Sedimentary Characteristics Of Guantao Formation In Beach In Liaohe Oilfield

Beach of Liaohe depression locates in northeast of Bohai Bay,which is extension sea of Liaodong bay.Recent years,as the finding of heavy-oil in Guantao formation,this strata of the area is listed target stratum to explore and research.This paper is opened from the cognition of sedimentary facies.According to sismic data,well logs supplied by predecessor dividing of ashore sequence and theogy of petroleum geology , sequence stratigraphay and the technology of geophysics,systemic research of Guantao formation sedimentary characteristics has been done in research zone.According to the recognition of sequence boundary,two three-order sequences are divided in the Guantao formation of Liaohe bay.On the basic of core observation,fractional analysis, lithology analysis, borehole log characteristics analysis,thickness and color of mudstone analysis, category and content of palaeocoenosis analysis, seismic reflection charateristics analysis and correlation of syndepositional strata in the vicinity, Braided-delta is confirmed the main sedimentary facies in this formation.The evidences are as follows:Rock styles is dominated by glutenite, overlapping erosion and perpendicularity pebble appears in core; grain size accumulation curve are two-stage,three-stage and multi-stage,C-M crossplot position granularity PQ and QR stage; oxidized mudstone distributes in western basin bondary and north and south of eastern uplift , transitional mudstone like gray-green mudstone is in front of oxidized mudstone followed the orientation of provenance,reducing mudstone like gray and hoary one is in inner basin;palaeontologic species like Leiosphaeridiasp, Comasphaeridiumsp, Pediastrumsp and so on can indicate lakes environment;sismic reflection styles are dominated by divergent and imbricated foreset reflection;sedimentary characteristics above of Guantao formation in Bozhong sag are similar to research area .On the basic of recognition of sedimentary facies , simultaneous-well correlation and plane distribution of geologic and sismic parameters,distribution of sedimentary facies is finished.