Study On The Sedimentary Micro-phase And Reservoir Of Qianjiang Group Of Qian 3 In Guanghua Oilfield

At present,the exploration and development of various oil fields in China has entered the middle and late stage,and the difficulty of stable production increase is increasing year by year.After more than 40 years of exploration and research in Guanghua Oilfield in Qianjiang Depression,most of the large and simple structural areas have been explored and developed at present,and it is increasingly difficult to find large and favorable structural reservoirs.At present,because there are many sedimentary systems in Guanghua oilfield,the deposition situation is complicated.Therefore,in this paper,the sedimentary rocks of the Qian Ⅲ of the Qianjiang Formation in Guanghua Oilfield are studied.Based on detailed core description and scanning electron microscope observation,the relevant logging data and test data are used to study the petrological characteristics,sedimentation and sedimentary facies division in this area,clarify the sedimentary evolution law,provenance direction and reservoir characteristics,and grasp the characteristics and distribution of reservoirs in this area.Based on the sedimentological theory and guided by the theories and methods of underground geology and well logging geology of oil and gas fields,this paper studies the stratigraphic correlation division of the third member of the Qian Ⅲ of the Qianjiang Formation in Guanghua Oilfield by synthesizing the relevant data of core,lithology and well logging.In this study,the method of cycle correlation,the division of small beds in a single well and the establishment of a joint well skeleton profile were used to divide and compare the strata of the target interval,and the high-precision stratigraphic framework of the study area was established.6 sand groups and 13 small beds were divided in the Qian3 member of Guanghua oilfield.By analyzing zircon dating and heavy mineral distribution characteristics,it is clear that the source of the Qianjiang depression is divided into two sources,Jingmen depression in the northwest of Guanghua Oilfield and Hanshui depression in the northeast of Guanghua Oilfield,and the two sources control the source supply of the whole depression.Starting from core observation,logging curve and other information to clarify the characteristics of sedimentary phases,the deltaic sedimentary system and the salt lake sedimentary system were identified in the study area:for the deltaic sedimentary system,a total of five sedimentary micro-phase types were identified,including submerged divergent channels,submerged divergent interbay,estuarine dams,matted sands and far-sand dams,and the corresponding deltaic sedimentary model was established;followed by the salt lake sedimentary system,a total of mudflats,paste salts and salt rocks were identified.A total of three sedimentary micro-phase types were identified.Through the systematic analysis of single-well and continuous-well phases,the sedimentary micro-phase types,vertical evolution pattern and planar spreading characteristics of the study section were determined.The lithological and porosity characteristics of the study area were studied by using physical parameters,SEM images and logging interpretation results,and the reservoir evaluation was carried out for the Qian 3² and the Qian 3⁴,which have good physical properties.The average values of porosity and permeability in the Qian 3²section were 18.3%and 184×10^-3μm²,while the average values of porosity and permeability in the Qian 3⁴ section were 14.4%and 143×10^-3μm²,respectively.The results show that the Qian 3² is mainly divided into class I,class II and class Ⅲ reservoirs,and the Qian 3⁴ is mainly divided into class Ⅱ,class Ⅲ and class Ⅳ reservoirs.