Assembling drill strings that operate reliably requires detailed calculations and comprehensive well designs. One of the major factors that determine the efficiency of a well is determining the kinds of oilfield pipe threads needed, their size, and what their strength should be for the different casings, tubes, and downhole equipment.
In fact, it's not always possible to procure new Oil Country Tubular Goods (OCTG) for every well. This makes it important for producers to understand the compatibility and suitability of different types of threads and connections. The evolution of the oil and gas industry this past century led to a variety of manufacturing standards and thread types for different pieces of equipment.
Different Standards for Oilfield Pipe Thread Types
The American Petroleum Institute (API) provides a set of standards for threaded pipes and couplings. Specifically, API 5CT (currently in its 10th edition) lists the minimum requirements for designing and constructing wells for oil and gas operations.
The types of pipe threads specified by the API for casing and tubing include:
- Short Thread Coupled (STC)
- Long Thread Coupled (LTC)
- Buttress Thread Coupled (BTC)
- Line Pipe (LP)
- External Upset End (EUE)
- Non-Upset End (NUE)
While these provide the minimum design requirement for threaded connections, manufacturers also have their own variations called Premium Threads. These connections provide additional tensile capacity and improved hydraulic sealing, while also providing easier makeup of the string.
What are Premium Oilfield Pipe Threads?
Premium oilfield pipe threads usually attempt to improve on the API standards. This can include modifying the thread form, crest-root design, torque shoulder, or integral flush. A premium thread may increase the cost of the OCTG, but with superior performance and reliability, it can increase both the lifespan of a well, as well as its overall yield. Operators and well designers need to consider the environment and geological profile of a site before determining what set of products will serve their needs.
Maintaining the Integrity of Oilfield Pipe Threads
Regardless of what type the designers select, the reliability of each connection will depend on the integrity of the thread. As corrosion, debris, and shock damage can lead to a compromised connection, ensuring all threads remain protected prior to installation remains important for a well's efficiency.
Vigor can customize the threading of the product according to your needs, and Vigor's quality department will carry out the whole process of planning and on-site supervision to ensure that everything is produced according to the customer's requirements. After the production is completed, we will also assist in third-party inspections and various rigorous tests according to the customer's needs to ensure the integrity of the thread. If you are interested in Vigor's services, please do not hesitate to get in touch with us to get the most professional technical support and the most accurate and free commercial quotes.
For more information, you can write to our mailbox info@vigorpetroleum.com & mail@vigorpetroleum.com
