鄂尔多斯盆地东缘煤层气储层物性特征规律研究

Study on Physical Characteristics of Coalbed Methane Reservoirs in Eastern Margin of Ordos Basin

鄂尔多斯盆地东缘是煤层气开发的重要区块,资源量丰富,但东缘煤层气南北向发育范围广泛,不同目标区地质及赋存条件不同,导致煤层气的富集规律不一致,对东缘的煤层气控藏因素缺乏整体研究。本文针对东缘煤层气控藏因素,研究不同煤储层的孔隙特征,结合煤变质程度寻找煤储层吸附能力的影响及控制因素,总结储层物性的影响因素,通过物性分析发现:(1)东缘发育不同煤阶的煤层,种类齐全,不同煤样孔隙度发育较好,平均值可达5.5%,孔隙形态主要分为开放性连通孔、一端不透气孔和墨水瓶孔;(2)煤储层孔隙形态对吸附能力控制作用较强,尤其墨水瓶孔有利于甲烷吸附,煤质成分中固定碳含量有利于增强储层吸附能力。在储层物性发育特征分析的基础上,建立了东缘煤层气储层评价参数,优选Ⅰ类、Ⅱ类目标各5个,为下一步煤层气勘探开发指明方向。

The eastern margin of the Ordos Basin is an important block for the development of coalbed methane with abundant resources.However,the north-south development range of coalbed methane is wide in the eastern margin.The geology and occurrence conditions in different target areas are different,which result in inconsistent coalbed methane enrichment patterns.There is a lack of overall research on the controlling factors of coalbed methane accumulation in the eastern margin.Aiming at the controlling factors of coalbed methane accumulation in the eastern margin,the pore characteristics of different coal reservoirs are studied,and influence and control factors of adsorption capacity of coal reservoir may be known combined with the degree of coal metamorphism in this paper.Influencing factors of reservoir physical properties are summarized.Physical property analysis presents that :(1) Coal seams with different coal ranks are developed in the eastern margin with a complete range of types.The porosity of different coal samples is well developed with an average value of up to 5.5%.The pore morphology is mainly divided into open connected pores,air-impermeable pores at one end,and ink bottle pores.(2)Pore morphology of the coal reservoir has a strong control on the adsorption capacity,especially the ink bottle pores are conducive to methane adsorption,and the fixed carbon content of coal is conducive to enhancing the adsorption capacity of the reservoir.Based on the analysis of the development characteristics of the physical properties of the reservoirs,the evaluation parameters of coalbed methane reservoir in the eastern margin are established,and 5 Class Ⅰ and Class Ⅱ reservoirs for each are optimized.It indicates the direction for the next step of coalbed methane exploration and development.