Tectonics And Sedimentary Evolution Of Roebuck Basin In Australia Northwest Shelf

The oil and gas fields in Western Australia super basin are the hot spots of oil and gas exploration in the world and have good development prospect and exploration value.The research and development degree of Roebuck Basin is relatively low.In recent years,some progress has been made in the Bedout sub-basin,while there is no harvest in the Rowley subbasin in the north.The study of its geological conditions will help us to guide and reference the further exploration and development of the Rowley sub-basin.Roebuck basin is a passive continental margin deep water basin,which has experienced the pre-rifting stage of craton basin rifting stage and intracontinental depression stage.Synrifting stage continental rifting stage;The passive continental drift stage in the post-rift period is now the decaying continental margin.The fault strike in Rowley sub-basin is mainly NE-SW,and some deep and large faults strike NW-SE.The main faults generally developed in the continental rifting stage from late Jurassic to early Cretaceous.The main faults are normal faults formed by tensile stress,and the fracture style profiles can be seen as "X","Y",negative flower,cabbage,straight faults,etc.In the plane,dendritic,parallel and broom fracture combinations can be seen.The fault strike and stress were analyzed from the fault strike rose chart.It was found that the fault strike of the strata in the study area changed clockwise since ancient times,and the stress mainly changed from NW-SE extension stress to NW-SE and NE-SW extension stress to NE-SW.The sedimentary environment in the study area has undergone three stages of evolution:continental facies,Marine and continental transitional facies,and Marine facies,during which the sedimentary environment has undergone many changes.The seismic facies and lithology of the study area are identified by the method of well seismic combination,so as to restore the sedimentary environment of each period in the study area.There are several kinds of seismic facies in the study area,such as forestave facies,carbonate platform facies,coral reef facies,"V" type gully facies,"U" type fluvial facies,syngenetic sedimentary facies and slump facies.The sedimentary strata evolved from Triassic land-coastal facies to Jurassic shallow Marine facies and continental facies to Cretaceous period,in which the overall sedimentary environment was dominated by shallow Marine environment,partly in semi-abyssal to deep sea sedimentary environment,and finally evolved into Paleocene to present,and the basin entered into semi-abyssal to deep sea sedimentary environment as a whole.Finally,the evolution process of the basin is reduced by combining the geological historical events of the Northwest Continental Shelf and the tectonic sedimentary characteristics of the basin in various periods.Then the petroleum geological characteristics of the basin where the study area is analyzed and discussed.