Reservoirs in the Songliao Basin are characterized by strong heterogeneity, which increases the difficulty of exact reservoir prediction. The clay interlayer developed in the reservoir is an important factor affecting the heterogeneity of the reservoir. Using the reservoir numerical simulation technology, an attempt has been made to investigate the storage efficiency during CO2 sequestration in Songliao Basin considering different types of interlayer in underground formations. Results indicate that type I interlayer, with a large thickness embedded between the two sand bodies has function of shunting and blocking to alleviate the impacts on cap rock. The type II interlayer has a small thickness and locates inside a single sand body, with poor physical properties and continuity, which has the same blocking effect on CO2 distribution and moderating influence on the cap rock. The physical properties of type III interlayer are same as the type II interlayer, but it has uneven distribution and poor continuity. In addition, three schemes of perforated zone were designed and their effects on CO2 storage efficiency and stability were studied. For a single reservoir, the scheme I is to perforate a whole reservoir, which is more conducive to maintain the reservoir’s stability. For multiple sets of “single-reservoir”, the scheme II can be preferentially selected to perforate the reservoir section below the interlayer when the injection volume is small. However, the scheme III can be used to perforate the interlayer and the reservoir below that when the injection volume is large. The study is beneficial to provide guidance and advice for selecting a suitable CO2 geological storage and reduce the risk of CO2 leakage.

The abandonment process is a highly important part of project management for CO2 capture and storage (CCS) projects. For the first full procedure of a CO2 geological storage demonstration project in a deep saline aquifer in China, this paper describes the abandonment process of a CO2 operating well. The key idea that we advance is that wellbore integrity tests should be conducted before the abandonment, and consideration must be given to the CO2 corrosion resistance materials, the design method of sealing the plugs, monitoring tests (such as pressure tests), and the use of a long‐term monitoring system (such as the original pressure test and a packer isolation test every year). According to Chinese regulations and related experience in the oil and gas industry, the factors chosen are the pressure factor, cap rock, potable water layer, unexploited resource layer, suspected leak path, perforated zone, productive hydrocarbon zone without perforation, and water‐injection and waste‐water treatment layers. We intuitively evaluate and quantify the plugged zones using the modified analytical hierarchy process (M‐AHP) method to determine the positions of the plugs. Next, referring to the Chinese regulations on Well abandonment and inactive well practices, the last plug located in the Quaternary strata is compulsorily ensured, and the length of all plugs is also determined. Finally, the paper summarizes the methodology and presents suggestions for the abandonment process of the Shenhua CCS project. © 2017 Society of Chemical Industry and John Wiley & Sons, Ltd.

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