As the petroleum reserve discovery goes deeper in the offshore oil industry, high pressure reserves are discovered. Those wells will produce at very high initial flowing wellhead pressures (> 10,000 psi) and at much lower flowing wellhead pressures after a period of production. This presents a significant challenge for design and operation of the production system, especially, the subsea production choke, being required to have very low flow coefficient (Cv) in early life to restrict flow, and very high Cv in late life to reduce pressure loss. Initially, the pressure across the choke is required to be 5000 psi or higher. Associated with the high pressure loss across the choke, the Joule-Thompson effect will cause much higher temperatures (up to 30-40 °F) at the downstream of the subsea choke compared to non-restricted flow. The elevated temperature challenges the materials of the downstream equipment and the pipelines/risers.
This paper presents an innovative concept — using dual subsea chokes to split the pressure to protect the chokes and improve production operations. The advantages and disadvantages of using dual subsea chokes are presented.