OIL AND GAS PROSPECT OF THE CAMBRIAN AT LAOSHAN UPLIFT:A COMPARATIVE STUDY TO SICHUAN AND SUBEI BASINS

As the main part of the Lower Yangtze Craton, the South Yellow Sea Basin has remained as the only area without breakthrough of oil and gas up to date. There is no conclusion being made for the region, especially for the Laoshan uplift, since there are lack of drilling wells. The oldest strata penetrated by drill hole so far are the Carboniferous, and the seismic exploration degree is low. In fact, there is no actual data enough to reach a conclusion on oil and gas potential. However, the South Yellow Sea Basin is similar to some extent to the Sichuan Basin and the Subei Basin in such aspects as hydrocarbon source rocks, reservoirs, cap rocks and accumulation mechanisms. By comparison, it is found that there are abundant and thick source rocks in the South Yellow Sea Basin. The average organic carbon contents are 4% and 3.32% respectively, which belong to the category of good hydrocarbon source rocks. In addition, there are widely distributed Sinian and Cambrian dolomite reservoirs, and the porosity and permeability of the reservoirs are rather high because of dolomitization and tectonic crackings. Moreover, there are three types of oil and gas accumulation models, i. e. the oil and gas generated newly and stored in the old, the oil and gas generated elderly and store in the new, and the oil and gas self generated and self stored. Of course, the Sichuan Basin has better preservation potentials comparing to the Subei Basin because of the influence of tectonic movement. With regard to the lower Paleozoic, the preservation conditions of the two basins are very similar indeed. By basin correlation, it is inferred that the oil and gas geological characteristics of the Cambrian on the Laoshan Uplift are comparable with the Sichuan Basin and the Subei Basin, and is a favorable target for further oil and gas exploration.