The casing and tubing are key parts of well design, construction and commissioning. Each oil well must always be equipped with a casing and tubing consisting of materials known for their robustness and technical features.
Tubing is the conduit through which oil and gas are brought from the producing formations to the field surface facilities for processing. Tubing must be adequately strong to resist loads and deformations associated with production and workovers.
Tubing string construction
The tubing drain provides a simple method for draining the tubing string before tripping out of the well. The opening pressure setting is 2 800 psi, but can be adjusted using 6 shear screws.
Connected to the top of the stator, the pup joint allows the rotor’s eccentric motion.
PCM recommends the use of Torque Anchor in order to handle torque and avoid tubing back off. Large ranges of model proposed and associated repair kits are available in PCM catalog.
Connected below the torque anchor, the gas separator uses centrifugal forces to separate gas from the produced liquids, before they enter the pump. There are 2 configurations of the PCP Gas Separator:
- Light Oil: for oil 24° API and greater
- Heavy Oil: for oil less than 24° API
Benefits of the tubing string
- The use of tubing permits better well control because circulating fluids can kill the well
- Workovers are simplified and their results enhanced (flow efficiency typically is improved with the use of tubing)
- Tubing is required for most artificial lift installations
- Tubing with the use of a packer allows isolation of the casing from well fluids and deters corrosion damage of the casing.
Further, tubing must be sized to support the expected rates of production of oil and gas. Clearly, tubing that is too small restricts production and subsequent economic performance of the well. Tubing that is too large, however, may have an economic impact beyond the cost of the tubing string itself, because the tubing size will influence the overall casing design of the well.
The proper selection, design, and installation of tubing string are critical parts of any well completion. Tubing strings must be sized correctly to enable the fluids to flow efficiently or to permit installation of effective artificial lift equipment. A tubing string that is too small causes large friction losses and limits production. It also may severely restrict the type and size of artificial lift equipment. A tubing string that is too large may cause heading and unstable flow, which results in loading up of the well and can complicate workovers. The planned tubing must easily fit inside the installed casing. When selecting the material, environmental conditions, the projected corrosivity of the well fluids, the minimum and maximum pressures and temperature, safety aspects, and cost-effectiveness must be considered.