Volcanic Facies of the Songliao Basin:Sequence,Model and the Quantitative Relationship with Porosity & Permeability of the Volcanic Reservoir
WANG Pu-jun~1, WU He-yong~2, PANG Yan-ming~2, MEN Guang-tian~2, REN Yan-guang~2, LIU Wan-zhu~1,BIAN Wei-hua~1 1.College of Earth Sciences, Jilin University, Changchun 130061, China 2.Daqing Exploration &Development Instiute, Daqing, Heilongjiang 163712, China
Facies sequence of volcanic rocks is predominantly controlled by lithotypes in the Songliao Basin. Acidic eruption cycles generally begin with explosive facies and end with extrusive facies. Andesiticbasaltic eruption cycles usually begin with effusive facies and end with volcanogenitic sedimentary facies. Interbeded acidic-intermediate-basic volcanic eruption cycles have complex facies sequence ge- nerally from effusive facies through explosive facies to volcanogenitic sedimentary facies. Weathered crust and sedimentary intercalation are indicative of volcanic intervals. Extrusive and volcanogenitic sedimentary facies are the end-members of an eruption cycle. Facies model described here has been effectively used in seismo-reservoir interpretation in the gas field of volcanic rocks of the Songliao Basin. Only four of the 15 volcanic sub-facies can form high-quality volcanic reservoirs, which include volcanic neck, pyroclastic-bearing lava flow, upper effusive and inner extrusive sub-facies. Well understanding about volcanic facies can make gas exploration easier and more effective: volcanic reservoir exploration → effective reservoir finding → focusing on seismic analytic interpretation of the best four types of volcanic sub-facies which can become potential good reservoirs.