苏北地区上二叠统龙潭组页岩气形成条件及有利区预测

Formation Conditions and Favorable Exploration Zones of Shale Gas in Upper Permian Longtan Formation of Subei Area

苏北地区龙潭组发育一套富有机制泥页岩,主要分布在苏北东部地区,为滨岸沼泽相沉积,干酪根类型主要为Ⅱ2、Ⅲ型,有机质含量高、热演化程度高、生气潜力大,微裂缝和微孔隙较为发育,提供了良好的储集空间。矿物成分以石英和黏土为主,黏土矿物主要以伊利石和伊-蒙间层为主。泥页岩具有良好的气体吸附能力。泥页岩本身就具有一定的抗破坏性,且研究区构造运动并未对页岩气藏造成大的破坏,保存条件良好。依据页岩气的生成条件,结合泥页岩的厚度、有机碳质量分数、成熟度、埋深指标,采用叠合法对有利区进行预测,初步预测海安-如皋市一带为有利勘探区。

A set of organic-enriched shale was developed in Longtan Formation of Subei Area,it was mainly distributed in the east of Subei Area,it was of coastal swamp facies,where kerogen was mainly humic-sapropelic Ⅱ2 type and humic Ⅲ type with high organic matter content,high levels of thermal evolution and high potential of gas generation,micro fracture and pore were relatively developed,by which good reservoir space was provided.The mineral component was quartz and clay primarily.The clay mineral was mainly the illite and interbedded illite and montmorillonite.Shale had a good ability of gas adsorption.The shale itself had a certain damage resistance,and the tectonic movement in the area did not cause the big destruction to the shale gas pool,its storage condition was good.On the basis of shale gas generating conditions and combined with the thickness of shale,the content of organic carbon,maturity,buried depth indicator,it is forecasted that favorable exploration area is Haian-Rugao Area.