Qualification and Use of a Self-Equalizing Subsurface Safety Valve in Large-Bore, High-Rate, Gas-Well Applications in the Middle East

摘要

The desire to use natural gas as an energy source has increased to such an extent that there has been a notable worldwidernincrease in its usage. Supplying this growing demand has been a gas-exploration and production industry challenge. To thisrnend, many operators have implemented the use of large-bore, high-rate gas wells for effective development of the world’srnprolific gas fields. One of the key components in this type of completion is the subsurface safety valve (SSSV), because it hasrna primary role in containment of the hydrocarbon should a well-control loss event occur. The SSSV is critical to thernprotection of the lives, assets, and the environment in the surrounding vicinity of the well completion.rnDuring normal operations or after a well-shut-in event occurs, pressure must be equalized across the SSSV closurerndevice; typically, a flapper device to reopen the valve and return the well to production is used. Because of the relatively highrnvolumes of gas carried in the production tubing of a large-bore completion, non-self-equalizing SSSVs have been the productrnof choice. This feeling has evolved from the traditional feeling that passing the large volumes of gas through a self-equalizingrnfeature would be detrimental to valve long-term reliability in large-bore applications.rnWhen using a non-self-equalizing SSSV, the supply of tubing pressure to equalize the pressure across the flapper must bernintroduced above the SSSV from the surface, and in many situations, this may not be operationally efficient or economical.rnConversely, if a self-equalizing-type SSSV could be installed in a large-bore gas completion, there would be significantrnbenefits, which would include:rn? Reduction in capital expenditure for surface-pressure equipmentrn? Operational simplicityrn? HSE benefits.rnThis paper will discuss the collaboration between a Middle East operator and the SSSV supplier to qualify a large-borernsubsurface safety valve with a self-equalizing feature for use in high-rate gas-well applications. It will also review fieldrnimplementation and benefits resulting from the use of these valves.