| With the increasing degree of the Permain Changxing Formation reef-bank reservoirs in northeastern Sichuan,in the same conditions,more and more researchers want to explore the Panlongdong section,which are located in the western of Chengkou-exi Though,because of its completely construction,it has became a typical section of surrounding in Chengkou-Exi Though.Influenced by the Panlondong Section,the relevant scholars are going to carry out the research on the reef facies of Changxing Formation in the around area in Chengkou-Exi area.But compared with the research of ‘Kaijiang-Liangping' Though,the study on Changxing Formation in Chengkou-Exi Though is lagging behind.Especially,the study of distribution characteristics of sedimentary facies in the sequence stratigraphic framework is relatively weak,so we do this study have a theoretical and practical significances.This paper,which is research on the sequence and sedimentary system of Changxing Formation in the studying area in Chengkou-Exi area,mainly obtains following conclusions:(1)In this study,through the reflection characteristics of the sequence boundaries in seismic profile,and the response characteristics of lithology profile on logging curve,we identified the key sequence boundaries.In this study,Changxing Formation was divide into two type II 3rd-level sequences,namely Sq1 and Sq2,which are composed of TST and HST,and Sq1 is corresponded to the first and second part of the three members of Changxing Formation,and Sq2 is corresponded to the last member of Changxing Formation.Combined with the 4th sequence scheme,the Changxing Formation was divided into five 4th sequences,namely sq1~sq5.And we built the sequence stratigraphic framework of Changxing Formation in study area.(2)According to the observation and identification of core and thin section,and the investigation of outcrops,combined with the sedimentology research methods,on the basis of previous research,two depositional models were developed in the Changxing Formation in Chengkou-Exi area.The early stage of Changxing Formation are developed “carbonate ramp mode” and the middle and late stage of Changxing Formation are developed “carbonate platform model”.(3)In this paper,we draw many pictures about the sedimentary facies distribution in the HST of 4th sequence,we known the characteristics and evolution of sedimentary facies in sequence framework in Changxing Formation in the study area.Sq1-TST was carbonate gentle slope deposition;since the start of sq1-HST,from west to east in the study area,the facies are open platform,platform margin,platform margin slope-basin.In Feng1 and Fengtan1wells,the platform margin reef-bank are highly developed and mainly distributed in sq2 and sq3.In sq4 and sq5 period,the section from west to east was developed the open platform facies and platform edge facies.Lou 1 well were located in a Basin sedimentary environment.(4)In one word,from the reservoir physical properties,the reservoir of Changxing Formation is belongs to a low porosity and a low penetrative reservoir in the study area.And the development of reef-bank reservoirs of Changxing Formation in the study area is mainly controlled by different lithology,different sedimentary facies,the change ofsea level and the join of diagensis.With the superimposed of the sedimentary facies maps of 4th sequences of Changxing Formation,we predicted the distribution of favorable reservoir facies. |
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