The Jurassic Hith formation is one mainly composed of anhydrite and other evaporitic deposits, and it represents the seal of many of the world's largest oil and gas reservoirs, all located in the Middle East.
However, being an excellent seal for oil or gas is not garantee that the Hith Formation will behave well during more complex subsurface operations, for instance during carbon capture and storage (CCS) when the chemistry of the pore fluids and the pore pressure will be drastically changed.
This highlights a need for further research on anhydrite caprocks, in particular in terms of their heterogeneities at the interwell scale. The main rational is that one needs to be able to predict reasonably well the nature of the seal away from an injector well (where control exists as to the nature of the lithologies) and on to the final migration direction of the CO2 plume (where no controls exit).
The best approach to solve this problem is to use outcrop analogues and study how the depositional context of evaporite rocks impact on the architecture of seals. Since evaporites dissolve at the surface, we use instead anhydrite mines to understand the small scale depositional architecture of evaporite, as well as what control the lateral variation in mineralogy and geochemistry of the anhydrite rocks.