Font Size: a A A

Study On The Genesis And Reservoir Characteristics Of Jurassic Dolomites In Shuanghu Area, Qiangtang Basin

Posted on:2006-03-18Degree:DoctorType:Dissertation
Country:ChinaCandidate:X Q ZhangFull Text:PDF
GTID:1100360185969927Subject:Mineralogy, petrology, ore deposits
Abstract/Summary:PDF Full Text Request
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...
Keywords/Search Tags:Qiangtang Basin, Jurassic, Dolomite, Genesis, Porosity evolution, Reservoir characteristics
PDF Full Text Request
Related items