API standards are critical for ensuring the quality and safety of drill pipe inspections. By following API standards, drilling contractors can be sure that their inspection procedures meet industry best practices.
In this blog post, we'll take a closer look at some of the most important API standards for drill pipe inspections.
The American Petroleum Institute (API) has published several specifications for drilling pipe used in drilling oil and natural gas wells.
Three of these are API 5A, RP 7G-2, and 5DP. These documents establish minimum requirements that should be considered part of an effective management system to ensure that customers receive products that meet their needs. They provide guidance on the materials, dimensions, tolerances, strength properties, tests, and inspections typically required by different applications found in the industry today.
From a driller's perspective, it will ultimately help ensure that the drill pipe you are using is still fit for purpose and could potentially reduce impact to operational time as a result of an inspection failure. Once these standards are implemented, any drill pipe that is found to be within specification will need to be re-certified if it is removed from the hole.
Most of us have seen improperly installed gas lines or appliances in homes or businesses resulting in fumes, carbon monoxide leaks, lack of heating or cooling, poor cooking results etc., the consequences of which could be deadly. It's not a stretch to say that poorly installed oil and natural gas wells also present risks for potentially fatal consequences such as fires, explosions, and blowouts.
The installation methods used in oil and natural gas wells are essentially the same as those in buildings: threaded connections secured with nuts and bolts (or torqued joints). Drilling fluid is typically circulated down through the drill string and the formation is fractured by pumping small explosive charges down through the casing. The fracturing fluid can include water, chemicals and proppants. The proppants used to keep the fractures open while oil or natural gas is produced are very fine particles of sand, ceramic beads, or sintered bauxite.
Once the well begins producing, the drill pipe and other components must be removed from the well bore to prevent damage to production equipment and reduce risks of safety hazards such as fires and explosions.
The consequences could range from faulty equipment and/or poor production rates to catastrophic blowouts. The time when the most wear occurs on drill pipe is during its use for fracturing operations. If a faulty pipe is used, it can fail in very little time after installation due to high stresses at the fracture face where the pressure of the fluid pumped down through the well bore exceeds 15,000 psi (normal operating pressures range from 5000 to 10,000 psi).
Because this happens so rapidly and because there are so many joints typically involved in a fracturing operation, it's easy to see that even one failed joint could cause significant damage if not safety hazards. Bear in mind that these extremely high pressures occur in formations that contain gas and/or oil under tremendous pressure beneath thousands or sometimes millions of tons of rock. The results of a fracture going into a gas or oil reservoir could be catastrophic.
Where appropriate, API develops standards that promote public safety and environmental protection. Standards are based on consensus among industry leaders and provide a means for companies to show that they have met the criteria necessary to be in compliance with the standard.
The development of standards is often driven by real-world evidence brought forth by member companies that have identified problems or concerns about their equipment, facilities, or practices that must be addressed by all members throughout the industry. This helps address inconsistencies where one company's interpretation of requirements differs dramatically from another company's interpretation even though both customers may think they are covered by the same requirement because neither realized interpretations varied so widely.
Because of the diversity in the type and mission of oil field companies, there are three different categories of standards:
In 1999, API developed standard 5A with consensus from industry leaders to establish a common set of equipment inspection requirements for drill pipe.
The impetus behind developing a drill pipe inspection standard began in February 1996 when a blowout occurred at the Enoch Point Field in California. The incident resulted in an uncontrolled release of oil into the environment that caused considerable damage to wildlife, vegetation and property. The incident was traced back to a pre-existing fracture in drill pipe that had not been detected during routine inspection of the production casing several months before the blowout occurred.
There were two other incidents at this field within ten years of this event where fractures due to undetected faulty drill pipe existed that, had they progressed to a well control situation could have been catastrophic.
API 5A was developed out of these incidents and the need for a common set of inspection requirements throughout the oilfield industry where any changes in dimensions can be detected. The section on inspection criteria contains many different size measurements but all meet a minimum standard of size and all can be measured with a minimum of tools – the API 5A inspection gauge.
All drill pipe used in oil and gas wells must comply with the requirements and since it is common practice that drill pipe is exchanged between various companies, there are no exclusions for single well operators even if the drill pipe is installed by the customer. Most well construction companies also specialize in API 5A inspections for their customers to help ensure compliance with API standards.
API RP 7G-2 specifies the required inspection for each level of inspection, procedures for the inspection, and testing of used drill stem elements. For the purposes of this standard, drill stem elements include drill pipe body, tool joints, rotary shouldered connections, drill collar, heavy-weight drill pipe (HWDP), and the ends of drill stem elements that make up with them.
This standard specifies the required inspection for each degree of inspection, as well as inspection and testing procedures for used drill stem components. Drill stem components are defined in this standard as including drill pipe bodies, tool joints, rotary shouldered connections, drill collars, heavy-weight drill pipe (HWDP), and the ends of drill stem components that make up with them.
The API standard for used drill stem elements specifies the standards for each degree of inspection and testing, as well as procedures and requirements.
Inspectors and operators may sleep well at night knowing that following the API Recommended Practice will guarantee that they are maintaining high-quality drill pipe and will not encounter non-productive time (NPT) as a result of drill pipe problems.
This standard applies to all drill pipe used in oil and gas wells within the United States, wherever it is made, shipped or used in service.
The requirement for a minimum diameter for work-performing drill pipe is not intended to apply to drill pipe used as casing or liner, as such components must meet the minimum dimensions as stated in API Spec 8C.
API 5DP provides guidance for the inspection of inside diameters (IDs) and lengths of drill pipe. For API 5A, only the outside dimensions are measured; ID measurements are not required to be taken on straight threaded connections. Under API RP 7G-2, both inside and outside dimensions must be measured at each level of inspection.
At the first level of inspection, the drill pipe must pass all measurements at or above minimum thickness (wall) using a no-go gauge.
The second level of inspection is based on both inside and outside measurements; however, only thin wall sections are to be measured with an external micrometer. Typically, thin sections are identified as being those with wall thicknesses of 0.035 inch or less.
The third level of inspection applies to all sections and is based on measurements taken with an inside micrometer for the exterior and a no-go gauge for the ID. The fourth level of inspection also requires ID measurements, and these must pass a no-go gauge. However, the exterior dimensions are measured with an outside micrometer.
API 5DP went into effect on February 1, 2009 for all drill pipe shipped from the manufacturer to the job site or used in service after this date. For existing fleets of drill pipe, API RP 7G-2 is to be implemented no later than July 1, 2009.
There is an exception to this requirement: API RP 7G-2 does not need to be followed for drill pipe used as liner or casing components. These connections must meet the minimum requirements as stated in API Spec 8C.
API 5DP is a valuable tool for improving the quality of drill pipe and avoiding NPT. It provides a consistent method for measuring ID and thickness, thus eliminating variability; it also requires that all measurements be taken on each standard level of inspection.
To define the delivery requirements for drill pipe production, there are several API standards in place. These API documents will show you what the new form of drill stem components should look like:
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