The Tiehchanshan structure of NW Taiwan: A potential geological reservoir for CO2 sequestration

  • Author(s): Kenn-Ming Yang, Bo-Iuan Chuang, Ching-Yun Hsieh, Bee-Der Yuan, Hsin-Hsiu Ting, and Jar-Ben Wang
  • DOI: 10.3319/TAO.2017.05.25.01
  • Keywords: Carbon dioxide sequestration, Structural geology, Sequence stratigraphy, Tiehchanshan structure
  • Softly linked subsurface settings with opposed vergence of Tiehchanshan structure
  • Kinematics and strain variation of thrust-related folds
  • Stacking pattern of sequence units of sandstone layers for CO2 storage
Abstract

The Tiehchanshan structure is the largest gas-field in the outer foothills of north­western Taiwan and has been regarded as the best site for CO2 sequestration. This study used a grid of seismic sections and wellbore data to establish a new 3-D geom­etry of subsurface structure, which was combined with lithofacies characters of the target reservoir rock, the Yutengping Sandstone, to build a geological model for CO2 sequestration. On the surface, the Tiehchanshan structure is characterized by two seg­mented anticlines offset by a tear fault. The subsurface geometry of the Tiehchanshan structure is, however, composed of two thrust-related anticlines with opposite ver­gence and laterally increasing fold symmetry toward each other. The folds are softly linked via the transfer zone in the subsurface, implying that the suspected tear fault in the surface transfer zone may not exist in the subsurface. The Yutengping Sand­stone is composed of several sandstone units characterized by coarsening-upward cycles. The sandstone member can be further divided into four well-defined sand­stone layers, separated by laterally continuous shale layers. In view of the structural and stratigraphic characteristics, the optimum area for CO2 injection and storage is in the structurally high in the northern part of the Tiehchanshan structure. The integrity of the closure and the overlying seal are not disrupted by the pre-orogenic high-angle faults. On the other hand, a thick continuous shale layer within the Yutengping Sand­stone isolates the topmost sandy layer from the underlying ones and gives another important factor to the CO2 injection simulation.

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