Oil & Gas Geology ›› 2022, Vol. 43 ›› Issue (1): 207-218.doi: 10.11743/ogg20220117

• Methods and Technologies • Previous Articles     Next Articles

Hierarchy modeling of the Ordovician fault-karst carbonate reservoir in Tuoputai area, Tahe oilfield, Tarim Basin, NW China

Wenbiao Zhang1(), Yaxiong Zhang1, Taizhong Duan1, Meng Li1, Huawei Zhao1, Yan Wang2   

  1. 1.Petroleum Exploration and Production Research Institute, SINOPEC, Beijing 100083, China
    2.Northwest Oilfield Company, SINOPEC, Urumqi, Xinjiang 830011, China
  • Received:2020-06-12 Revised:2021-12-06 Online:2022-02-01 Published:2022-01-28

Abstract:

Reservoirs of fault-karst type, special to the carbonate reservoir of the fractured-vuggy type, feature complicated storage structure, irregular geometry and stochastic spatial distribution under the impact of large strike-slip fault zones, which is bound to bring new challenges to their 3D quantitative characterization and geological modeling. Based on diversified research data of multiple scales, the hierarchical scheme of fault karst is established in Tahe oilfield, Tarim Basin, focusing on the principles of hierarchical constraint, genetic control and hierarchical modeling. The results show that the fault-karst hierarchy can be divided into four levels according to genesis and scale, namely the strike-slip faulted fracture zone, the fault karst, the fractured-vuggy zone inside the fault karst, and the karst cavern filling. In detail, the strike-slip faulted fracture zone framework model is established with deterministic data of the main and secondary faults, envelope range and key geological horizons obtained from fine interpretation of seismic coherence. Based on the seismic fault likelihood (FL) attribute, the external envelope model of the fault karst is established with deterministic method through automatic attribute segmentation and drilling calibration. With the constraint of the external envelope, the internal architecture elements are classified and modeled. Besides, a large-scale karst cavern model and a mesoscale discrete fracture distribution model are established with deterministic method based on seismic attributes such as texture and ant tracking truncation. As controlled by well data and constrained by seismic-geological probability, the sequential indication simulation and object-based marked point process simulation methods are applied to obtain the dissolved pore distribution model and the small-scale fracture discrete distribution model respectively. A filling model of the karst cavern is built by sequential indication simulation as constrained by wave impedance and large-scale cavern. Finally, a typical fault-karst reservoir in Tuoputai area, Tahe oilfield, is studied as an example to test the modeling method mentioned above, and the 3D integrated model thereby built can reflect the spatial hierarchy of the fault-karst carbonate reservoir.

Key words: geological modeling, fault karst, fractured-vuggy reservoir, carbonate rock, Tahe oilfield, Tarim Basin

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