Research On Sedimentary Facies Of The Lower Jurassic Ziliujing Group In The Yuanba Area Of The Northeast Sichuan Basin

The Yuanba area of the northeast Sichuan basin is the favorable block of oil andgas reserves, Which showed good exploration potential in the the Ziliujing groupsegment of yuanba drilling process. Specifically,Zhenzhuchong and Daanzhai indrilling showed the good oil and gas shows. The success in exploration for oil and gashas the great significance in relieving pressure of LNG supply in the Sichuan provinceand ensure success of ambitious plan of The gas from Sichuan province is suppliedto other province. Therefore, this research has obviously economic benefits andsocial benefit.In this paper,based on the results of previous studies,supplemented byobservations of outcrop and core data,Drilling,mud logging, logging,seismic and test toanalyze the data, guided by the theory of geotectology, study of sedimentary basin andsedimentology,To research the stratum characteristics and Fine division the Ziliujing ofthe northeastern Sichuan yuanba area.Based on the research methods of "point-line-face", carry out from the analysis of single well to well connection contrasts, from thecharacteristics of petrology, sedimentary facies and seismic reflection characteristics,research, combined with the actual production situation of the Zhenzhuchong and theDaanzhai, relying on the drilling core data and drilling data, Specially to supplementedby seismic data in the area with few wells,finally draw the distribution map ofsedimentary microfacies. So the sedimentary facies study for future research areaprediction of natural gas and development support.Studies suggest that in the the northeastern Sichuan Yuanba area Ziliujing groupfrom bottom to top to be designated as the Zhenzhuchong,the Dongyuemiao,theMaanshan and the Daanzhai, in which the Zhenzhuchong and the Daanzhai can be further subdivided into upper and lower sub-section. Zhengzhuochong series maindeveloped sandy gravel, and get less to the top. The combined characteristicrepresented extremely low box, campaniform, infundibular, digitiform or serrate form,and the seismic section released that obvious washout developed in the bottom ofZhengzhuochong series. Dongyuemiao series and Maanshan series sediments werealternative sandstone and mudstone, the content of calcareous mudstone was raletivehigh in Dongyuemiao series, and the sediments in Daanzhai series main was greymeso-macrocrystalline shelly limestone, limestone with shale and grey micrite-micrite.The response to log from Dongyuemiao series to Daanzhai series main was majormicro-serrate curves with high gamma or curves with alternatively high or low gamme.The amplitude of Dongyuemiao series was mian medimum to strengh, and the responseof Maanshan series was weak, the inner of which developed discontinuouslyparalleling weak response, the amplitude of Daanzhai series was smoothly medimumfluctuation, and developed compound wave.In the study area,the Ziliujing group mainly developed the fan delta-lacustrinedepositional model, the fan-delta sedimentary system is mainly developed fan deltafront subfacies, including underwater distributary channel, interdistributary bay, mouthbar, distal bar and subaqueous levee microfacies development. The lacustrinedepositional system is mainly developed Lakeside, shallow lacustrine, Which Lakesidesand and mud, shallow lake sand dams, shallow lake mud, shells and shelly coastal,et al.sedimentary microfacies development.In the Yuanba area, The source direction of the Ziliujing group Zhenzhuchongmember mainly are the Micang mountain and Longmen mountain which in the northand the northeast of the Sichuan basin. Affected by the Yanshan Movement,theunderwater distributary channel sand of the fan delta front mainly is NW-ESdistribution.From the later of the sedimentary in Zhenzhuchong to the earlier of thesedimentary in Daanzhai,the lake level is on rising.The Source of the MiCang mountaindrow back.The thrust effect of the Longmen mountain increased and has became themain source area.From the Dongyuemiao to the Daanzhai mainly developed thelacustrine facies,and the shells and shelly coastal only developed in the Daanzhai.