Advances in technology enhance permanent completion safety

As reaction to the Macondo disaster continues to put safety standards in the spotlight, the drive to ensure that every well, every platform, and every pipeline operates safely is at an all-time high. As a result, efforts to improve safety are emerging in the form of new and enhanced codes of safety practices and technologies, especially those that monitor permanent completions around the clock.

Companies today are no longer relying solely upon industry standards set by government agencies and trade organizations to police safe operating practices but are taking it upon themselves to create their own detailed requirements by drawing upon these existing industry standards. Some are even helping to interpret the standards by providing requirements that are often more stringent than the base standards.

FIGURE 1. To be validated, pressure and temperature must follow a set test-cycling pattern. (Images courtesy of AnTech Ltd.)

In a break from standard practice, some operators are requisitioning bespoke, highly specified pre-safety-certified equipment. For example, in the Middle East where there are many HP/HT wells, operators are requesting that wellhead interfaces are manufactured using high-specification materials that resist the often high concentrations of acidic fluids found downhole. Although such materials cost 10 times that of others on the market, these operators are taking the long view by making certain that their wells will operate smoothly and adhere to increasingly stringent safety legislation.

Safety standards evolving

In a bid to ensure that all wells operate with reliable fail-safe systems in place, some operators now require redundant metal-to-metal barriers to be installed. In the event that the first barrier (or seal) should fail, the additional barrier provides a fail-safe method to hold back the pressure in the wellhead, thus preventing leakages.

API 6A is the standard that sets the requirements that all wellhead connections must adhere to in the US. The standard API product requirement for design that the majority of companies comply with is Performance Requirement 1 (PR1).

Adhering to these standards ensures validation of equipment through objective evidence such as pressure testing, finite element analysis, and calculations. In addition, API 6A also details a more stringent level of design validation in API PR2 (also referred to as Annex F). By far the largest component of this level of validation is pressure and temperature testing, which must follow a specific cycling pattern (Figure 1). Every wellhead connection must be tested for its ability to function at a variety of temperatures and pressures as well as adhere to the pre-set cycling pattern. For example, a wellhead outlet – which continuously monitors pressure and temperature in the wellhead – must have its flanges tested for pressure and temperature in this manner to ensure that they will not collapse.

The industry is beginning to witness a rise in the number of companies requesting wellhead connections to this higher level of design validation.

In regards to fire testing, operators need to ensure that in the event of a serious fire, equipment will remain safe and hold pressure for at least 30 minutes to allow workers to evacuate the well site/rig. It is becoming increasingly common to test equipment to API 6FB, the standard that addresses product performance capabilities under extreme fire conditions. Under these standards, equipment such as christmas trees and wellhead outlets must be fire-tested to more than 900°C (1,652°F). Fire-testing of this nature has been a requirement in the North Sea for many years but is now on the rise on a global scale, especially in the US and Canada.

Along with the European standard for equipment used in potentially explosive atmospheres (ATEX), companies are increasingly requiring new systems to comply with the International Electrotechnical Commission Explosive (IECEx) certificate and recently introduced North American AEx regulation. For some operators in the Gulf of Mexico, it is not uncommon to request ATEX- and IECEx-certified equipment to be recertified to AEx standards. Although each of these standards has similar requirements, they are discreetly different with no clear read-across and will commonly require testing regimes such as testing in different types of gas environments.

FIGURE 2. Although the vast majority of wellhead outlets are used to monitor offshore wells, they are being used increasingly in onshore wells in the US and Australia, particularly coalbed methane wells.

Demand for data drives advances in technology

While operational safety is a significant factor affecting the type and quality of equipment selected, there are also other forces at work. For example, the rise in the number of HP/HT wells is having a dramatic effect. Due to the severe downhole conditions found in these wells, fluctuations in pressure and temperature must be closely monitored at all times by operators and service companies. This information is crucial not only for safety purposes but also to maintain control and ultimately production.

This demand for constant flow of data is driving advances in technology, particularly for wellhead outlets, which monitor conditions downhole and transmit data back to the surface via downhole lines that travel through a pressure barrier. To achieve this, different types of downhole lines must be used. The use of fiber-optic lines has increased dramatically because they allow faster transmission of greater volumes of data than copper lines. As a result, demand for fiber-optic wellhead outlets that cope with a range of downhole surface cables is increasing.

The market has provided a solution by developing reliable, fully certified wellhead outlets that can adapt to every need, ensuring continuous connectivity to keep production flowing. For example, a wellhead outlet can be hybridized so that it can run a combination of electrical and fiber-optic lines downhole simultaneously, making it possible to monitor electrical and fiber-optic gauges and equipment.

Although the vast majority of wellhead outlets are used to monitor offshore wells, these are being used increasingly in onshore wells in the US and Australia, particularly in coalbed methane wells. The wellhead outlet is the standard method of connecting downhole sensors with surface monitoring equipment. The majority of operators use a flanged or bolted system such as those offered by AnTech Ltd. These include the Type X wellhead outlet or standard threaded connection such as the Type C wellhead outlet (Figure 2).

The move toward intelligent completions also is having an effect. These sophisticated systems can utilize up to three conductors to remotely operate valves and shut down various zones of the well when necessary. As a result, these require gauges and fiber optics to monitor and transmit downhole data, triggering even greater demand for these technologies.

The continual drive to improve wellsite safety is having an effect across the oil and gas industry. Safety practices are improving, and technologies continue to evolve in response to market demand for systems that adhere to stricter standards of practice. This safety driving force, coupled with the demand for more data that must be reliably monitored, is good news for the industry. The ability to operate wells safely and efficiently is no longer just a vision for the future; it is a reality.