Wednesday, 29 August 2018


Drilling at great depths in the search for new supplies of oil or gas is a highly technical and difficult task. The drill must be able to keep operating despite huge amounts of pressure, temperature and debris as the well gets deeper. An essential part of the drilling process is the use of drilling fluid, or as our engineers call it, ‘mud’. This is pumped down the drill pipe to keep the drill bit cool. The fluid also brings drilled cuttings back to the surface, where the cuttings are removed for examination and then safe disposal. The fluid is then recycled and reused – all with no harm to the environment

High-Pressure challenges

Many of the biggest energy reserves lie in so-called High-Pressure/High-Temperature (HP/HT) reservoirs. Drilling these reservoirs is extremely challenging with reservoir pressures up to 1,100 bar and temperatures beyond 200°C. Once discovered and put into production, the pressure in the reservoir reduces as gas is removed and carried to the surface. This pressure reduction in the reservoir creates a situation where the reservoir is at a pressure much lower than that of the rock formation immediately above it. The drilling mud must be kept at a density heavy enough to hold back the formation fluids but not be too heavy to fracture and damage the now depleted reservoir. Managing this balancing act successfully without fracturing the reservoir is critical to be able to drill wells on aging HP/HT reservoirs.

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