Research On Sedimentary Characteristics Of F1 And F2 Oil-bearing Formation In Shuangcheng Oil Field

This research analyses the stratigraphic division and comparison, the sedimentary characteristics, the reservoir characteristics, the oil gas pool distribution rule of Fuyu oil bearing layer in Shuangcheng oil field, based on the theory and the method of sedimentology, seismic stratigraphy and reservoir geology, and comprehensively using the data from seism, logging, geological log and core.Shuangcheng oil field runs across Changchun ridge anticlinal belt and Bin county Wangfu sag Secondary construction units. The main oil-bearing layer in the area is Fuyu oil layer in the fourth part of Quantou group, with the thickness range of 78.0～111.0m. Fuyu oil bearing layer is divided into F1 and F2 two oil layer sets, and F1 is subdivided into three sub-reservoir (F1s, F1z, F1x); F2 is subdivided into two sub-reservoir (F2s, F2x).During the depositional period of Fuyu oil bearing layer, this area was mainly controlled by the southern Huaide depositional system, and was belonged to the shallow water delta system, developing many types of microfacies, such as water distributary channels, natural levee, crevasse splay, delta front sheet sand and inter- sheet mud. The microfacies types were mainly distributary channels, crevasse splay during the depositional period of F2x, F2s, F1x, F1z, and water distributary channels was extremely wide with sand bodies of good conjunction, and reservoir development was good. When the stratum of Fls oil formation was deposited, water becomed deeper, and the area was in mainly underwater sedimentary environment, and river sand was relatively small, shallow lake sand bar was developed. So the thickness of channel sand was thin, the sand bodies connectivity was poor, reservoir development is common.With the properties data of core well in this area, the lithology of Fuyu oil layer are mainly fine sandstone, siltstone; and the lithology granularity distribution is fine-grained; and sorting coefficients is primary between 1.5 and 3.5; and the separation quality is between good and medium. The lithology of F2, F1x and F1z are mainly purple, purple-red, purple-gray, indicating the water oxidation sedimentary environment; the lithology of F1s is green, gray-green, indicating the underwater weak reducing sedimentary environment. According to the distribution and rank of core well porosity and permeability in this area, Fuyu oil bearing reservoir primarily is middle prosperous and low permeable.The factors analysis which control the reservoir formation in the researched area shows that the oil reservoirs are primary anticline reservoir and fault-lithology reservoir. With the reservoir characteristics, the structural conditions, and the sedimentary microfacies characteristics, the prediction of superior targets is carried out to guide the next step of block selection laying wells.