Controlling Factors And Depositional Mode Of "Slope Sedimentary Rocks" On The Buried Hill In The Southern Jinzhou 25-1 Oilfield

Buried hill oil reservoir is a special type of oil reservoir, which are protruding oil-hearing bodies of older strata located below the regional unconformity. With the continuous progress of oil drilling, buried hill oil reservoirs with industrial exploitation value have attracted more and more attention. In this paper, taking the buried hill reservoir of southern Jinzhou 25-1 Oilfield as an example, we have analyzed the distribution of slope sendimentary rocks in detail, and established the deposition mode of the overlying slope sendimentary rocks on the buried hill, using a large amount of core, drilling, logging and seismic data. The research results show that the southern Jinzhou 25-1 area is a buried hill-cladding anticline structure. The reservoir type is massive bottom water reservoir. The overlying slope sendimentary rocks on the buried hill are mainly sandstone and mud stone, which can be further divided into slope sedimentary sandstone, slope sedimentary mudstone and beach bar sandstone. Slope sedimentary sandstone and mudstone are mainly formed by accumulation on the hillside due to the weathering of the mountain top. The beach bar sandstone is mainly formed by normal deposition. The controlling factors for the formation of slope sedimentary rocks include structural and sedimentary factors. A large slope is not conducive to the accumulation of slope sedimentary rocks. Only when the slope is slow, can there be slope sediments in the uplift area with higher altitude. The fault activity in the Bohai Bay promoted the formation of joints and intensified deep leaching, which promoted rock ruptures and weathering, thereby providing a reliable source for the formation of slope sedimentary rocks. The deposition control factor is mainly the change of the tolerance space. Finally, the deposition mode of the slope sedimentary rock was established. That is, weathering occurs in the bedrock at the original high place, and the rock is carried along the slope and moved to the relatively low-lying accommodating space to form slope deposits. Slope sediments are a set of near-source deposits, which are poorly sorted and rounded, and their composition is basically the same as that of the bedrock. During the accumulation of slope sediments, there is almost no effect of water flow, and the gravity component along the slope is its main transportation power.