Print this pageYuanba Gas Field: A New Discovery in NE Sichuan Basin, SW China
The exploration area is in mountain region with complicated structural configuration and high surface relief,The Yuanba Gas Field was found by WellYuanba-1, in which the depth of the target Formation is nearly 7000m deep.Gas in this field is mainly contained in the Lower Triassic and Upper Permian. The best reservoirs are oolitic dolomites of platform margin shoal/reef facies.Although deeply buried, reservoirs in the field have relatively high porosity (1 to 12%, average 6%) and permeability (0.01to1200, average 40 md),which resulted from the combination of dolomitization, early accumulation of crude oil, and alteration by thermochemical sulfate reduction (TSR).Abundant solid bitumens were found in all cored wells in marine carbonate reservoirs.The marine carbonate reservoirs in the Puguang gas field were still buried to a depth of about 7000 m and experienced maximum temperature up to 210°C. Oil accumulation took place mainly in early Jurassic, and thermal cracking of formally accumulated oils occurred mainly late Jurassic and early Cretaceous (160 to 120 Ma).
The discovery of the Puguang gas field indicates that huge potential reservoirs still remain in the depth more than 7000m.Giant oil/gas fields could be preserved even after complex post-accumulation alteration in areas with highly overmature source rocks and complicated tectonic evolution history
AAPG Search and Discover Article #90100©2009 AAPG International Conference and Exhibition 15-18 November 2009, Rio de Janeiro, Brazil