Shale Gas Geological Characteristics Of Lucaogou Formation In The Southeastern Margin Of Junggar Basin

Based on the previous research,the thesis has researched systematically the sedimentary characteristics,hydrocarbon source characteristics,reservoir characteristics and gas-bearing characteristics of the black shale in Middle Permian Lucaogou Formation in the southeastern margin of Junggar Basin,according to field geological observations and section measuring,combining with drilling data and sample test data,and gets the following results and understanding:1.The vertical lithology variations and plane distribution feature demonstrate that Lucaogou Formation was deposited in fan-delta,semi-deep to deep lake facies with the water expansion from the bottom up.Bogurda region is not only sedimentary center but also settlement center.2.In terms of organic geochemistry,Lucaogou Formation organic-rich shale has high abundance of TOC(average of 4.40 %).The kerogen types are mainly type?.Type ? 1 comes second.Ro value is in the range of 0.62%-1.27 %(average of0.8%),which manifests that the black shale remains at a low-mature stage.3.In terms of reservoir capacity,the shale of Lucaogou Formation has ultra-low matrix porosity(average of 0.98%)and penetration rate(average of 0.04mD).From the microscopic view,matrix intergranular pore is widely developed,the connectivity of which is poor.Combined with the measuring logging data of Well-ZY3,It can be found that the reservoir space types are mainly cracks and Micro cracks,instead of pores.4.In terms of reservoir capacity brittleness,the average value of Poisson's ratio and Young's elastic modulus are 0.22 and 1.34×104MPa.The crossplot and the brittleness index tested quantificationally by X-ray scattering techniques both reflect that the black shale of Lucaogou Formation has high brittleness,which could be helpful to the implementation of fracturing later.5.In terms of gas-bearing,the average value of gas content is 0.39m3/t from 54 samples.The accumulative strata thickness is 77 m,from which the samples have high total gas content(more than 0.5m3/t).Fracture in high gas sections is more developed.Langmuir adsorption isothermal experiment reveals the strong adsorption capacity of black shale of Lucaogou Formation.6.Partial advantageous and disadvantageous factors have been summed up through analysis and research as follows.Advantageous factors: Lucaogou Formation organic-rich shale is developed in semi-deep to deep lake facies,Which has large continuous thickness,high abundance of TOC and strong adsorption capacity.Disadvantageous factors: low thermal maturity,complex tectonism and developed fault.7.Urumqi syncline is considered to be the favorable area in the studied region for the exploration of Lucaogou Formation preliminarily.