Under Pressure – Drilling for Oil and Gas

Keeping the pressure of an oil or gas rig under control is of paramount importance. Too little pressure and the well may not function correctly, too much pressure and there could be an expensive and dangerous blowout. The wellhead is present to keep the pressure of a production well under control. The wellhead performs this task using a series of valves, spools and adapters, and is situated at the terminal of the wellbore, usually above ground at surface level, welded to the casing strings that stretch far below ground. It provides facilities for casing and tubing hangers, as well as fittings for the Christmas tree and flow control devices.

Due the very dangerous nature of drilling for oil both in terms of the safety of the oil rig workers, and the impact a blowout could have on the environment, production of wellhead components is strictly regulated and each part is tested for potential failure at a microscopic level. There are regulations that must be complied to and these are API 6A Specification for Wellhead and Christmas Tree Equipment and ISO10423 Wellhead and Christmas Tree Equipment. Quality control is the key to the manufacturer of wellhead components, down to the last bolt and nipple. The components must be very strong and must withstand very high pressure levels. Testing in the factories where wellhead components are produced is rigorous. A complete radiographic examination of each part can help expose weaknesses in the casings before they become part of a working wellhead and cause an incident to occur.

Once in place, parts must be checked regularly and replaced when worn. Although wellhead components are manufactured to the highest standards, and much research has gone into creating components for wellheads that will suffer the minimum amount of wear and tear, sometimes there are crevices within the components that simply must be there for the structural integrity of the wellhead as a whole, but that can suffer from corrosion and erosion. A close eye must be kept on any parts that are known to be susceptible to corrosion. They must be checked regularly and the wellhead must be maintained to ensure safety, and continued production.

Many drilling companies will employ maintenance companies to look after their wellheads, performing all the maintenance and repair duties expertly. These professionals generally work solely on wellhead components, so they literally know the wellhead inside out. Regular maintenance will help keep the components in good working order for longer, so it can be a good money saving exercise too, as well as ensuring the well is safe. Parts may need to be replaced or repaired. A maintenance crew will either repair components on site or will take them away to their own facilities to be repaired. 

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