Tectonically,Lunnan area was located in the North Tarim Rise of the Tarim Basin. There were good geological conditions for hydrocarbon accumulating in the western Lunnan area,a part of inherited palaeohigh,with fractures,dissolved fractures and cavernous being main reservoirs in the Ordovician buried hill. The oilfield in western Lunnan area was filled mainly during the late Hercynian period and was degraded into heavy oil during the latest Hercynian period due to the high denudation of the Carboniferous and Permian strata. Because of ceasing of regional first order faults,the hydrocarbon charging did not occur in the heavy oilfield in western Lunnan area during the late Indosinian to Himalayan periods. Based on what mentioned above,an accumulation model for Ordovician buried hill in western Lunnan area was summarized,which emphasized the Late Hercynian period being a key accumulation epoch and function of the faults with different orders. The study on accumulation process of the Ordovician buried hill reservoir represented an important implications for the exploration potential of early oil and gas accumulation in the cratonic area of the Tarim Basin.
Pan Wenqing,Zhao Mengjun,Zhang Baomin et al. Ordovician buried hill oilfield in western Lunnan area:An example of heavy oilfield formation for hydrocarbon charging and degrading in Hercynian period[J]. Chinese Journal of Geology, 2008, (2): 321-332.