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Shale Gas Accumulation Characteristics And Evaluation Of Target Area In NW Hunan Area

Posted on:2014-08-05Degree:MasterType:Thesis
Country:ChinaCandidate:W JiangFull Text:PDF
GTID:2180330482478968Subject:Mineral prospecting and exploration
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Through field geological observation, sample collection, indoor microscope characteristic together with various test methods such as Rock pyrolysis,Organic petrology analysis,Scanning electron microscope analysis,Mercury injection test,Cryogenic nitrogen isothermal adsorption experiment,we systematiclly analysis the geochemical,physical properties and gas content characteristics of the shale in this areaThe Lower Cambrian Niutitang: Almost deep-sea basin sedimentary, thickness between 50-250 m, most of the region is greater than 90 m. Mainly carbonaceous shale, local folder powder sandy shale black carbonaceous shale. TOC is between 0.18% to17.7%, an average of 3.63%, the I type of organic matter, Ro is from 0.95% to 4.44%, 2.46% on average, belongs to the high- too mature stage. Rock cracks are well developed, mainly for micro-cracks; the pores are aimost tiny holes, porosity ranges from 0.2% to 25.9%, an average of 9.5%. Adsorbed gas content is up to 0.76m3 / t.The Lower Silurian Longmaxi: mainly belongs to the semi-confined shore to the confined shallow water basin sedimentary environment, development a set of marine sedimentary rocks mainly composed of graptolite. Thickness between 20 to 150 m, an average of 60 m. TOC is between 0.12% to 3.86%, an average of 1.02%, the I type of organic matter, Ro is from 1.06% to 3.95%, with an average of 1.99%, belongs to the mature- over mature stage. mainly for micro-cracks; the pores are aimost tiny holes, porosity ranges from 1.9% to 10.6%, with an average of 5.6%. Adsorbed gas content of up to an average of 1.58m3 / t.Basied on the mercury injection test and low-temperature nitrogen adsorption isotherm data the influence factors of the shale storage are explored by means of fractal theory. Pressure mercury features show that the penetrate holes structure of the fine pore is simple; microporous diffusion holes structure is complex, which determining the permeability of the shale. Low temperature nitrogen adsorption experiment shown positive correlation between the specific surface fractal dimension(Db) and BET superficial area, while the Db is negative correlation with the BJH total hole capacity and average pore size; The body integral dimension number(Dt) is negative correlation with the BET surface area and BJH total hole content, positive correlation with the average pore size. The more complex the rock pore surfaces the smaller surface area is. Pore volume and pore radius is distorted due to surface fold decrease; Complex morphology of the rock pore volume will increase the surface area of the rock and reduce the pore radius and pore volume. In addition, there is slight negative correlation between the total organic carbon(TOC) and the surface integral dimension Db, positive correlation between the TOC and the volume integral dimension Dt; Organic maturity(Ro) and the surface integral dimension Db is negative correlation with the volume integral dimension Dt.At last, according to the analysis results of the methane isothermal adsorption curve and characteristics of geochemical and the pores, we aimed to prospecting for the favorable area of the shale gas accumulation.The target area of The Lower Cambrian Niutitang is in Baojin-Yongshun-Sangzhi-Cili area;the target area of The Lower Silurian Longmaxi is in Longshan-Yongshun-Sangzhi-Zhangjiajie area.
Keywords/Search Tags:The northwestern Hunan Province, Shale gas, Geological characteristics, Reservoir forming conditions, Favorable area optimization
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