High Reliability Gas Lift Flow Control Device Technology and Erosion/Endurance Tests

摘要

High reliability gas-lift flow control devices (FCD) enable gas lift for wells with the potential for H2S in the produced gas and where casing is not qualified for H2S service. H2S is a potential for wells undergoing a waterflood, so the business impact of this technology is significant with the growing use of waterfloods in offshore fields. Specification of these valves is such that no leakage is allowed at both high (8000 psi) and low (1 psi) differential pressures across the valve. In addition, the extremely high intervention cost of subsea or TLP wells coupled with HSE challenge posed by sour fluid production in non-Shell qualified casing service require a higher level of gas-lift valve's reliability under this extreme environment. This paper describes the new technology of high reliability gas-flow control devises ensuring that the annulus volume is displaced only once. A series of testing programs were designed utilizing the ESS (environmental stress screen) concept and harsh test standard that greatly exceeds API specification for gas-lift FCD. In 2009, Shell UA deepwater qualified three vender's gas-lift flow control devices using the Shell specified high reliability qualification standards. In 2010, Shell conducted valve cycling tests on the qualified valves at the Colorado Engineering Experiment Station. In 2011, Shell continued to work with Tulsa University to build up a new erosion testing facility and carry out a series of erosion/endurance tests on Shell qualified gas-lift flow control devices with Barite and water mixture. The purpose for Barite erosion tests was to determine if the Shell qualified gas-lift control devices can survive high density and high volume flow without the failure of the check system. This paper details the test procedures developed and some of the key findings of this qualification program.