Functional Verification of the Worlds First Full Field Subsea Separation System - TIORA

Abstract

Abstract The dream of separating water from hydrocarbons on the sea floor is becoming a reality with StatoilHydro's Tordis IOR -Increased Oil Recovery - project in the North Sea. FMC Technologies has delivered the world's first full field subsea separation system, named TIORA, which was brought on-stream at the end of 2007. StatoilHydro expects to improve the Tordis field's recovery rate from 49 to 55 percent - an additional oil production of 35 million barrels. To ensure success FMC Technologies has invested in a comprehensive test program, beyond the standard subsea functional and mechanical integration testing, to verify right functionality and minimum start-up time. Since the Tordis subsea separation system introduces new types of equipment and functionality in a subsea field development, FMC has performed extended functional testing to secure the technical integrity of the system. The tests performed were categorized as follows:Technology QualificationsFactory Acceptance Tests (FAT)Extended Factory Acceptance Tests for sub-systems (EFAT)System Operation Test (SOT)System Integration Test (SIT) These tests also included testing of the two main operational functions:Closed-loop control of the water injection and multiphase pumpsFunction and control of the de-sanding operations through an extended technology qualification In the System Operation Test, the 2,3 MW water injection and multiphase pumps from Framo Engineering were connected to the FMC control system in order to run a complete functional test of the pump operation. Since separator level and pressure are important parameters in the pumps control algorithms, an online dynamic process simulator was connected to the real subsea instruments communicating through the FMC subsea control module. The control loops were then closed and the tests were performed as close to reality as possible. For the extended robustness verification of the de-sanding operations, spare modules were combined with purpose-built equipment in a test rig simulating expected operating conditions. In addition to testing, the platform operators used the test facilities for familiarization with the operation of the equipment. The lessons learned through the additional functional verification tests provided a significant contribution to a smooth and efficient start-up and operation of the subsea separation system, and also resulted in important feedback for use in the design of next-generation subsea processing systems. A softer lesson learned is that tests need to be planned in an overall test road map to ensure that all tests provide a combined better knowledge of the system - without degrading the resulting overall system performance.