| 其他摘要 | An important breakthrough continuously in the exploitation of natural gas in the Kuche depression not only exhibit the huge potential of gas in this area but also establish its important position in the development of gas industry of China. Meanwhile, the discovery of such a huge gas field in overpressure zone have attracted much attention either Chinese or foreign petroleum and gas geologists Theory speaking, the gas would start leak when the porosity fluid pressure of strata is higher than natural fracture pressure of the strata (pressure index: 1.963), that make gas pool difficult to be kept. Therefore, the huge gas field will be really difficult found in the areas with the pressure index over 2.0. So, there should be some special and characteristic geological factors controlling the formation of huge gas field within the overpressure zone in the Kuche depression, which are worthy of studying and analyzing in detail. The studies here include three fields as (1) the major controlling factors of abnormal overpressure in Kuche have been identified and studied, and the formed episode and evolution have been identified too based on a resume of paleo-pressure. (2) The process of formation of the huge Kuche gas field has been identified according to analyses of histories of structure evolution, sedimentary, hydrocarbon generation and reservoir geochemistry. (3) The effects of abnormal overpressure on the formation of gas pools have been summarized depending on the analyses and correlation of distributing characters and evolution process between the gas pools and abnormal overpressure in this area. At the movement, the common studies of this area just focus on description of "characteristics" and "results", for this study, the relationship between abnormal pressure in the Kuche depression and formation of oil and gas pools have been deeply discussed and expounded according to analysis of origin and evolution of the abnormal overpressure. Still, some geological information have been comprehensively used in this study on a purpose of researching the distribution and development of abnormal overpressure and the relationship between the accumulation of natural gases and the overpressure, which include analyses and integrate practical geologic, geophysical and drilling information and thermodynamics, hydrokinetics and mathematical modeling and then the histories of compression of the mudstone, thermal fluid and evolution of tectonic stress field can be studied and identified for the continuous researches. For this study, the author have searched over 400 papers covered either home or international information, more than 60 pieces of inner system reports; had two times of field working in the Tarim Basin and collected over 200 samples there; collected seismic sections (about 1200km) and interpreted information of 22 well logging; processed some data as acoustilog of mudstone, double directional electrical resistively and density well logging etc. And, the author have scanned and described cores taken from 6 wells. The experiment of pore change of rock samples has been processed on the sandstone with different grain size of 18 system in 4 sets. Many kind organic geochemical analyses have been done for this study, including extracting of dissolved organic matte, gas chromatography of saturated hydrocarbon r and GC-MS. Meanwhile, the system of diagenesis has been analyzed based on the sections of rock samples; fluid inclusions have been analyzed and measured in detail for studying its size, shape, color and facies and homogenization temperature. At same time, ten samples have been selected for XRD and SEM analyses and age dating by using K-Ar isotopic ratio. During the doctoral student's studies, the author have published 12 papers on either Chinese or international core magazines, in which 8 are first author, and 4 papers as the first author and 1 as a second one have been collected by SCI. The Ph.D's thesis composed by 130,000 words. The conclusion about the research and thesis are as follows: l.Some contentious origins of the abnormal overpressure have been deeply and theorizally studied, suggesting that at any possible geological conditions, tectonic uplifting would be the generation of abnormal overpressure. Tectonic uplifting could cause abnormal low pressure in case of that not any other factors of causing the abnormal overpressure. |
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