Organo-amine and ammonium compounds are particularly useful for the oil and gas exploration sector as they aid in the inhibition of swelling in clay mineral-rich shale formations which are encountered whilst drilling for oil. Shale swelling inhibition is required due to the increased use of water-based drilling fluids which have adverse effects on drilling operations leading to well-bore instability; the loss of production costs for this are estimated as greater than $500 M per annum. Fundamental knowledge about how these compounds work is still lacking making optimisation of swelling inhibition difficult. A high p/T rig combined with the resolution of NIMROD and H/D substitution will allow us to conduct measurements of structural changes under oil-well conditions of organo-amine/ammonium intercalated Na+ montmorillonite for the refinement and optimisation of clay swelling inhibition.