Distribution of Natural Fractures and Mechanical Characteristics of Orogenic Movement in Carbonate Formations in Shunbei Oilfield

doi:10.7657/XJPG20210501

Abstract

Abstract:

Natural fractures in the Ordovician carbonate formations in the Shun 8B block in Shunbei oilfield were investigated, and the classification and distribution laws of the natural fractures were summarized. Then through damage and finite element numerical simulation, a theoretical tool for simulating the damage to the carbonate formations was developed, and the displacement direction and strain of orogenic movement corresponding to the development of natural fractures were determined. The results are as follows: ① Based on the stratigraphic structure from seismic waves and the histories of sedimentation and orogenic movement in the study area, the natural fractures/faults in 7 sections in the Carboniferous Kalashayi formation to the Middle Ordovician Yijianfang formation are divided into 5 natural fracture systems; ② The natural fractures in the Upper Ordovician Qarbag formation to the Middle Ordovician Yijianfang formation correspond to the orogenic movement of the middle Caledonian PhaseⅠand the middle Caledonian PhaseⅡ, and they are mainly open fractures and strike-slip fractures/faults penetrating the formations; ③ Based on seismic horizons, a 3D finite element model was established and 3D damage finite element numerical analysis was carried out. Forward numerical calculation provided the 3D distribution of the natural fractures/faults represented by localized damage zones under the action of the middle Caledonian orogenic movement in the study area. Numerical calculation verified that the mechanics of the middle Caledonian orogenic movement extruded the Ordovician carbonate formation at the azimuth of 15°, and the extrusion degree of the formation is equivalent to 2.4% of the strain.

Key words: Shunbei oilfield, carbonate rock, reservoir, natural fracture, orogenic movement, mechanical characteristic, damage

CLC Number:

TE112.221

CHEN Xiuping, SHEN Xinpu, LIU Jingtao, SHEN Guoxiao. Distribution of Natural Fractures and Mechanical Characteristics of Orogenic Movement in Carbonate Formations in Shunbei Oilfield[J]. Xinjiang Petroleum Geology, 2021, 42(5): 515-520.

Figures/Tables 6

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