Wellhead & Well Control

An annular BOP features a universal rubber packing element capable of sealing around almost any bore configuration (drill pipe, tubing, open hole), and the stack’s flexible first line. An individual ram BOP uses one or two steel rams designed for a particular function: pipe rams seal around a set size of pipe; shear rams can cut the pipe and then seal; or variable rams can adjust around a range of sizes. Nearly every well-control stack includes an annular preventer as the uppermost component, over one or more ram preventers.

When selecting sour-service material, we look at the well fluid, not the pressure: under NACE MR0175 / ISO 15156, it is your operating envelope — H2S partial pressure, temperature, chlorides and pH — that determines your API 6A class, from sweet service AA/BB/CC to sour service DD/EE/FF/HH. These fluid and temperature ranges select the material group, with carbon and low-alloy steels constrained to 22 HRC maximum to combat sulfide stress cracking. Once that fluid data is available, China Welong determines the proper group; if it is not, it is our engineers’ first question — because assuming the class is the fast track to the wrong equipment.

PR1 and PR2 are levels of performance and requirements in API 6A that indicate the intensity of validation of a component. PR2 includes the cyclic and endurance tests of the requirements PR1 and safety valves are usually specified PR2. Casing and tubing heads are usually specified PR1.

A wellhead is built mainly from two pressure-containing bodies plus their accessories: the casing head mounts the surface casing string and seals it at ground level. The tubing head sits just above the casing head, supports the production tubing string on tubing hangers, and provides the top connection for the Christmas tree. Hangers, spools and seals are the essential equipment and accessories that go with them, and together the casing head and tubing head form the well’s surface foundation.

You don’t have to, but there’s a real advantage: when BOPs, casing and tubing heads, wellhead, Christmas tree and choke & kill manifold are coordinated against the selected configuration and interface requirements, the seals, material grades and pressure ratings at the interfaces are confirmed for the selected interface. That removes the integrity risk of adapting components from different makers and cuts the documentation, traceability and spare-parts burden to a single point of contact — which is exactly why China Welong offers the selected equipment families in the selected configuration. China Welong confirms replacement-part compatibility for the selected configuration in the quotation.

Yes – the four families are sized for surface wellhead applications on both onshore and offshore drilling & production, and the subsea wellhead configurations can be quoted from the well data. Offshore work makes the evidence for specifications and inspection more critical, because rigs are (relatively) expensive, and once equipment is on the seabed there is little opportunity for access, so third-party inspection and complete traceability is the norm rather than the exception. As the oil and gas industry explores deeper waters and higher pressures, matching the correct pressure rating and material class to the specific well is what keeps the drilling & production equipment reliable over their service life.

There is no fixed umbrella minimum – orders are quoted by configuration, and single critical assemblies are normal. Delivery lead time is driven by whether the item is a stock item or requires custom manufacture, and a realistic committed date is quoted at time of quotation rather than upon receipt of order.

Any warranty, replacement part, response or compatibility term is stated by the quoted manufacturer and confirmed for the selected configuration in the supply contract.