Font Size: a A A

Shale Gas Accumulation Conditions And Favourable Areas Forecast Of Lower Silurian In East Chongqing

Posted on:2015-03-15Degree:MasterType:Thesis
Country:ChinaCandidate:Y J DiFull Text:PDF
GTID:2250330428466819Subject:Marine Geology
Abstract/Summary:PDF Full Text Request
Multi-stage tectonic evolution occurred in the area of East Chongqing, locatedbetween high-steam tectonic zone in east Sichuan and transition tectonic zone inHubei and Chongqing.With the basis of deep water shelf sedimentary environment inthe period of early Silurian, a layer of organic-rich shale developed at the bottom ofLongmaxi Formation, with characters of abundance of organic matter, high thermalevolution, widespread distribution, which can be discovered in the area range ofShizhu-Pengshui–Fuling, deserves a good exploring potential.The content of organic carbon is between0.5%and4.0%, generally more than2.0%.The main type of organic carbon can be defined as I-II type, with a high degree ofthermal evolution, generally greater than2%. Microns-nanoscale pores and cracksare widely found in the shales, with rich reservoir pore types which developed in theshale. The shale has good reservoir properties, because of permeability mainly beinggreater than0.05md and porosity mainly being between4-6%.55%content of quartz,a relatively low content of clay minerals and high content of brittleness mineral in theshale are conducive to shale fracturing in the late stage. Two factors contributing tothe preservation of shale gas are cap layers and tectonics. Although a multi-stagetectonics can be recognized with the fracture developing in the area, thick and densecarbonate rocks provides a possibility for the preservation of shale gas.Gas content in exploring wells in study area stays in a high level, with the averagecontent of2.96m3/t. The content of organic carbon, porosity, brittleness mineral andclay mineral are employed here for factors influncing gas content. The positiverelationships of organic carbon and free gas, organic carbon and adsorbed gas indicatesignificant impacts to the accumulation of shale gas.Based on an integrated analysis on3wells for shale gas in Lower Silurian in studyarea and different geological characters of shale gas concentration areas comparisonbetween China and the US, the factors influncing the accumulation of shale gas arethe development of organic-rich shale, superior accumulating and preservingconditions. With the research on formation conditions of organic-rich shale and the property of gas containing, a prediction of vantage area for shale gas exploration inLower Silurian in the area east Chongqing is implemented by the method of anoverlaying of multi-factors (shale thickness, organic carbon content, organic maturity,depth, etc.), integrated geological evaluation methods and geological analogy. Theresult of integrated analysis on shale gas shows that the vantage area for shale gas islocated in the area of Shizhu-Fengdu-Fuling in Chongqing City.
Keywords/Search Tags:Shale gas, East Chongqing, lower Silurian, main controlling factor, favorable area
PDF Full Text Request
Related items