Sand injectites are complex geological features formed by remobilised liquified sediment being forcibly intruded upwards into surrounding host rocks, leading to formation of clastic dikes and sills. They are commonly associated with in-situ remobilised 'parent' sand bodies from which they were sourced, and which exhibit similar lithological properties. Both can act as excellent reservoir rocks due to remobilised sands often exhibiting exceptionally high porosity and permeability. In the North Sea there are many producing fields with reservoirs consisting of remobilised sands, and there has been a renewed interest in injectites as infill drilling targets and exploration prospects, with recent discoveries including Frosk, Froskelar and Agar-Plantain on the Norwegian Continental Shelf (Breesch; 2019). Even when they are not the direct exploration target trap, if situated in proximity of a reservoir, injectites can still play a critical role on the viability and production performance. They can impact on lateral and vertical connectivity, thus the sealing and production performance of a reservoir, as the sands act as excellent fluid conduits through otherwise low-permeability units (Hurst and Cartwright, 2007; Jonk et al. 2005). Injectites and remobilised sands can also represent a geohazard, as they are generally less stable and often have very different geo-mechanical properties to surrounding host-rocks. In addition, their high porosity, which can exceed 30, means that they are highly prone to gas charge and over-pressuring. They therefore need to be avoided or planned for during drilling of deeper targets, or infrastructure placement.
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