LI Qianwen, PANG Xiongqi, HUO Zhipeng, CHEN Junqing. 2016: FORWARD ANALYSIS OF SOURCES AND RELATIVE CONTRIBUTIONS OF MARINE OIL AND GAS IN TAHZONG AREA, TARIM BASIN. JOURNAL OF ENGINEERING GEOLOGY, 24(5): 833-846. DOI: 10.13544/j.cnki.jeg.2016.05.013
    Citation: LI Qianwen, PANG Xiongqi, HUO Zhipeng, CHEN Junqing. 2016: FORWARD ANALYSIS OF SOURCES AND RELATIVE CONTRIBUTIONS OF MARINE OIL AND GAS IN TAHZONG AREA, TARIM BASIN. JOURNAL OF ENGINEERING GEOLOGY, 24(5): 833-846. DOI: 10.13544/j.cnki.jeg.2016.05.013

    FORWARD ANALYSIS OF SOURCES AND RELATIVE CONTRIBUTIONS OF MARINE OIL AND GAS IN TAHZONG AREA, TARIM BASIN

    • Due to the blend of multi-source oil and gas as well as multi-period tectonics in Tarim Basin, the origin and relative contribution of these marine oil and gas has not been clear. According to oil-source correlation, source rocks of O1+2 are the main origin of these oil & gas. However, the fact that the distribution of source rocks with high TOC(>0.5%) is quite partial, can not reflect the large-scale found reserves. Furthermore, the found gas reserves in Tarim Basin have exceeded the result of the 3rd resource evaluation. These contradictions show the limitation of oil-source correlation in the superimposed basin. For this study, forward modelling method is used to simulate the processes of hydrocarbon generation and expulsion of potential marine source rocks. Effective quantity of hydrocarbon accumulation namely quantity of resources can be obtained by deducting the critical saturation of residual hydrocarbon, loss of diffusion phases, loss of hydrocarbon residued in the migration and damaged by tectonic movements from the total amount of hydrocarbon expulsion, which can be used to assess the relative contributions of oil & gas of each set of source rock. Studies show that the amount of resources can be provided by the Cambrian source rocks is higher than that by Ordovician source rocks. The ratio is about 63%to 37%. The amount of resources that can be provided by source rocks with low abundance is lower than those by source rocks with high abundance. The ratio is about 32%to 68%.The reason that the scale of reserves in Ordovician is larger than the predicted may be the contribution of part oil & gas coming from the Cambrian or source rocks with low TOC(≤0.5%).
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