| In recent years, a large number of low resistance oil layers have been found in the new gravel rocks of Shijiutuo Swell in the central part of Bohai Sea, and the oil and gas exploration potential is greatly restricted by the lack of clear causes, the small difference of oil and water layer, and the difficulty of distinguishing conventional data. In order to clarify the main controlling factors of low resistivity oil layer in this area and make effective judgment, the core, logging, mercury, thin, nuclear magnetic analysis, laboratory data are used. On the basis of system analysis of low-resistance oil layer characteristics, the main controlling factors and differences affecting oil-water layer resistivity are quantitatively analyzed by statistical means, and a mathematical function is established to realize the effective identification of low-resistance oil-water layer by conventional logging data. The study shows that the low-resistance oil-bearing formations in this area are primarily composed of braided river channels and mid-channel deposits, characterized by conglomerate sandstone, medium-fine sandstone, and siltstone sediments. These formations exhibit low compositional maturity, strong pore-throat heterogeneity, and high impurity content. The primary controlling factor for low-resistance oil layers is the elevated bound water saturation in the rock, which shows a negative correlation with resistivity. The study proposes using exponential functions to amplify resistivity measurements for effective identification of oil and gas potential, with practical verification confirming the method's scientific validity. This research enriches the genesis theory and identification methods for low-resistance oil layers, providing valuable references for assessing hydrocarbon exploration potential in the Bohai Sea and similar blocks worldwide. |
