Accurate 3D Seismic Interpretation of Large Braided Delta Reservoir and Outcrop Analogs in Northwest China

This paper presents a first discovered braided delta images (area of 562.5 square kilometers, depth more than 3400 meters) with perfect river channels by accurate 3D seismic interpretation in the hinterland region of JR basin in northwest china. We can clearly identify micro facies like the main channels in the delta plain, underwater distributary channels in the delta front, mouth bar and sheet sand from the very fine 3D seismic images. Methods are discussed for identifying and dividing the features of braided delta sediments, using sequence stratigraphy, well log characteristics, core observation, 3D seismic data and outcrop analogs. The most effective and visual methods to reveal the characteristics of this special geological body are 3D seismic interpretation and outcrop analogs. Based on high-resolution sequence stratigraphic framework and well drilling, a work program focused on the fine description of this large braided delta reservoir has integrated accurate 3D seismic interpretation and outcrop analogs, which include: synthetically seismic attribute analysis, spectrum analysis, seismic waveform classification display, 3D coherency interpretation, logging constrained seismic inversion, 3D visualization Interpretation and outcrop studies. This method is a key to do a multi-angle research, and to find out the distribution law of favorable sedimentary facies belt. Matching the modern outcrop sedimentary observation, accurately identify geophysical response of special geological body from 3D seismic images has greatly promoted present oil exploration. The high quality of this complete braided delta images will not only provide a new typical braided delta geologic model for geologists to do deep studies, but also be very useful to further develop the similar reservoir at home and abroad.