Drilling and Extraction

Once oil and gas deposits have been identified, they need to be extracted. Rotary drill bits with diamond teeth and hardened steel, attached to the end of a string of pipes, are used to drill through rock and into the oil and gas deposit. The average well is 1-5km deep, but some wells may be as deep as 8km. The deeper the well, the more difficult it becomes to accurately predict and drill to the oil and gas.

Oil and gas can sometimes flow up to the surface due to the high pressures found in reservoirs. This is particularly true for natural gas which is lighter than air. However, beam pumps, also known as “nodding donkeys” or “horse head” pumps, are also used to extract petroleum reserves where the reservoir pressures are low or the oil is thick and does not flow easily.

To aid the extraction process, water or compressed gas can be pumped in through another well drilled into the same reservoir to help maintain high pressures. This technique has also been used with compressed CO₂, which has the added benefit of capturing and storing CO₂ in the reservoir, thereby reducing greenhouse gas emissions which contribute to climate change. Once the well has been drilled and is operating effectively, it is capped by a wellhead which is a collection of pipes and valves used to manage the flow and pressure of the oil and gas before being sent along transmission lines to refineries.