产能，需要做好防水及治水措施。

Productivity evaluation of water-producing fractured horizontal wells in low permeability gas reservoir

Low-permeability gas reservoirs have low natural productivity, and usually require effective reservoir reforming methods such as hydraulic fracturing to normal production, and the influence of formation water production on gas well production cannot be ignored. Based on the analysis of the seepage law of fluids, the Darcy effect and non-Darcy effect are fully considered. The flow is divided into elliptical flow within formation and linear and radial flow within fracture. Based on the equivalent wellbore theory and the potential superposition principle, the comprehensive productivity of the flow in the formation and within the fracture was established respectively by introducing the scale factor and the two-phase pseudo-pressure function, converting the elliptical coordinate system and the rectangular coordinate system. The equation can calculate the open flow capacity of gas wells more accurately and has strong field practicability. From the sensitivity analysis, the stress sensitivity of the fracture and the technical parameters of the fracture have great influence on the productivity. There is an optimum design value of the fracture parameters, which can bring about the optimum economy while exerting the productivity of the gas well. Water production in gas wells has a great influence on gas well productivity, and it is necessary to do waterproof and water control measures.