| Based on 3D seismic data interpretation, drilling core observation, sample testing, FMI and oil test data
analysis, the differential deformation characteristics of Ordovician strike-slip fault zones in different areas of Tahe
Oilfield are analyzed in detail, three deformation and evolution models of strike-slip fault zones are established, and their
control effect on the development of Middle-Lower Ordovician large-scale reservoirs in different areas is discussed. The
results show that: (1) Controlled by the transformation of regional tectonic stress field and the evolution of ancient tectonic
pattern in Tabei Uplift, three types of typical strike-slip fault zones are mainly developed in the Ordovician of Tahe
Oilfield. In the main area of Yoputai-Tahe, NNE and NNW strike-slip faults that are symmetrically conjugate cut in “X”
shape, form closely integrated network, and are associated with primary and secondary faults; they are formed
simultaneously in the Middle Caledonian, and the NNE faults were continuously active in the Yanshanian-Himalayan. In
the central and western regions of Yuqi, the NE and SN strike-slip faults are asymmetrically conjugate, distributed in
strips and intermittently respectively, and locally cut each other; they were initially formed from late Caledonian to early
Hercynian and late Hercynian respectively, both of which were continuously active during Indosinian-Himalayan, and the
NE faults were more active. In the southeast slope area, the NNE, NEE, SN and NNW strike-slip faults are distributed
intermittently and the NNE, NEE faults limit the extension of SN faults; they were initially formed in the middle
Caledonian-Hercynian, and the NE, NNE faults continued to be active in the Yanshanian-Himalayan. Affected by the
Carboniferous salt layer, the shallow en echelon faults are not developed. (2) Based on the differential deformation,
formation and evolution of three strike-slip fault systems, three types of typical reservoir control models of Ordovician
strike-slip faults in Tahe Oilfield are established. Contemporaneous coupling type of epikarst+faults in the main area of
Tahe Oilfield: supergene karstification coupling with activities of strike-slip faults from middle Caledonian and early
Hercynian developed a large area of karst fracture-cave reservoirs under the T74 interface, and the reservoirs is more
developed along the NNE strike-slip fault zone that was continuously active in Yanshanian-Himalayan. Inner karst+late
fault reconstruction type in central and western |
