宣威热水—沾益德泽地区下寒武统筇竹寺组页岩气成藏条件分析
2017-02-16蒋源
蒋源
摘要: 宣威热水-沾益德泽地区早寒武世筇竹寺期沉积了一套以砂、粉砂和泥质沉积为主的黑色页岩。该黑色页岩成藏了一个良好的页岩气藏。区内黑色页岩有机碳(TOC)的平均值大于2.0%、有机质类型为Ⅲ型、热成熟度3.5%、脆性矿物含量占52.2%~92.8%,平均73.02%、隙度为0.8850%~20.2926%,平均6.0554%、厚度400~200m、埋深1500~3500m、含气量3.70cm3/g~3.81cm3/g,平均3.755cm3/g。区内的盖层、储层和水文条件都有利于页岩气藏的保存。并且区内发育了多条逆断层,断裂构造使页岩形成了很多裂隙构造,对页岩气的成藏起到了促进作用。
Abstract: There were a lot of black shales in Reshui, Xuanwei-Deze, Zhanyi area of Yunnan province. These black shales include deposition of most of sand, silt and clay. Meanwhile, these black shales bring a high quality of disposition of shale gas. In this area, the average of organic Carbon lied in black shales is greater than 2.0% and the type of organic matter is Ⅲ and the thermal maturity is 3.5%. the brittle mineral content accounts 52.2%~92.8%, its average is 73.02%. the gap is 0.8850%~20.2926%, its average is 6.0554%. The thickness of black shales is 400~200m, the depth is 1500~3500m, gas content is 3.70cm3/g ~3.81cm3/g, its average is 3.755cm3/g. The caprock, reservoir and hydrological conditions are favorable for the preservation of shale gas reservoirs. Many faults are developed in the area, and the fracture structure makes the shale a lot of fracture structures. These can promote the shale gas reservation.
關键词: 页岩气;下寒武统;筇竹寺组;黑色页岩;成藏条件
Key words: shale gas;the lower Cambrian;Qiongzhusi formation;black shale;accumulation conditions
中图分类号:P548 文献标识码:A 文章编号:1006-4311(2017)04-0176-05
0 引言
页岩气是一种特殊的自生、自储型气藏,它集生、储、盖于一体。页岩不仅是页岩气的气源岩,而且它还充当着页岩气的储层和盖层。页岩气系统中,烃源岩和常规天然气一样是富有机质的页岩相,但是页岩气的储层和盖层却有着自身的特点,它与常规天然气是完全不同的。常规天然气的储层是高孔高渗的硅质碎屑岩或碳酸岩,而页岩气的储层则是低孔低渗的页岩。并且,页岩组中的贫有机质的碳酸岩和粉砂岩相,也是页岩气藏的有效储层。
页岩气成藏的生烃条件和过程与常规天然气是一样的,其生烃能力和时间都是由泥质页岩的有机质丰度、有机质类型和热演化特征决定。但是烃类气体的运移,页岩气成藏却体现了自己的特征。气藏运移的距离很短或没有运移,泥岩中的裂隙和微空隙是它的主要运移通道。……
