多因素影响下低渗压裂气井产能分析

Analysis of the Low Permeability Fracturing Gas Well Productivity under the Influence of Multiple Factors

低渗气藏具有低孔、低渗、高含水等地质特点,气体流动一般会受到高速非达西效应、启动压力、应力敏感、滑脱效应影响,且气藏生产井往往需要压裂改造才具有工业价值。通过保角变换建立了同时考虑这4种因素影响的压裂气井产能方程,可以根据现场需要分析任意组合情况下的气井产能。分析了各种因素对压裂气井产能的影响,认为应力敏感、启动压力、高速非达西效应会减小气井产能,其中应力敏感影响最大;启动压力影响相比未压裂气井影响很小;滑脱效应可以小幅度增加气井产能。考虑这些因素影响的气井无阻流量比不考虑时下降13.68%,因此在条件允许的情况下尽可能的考虑这些因素的影响。该研究为压裂气井产能预测和合理配产提供了理论依据。

The low permeability reservoir has the geological characteristic of low porosity,low permeability and high water saturation,the gas flows will be effected by high-speed non-Darcy effect,start-up pressure,stress sensitivity and slippage effect,and the gas production wells always do not have the industrial value unless fracturing the reservoir. By conformal transformation,the fracturing gas well productivity equation is built considering the 4 factors,which can analyze the gas well production capacity of arbitrary combination based on the need of the field. By analyzing the effect of each factor on the fracturing gas well deliverability equation,it shows that stress sensitivity,start-up pressure,high-speed non-Darcy effect can decrease gas well productivity,among them the effect of stress sensitivity is the biggest,the effect of start-up pressure in fracturing gas well is far smaller than in the not fracturing,and the slippage effect can increase the fracturing gas well productivity a certain extent. The gas well open-flow capacity considering these factors is less 13. 68 than that of no considering. So,the influences from these factors should be considered in the conditions allow. This study provides the theoretical foundation for fracturing gas well productivity forecast and rational proration.