Who is the person usually responsible for purchasing production casing used when drilling for oil?

The purchasing department of any oil company is responsible for the actual paperwork involved in the purchase, but the specs, size, etc is all decided by petroleum engineers who give the specs to the purchasing dept so they can get bids or find the product needed.Who is the person usually responsible for purchasing production casing used when drilling for oil?
The design of the oil well is usually the responsibility of the petroleum engineer, sometimes the geologist. That design includes types of casing, size, characteristics, schedule and budget. In the contracts with the drilling company that information is used by the driller who purchases the materials, including production casing.





However, a salesman with a large production casing manufacture may work out a deal with the oil company to use their casing on holes. Then the driller will use that casing.





There can be other wheeling and dealing going on such as using excess inventory for canceled holes or adhoc purchases. This is usually done when there are small independent oil companies involved.Who is the person usually responsible for purchasing production casing used when drilling for oil?
The company, the operator, that is drilling the well has a representative on site, the ';company man';. He decides how everything is done below the surface. And everything is billed to the operator.