贵州凤冈二区块下寒武统牛蹄塘组页岩气成藏特征研究

发布时间：2018-12-17 05:16

【摘要】：贵州省页岩气资源地质储量达10.48×1012m3,位列全国第四,具有良好的页岩气勘探开发前景。其中凤冈二区块是2012年9月10日国土资源部对页岩气探矿权出让进行国内第二轮公开招标时划分的区块,具有很好的页岩气勘探开发前景。凤冈二区位于贵州北部,地势南高北低,地形起伏大,地貌类型复杂,且为油气探矿权空白区,地质工作程度低,针对下寒武统牛蹄塘组页岩气地质特征的研究相对薄弱,页岩气地质条件不明确,页岩气勘查尚处于起步阶段,可用于页岩气资源潜力预测的资料也非常有限。本文以凤冈二区下寒武统牛蹄塘组黑色页岩为研究对象,通过文献检索、资料收集与整理、野外地质调查、地化实验测试等方法,对研究区牛蹄塘组页岩气成藏特征进行系统研究,结果表明:凤冈二区下寒武统牛蹄塘组沉积环境以深水陆棚沉积为主,水体环境较为稳定,全区牛蹄塘组广泛发育,沉积厚度较大,其中黑色页岩厚度平均为100m左右,呈由东南向西北方向逐渐增厚的趋势。区内牛蹄塘组埋藏深度基本处于500-3500m左右,埋深主要受构造发育的控制,埋深总体呈现由南往北、自西向东增加的趋势。区域构造以宽缓褶皱为主,逆断层发育,偶见正断层,总体对页岩气的生成及保存提供了有利条件。凤冈二区全区广泛发育牛蹄塘组黑色页岩,TOC介于2.15-6.50%,相对较高,且具有自东向西增高的趋势;纵向上有机碳含量呈自上而下增加的趋势,中上部分TOC值基本处于0.5%左右,下部TOC值普遍达到5.0%以上,最高值为11.8%。区内干酪根以Ⅰ型为主;类镜质体岩心样最大反射率介于3.16-5.59%,平均4.67%,处于过成熟阶段,已进入生气晚期或裂解气阶段。矿物组分以石英、长石及黏土矿物为主,黏土矿物平均在25%左右,石英与斜长石矿物含量平均在70%左右,黏土矿物以伊蒙混层及伊利石为主;黏土矿物为页岩气提供大量的吸附表面积,有利于页岩气的富集成藏。凤冈二区区内牛蹄塘组页岩气以热成因为主,显微镜、扫描电镜观察牛蹄塘组页岩孔隙类型包括粒内孔、晶间孔、有机质孔、粒间孔和溶蚀孔等,裂缝则有宏观裂缝及微观裂缝;孔隙以nm级与μm级为主,宏观裂缝mm级,微观裂缝以μm级为主,孔裂隙多被沥青、黄铁矿、方解石等充填。压汞实验、低温液氮吸附实验与二氧化碳吸附实验结果表明页岩微孔、介孔及大孔发育良好,微孔及介孔的表面积较大,为页岩气提供了大量的吸附空间,而连通性很好的开放孔则为页岩气提供了大量的游离气赋存空间,总体上研究区目标层有利于页岩气的赋存。牛蹄塘组页岩等温吸附实验结果显示具合村露头实测剖面最大吸附量较小,介于0.77-0.94 cm3/g,而ZK2井最大吸附量分布于1.18-5.65 cm3/g,平均为3.57cm3/g,鉴于露头样风化较严重,综合认为研究区牛蹄塘组最大吸附量整体较好。凤冈二区牛蹄塘组目标层经历了持续的埋藏阶段,保证了有机质向油气转化的顺利进行,生成大量页岩气,而白垩纪之后的地层隆升为现今商业开发提供了有利条件。通过对储层微观因素与含气性关系研究发现,区内牛蹄塘组页岩气吸附量受有机碳含量控制明显。综合考虑研究区内构造作用、沉积作用、埋深及储层微观因素对页岩气成藏的影响,认为区内有利区主要受构造作用与埋深的控制,构造稳定(区内不含落差超过20m的大、中型断层)、埋深处于1000-3500m作为有利区优选参数,并据此划分出两个页岩气富集有利区(有利区Ⅰ和有利区Ⅱ)。
[Abstract]:The geological reserve of the shale gas in Guizhou is 10. 48-1012m3, the fourth in the whole country, and has a good prospect of gas exploration and development. The two-block of Fenggang is the block divided by the second round of public bidding for shale gas exploration right by the Ministry of Land and Resources on September 10, 2012, which has a good prospect of gas exploration and development. The two areas of Fenggang are located in the northern part of Guizhou. The terrain is high and the north is low, the relief of the terrain is large, the type of the landforms is complex, and it is a blank area for the exploration right of the oil and gas, and the geological work is low. The study on the geological features of the shale gas in the Lower Cambrian Niuhotang Formation is relatively weak, and the geological conditions of the shale gas are not clear. The shale gas exploration is still in the initial stage, and the data that can be used in the prediction of shale gas resource potential is also very limited. In this paper, a systematic study on the characteristics of the shale gas in the study area is carried out by the methods of literature search, data collection and sorting, field geological survey and geochemical test, and the results show that: The sedimentary environment of the Lower Cambrian Niuungtang Formation in Fenggang District is dominated by deep-water shelf deposition. The environment of the water body is more stable. The cattle hoof pond in the whole area is widely developed and the deposition thickness is large. The average thickness of the black shale is about 100m, which is the trend of gradually thickening from the southeast to the northwest. The buried depth of the cattle-hoofed pond in the area is about 500-3500m, the depth of the burial is mainly controlled by the structural development, and the depth of the buried depth is generally from the south to the north and from the west to the east. The regional structure mainly provides favorable conditions for the formation and preservation of shale gas. In the area of Fenggang, the black shale is widely developed in the whole region, and the TOC is in the range of 2.15-6.50%, which is relatively high and has a tendency to increase from the east to the west. The organic carbon content in the longitudinal direction is increased from top to bottom. The TOC value of the upper part is about 0.5%, and the lower TOC value is generally over 5.0%. The highest value was 11. 