A full chain CCS demonstration project in northeast Ordos Basin, China: Operational experience and challenges

Shenhua Ordos CCS project is the first Chinese pilot-scale demonstration for CO2 deep saline aquifer storage in combination with direct coal liquefaction (DCL) production. The injection site is geographically situated in the Chenjiacun village of Wulam Len town, about 40 km southeast of the Ordos city. The project was designed to inject 300,000 t CO2 captured from direct coal liquefaction plants into very low permeability (<50 mD) saline aquifers at depths of 1600+ m for 3 years. The injection operation started in January 2011 and the full operation began in May 2011. The project was extended for an additional one year and the injection ceased in April 2015. In this paper, a comprehensive and detailed introduction of the project is made in terms of CO2 capture, transportation, injection, simulation and monitoring, as well as key observations from the operation. Observations from both injection tests and site operation indicate a decreasing tendency in the initiation pressure and an increasing injectivity over the years, particularly for the uppermost Liujiagou sandstone. The injection initiation pressure decreased by 27.5%, from 6.19 MPa in 2011 to 4.49 MPa in 2014. Meanwhile, the corresponding injection index (i.e. injectivity) increased by 7.35 times, from 4.06 m(3) h(-1)(MPa)(-1) to 33.92 m(3) h(-1) (MPa)(-1). Site-specific numerical simulations have been overviewed based on the recent publications on this site. Challenges remain in terms of developing a three-dimensional site injection model to completely explain the key observations, due to various reasons such as geological uncertainties from the interpretation of seismic results, high heterogeneity of rock permeability and porosity, and coupled fluid flow between the long wellbore and reservoir. The CO2 injection operation at the site is thought to be safe in a storage point of view since the pore pressure of the reservoir is lower than 70% of the fracture pressure. Operation of this project demonstrates the feasibility of large-scale commercialization of Carbon Capture, Utilization and Storage (CCUS) in the Ordos Basin. (C) 2016 Elsevier Ltd. All rights reserved.