【作者】 张权；

【导师】 楼章华；

【作者基本信息】 浙江大学 ， 海洋科学， 2015， 硕士

【摘要】 黔北坳陷及周缘位于上扬子板块西南缘,具备良好的原始油气成藏地质条件。后期经历了加里东、海西、印支、燕山和喜山等多期构造运动,油气保存条件受到严重破坏,成为制约研究区油气勘探进展的关键。论文综合分析了盖层特征、构造作用、岩浆活动对油气保存条件影响,结合水文地质地球化学-动力学与油气保存间的耦合关系,初步建立了一套适用的油气保存条件综合评价指标体系,对黔北坳陷及周缘油气保存条件进行分级评价,并作出有利勘探区优选。论文主要取得以下成果认识：(1)从宏观和微观角度对黔北坳陷及周缘盖层封闭性进行综合评价,结果表明：中下寒武统膏盐岩、下寒武统牛蹄塘组-金顶山组泥岩、中下志留统龙马溪组-韩家店组泥岩为区域盖层。中下寒武统膏盐岩在研究区内呈北西向的连续分布,沉积厚度普遍在25-100m,属于Ⅰ类盖层,封盖性能好；下寒武统牛蹄塘组-金顶山组泥岩盖层在黔北坳陷镇雄-赫章一带、黔中隆起东南部清镇-修文一带累计厚度超过500m,属于Ⅰ-Ⅱ类盖层,封盖性能好-较好；中下志留统龙马溪组-韩家店组泥岩盖层呈现东南向北西增加趋势,在黔北坳陷东南部和黔中隆起北部分布较薄,属于Ⅱ类盖层,封盖性能较好；上二叠龙潭组、中下三叠盖层主要分布于川南坳陷,黔北坳陷仅向斜部位残余分布,具有局部封盖作用。(2)构造作用对于黔北坳陷油气保存条件破坏呈现由北向南的地区差异性：川南坳陷剥蚀厚度较小,覆盖较厚的陆相沉积,少量断裂发育,整体保存条件好；黔北坳陷中生界乃至上古生界剥蚀殆尽,断裂发育较密,陆相海相盖层在剥蚀作用和断裂破碎下整体封盖能力变差；黔中隆起大面积出露寒武系,局部可见震旦系,海相盖层已失去整体封盖作用,断裂密集发育,保存条件差。(3)通过研究区温泉分布及温泉水温数据分析,估算现今大气水下渗深度：黔北坳陷外围如滇东北彝良、黔中隆起息烽等地区,大气水下渗深度在1600m以上,水文地质开启程度高；黔北坳陷内现今大气水下渗基本在1200m以内,水文地质开启程度相对较低。结合钻井地层水资料以及水动力环境分析,从黔中隆起经黔北坳陷至川南坳陷,构造活动减弱,呈现向心流区-越流泄水区-离心流区变化趋势,地层水逐渐浓缩,矿化度逐渐增加,油气保存条件变好。纵向分析,黔北坳陷浅部地层水文地质开启程度较大,深部地层油气保存条件相对较好。(4)综合盖层分布、构造作用、岩浆活动、水文地质地球化学-动力学特征,认为川南坳陷为油气保存有利区,而黔北坳陷油气保存条件普遍一般。黔北坳陷保存条件相对较好的低潜构造、复向斜深层及川南盆缘区是研究区常规油气勘探的有利区,下古生界是常规天然气的主要勘探层系。更多还原

【Abstract】 Qianbei Depression and its margin locate on the southwestern edge of the upper Yangtze plate, with good raw hydrocarbon accumulation geological conditions. While, its hydrocarbon preservation condition was seriously destroyed by a multi-phase of late stage tectonic movements (Caledonian, Hercynian, Indosinian, Yanshanian and Himalayan). And the oil and gas exploration process was restricted. In this paper, firstly, the impacts of the caprock characteristics, tectonic movements, magmatic activity on the hydrocarbon preservation was discussed. Then, the coupling relationship between hydrological geological and geochemical dynamics and hydrocarbon was researched systematically. At the end, a comprehensive evaluation system for hydrocarbon preservation conditions was set up. The evaluation system was used to grading evaluation and selecting the favorable exploration fields in the Qianbei Depression and its margin, which also provides the basis for oil and gas exploration in the future. The paper mainly has the following results:(1)The sealing ability of cap rock in Qiannan-Guizhong depression was evaluated synthetically through both macroscopic and microscopic study. Results show that the Middle-Lower Cambrian gypsum salt rock, Lower Cambrian Niutitang Formation-Jinding Mountain Formation mudstone, Middle-Lower Silurian Longmaxi Formation-Hanjiadian Formation mudstone are regional cap rocks. The Middle-Lower Cambrian gypsum salt rock in the North West of continuous distribution in the study area,the deposition thickness is general 25-100m.It is I type cap rock, and with good sealing capability. The total thickness of Lower Cambrian Niutitang Formation-Jinding Mountain Formation mud cap rock in Zhenxiong-Hezhang region of depression in north Guizhou and Qingzhen-Xiuwen region of the southeast of Guizhou uplift is above 500m. They are II type cap rock, with middle-good sealing capability. The Middle-Lower Silurian Longmaxi Formation-Hanjiadian Formation mud cap rock show increasing trend of southeast to Northwest and their thickness is thinner in the southeastern depression in northern Guizhou and the north of Qianzhong uplift. They are Ⅱ type cap rock, with middle-good sealing capability. Upper Two Triassic, Middle-Lower Three Triassic cap rock major distribute in Sichuan depression of Tarim Basin. The distribution of residual cover only in syncline depression in northern Guizhou, with local sealing ability.(2)Tectonic action for depression in northern Guizhou depression oil and gas preservation conditions showed regional differences from the south to the north: Denudation thickness in southwest Sichuan is small, covered with thick continental deposit, a small amount of fracture development, overall good preservation conditions; Paleozoic Mesozoic and Paleozoic eroded in Qianbei depression, fracture development is dense, Continental marine cap rocks in erosion and fracture under the overall poor sealing ability; A large area of Qianzhong Uplift exposed Cambrian, partially visible Sinian, marine layer has lost the whole sealing ability, faults intensive development, with poor preservation conditions.(3)Based on the study of distribution and temperature of hot spring, the present meteoric water infiltration depth can be estimated. That of Qianbei Depression margin, e.g. northeast of Yunnan Yiliang, Xifeng of Qianzhong uplift, is above 1600m,with high hydrogeology open degree; While the present meteoric water infiltration depth in Qianbei Depression interior is below 1200m, and with low hydrogeology open degree. Combined with drilling data and hydrodynamic analysis of water environment, from the Qianzhong Uplift to Chuannan depression, tectonic activity decreased, showing the centripetal flow zone-the flow discharge area-centrifugal flow area change trend, the degree of mineralization increases, preservation conditions of oil and gas gets well. The longitudinal analysis, the shallow strata of Qianbei depression with low hydrogeology open degree, deep formation is the major exploration target layer.(4)The comprehensive study of cap rock distribution, tectonism, magmatism, hydrological and geological and geochemical dynamics characteristics shows that: Chuannan depression is the favorable area of oil and gas preservation, but Qianbei depression has generally preservation conditions. Low latent structure, deep area of synclinorium and the southern Sichuan basin margin with relatively better preservation conditions in Qianbei depression are favorable areas for oil and gas exploration in the study area of conventional depression, the lower Paleozoic is the main exploration for conventional natural gas layer.更多还原