【作者】 张小青；

【导师】 伊海生；

【作者基本信息】 成都理工大学 ， 矿物学、岩石学、矿床学， 2005， 博士

【摘要】 羌塘盆地位于青藏高原的腹地，是中国油气勘探程度最低的盆地之一，也是我国在特提斯域内最具潜力的油气勘探目标。侏罗系具有良好的生烃潜力，但是本地区储集层物性整体偏低，明显具有致密层的特点，能否找到优质储层已经成为制约对该盆地评价的关键问题之一。目前地表所发现的含油层系几乎都与白云岩有关，故确定白云岩的成因及孔隙演化史与油气运聚的关系，对于研究白云岩油藏至关重要。 本论文详细研究了双湖地区毕洛错—昂达尔错区块侏罗系白云岩成因及油气储集性，取得了以下进展和创新： 1．通过对主干剖面沉积相研究，确定了研究区侏罗系白云岩所处的相带：局限台地潮坪相和台地边缘礁滩相。米级旋回层序揭示了高频海平面变化引起的海水—淡水和盐水—淡水混合水白云石化。 2．在本研究区，首次应用岩相学、同位素地球化学、微量元素、电子探针、X-衍射等手段，对白云岩的白云石化过程从微观角度上进行了深入研究，得出本区白云石的三个世代及其相应的形成环境，第一世代为同生成岩阶段混合水白云石化形成，第二世代为早成岩期调整白云石化形成，第三世代为晚成岩期热液白云化作用形成。白云石的有序度高，为0.81-1.00。 3．对白云岩储层的储集性研究表明，储集空间主要为晶间孔、晶间溶孔、溶孔，孔隙度平均为6.50％；渗透率平均为15.24×10^-3μm²，排驱压力很低，一般为0.06-0.42Mpa。喉道类型主要为片状和缩颈状，喉道分选较好，孔隙结构以大孔粗喉、中孔中喉为主。综合孔隙结构特征，本区块白云岩储层属Ⅰ、Ⅱ类型，为中孔中渗、低孔低渗类储层，整体评价为较好—好。 4．白云岩油气储集层的荧光发光部位以晶间溶孔、晶间孔、裂缝、溶孔、为主。荧光颜色主要为黄绿色、绿黄色、和黄色，发光强度大部份为亮和中亮。本区块油气绝大部分是晚成岩作用阶段后期二次运移进的。 5．研究区白云岩的孔隙演化经历了同生成岩、早成岩、晚成岩三个阶段，由最初的孔隙度35％降至如今的7％。孔隙演化与白云岩的埋藏史、研究区的生烃史和两次构造运动紧密相联。孔隙演化、圈闭形成、油气充注比较匹配，形成了如今布曲组白云岩的构造—岩性油藏。 6．利用激光碳氧同位素技术和包裹体分析并结合岩相学，研究了异形白云石对白云岩储集层物性的破坏作用，降低了孔隙度和渗透率。异形白云石的形成对应于燕山运动对油藏的初次破坏，同时表明有两期热液活动。 通过以上研究证实，双湖地区毕洛错-昂达尔错区块侏罗系白云岩的白云石化和孔隙度演化，与本地的生烃史、构造史匹配恰当，储集性能和含油气性良好，是羌塘盆地重要的油气储集层和潜在的产层，为下一步羌塘盆地油气勘探指明了方向。更多还原

【Abstract】 Qiangtang Basin is located in the center of Qinghai-Xizang（Tibet） Plateau. It is a basin with the lowest degree in oil and gas exploration in China and is the most potential target for petroleum exploration in Tethys region. The Jurassic strata have a good hydrocarbon-generating potential, but the physical characteristics of reservoirs in the study area are poor on the whole, which are obviously characterized by densed reservoirs. Searching for the reservoirs of good quality is crucial to assessment of the basin. At present, oil-bearing layers found on the surface are nearly associated with dolomites. Hence, it is of significance in studying dolomite oil pool that the relationship between the origin and porosity evolution of dolomite and the migration and accumulation of oil-gas.The dissertation has in detail studied the genesis and oil-gas reservoir properties of Jurassic dolomites of Biluoco-Angdarco block in Shuanghu area, and made the following progress and innovation.1. Based on the research on the sedimentary facies of main sections, the facies belts of Jurassic dolomites in the study area are differentiated as refined platform tidal flat and platform margin reef or shoal facies. The meter scale cyclic sequences reveal the mixing water dolomitization resulted from frequent fluctuation of sea level.2. In the study area, the dolomitizing process of dolomites has been deeply studied from microcosmic aspect for the first time by means of petrography, stable carbon and oxygen analysis, trace elements analysis, electrical probe and X-ray diffraction analysis, and it is acquired that three generations and corresponding forming environment of dolomites in the study area. The first generational dolomites were resulted from mixing water dolomitization in the syndiagenetic stage, the second generational dolomites were induced by regulating dolomitization in the early diagenetic stage, and the third generations were formed under the hydrothermal dolomitization. The ordering degree of dolomite is very high, ranging from 0.81 to 1.00.3. Research on the reservoir properties of dolomites indicates that reservoir space consist of intercrystal pore, intercrystal dissolved pore and vug, and the porosity and permeability of dolomites are 6.5% and 15.24×10^-3 μm² respectively. In addition, the value of replacement pressure is lower, ranging from 0.06 to 0.42Mpa. The types of throat are dominantly sheet and necking down, and the sorting of throats is good. The big pore with wide throat and the moderate pore with moderate throat are primary更多还原