The deeply buried shoal dolomite reservoirs of the
Lower Triassic Feixianguan Formation, giant Puguang Gas
Field, NESichuan Basin, are exceptionally porous. The
influences of diageneses on pore evolution are studied. Through petrologic
investigation, diagenetic phases are divided into four stages, i.e.,
near-surface, pre-oil window, oil window, and gas window. The Adobe Photoshop
system is used to quantify the rock texture components, porosity constitutions
and the influences of diageneses on reservoir porosity. Porosity evolution
curves are quantitatively recovered. The Feixianguan reservoir porosities are
mainly created by early meteoric dissolution, dolomitization, and organic acids
dissolution. Dissolution during deep burial is insignificant. Pores are formed
in near-surface and pre-oil window stages and effectively preserved till
present. This result may be of great significance to the further exploration of
deeply buried carbonate reservoirs not only in NE Sichuan Basin, but also
around the world.
Cite this paper
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