Modeling Of The CO₂Storage Body In The JT203Well Area In Qiaojiawa Of Jingbian Oilfield

Chang6Reservoir of the Triassic Yanchang Formation is located in the JT203well area in Jingbia—the central district of Ordos Basin. This region is tectonically stable and flat. In the control of the delta plain depositional system, the Chang6Reservoir combines with the upper Chang4+5Strata to form a good reservoin-caprock, which is an advantageous geological storage site of CO2. Geological survey in the site offers necessary information to evaluate the safety and efficacy in the first stage of CO2storage. The relevant overseas researches indicate that accurate identification of trap conditions for the geological body to store CO2and models in line with the actual situation are the key factors.Basing on the theory of CO2storage, the present work focuses on the description of the trap from the static aspects of geological storage conditions. Fitting interpretations were conducted by using logging and core analysis data. The storage capacity of the reservoir was comprehensively evaluated and the characteristics of the caprock were analyzed. In addition, a geological storage body model was built in line with the real underground situation. The results show that:(1) Chang6Reservoir and the Chang4+5Strata are tectonically stable and flat. Sedimentation is the main control factor for the formation of the lithologic traps in this area. In the control of the delta plain depositional system, distributary channels superimpose each other. Chang6strata develops multiple structures—the sandstone up pinch out trap, which forms the good CO2storage body; and the bay deposition which dominates in the Chang4+5strata, where the argillaceous rock forms the advantageous caprock.(2) The reservoir is characterized as low porosity and permeability. Studies have shown that the reservoir is moderate with a relatively strong heterogeneity. Therefore, reasonable evaluation parameters are selected to divide the reservoir into Four Types: A, B, C, and D from good to bad. Type A and Type B are the main CO2storage zones with good properties while Type C and Type D could conduct the longitudinal and lateral occlusion for the Type A and Type B to some extent.(3) Considering the development scale of the mudstone and its relationship to the lower reservoir, the strata is classified to regional caprock, direct caprock, and interlayer. Through the various macro and micro analysis of the caprocks, reasonable parameters for the actual geological characteristics of the study area are selected to assess the capillary sealing ability of caprocks. Four Types are classified from good to bad: Ⅰ, Ⅱ, Ⅲ, and Ⅳ, among which Type I and Type II are the ideal capping layers.(4) Using a phase-based modeling approach with the static description and data preparation for the trap conditions, a analysis model is built including the structure of the geological storage body, lithofacies, reservoir property parameters, and the spatial distribution of caprock displacement pressure, which lays a geological foundation for the storage potential assessment and risk evaluation.