The Centre for Computational Science



Official Site: http://www.nimes.org.uk/

When exploring for oil offshore, a well bore is drilled down through the sediments to access the oil. During drilling a technical drilling fluid (sometimes called a “mud” by the industry) is used to lubricate the drill and remove the cut rock. Invariably, the drill bit will pass through shale in the sediment that is unstable because it contains a lot of clay. Clay minerals can be imagined as a large club sandwich, they consist of many microscopic layers of mineral (like the bread in a sandwich) between which sits a filling of cations, such as sodium, and some water. When clay is exposed to water it swells by sucking the surrounding water into the inside of the mineral, between the bread layers to continue our analogy, forcing the layers apart. This happens because the cations have a high affinity for water and is why clay soils crack in the dry summer and turn to mud in the wet autumn, and also why talc powder (another type of clay) dries you after a shower. In the garden or after a bath the swelling of clay it is not a huge problem.

However, when clays swell whilst drilling for oil, water is removed from the drilling fluid preventing it working efficiently. This swelling causes the bore-hole to become unstable and trap the drill bit. This causes a delay in drilling operations and damage to equipment. Such instability problems are estimated to cost the oil industry approximately $500M to $1 billion per annum! To prevent this occurring, drilling fluids have a clay swelling inhibitor added to them. To date, these swelling inhibitors have not been particularly environmentally friendly. However, recent changes in legislation mean that to explore and continue drilling for oil in areas such as the North Sea, all drilling fluids must be biodegradable.

The NIMES project will use the latest developments in scientific computing, grid computing and high-end visualization, at Technium CAST, Durham University and University College London to engineer, design and test new biodegradable swelling inhibitors at a nanoscopic atomic level before another team of chemists at North East Wales Institute then make the swelling inhibitors in the laboratory. Using computers to design and test the molecules before they are made makes the production process a far “greener’ one by cutting down on the preparation of a large number of molecules that would be necessary in a typical experimental trial end error method. Once made, the lead industry partner M-I SWACO will test the new drilling fluids for biodegradability and performance in off shore oil drilling operations.