On the Northwest European Continental Shelf, the principal area of high pressure/high temperature (HP/HT) gas and gas condensate production is in the Central North Sea. In the UK sector HP/HT conditions are defined as those with a bottom hole temperature of greater than 300°F and either a maximum pore pressure in any porous formation in excess of 0.8 psi/ft hydrostatic gradient or the requirement for pressure control equipment rated in excess of 10,000 psi. HP/HT wells are commonly associated with hostile produced fluids, typically corrosive brines and hydrogen sulphide.

• Issues of importance in the development of HP/HT field assets include:

• gas condensate fluid management, including fluid properties determination and gas recycling;

• drilling safety and efficiency, with factors such as pore fluid pressure prediction and gas kick detection/control critical;

• bore-hole integrity and formation damage, including prediction/avoidance of permeability reduction, sand production or borehole collapse upon rapid pressure drawdown;

• reliability of downhole equipment (electronics, seals, valves) in a high temperature, chemically hostile environment;

• sub-sea production systems for well testing and fluids management.

Capability to produce the North Sea's HP/HT fields is being developed on a fast track by a small number of major operating companies. It is too early to gauge the extent to which the best use of available technology, coupled with adaptations for HP/HT service, will provide optimal solutions in the longer term.

RTD topics of relevance to HP/HT field development are included in Sections 5.3 and 5.4.