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