Braided channel characters in palustrine environment and its identified methods
1,2
Geophysical Computer Center Institute of Exploration and Development, Changqing Xinlongyuan Sub-District Weiyang District, Xi'an City, Shanxi Province, 710021, China
Abstract：The lithological gas reservoir of P2h2 sandstone in Ordos basin belongs to braided deposition palustrine background. The sandstones are mainly coarse, medium-coarse and medium sandstones. Clumpy bedding and tabular cross-bedding are the main types. The sedimentary sequence generally presents a positive cycle characterized by upper——groase and lower——fine. Channel bar sedimentary micro-facies is most important effective sedimentary unit of the reservoir, the inner structure is more uniform and Gamma ray curves are characterized by more smooth and box with low amplitude. The configuration of channel seismic reflections shows lenticular or mounded form and belongs to bad continuity, medium amplitude and on-lap filling seismic facies. In the earlier days of development characterized by fewer drilled wells and larger well spacing,integrative application of seismic, geologic, logging and drilling data and using cluster analysis of seismic waveform and restoration of paleostructure to identify channel, which obtained planar distributed feature of P2h2 braided channel. The optimized construction blocks and arranged development wells on these grounds achieved good results.
