Taking the Cretaceous Basijiqike Formation sandstone reservoirs in the Kuqa foreland basin as an example, this paper studies the characterization and evaluation methods of fracture-pore (fracture-primary pore and fracture-dissolution pore) ultra-deep reservoirs under the double effects of diagenetic compaction and tectonic compression. Buried over 6 000 m deep, the sandstone reservoirs of Basijiqike Formation are ultra-deep reservoirs, aimed at which, an ultra-deep fracture tight sandstone reservoir characterization technique is built, which integrates macroscopic microfacies-lithofacies identification, centimeter-micron scale fracture description, micron pore depiction and nano-throat characterization. The research indicates that the effective reservoir space consists of structural fractures, micron pores and nano-pore throats. The main radius of matrix pores is 2-100 μm, that of matrix throats is 10-500 nm and the main area of fracture opening degree is 100-300 μm. Effective reservoirs are mainly controlled by microfacies-lithofacies, tectonic compression and erosion. Relatively high-quality reservoir spaces consist of fractures, residual intergranular pores and dissolution pores, developed in weak compacted structure zone and stacked underwater distributary channel zone. Favourable reservoirs over 7 000 m deep can be in continuous band distribution, there still could be effective reservoirs in formations over 8 000 m deep. © 2014 Research Institute of Petroleum Exploration & Development, PetroChina.
Zhang, H., Zhang, R., Yang, H., Shou, J., Wang, J., LIu, C., & Chen, G. (2014). Characterization and evaluation of ultra-deep fracture-pore tight sandstone reservoirs: A case study of Cretaceous Bashijiqike Formation in Kelasu tectonic zone in Kuqa foreland basin, Tarim, NW China. Petroleum Exploration and Development, 41(2), 175–184. https://doi.org/10.1016/S1876-3804(14)60020-3