HPHT Well Completion
Drilling high pressure high temperature wells are dangerous and need to be done after careful planning and preparation. These wells put out temperatures on excess of 300°F (146°C) and have a pressure in excess of 0.08 psi per foot. This means that these well require not only expert skill and knowledge, but also specialised equipment.
Once a well has been drilled, the content is analysed and it is then decided whether the project will continue, or the well must be plugged and abandoned. This decision is not an easy one as drilling a high pressure high temperature well is extremely expensive. However, working a dry well is also not an economical alternative.
When the well is found to be viable, the proper equipment is brought in and the following steps are followed:
- Casing
The casing consists of a steel pipe forming a hollow tube and is used to prevent the well’s hole from closing in on itself. The pipe is fed into the hole and will start varying in diameter as the various stages of the hole are reached. There are 2 types of casing that can be used. The first one is solid casing which consists of 1 piece of solid steel. This type of casing is used in solid formations. When there is loose sand and other agents that can block the pipe, the casing is also equipped with a sieve. - Cementing
Cementing the well means literally pumping cement into the spaces between the pipe and the side of the hole to firm it up and prevent it from collapsing. When the cement is pumped in, it displaces the drilling fluids and makes the well firmer. - Perforation
The casing of the well is run into the reservoir. To enable production, the casing walls are the perforated so that the hydrocarbons can enter the pipe and taken into the well. - Gravel packing
In some wells there is a chance that sand will enter the well. Although a casing with a filter lining is inserted, gravel is pumped into the well, fitting between the lining and the sides of the wellbore.
Completing the well is just as dangerous as drilling it as there is always the risk of a blow-out. There are also a variety of factors that play a role in the successful completion of the well. If each step is not carefully executed, the drilling crew’s lives will be in grave danger. So much depends on the planning and preparation of the project, as well as the continued teamwork of the drilling crew. Without these components, the well cannot be successfully completed and many lives could be lost.