威远构造W202区块龙马溪组龙_(1)^(1)亚段页岩气储集层岩石学特征

Petrological Characteristics of Shale Gas Reservoirs in Long_(1)^(1) Sub-member of Longmaxi Formation in W202 Block of Weiyuan Structure

为明确四川盆地川西南地区低陡褶皱带威远构造页岩储集层岩石化学成分及矿物性质与含气性的关系,选取威远构造W202区块下志留统龙马溪组岩心样品,对岩石化学元素、页岩矿物类型及特征、有机碳含量与吸附能力等进行研究。研究表明:龙马溪组龙11亚段岩性主要为灰质(云质)页岩、硅质页岩、炭质页岩、黏土质页岩;矿物类型以陆源矿物、自生矿物、生物碎屑和少量有机质为主;纵向上发育4个小层,但其岩石化学特征存在明显差异,其中,龙1^(1)Ⅰ小层发育石英,脆性好,多见黄铁矿,有机质丰度高,吸附能力强,为页岩气优质储层。该研究为页岩气勘探和开发方案调整提供技术支持。

In order to identify the relationship between the petrochemical composition and mineral properties and the gas-bearing property of the shale reservoirs in Weiyuan Structure in the low-steep fold belt in the southwestern Sichuan Basin.Core samples were taken from the lower Silurian Longmaxi Formation in the W202 Block of the Weiyuan Structure,and studied on rock chemical elements,shale mineral types and characteristics,organic carbon content and adsorption capacity.It was found in the study that the lithology of Long 1^(1) Sub-member of Longmaxi Formation was mainly lime(dolomitic)shale,siliceous shale,carbonaceous shale,and clay shale;mineral type was dominated by terrigenous minerals,authigenic minerals,bioclasts and a little amount of organic matter;there were 4 layers in the vertical direction,but their petrochemical characteristics were obviously different;the Layer I of the Long 1^(1) Sub-member was developed with quartz,with hight brittleness,rich pyrite,high organic matter abundance and strong adsorption capacity,and it was a quality reservoir for shale gas.This study provides a technical support for the adjustment of exploration and development plans for shale gas reservoirs.