High-pressure and -temperature wells ­(HPHT wells)

With state-of-the-art equipment we can now reach reservoirs that are deeper and further away than ever before but our engineers and technicians need to be prepared for the conditions that occur there. Temperatures up to 200° celsius and pressures of up to 1,000 bar demand specialist equipment and sophisticated technology.

Drilling in heat

In the industry we talk about high-temperature wells when the temperature is higher than 140° C. That is the case in nearly all our gas wells since, as a rule, they are drilled deeper than oil wells. 5,000 metres is a typical depth, which means temperatures of around 160° C.

Drilling under pressure

High-pressure wells start at around 10,000 pounds per square inch (psi), which is equivalent to 700 bar. Pressures of this nature are to be found under the Caspian Sea. This can be compared with the average car tyre which is pumped up to 4 bar. Our normal wells have pressures of around 350 bar. Such high pressure in a reservoir is initially a good thing for oil and gas production. Under normal circumstances the hydrocarbons will simply flow to the surface on their own unaided by pumps or water. The pressure increases by around one bar for every ten metres that is drilled downwards. Under conditions like this, stringent safety measures are of utmost importance. To prevent uncontrolled leakage of oil or gas, wellhead valves and pressure sensors are installed above the borehole.

Harsh conditions place stress on drilling equipment

Under such extremely tough conditions many items of equipment and tools simply cease to function. During a drilling operation, the sensors and electronic equipment installed in the drill string are subject to enormous pressures generated by the cutting forces and string vibrations. That is why sensors and electronic equipment "swim" in a special silicone substance to protect them from damage. Development work that could lead to more robust materials or completely new technologies is important and if such developments are approved by our experts, they are immediately employed in our drilling operations.