Sedimentary microfacies and oil/gas-bearing ability of the upper member of Es1 in the Xi-6 area, Raoyang sag
LYU Chuanbing, PANG Xiongqi, PANG Hong, FU Liangliang, ZHENG Dingye, LIU Benfen, GENG Rongyan
1 Huabei Oilfield company of PetroChina, Renqiu 062552, China 2 State Key Laboratory of Petroleum Resource and Prospecting, China University of Petroleum-Beijing, Beijing 102249, China 3 College of Geoscience, China University of Petroleum-Beijing, Beijing 102249, China
The Raoyang sag is an old exploration area and the annual oil and gas production is decreasing each year. It is urgent to find new oil and gas reserves to meet the needs of national strategic development. Limited by the early production technology
and the theoretical model, the stratigraphic framework is roughly divided, and the evaluation target is mainly concentrated on the member or sub-member level, and the oil group is the main one with higher accuracy. Single sand body scale reservoirs are affected by heterogeneity, which leads to the inaccurate division of sedimentary microfacies, which brings challenges to the increase of reserves and production, and seriously restricts the development of oil and gas exploration and development. Based on this, using the core, logging, and logging data, this paper takes the Xi-6 block in the Nanmazhuang area of the Raoyang sag as an example to characterize the sedimentary microfacies of each small layer (single sand body) in the upper member of Es1, and analyzes the oil and gas bearing properties of sand bodies in various microfacies. The results show that the upper SHA-1 member of block Xi-6 is divided into 3 oil formations and 9 sub-layers; the lithology is mainly composed of mudstone from a partially oxidizing environment and sandstone from a partially reducing environment, which is characterized by water oscillation during deposition; the type of sedimentary subfacies is delta plain with three microfacies: distributary channel, natural dike, and river swamp; the distribution range of sedimentary microfacies controls the distribution characteristics of sand bodies, specifically, the distributary channel controls the ratio of sand and sand infiltration thickness distribution of the sublayer, among which the ratio of sand of sublayer II1 and II2 is the largest, up to 0.75 and 0.85, and the sand infiltration thickness of sublayer I and II1 is the largest, up to 30 m and 25 m. Under the control of distributary channel microfacies
of each small layer in oil group III, the overall oil-bearing property of reservoir sand bodies is relatively high, and the largest proportion of oil-bearing layers in II4 and III2 is 69.6% and 65.5%. Based on the combination of sedimentary microfacies and oil-bearing layers, the relationship between sedimentary microfacies and oil-gas distribution in the upper Es1 member is analyzed, and it is pointed out that the favorable oil-gas accumulation area is where the thickness of permeable sand in the superimposed area of microfacies such as distributary channels and natural dikes is more than 5 m.
Key words：
Raoyang sag; Xi-6 area; upper member of Es1; sedimentary microfacies; oil/gas bearing ability; favorable area for oil/gas accumulation
LYU Chuanbing, PANG Xiongqi, PANG Hong, FU Liangliang, ZHENG Dingye, LIU Benfen, GENG Rongyan. Sedimentary microfacies and oil/gas-bearing ability of the upper member of Es1 in the Xi-6 area, Raoyang sag. Petroleum Science Bulletin, 2021, 04: 553-565. doi: 10.3969/j.issn.2096-1693.2021.04.038
