Seismic facies to analyze lacustrine-basin evolution and predict shale blocks extended into the Jurassic Lianggaoshan Formation,Sichuan Basin
Currently,there are not systematic studies on both sedimentary evolution in the Jurassic Lianggaoshan Formation of Sichuan Basin and shale blocks extended into the formation,resulting that the basin-scale lacustrine-basin evolution and shale extension remain unknown.It is challenging to pinpoint favorable exploration prospects of shale oil and gas on the basin scale.Thus,seismic-facies attributes were identified for each Lianggaoshan members based on seismic,well-logging and testing data to clarify lacustrine-basin migration and predict shale oil and gas exploration direction for the whole formation.Results show that(i)this formation features thin in the west and thick in the east.And the depocenter in Lianggaoshan 1 Member is located in eastern basin and east of central basin,and that of Lianggaoshan 2 Member in eastern basin and north of eastern basin,and the largest sedimentary thickness of Lianggaoshan 3 Member in eastern basin,respectively;(ii)four categories of seismic facies can be found in this formation.Among them,category III is characterized by big thickness,continuous and strong reflection response,which corresponds to deep to semi-deep lacustrine shale;(iii)the formation experienced lacustrine flooding three times which are meant for lacustrine-basin migration.The deep to semi-deep lacustrine facies was extended into eastern basin during the deposition of Lianggaoshan 1 Member,migrated to central basin during the deposition of Lianggaoshan 2 Member,and developed into north of central basin during the deposition of Lianggaoshan 3 Member;and(iv)both Lianggaoshan 1 and 2 members are the main intervals developed with the deep to semi-deep lacustrine shale.Covering 2.2×104 km2,the superimposed shale block is situated in Pingchang-Quxian-Dianjiang area,signifying great potential for shale oil and gas exploration.
万方数据
维普
