Three-dimensional Seismic Interpretation And Sedimentary Study Of Guai8 Well Area On The Northwest Margin Of Junggar Basin

Guai 8 Area is located in the northwest margin of Junggar Basin,which belongs to the Zhongguai uplift structurally.As an inherited ancient uplift,Zhongguai uplift is close to three major hydrocarbon generation depressions.And it is the key point for oil and gas migration and accumulation.The main reservoir is the Formation Sangonghe.In Guai 8 Area,the exploration degree is low and the well density is low.Therefore,we take seismic data as the main and well data as the secondary means to further study the region.This study is guided by 3D seismic interpretation,sequence stratigraphy and seismic sedimentology.The key point of this research is the comprehensive analysis of seismic data and logging data.The specific working steps include:stratigraphic sequence division and correlation,fine structural interpretation,sedimentary microfacies and sedimentary evolution research,the use of seismic attributes to divide sand bodies,prediction of favorable zones and optimization of drilling objectives,a total of five aspects.According to the well-seismic-drilling-test data,isochronous correlation,phase-controlled correlation and cycle correlation are used to divide strata and determine the sequence boundaries.Based on the sequence stratigraphic correlation study of single well and well-connected skeleton profile,the sequence stratigraphic framework of the whole region was established.The Formation Sangonghe SQJ_1s was divided into four three-order sequences SQJ_1s1,SQJ_1s2 and SQJ_1s3.Based on the well logging data,we make the synthetic seismic record of a single well accurately,so as to accurately calibrate the target layers.Based on the seismic data,we make detailed structural interpretation of the target layer and determine traps.Finally,6 major fault zones were identified,and 5 stratigraphic structure maps were drawn.Based on seismic facies analysis and data from four key wells,we analyzed sedimentary facies.Sedimentary facies such as littoral shallow lake and braided river delta were found in the study area.The subfacies of littoral shallow lake mainly consist of two kinds of sedimentary microfacies:littoral shallow lake mud and beach and bar.Braided river delta includes braided river delta plain and front subfacies,among which braided river delta front subfacies include underwater distributary channel and underwater distributary channel between two kinds of sedimentary microfacies.We extracted and optimized seismic attributes,and made the slices of seismic attributes to analyze the changes of sedimentary environment and sedimentary bodies in the study area.The above data were used to identify sand bodies of 5 stages,and the spatial superposition relation and the source was defined.Finally,combined with the research results of regional oil and gas accumulation,the favorable oil and gas accumulation areas are predicted.The favorable zones for oil and gas accumulation in the Formation Sangonghe were defined,2 favorable oil-gas bearing zones were determined.