致密气储层渗透率瓶颈区表征及气相相对渗透率改善方法研究

Tight gas production in China has accounted for one third of total annual natural gas production, and becoming more and more important for the supply of natural gas. One of the characteristics of tight gas reservoir is the compactness of the reservoir, and it leads to the complexity of fluid percolation law. There is a permeability jail that the gas-water two phase cannot flow in this area. The classification and characterization of permeability jail and the improvement of gas relative permeability should be solved to enhance the development effect of tight gas reservoir. In this study, tight gas reservoirs are took as research examples to study these scientific issues. Firstly, some experimental methods will be used to study the pore structure features of tight reservoir. Secondly, the characteristics of gas-water relative permeability curves will be analyzed. It will clear that the narrow sense of permeability jail in tight reservoir is whether exists or not. The classification limit and characterization parameters will be studied for the broad sense of permeability jail. The relationship between relative permeability curve and pore structure will be researched in this part. Thirdly, the capability of organic solvents will be studied through experiments, and these organic solvents will be used to influence pore structure and the relative permeability of gas phase. Finally, according to the parameter values obtained from the evaluation results, the dynamic changes of the production of tight gas wells will be analyzed by numerical simulation technology. The innovations of this study are reflected in the classification and characterization of permeability jail, and the improving methods of tight reservoir gas relative permeability. Through the study, the research methods about how to characterize permeability jail and improve the relative permeability of gas phase will be established. The results can provide a scientific basis for the efficient development of tight reservoirs.

我国致密气年产量已占天然气总年产量的1/3，成为天然气供应的一支重要力量。储层的致密特征导致流体渗流规律复杂，储层中气-水两相流体能够共同流动的区间范围相对较小，甚至存在一个渗透率瓶颈区，气-水两相都不能流动。如何划分与表征渗透率瓶颈区，改善气相相对渗透率是提高致密气开发效果急需解决的科学问题。项目首先利用室内实验，研究致密储层的微观孔隙结构特征，分析气-水相对渗透率曲线特征，明确狭义渗透率瓶颈区是否存在，提出广义渗透率瓶颈区的表征参数及划分界限，探寻孔隙结构与相渗曲线的关系；在此基础上，研究有机溶剂对岩心微观孔隙结构、气相相对渗透率的影响，应用数值模拟技术对致密气井的生产动态进行分析。创新点体现在渗透率瓶颈区的划分与表征，以及致密储层气相相对渗透率的改善方法研究。通过项目的研究，能够形成系统的致密气储层渗透率瓶颈区表征及气相相对渗透率改善方法，为致密油气储层高效开发提供科学依据。

我国致密气年产量已占天然气总年产量的1/3，成为天然气供应的一支重要力量。储层的致密特征导致流体渗流规律复杂，储层中气-水两相流体能够共同流动的区间范围相对较小，甚至存在一个渗透率瓶颈区，气-水两相都不能流动。如何划分与表征渗透率瓶颈区，改善气相相对渗透率是提高致密气开发效果急需解决的科学问题。. 基于储层地质、油层物理、气藏工程等理论方法，主要以室内实验为手段进行研究。首先明确与相渗曲线有内在关系的储层微观孔隙结构特征；其次是利用实验方法测定岩样的相渗曲线，表征渗透率瓶颈区；在有机溶剂溶液性能测定的基础上开展气相相对渗透率及渗透率瓶颈区变化的定性分析与定量评价；最后利用数值模拟技术，模拟生产动态的变化并形成系统的致密气储层渗透率瓶颈区表征及气相相对渗透率改善方法。. 按照研究计划完成了所有的研究工作，取得的重要成果如下：. ⑴刻画了致密气储层微观孔隙结构特征；明确了致密气储层气-水相渗曲线形态，制定了相渗曲线分类标准，可以为其他研究提供数据支撑及支持，具有推广价值。. ⑵建立了渗透率与微观孔隙结构表征参数之间的关系式，对于致密气储层，形成了新的一套渗透率评价方法。. ⑶创建了广义渗透率瓶颈区划分及表征方法，创新完善了致密气藏生产动态预测理论基础。. ⑷筛选得到改善渗透率瓶颈区的有机溶剂类型及浓度，通过模拟对比验证了有效性，可以在现场推广，提高致密气藏开发效果。. 以第一/通讯作者发表SCI论文4篇，授权国内发明专利1件、申请国内发明专利2件，登记软件著作权2项，申请人入选自然资源部高层次科技创新人才工程，获省部级科技进步一等奖2项，培养硕士研究生5人。