鄂尔多斯盆地苏里格致密砂岩气藏多层合采干扰指数模型及应用

Model of cross-flow interference index and application for multi-layer commingled production in Sulige tight sandstone gas reservoir,Ordos Basin

多层合采是鄂尔多斯盆地苏里格致密砂岩气藏目前开发的主要方式,致密气、水层层间是否存在干扰、如何表征是气藏能否有效开发需要关注的重要问题。通过设计裂缝沟通的层间合采物理模拟实验流程和方案,开展了不同层间组合模式的开发模拟实验。结果表明:致密气、水层多层合采过程中,无论是只射开气层,还是同时射开气、水层,都普遍存在层间气、水交互越流的现象,从而产生层间干扰,降低气藏采出程度。基于此提出致密砂岩气藏多层合采层间干扰指数概念,并运用多元线性回归方法拟合得到干扰指数模型。干扰指数决定于储层物性的好和差,含水饱和度越高、水层与气层渗透率比值越大(大于临界值1),层间干扰出现得越早,干扰指数越大。最后基于干扰指数模型,建立致密气藏气井产能评价新方法,气井实例计算结果表明,干扰指数曲线可以有效描述气井的层间干扰动态,基于干扰指数模型的产能评价方法计算的气井产能和生产动态与生产历史基本一致,证明了干扰指数模型的有效性与准确性。因此,干扰指数模型可以有效预测苏里格致密砂岩气藏气井的产能和生产动态。研究成果对于苏里格致密砂岩气藏的高效开发具有重要的理论指导和实践意义。

Multi-layer commingled production is the main feature of gas well development in Sulige tight sandstone gas reservoirs,Ordos Basin.Whether there is interference between layers and how to characterize them are important issues for effective development of gas reservoir.The physical simulation experiment process and scheme of interlayer commingled mining with fracture communication are designed,and the development simulation experiment of different interlayer combination modes is carried out.The results show that in the process of multi-layer commingled production of tight gas and water layers,whether it is only gas layers production or gas and water layers production at the same time,there is a common phenomenon of cross flow of gas and water between layers,resulting in interlayer interference and reducing the recovery of gas reservoirs.Based on this,the concept of interlayer interference index in multi-layer commingled production in tight sandstone gas reservoirs is proposed,and the interference index model is obtained by fitting the multiple linear regression method.The interference index is related to the physical properties of the reservoir.High water saturation and great permeability ratio of water layer to gas layer(greater than the critical value 1)can result in the early occurring of interlayer interference and great interference index.Finally,based on the interference index model,a new method for productivity evaluation of gas wells in tight gas reservoirs is established.The calculation results show that the interference index curve can effectively describe the interlayer interference performance of gas wells.The productivity and production performance of gas wells calculated by the productivity evaluation method based on the interference index model are consistent with the production history,which proves the effectiveness and accuracy of the interference index model.Therefore,the interference index model can effectively predict the productivity and production performance of gas wells in Sulige tight sandstone gas reservoir.The research results have important theoretical guidance and practical significance for the efficient development of Sulige tight sandstone gas reservoir.