8%. In the region, kerogen is dominated by type I; the maximum reflectance of the core-like core sample is 3.16-5.59%, the average is 4.67%, it is in the stage of over-maturity, and has entered the stage of late stage of regeneration or pyrolysis gas. The mineral components are mainly quartz, feldspar and clay minerals, the average clay mineral is about 25%, the mineral content of the quartz and the plagioclase is about 70%, the clay mineral is mainly composed of the isimon layer and the illite, and the clay minerals provide a large amount of adsorption surface area for the shale gas, and is beneficial to the enrichment of the shale gas to be hidden. The shale gas in the Tiaotang Formation of the two district of Fenggang is the main cause of the heat. The microscopic and scanning electron microscope is used to observe the pore type of the shale in the cattle hoofed pond, including the inner hole, the intercrystalline pore, the organic matter hole, the interparticle hole and the dissolution hole, etc., and the fracture has macro-cracks and micro-cracks; the pores are dominated by the nm and the. m At the macro-fracture mm, the micro-cracks are dominated by the micron level, and the pore fractures are filled with asphalt, pyrite, calcite and the like. The experimental results of the pressure mercury experiment, the low temperature liquid nitrogen adsorption experiment and the carbon dioxide adsorption experiment show that the shale micro-pores, the pores and the large pores are well developed, the surface area of the micro-pores and the pores is large, and a large amount of adsorption space is provided for the shale gas, and the well-connected open hole provides a large amount of free gas occurrence space for shale gas, and the target layer of the whole research area is favorable for the occurrence of the shale gas. The experimental results show that the maximum adsorption capacity of the outcrop is small, between 0.77 and 0.94 cm3/ g, while the maximum adsorption capacity of the ZK2 well is 1. 18-5. 65 cm3/ g, with an average of 3.57cm3/ g. In view of the severe weathering of the outcrop, the maximum adsorption capacity of the cattle hoof pond in the study area is considered to be better. The target layer of the cattle-hoofed pond in the two districts of Fenggang has undergone a continuous burial stage, so that the smooth progress of the organic matter to the oil and gas conversion is ensured, and a large amount of shale gas is generated, while the formation on the back of the cretaceous period provides favorable conditions for the present commercial development. The study on the relationship between the micro-factors and the gas-bearing property of the reservoir shows that the amount of shale gas adsorption in the cattle-hoofed pond in the region is controlled by the organic carbon content. Considering the influence of the tectonic action, the sedimentation, the buried depth and the micro-factors of the reservoir on the formation of the shale gas in the study area, it is considered that the favorable area in the area is mainly controlled by the structure and the buried depth, and the structure is stable (the large and medium-sized fault with no drop of more than 20m in the area). The buried depth of 1000-3500m is the preferred parameter of the favorable zone and the two shale gas-enriched favorable zones are divided accordingly (the favorable zone I and the favorable zone II).
【学位授予单位】：中国矿业大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：P618.13

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