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Mechanism And Resource Potential Of Shijiazhuang Shale Gas Accumulation In Southeastern

Posted on:2013-01-06Degree:MasterType:Thesis
Country:ChinaCandidate:C YuFull Text:PDF
GTID:2270330467452857Subject:Mineral prospecting and exploration
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In this study, Based on systematically surveying date of theory research and exploration and development of shale gas, a variety of oil and gas geology initial value and data of drilling and exploration and development around study area was collected sufficiently. The reservoir-forming conditions of shale gas of Lower Siluric in southeastern Sichuan region were systematically studied by detailed field geological survey and experimental analysis of samples, observation and description of drill core, well-logging interpretation, basin modeling, etc, furthermore, the resources potential of shale gas was analysed and the favorable distribution zone of shale gas was forecasted.The development and distribution characteristic of shale was explicit through studying the areal geological background and observing the outcrops of shale in Lower Siluric and taking samples systematically. The Lower Siluric shale mainly distributes around southern Sichuan and western Hubei and eastern Chongqing which is deep-water shelf depocenter, and is a set of superior source rock with rich organic matter and graptolite, and has a big thickness which is mainly between20and120m. The burial depth of Lower Siluric shale changes greatly in study area whith complex tectonic evolution.,which is shallow in southeast and deep in northwest.Through experimental analysis of shale samples, the organic geochemistry characteristic of Lower Siluric was explicit. I i type of kerogen(standard sapropelic type) is main organic mater. Richness of organic matter is general greater than1%. Maturity of organic matter is general greater than2%, and thermal evolution degree is in high-excessive matural mature stage and has reached or passed the gas production peak period. Through physical property test and thin section authentication, etc of shale core, the reservoir space types and characteristic of shale were explicit. The Lower Siluric shale has fewer big pores, more small pores, higher porosity, worse permeability, thinner poreconstriction and worse connectivity, and the pores and fractures are storage space of shale gas. Through isothermal adsorption simulated experiment, the adsorptivity of shale was studied. In a certain temperature and pressure conditions, the adsorptivity of shale and richness of organic matter has a better positive correlation, but influence of clay minerals on the adsorptivity of shale is secondary. Through well logging data, the logging response characteristic of shale was analysed. The characteristic is "four high and three low" in normal log, moreover, some methods for gas-bearing shale resevoir qualitative identification are presented.Conservation conditions of Lower Siluric shale gas in study area were studied systematically on controlling factors and evaluation indicators. Lower Siluric shale has undergone intense tectonic reworking of Yansan-Xisan phases after gas-production peaked. Uplift-erosion, fracture development, change of sealing-capping conditions resulting from tectogenesis would give rise to significant impact on effective conservation after gathering of shale gas. Comprehensive evaluation index systems of Lower Siluric shale gas conservation conditions around study area were presented on the basis of study. It’s supposed worse in all and better partly to shale gas conservation conditions of Lower Siluric.Through the development characteristic of marine facies in south of China, the reference standard of marine facies shale gas prioritizing was presented. Based on taking a variety of parameter indexs into account, the characteristic of reservoir-forming condtions of Lower Siluric shale gas is "four big, two strong and one bad", which means wide shale distribution areas, big thickness, high richness of organic matter, high maturity, strong gas storage ability, strong brittleness, but bad conservation conditions. Favorable zones of shale gas development are forecasted by the method of comprehensive information superposition. Those zones along the northeast, which is around Qianjiang-Shizhu-Wulong-Qijiang-Chishui-Xingwen-Luzhou-Longchang, are supposed favorable zones of Lower Siluric shale gas development in study area, and the area is20976km2. Three computing methods of shale gas content that contain experiment analysis method, desorption method and logging interpretative method are presented, and through these methods, the gas content of some Lower Siluric shale is calculated. The shale gas geology reserves of favorable zones that are calculated by the volume method are1.86×1012m3, which indicates great exploration potential of shale gas resource.
Keywords/Search Tags:gas content, reserves, favorable zones, resevoir-forming conditions, shale gas, Lower Siluric, southeastern Sichuan
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