Research On The Sedimentary Facies For Fuyu Oil Layer In Gaotaizi Oil Field

Gaotaizi oil field is located in the south of Daqing Placanticline on central depression in Songliao Basin. Fuyu oil layer lies in cretaceous Quan4 member of Mesozoic. Based on the predecessors’ research results,3D seismic data, drilling and logging data of the study area, guided by theories of high resolution sequence stratigraphy, principle of seismic exploration and reservoir sedimentology, this paper systematically carry out high resolution sequence stratigraphic division and correlation, prediction of seismic attributes and reservoir inversion sedimentary microfacies, sandbody distribution.Fuyu oil layer consists of a upward shallowing half cycle with falling base-level and a upward deepened half cycle with rising base-level. It shows a regional lake reliction-immersion which is composed by a large set of water with big changes in the magnitude and strata of genetic relationships. On the basis of sequence stratigraphy study, we complete division and correlation of 109 wells and divide Fuyu reservoir into 3 oil groups,17 small layers in the method of the technology combined with logging and seismic. Isochronous stratigraphic framework has been established.We adopt a variety of reservoir prediction methods such as multiple seismic sequence attribute analysis and high-precision log constrained inversion. We establish a technology of reservoir prediction to describe sand distribution, which involves fine calibration and interpretion, sensitivity analysis of core, log and seismic data, quantitative-qualitative joint post-stack inversion.Based on the regional sedimentary setting, geologic features and log facies analysis, meanwhile combined with seismic profile and the reflecting structure analysis, we learn that typical fluvial-dominated shallow river to delta sedimentary system develops in the study area with 2 subfacies and 16 microfacies, overwater and underwater distributary channels develop most, the direction of material source is from Qiqihaer drainage, distributary channel sand body is the most favorable reservoir sand body.From sedimentary characteristics research and reservoir prediction results, we start with pilot zone and regional sandbody comparison, then we analyze the development and connectivity features of the channel sandbody in fuyu reservoir, finally, we find out sandbody distribution features of each layers. It is considered that most sand bodies exist in the middle of F I and top of FII, connectivity is poor in single layer, morphology and distribution of sand bodies control the planar distribution of oil. Combined with fault factors, test data and some other factors, four favorable channel sand blocks are optimized. It provides geological basis and advantageous safeguard for further evaluation of Fuyu reservoir potential in Gaotaizi oilfield, for oil and gas reserves submission and for development and deployment.