Fine Reservoir Analysis of Thin Interbed Layers in a Delta Based on Sedimentary Process

Key words: 
• sedimentary process /
• braided river delta front /
• thin interbed layers /
• Guantao Formation /
• sand formation /
• single sand body

Abstract: Because of the relatively low resolution of seismic data in the study area,continuous sand beds in interbedded sand-shale reservoirs cannot be distinguished by this method alone. By combining seismic,drilling and logging data in the study area,paleogeomorphological and sedimentary paleo-environment analysis revealed by drilling was carried out on the basis of precise time depth calibration. The distribution range of interbedded sand-shale reservoirs was obtained by combining this data with seismic minimum amplitude properties. The formation process of individual sand bodies in the complex interbedded sand-shale reservoir eventually led to locating a continuous monolayer sand body. Using an acoustic and apparent-thickness correction method of reconstruction established an isochronous stratigraphic framework of interbedded sand-shale reservoirs;the minimum amplitudes of the seismic data and the distribution characteristics of the interbedded sand-shale reservoir were obtained. Restricting the boundary of an individual sand body by using a sedimentary combination model and geological knowledge base enabled us to reconstruct the location of the single sand body. Finally,the reasoning behind this method of single sand body distribution was verified by dynamic data,including pressure measurement while drilling together with production and suction profile testing. The actual production data of P19 oilfield in Bohai Bay confirmed the reliability of the research results,guided well location deployment and optimization in a comprehensive adjustment project,and improved the accuracy of predicting the location of single sand bodies and the corresponding injection production rate.