Natural Gas
Geochemistry in the Tarim
Zhang, Tongwei1, Quanyou Liu2,
Jinxing Dai2, Yongchun Tang1 (1) California Institute of
Technology, Covina, CA (2) Research Institute of Petroleum Exploration and
Development, PetroChina,
Natural gases in the Tarim basin,
A positive relationship among d13C1, d 13C2, d 13C3 suggests
that the thermal genetic gases from organic matter cracking under high
temperature and pressure are a dominant source for natural gases in the Tarim
basin. Being taken coal-type gas as an example, dynamically understanding gas
recharging history to an effective trap is demonstrated by using quantitative
gas isotope kinetic modeling. The preliminary isotope modeling results show
that the natural gases derived from the Triassic-Jurassic humic matter are not
following the cumulative pattern, which indicates that earlier generated gases
were gone before the reservoir formed. Accumulated gas in reservoirs mainly
represents the late-stage generated gases from the Triassic - Jurassic source.
Based on the gas isotope pattern, we can reconstruct the gas filling history.
Our gas isotope modeling gives the recharging time of Kela 2 large-sized gas
field in the Tarim basin probably happened later than 5mybp.
AAPG Search and Discover Article #90063©2007 AAPG Annual Convention, Long Beach, California