Surface-Controlled Subsurface Safety Valves (SCSSVs) are designed to automatically shut-in a well below the earth's surface in the event of damage to the wellhead or other key components of a completion string. Flow rates in highly productive gas wells can produce stresses that exceed the design limits of a typical subsurface safety valve during closure in blowout conditions.High-rate uncontrolled flow conditions can act to prevent a SCSSV from closing or can subject the valve to stresses that the valve cannot withstand. Flow tests conducted to verify valve performance under certain flow conditions are often not capable of predicting valve performance when the valves are subjected to flow conditions different from the test conditions. Because the net force on the flapper is a function of the flow parameters, a valve that tests successfully at one set of conditions is not guaranteed to perform successfully in a different set of conditions. This paper will discuss the use of Finite Element Analysis (FEA) combined with Computational Fluid Dynamics (CFD) to economically and effectively determine 1) if a SCSSV will close under various flow conditions, and 2) whether it will withstand the associated forces generated during the closure.If this method is used, the flow tests could then be used to verify the accuracy and confirm results of the FEA and CFD analyses. After the FEA/CFD models are validated through flow testing, the performance of the valve in response to changes within the flow parameters or safety valve configuration can then be predicted using FEA/CFD models. Actual testing can be performed only to confirm the results of FEA/CFD or may be avoided completely. Introduction Traditionally, SCSSVs are used in well completion strings to permit the controlled production of formation fluids, but in the event of damage or destruction of the wellhead or surface-control equipment, the SCSSV will shut off production flow. SCSSVs are an integral part of the emergency shut-down systems of oil and gas offshore production platforms. In this scenario, the safety valves ensure that uncontrolled wellbore fluids can not reach the surface and contribute to a hazardous condition. SCSSVs are designed to operate in specific environments. Some of the design parameters that are considered when designing a safety valve are: the well operating pressure (initial and depleted), setting depth, operating temperatures, produced-fluid properties and flow rates, corrosive/erosive components in the production and completion fluids, surface-control equipment, umbilical constraints, and tubing- and well-operating envelopes. SCSSVs typically operate at pressures of up to 20,000 psi and in setting depths up to 10,000 ft, depending on the depth of the ocean floor and setting depth below the mud line. Gas wells can have an unconstrained flowrate greater than 450 million standard cubic feet per day (MMscf/D). These high flow rates produce high flow velocities, even when relatively large ID completion strings are used. Safety valves are exposed to fluids ranging from zonal-isolation cements, various weights and solid-content drilling muds, corrosive produced fluids with formation sands to corrosive fracturing fluids. Safety valves must operate in harsh environmental conditions that act to undermine the very function for which the safety valves were designed _ to close off and seal the wellbore in a blowout or potentially explosive event.
TX 75083-3836, U.S.A., fax 01-972-952-9435. AbstractSurface-Controlled Subsurface Safety Valves (SCSSVs) are designed to automatically shut-in a well below the earth's surface in the event of damage to the wellhead or other key components of a completion string. Flow rates in highly productive gas wells can produce stresses that exceed the design limits of a typical subsurface safety valve during closure in blowout conditions. High-rate uncontrolled flow conditions can act to prevent a SCSSV from closing or can subject the valve to stresses that the valve cannot withstand. Flow tests conducted to verify valve performance under certain flow conditions are often not capable of predicting valve performance when the valves are subjected to flow conditions different from the test conditions. Because the net force on the flapper is a function of the flow parameters, a valve that tests successfully at one set of conditions is not guaranteed to perform successfully in a different set of conditions. This paper will discuss the use of Finite Element Analysis (FEA) combined with Computational Fluid Dynamics (CFD) to economically and effectively determine 1) if a SCSSV will close under various flow conditions, and 2) whether it will withstand the associated forces generated during the closure. If this method is used, the flow tests could then be used to verify the accuracy and confirm results of the FEA and CFD analyses. After the FEA/CFD models are validated through flow testing, the performance of the valve in response to changes within the flow parameters or safety valve configuration can then be predicted using FEA/CFD models. Actual testing can be performed only to confirm the results of FEA/CFD or may be avoided completely.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.
hi@scite.ai
10624 S. Eastern Ave., Ste. A-614
Henderson, NV 89052, USA
Copyright © 2024 scite LLC. All rights reserved.
Made with 💙 for researchers
Part of the Research Solutions Family.