Performance and Injectivity of CO2 in Hyper-Saline Aquifers

Climate change is a global challenge imposed by excessive emission of anthropogenic greenhouse gases to the atmosphere. It is estimated that CO2 is responsible for two-thirds of global challenge. To decelerate this global challenge, several inter-governmental agreements and legislation have been established to reduce the atmospheric CO2 effects (e.g. 2015 Paris agreement, 2019 UK NetZero) through a combination of various technological, societal and industrial actions. One of the key pathways to reduce CO2 atmospheric emission is carbon capture and storage (CCS). In CCS, CO2 is captured from anthropogenic sources and is injected into deep saline aquifers, depleted oil and gas reservoirs or other geological traps. Deep saline aquifers play an important role as their capacity for safe storage of CO2 is two orders of magnitude greater than depleted oil and gas reservoirs.

Maintaining injection of CO2 into subsurface is a critical part determining the success of any CCS project, however, this is not always straightforward. Former studies show that with injection of dry super-critical CO2 in saline and hypersaline aquifers, salt forms in porous space and permeability decreases, leading to injectivity loss. Given this challenge it is essential to develop fundamental knowledge and a predictive model to establish know-how of injectivity loss under different thermodynamic conditions (pressure and temperature), hydrodynamic conditions (injection rate), and rock heterogeneity conditions, referred to as THR hereafter.

The PINCH project aims to establish fundamental science to develop a novel predictive model and apply it to real field data supported by industries. PINCH brings together scientists from University of Manchester, Durham University, Princeton University, BP, Equinor, Shell to deliver project aims in five work packages (WP).

WP1 addresses fundamental questions at pore scale to delineate impacts of THR conditions on salt formation and its aggregation regime under high-pressure high-temperature (HPHT) conditions. HPHT optical visualisation of micromodels and HPHT synchrotron-based X-ray imaging of micro-core flooding will be used to visualise the real-time change of pore morphology under different conditions. WP1 will deliver unique and valuable four-dimensional data sets to establish fundamental knowledge and to support WP3 data requirements.

WP2 addresses similar research questions as WP1 in real rock materials at a larger physical scale (core). BGS will facilitate access to the rock materials required. Additionally, pressure injectivity and rock mechanical properties will be measured under different THR conditions. We will address the knowledge gaps in the role of these factors on the injectivity loss. This will assist development of predictive modelling as envisaged in WP3.

WP3 is the core of PINCH project as a novel multiscale modelling approach is proposed. Pore-scale modelling will be developed to capture multiphase flow, phase change, salt formation. The model will be validated against the observations in WP1. Also a continuum-scale model will be developed which will incorporate the pore-scale modelling for parameterisation. The model will be validated against the experiments in WP2.

WP4 will deliver a high-impact research all fundamental science established in WP1 and WP2 and the engineering tools developed in WP3 will be employed to address real-life laboratorial and field-scale challenge related to the injection of supercritical CO2 in hypersaline aquifers and subsequent injectivity loss. Three candidate CCS fields are Endurance, Quest and Snohvit. BP, Equinor, Shell will provide very strong in-kind contribution to PINCH by providing required data from the aforementioned fields and technical advise.

To guarantee the impact of PINCH project, WP5 has been envisaged which covers impact generation, knowledge exchange between academia and industry, and training of junior staff.