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Differential sticking is a problem that occurs when drilling a well with a greater well bore pressure than formation pressure, as is usually the case. The drill pipe is pressed against the wellbore wall so that part of its circumference will see only reservoir pressure, while the rest will continue to be pushed by wellbore pressure.
Casing Diameters of a Borehole Casing Diagram premium gas tight connections on a casing string. Casing is a large diameter pipe that is assembled and inserted into a recently drilled section of a borehole. Similar to the bones of a spine protecting the spinal cord, casing is set inside the drilled borehole to protect and support the wellstream.
Scaling can occur at all stages of oil/gas production systems (upstream, midstream and downstream) and causes blockages of well-bore perforations, casing, pipelines, pumps, valves etc. Severe scaling issues have been reported in Russia and certain North Sea production systems. [6]
A well control company then will need to extinguish the well fire or cap the well, and replace the casing head and other surface equipment. If the flowing gas contains poisonous hydrogen sulfide , the oil operator might decide to ignite the stream to convert this to less hazardous substances.
In a completed well, there may be many annuli. The 'A' annulus is the void between the production tubing and the smallest casing string. The 'A' annulus can serve a number of crucial tasks, including gas lift and well kills. A normal well will also have a 'B' and frequently a 'C' annulus, between the different casing strings.
Deepwater wellbore integrity can be defined as the application of relevant engineering techniques and operational measures in deepwater drilling to control related risks during the drilling process, ensuring that deepwater oil and gas wells are always in a safe state throughout their entire life cycle.
In addition to controlling the downhole (occurring in the drilled hole) pressure and the flow of oil and gas, blowout preventers are intended to prevent tubing (e.g. drill pipe and well casing), tools, and drilling fluid from being blown out of the wellbore (also known as bore hole, the hole leading to the reservoir) when a blowout threatens.
The Westbay casing system is designed to allow the monitoring of multiple discrete levels in a single borehole. The casing comes in two different sizes, the MP38 system (38 mm, 1.5-inch) and MP55 system (55 mm, 2.25-inch). One single string of water-tight Westbay casing sections is installed in the borehole.