图1 湘西吉首斜坡带区域图(a)与B-B'线过湘吉地1井剖面图(B-B'线及湘吉地1井位置见图1a)(据文献[14]修改)

Fig.1 (a) Regional map of the Jishou steep slope zone of Xiangxi, and (b) cross-section along line B-B' acrossing well XJD1 (locations of line B-B' and well XJD1 see Fig.1a). Modified after [14].

图2 湘西湘吉地1井TOC柱状图及流体包裹体取样位置

Fig.2 A composite diagram showing the lithology, depth variation of TOC content and fluid inclusion sampling sites in well XJD1

图3 湘西湘吉地1井牛蹄塘组岩心脉体观察照片 A—样品编号:JS-7,2 034.7 m,碳质泥岩中发育的顺层滑动裂缝充填方解石;B—深度2 020.5~2 021.5 m井段碳质页岩中发育的滑脱镜面;C—深度1 790.0 m井段黑色泥岩在延性带发育的不规则裂缝及其充填方解石(具有流变特征);D—深度1 992.5 m钙质泥岩发育的剪切裂缝及延性带不规则裂缝具有流变特征;E—样品编号:JS-23,深度1 852.0 m黑色泥岩在延性带发育不规则高角度裂缝及其充填方解石;F—样品编号:JS-22,深度1 888.1 m黑色泥岩中发育不规则裂缝及其充填方解石;G—样品编号:JS-15,深度1 992.5 m钙质页岩高角度方解石脉;H—样品编号:JS-9,深度2 021.5 m碳质和云质泥岩中早期网状不规则白云石脉为晚期方解石细脉所切割;I—样品编号:JS-12,深度2 004.9 m碳质页岩中垂直剪性裂缝及充填方解石脉;J—深度2 002.8 m碳质页岩中开启的剪切裂缝。

Fig.3 Photos of the Niutitang Formation core specimens from well XJD1 showing mineral-bearing veins

图4 湘西湘吉地1井牛蹄塘组泥页岩脉体充填矿物岩石学特征观察照片 A1—样品编号:JS-25,牛蹄塘组,1 825.5m,浊积钙质粉砂岩薄片;A2—透射光观察照片;A3—阴极发光观察照片,显示两个世代纹层状钙质胶结;B1—样品编号:JS-27,牛蹄塘组,1 790.0 m,黑色泥岩薄片;B2—透射光照片;B3—构造石英细脉和方解石细脉;C—样品编号:JS-28,牛蹄塘组,1 790.5 m,泥岩中发育的顺层脉体岩心照片;C1—该样品薄片;C2—方解石脉透射光照片;C3—方解石脉阴极光照片;C4—石英+方解石脉透射光照片;C5—石英+方解石脉阴极光照片;D1—样品编号:JS-23,牛蹄塘组,1 852.0 m,黑色泥岩中延性带不规则高角度方解石脉薄片;D2—方解石脉透射光照片;D3—方解石脉阴极光照片;E1—样品编号:JS-19,牛蹄塘组,1 924.5 m,黑色泥岩顺层变形方解石脉夹黄铁矿薄片照片;E2—方解石脉透射光照片;E3—方解石脉阴极光照片显示方解石晶体背向式生长;F1—样品编号:JS-10,2 015.8 m,碳质泥岩,滑脱层石英脉+两期方解石脉;F2—透射光照片;F3—石英沿裂缝壁生长,后两期方解石脉依次充填;G1—样品编号:JS-21,1 900.5 m,黑色泥岩,方解石脉+石英脉;G2—透射光照片;G3—石英沿裂缝壁生长,后期方解石充填;H1—样品编号:JS-9,2 021.5 m,碳质泥岩,水力破裂形成的裂缝;H2—透射光照片,H3—白云石脉+方解石脉。

Fig.4 Photomicrographs and cathodoluminescence images showing the petrographic characteristics of vein-filling minerals from the Niutitang Formation of well XJD1

图5 湘西湘吉地1井牛蹄塘组方解石脉稳定O-C同位素组成关系图

Fig.5 Relationship between δ18O and δ13C for calcite veins of the Niutitang Formation of well XJD1

图6 湘西湘吉地1井牛蹄塘组方解石脉原生甲烷包裹体激光拉曼光谱图(甲烷峰位移:2 907.96 cm-1)

Fig.6 Laser Raman spectrum of primary methane inclusion in calcite veins of the Niutitang Formation of well XJD1 (methane peak at 2 907.96 cm-1)

图7 湘西湘吉地1井牛蹄塘组流体包裹体岩相学观察照片 a—JS-21,石英脉中的原生甲烷包裹体和盐水包裹体;b—JS-21,石英脉中的原生甲烷包裹体和沥青包裹体;c—JS-11,石英脉中的次生气液两相盐水包裹体;d—JS-15,方解石脉中的原生沥青包裹体和盐水包裹体;e—JS-19,方解石脉中的气液两相原生盐水包裹体;f—JS-22,方解石脉中的气液两相次生原生包裹体。

Fig.7 Photomicrographs showing the petrologic characteristics of fluid inclusions from the Niutitang Formation of well XJD1

图8 湘西湘吉地1井牛蹄塘组流体包裹体均一温度直方图

Fig.8 Histogram of homogenization temperatures of fluid inclusions from the Niutitang Formation of well XJD1

图9 湘吉地1井牛蹄塘组盐水包裹体均一温度与埋藏史投影图(埋藏史来自[14])

Fig.9 Diagram of homogenization temperatures and burial history for determination of events and ages of fluid activity in well XJD1 in Xiangxi area (burial history from [14])

图10 湘吉地1井牛蹄塘组烃类同期包裹体均一温度与埋藏史投影图(埋藏史来自[14])

Fig.10 Diagram of homogenization temperatures and burial history for determination of trapping ages of hydrocarbon related inclusions in Xiangxi area (burial history from [14])

图11 研究区页岩气成气过程示意图

Fig.11 A schematic illustration of shale gas formation process in the study area