Geochemical interactions between supercritical CO, and the Midale Formation. 11: Preliminary test experiments - initial fluid chemistry data

This report describes work undertaken at the British Geological Survey (BGS) that forms part of the international IEA Weyburn C02 Monitoring and Storage Project. This project aims to monitor and predict the behaviour of injected C02 into the Midale reservoir at the Weyburn oil field in southern Saskatchewan, Canada, using methods that include time-lapse geophysics, modelling its subsurface distribution and migration, and simulating likely chemical interactions with the host rock. This report aims to provide an initial description of certain fluid chemical data from a series of test experiments that have been conducted within the Hydrothermal Laboratory of the British Geological Survey. These test experiments were undertaken to ascertain appropriate sampling frequencies for later experiments. The experiments utilised samples of 'Midale Marly' material from the Weyburn field, and reacted this under in-situ conditions with synthetic formation water (h C02). The experimental techniques used are as detailed in Rochelle et al. (2002). The experiments were conducted at 60°C and pressurised to 160 bar [16 MPa] using either C02 or N2. Experiment durations ranged from one week to 10 weeks. Initial results show generally higher reaction in the C02 experiments compared to the N2 experiments. They also show relatively rapid carbonate mineral reaction and slower silicate mineral reaction.