Architecture Characterization of Braided River Reservoir Based on Dense Well Pattern in Daqing Oilfield, China
Western Sa-zhong Block of Daqing Oilfield, located in Songliao
Basin in northeast China, with 2573 wells in a 9.04km2 area, has the maximum
welling density, 250 wells/km2 on average in China. Data are abundant and
includes core data, horizontal wells, logging data, production data and
surveillance data, all of which are used for fluvial reservoir characterization
study. The fluvial types of Sa-Pu reservoir groups, the main oil-bearing
formation, are classified as meandering river, braided river, and delta distributary channel.
Take P1-3 small layer as a target layer, according to fine-grained interbed of flood plain in single wells, the stages of multiple stacking braided channels are divided and correlated vertically. Based on identification of single channel, rules of geostatistics and production monitoring data analysis, the width of single channel in this area is determined as 110-550m. There are 3 types of single sand bodies: mid-channel bar, braided channel and flood plains, which are identified in each stage with the method of ‘identification in single wells, boundary lateral division, and plane combination’, and the distribution pattern of single sand bodies in sandy braided river is summarized. Based on the interpretation of single sand bodies, the internal interbeds are also identified, which are mainly classified as fall-siltseam, mudstone between bars, and string groove filling. Guided by modern sedimentation theory and outcrops study, the distribution of architecture boundary surfaces in the mid-channel bar are predicted based on multiple wells correlation. Accordingly, 3D model of the interbeds inside the mid-channel bar is built with stochastic modeling. The results show that the interbeds in the thick sand body of braided river reservoir, which are associated with the bounding surface, are always unstable in the center part of the mid-channel bar. The research provides an accurate geological basis for production dynamic analysis and remaining oil potential tapping.
AAPG Search and Discovery Article #90142 © 2012 AAPG Annual Convention and Exhibition, April 22-25, 2012, Long Beach, California