The Shale Gas Prospective Evaluation Of Xujiahe Formation In South Sichuan

According to the data from the ministry of land and resources, the shale gasresource in Sichuan province is about27.5trillion cubic meters, accounting for20.46%of the country’s total, and recoverable resources of about4.42trillion cubicmeters, accounting for17.67%of the country’s total, ranking first in the country.Southern Sichuan region, located in the southern Sichuan province administrativeregion mainly Ya ’an, Meishan, Leshan, Ziyang, Suining, Nanchong, Neijiang, Zigong,Luzhou and other cities and counties. Southern Sichuan region is currently the largestshale gas resource potential in Sichuan province, and the development is also thebiggest region at the same time, which contains "Sichuan Changning-Weiyuannational shale gas demonstration zone" and some of the "North of Yunnan andGuizhou, Zhaotong national shale gas demonstration zone".Through data collection, geological survey, typical wells (cross-section)contrasting as well as systemic sampling and analysis for southern Sichuan XujiaheFormation shale of the spatial distribution, reservoir properties, organic geochemicalcharacteristics and gas-bearing properties a preliminary investigation and analysis,and to evaluate its resource potential.The main southern Sichuan region is located in Sichuan Basin in thesouthwestern margin of the Yangtze Block range. The western Sichuan Basin begandeveloping to foreland basin Basin in Late Triassic Norrie-Rhaetian, bottom-updevelopment of the tidecontrolled-rivercontrolled deltas, fluvial facies and alluvialfacies sediments.The major Shale gas bearing intervals of Xujiahe Formation in Southern Sichuanregion are Xu3and xu5.The Xu3is mainly distributed in shallow Weiyuan upliftarea,its high value center of total organic carbon content is located in Ziyang-Weiyuan uplift northeast, TOC values as high as8%.The Ro value of Xu3between1.21～1.85%. The porosity of Xu3distribution range of1.68%~3.25%, with anaverage of2.42%.The permeability of Xu3distribution in0.011×10-3μM2~0.0374×10-3μm2, with an average of0.024×10-3μm2.The Xu5is mainly distributed inCentral Sichuan-Southwest Sichuan, Weiyuan area in southern Sichuan is also shallow.The TOC of Xu5reaches3%or above, its Ro value of0.68～1.62%. Theporosity of Xu5distribution range of1.68%~3.25%, the main distribution area is1.8%~2%, the average value is2.12%. The permeability of Xu5distributed in0.003×10-3μM2~0.130×10-3μm2, with an average of0.053×10-3μm2.Shale lithology, color, TOC, porosity and shale gas enrichment of strong positivecorrelation, but the lithology and color related to the gas content is not linear. The gascontent of medium color and medium particle size rock is higher. Lateral resistivityand nature gamma curve correlation with gas content is good.Lakeshore facies andtidal flat facies are higher gas content.The Upper Triassic Xu3formation shale gas resources is about3272.23108m3.The Xu5formation shale gas resources is about17638.3108m3. Southern SichuanXu3selected three shale gas favorable area and Xu5selected four shale gasfavorable area.