云南恩洪地区煤储层孔裂隙特征及孔渗性分析

研究煤中孔隙和裂隙,对煤层气勘探开发至关重要。云南恩洪地区煤层气资源丰富,具有较好的开发前景。通过多种测试手段对该区煤层气储层的孔隙、裂隙进行了表征,分析了煤储层的孔渗特征,并探讨了煤中显微组分及不同类型的孔隙对储层孔渗性的影响。研究结果表明:恩洪地区煤层厚度大,煤级适中,微小孔发育,吸附能力强,有利于煤层气的吸附;渗流孔隙结构单一,非均质性不高,渗流能力相对较好,显微裂隙以较小微裂隙(D型)为主,定向性和连通性较差,可能造成渗流通道不连续和受阻等问题,导致渗透性变差,对将来煤层气的开发产生不利影响。

Characteristics of the pore-microfracture system of coal reservoirs in Enhong area,Yunnan province

As the largest medium and high volatile bituminite coalfield in Yunnan province, Enhong area is rich in CBM resources. Employing multiple testing methods, such as mercury intrusion porosimetry (MIP) and liquid nitrogen adsorption, this paper described the pore-microfracture system of the coal reservoirs in Enhong area, analyzed the characteristics of the porosity and permeability, and studied the influencing factors of porosity and permeability. Results showed that:the coal reservoirs in Enhong area have big thickness and medium coal metamorphism, micropores and transition pores are well developed, which are favorable for the methane sorption. The structure of the seepage pores is simple, and the permeability is relatively good with weaker heterogeneity. Mimicrofractures are dominated by type D, which have poor directivity and connectivity that may result in the decrease of permeability, and is not favorable for the further development of the CBM.