δwhich, generally, is a function of oil saturation of reservoir, temperature, pressure, geological sealing degree and structural uplifting.4. The gases in YN2 gas pool are a mixture of kerogen gas and oil cracking gas. The kerogen gas results from the Cambrian-lower Ordovician strata while the oil cracking gas is mainly derived from the cracking of oil in paleo oil pools in the upper part of the mid-upper Ordovician strata. The YN2 gas pool was charged mainly after the Tertiary period and is a secondary gas pool with deeper sources.5. The gases in Sang-nan gas pools are mainly composed of kerogen gas from mid-lower Cambrian strata with major source areas from the slopes to the structural high, i.e. from LN46 and LN59 in the southwest and southeast slopes, respectively, to LG13 in the structural high. In addition to the mid-upper Ordovician source rocks, the cracking of Cambrian oils in paleo oil pools is an alternative source for the condensates. Approximately, the effective gas accumulation initiated at the end of Triassic period, but the major charging occurred after the Tertiary period.
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