A review on subsea process and valve technology

Abstract

The world’s energy consumption continues to increase steadily. Fossil fuels (oil, natural gas, and coal) still comprise more than approximately 85% of the world’s energy consumption. Offshore oil field development and operation began by using platforms and ships, but oil producers and operators are looking for new and innovative ways to reduce production costs and improve recovery and production rates from reservoirs. As a result, subsea production solutions are becoming more popular. A subsea production system consists of subsea completed well(s), seabed wellhead(s), production tree(s), subsea tie-ins to flow line systems, and subsea equipment and control facilities to operate the well(s). The wellhead consists of the pressure-containing components at the surface of an oil and gas well that provide the interface for drilling, completion, and testing of the well, in addition to production equipment. Subsea manifolds are used to simplify the subsea system, minimizing the usage of subsea pipeline and risers while optimizing the fluid flow. Subsea valves, which are mainly ball or through conduit gate valves, are located on the trees and wellheads and designed based on API and ISO standards. They are made in exotic corrosion-resistant alloys to avoid different types of corrosion such as hydrogen-induced stress cracking, and should withstand high-pressure classes. These valves can be manual or actuator-operated with or without the help of a remote-operated vehicle. The subsea industry is shifting from hydraulic-type to electrical-type actuators for important reasons including reduced costs and faster operation. Newly designed subsea valves should pass strict qualification tests such as hyperbaric tests, endurance tests, and pressure and temperature cycle tests.