贵州下寒武统牛蹄塘组页岩储层特征及其分布规律

为合理评价贵州省下寒武统牛蹄塘组页岩气的资源开发潜力,利用野外地质调查及页岩气井勘探成果资料,结合钻井岩心样品测试、现场解吸及等温吸附实验等分析结果,研究了牛蹄塘组页岩储层发育的特征及其分布规律。结果表明:1该区牛蹄塘组页岩主要分布于黔北、黔中及黔南—黔东南地区,岩性主要为含粉砂—粉砂质、碳质泥岩页岩;2牛蹄塘组页岩干酪根以腐泥型和偏腐泥混合型为主,生烃能力较强,有机碳含量介于0.7%~14.6%,有机质成熟度较高(Ro普遍大于2.5%),处于过成熟演化阶段;3牛蹄塘组页岩脆性矿物含量高,黏土矿物以伊利石和伊蒙混层为主,具较好的破裂潜力,页岩孔隙度中等,渗透率极低,且两者呈线性负相关关系;4黔北西部、黔中地区牛蹄塘组页岩气富集区主要位于毕节—大方—黔西一带,含气量范围为1.5~2.5m3/t,黔北东部、黔东地区牛蹄塘组页岩现场解吸气量整体较好,而黔南、黔东南地区页岩气富集区位于丹寨—麻江—黄平一带,含气量范围为0.01~1.13m3/t。

Characteristics and distribution patterns of the Lower Cambrian Niutitang Shale reservoirs in Guizhou,China

In order to evaluate the shale gas potential of the Lower Cambrian Niutitang Fm in Guizhou, various data including field geologic survey, shale gas exploration achievements, core sample test, well-site desorption and isotherm adsorption experiment results were integrated to study the characteristics and distribution patterns of the Niutitang Shale reservoirs. The following conclusions were obtained. (1) The Niutitang Shale is mainly distributed in the northern, central and southern-southeastern parts of Guizhou province and its dominant lithologies are silt shale silty and carbonaceous shales. (2) The organic matters are dominated by kerogens of Ⅰ- and Ⅱ₁ type with a relatively strong hydrocarbon generation capacity, TOC content of 0.7~14.6% and relatively high maturity (R_omostly ＞2.5%), indicating a over mature evolutionary stage. (3) The content of brittle minerals are relatively high. The clay minerals are dominated by illites and mixed illite-smectites. Its porosity is moderate but the permeability is very low and they are in a negative linear correlation. (4) In western North Guizhou and Central Guizhou, the play fairways of Niutitang Shale are mainly located in Bijie – Dafang - Western Guizhou, where the gas content is in the range of 1.5~ 2.5 m³/t. In eastern North Guizhou and Eastern Guizhou, the desorption gas content is relatively high as a whole. In South and Southeast Guizhou, the play fairways of the Niutitang Shale occur in Danzhai – Majiang - Huangping areas, where the shale gas content is in the range of 0.01~1.13 m³/t.