Vertical trees (VXT) typically have one or two production bores and one annulus bore running vertically through their entire length (as shown in Figure A.3). These bores permit the passage of plugs and tools down through the XT and into the TH or completion string. The vertical bores pass through a series of gate valves (production valves) used to isolate the vertical bores at differing levels. Two or more horizontal bores intersect the vertical bores to permit the passage of fluids into or out of the well, and each has an isolation gate valve (wing valves) to allow flow shut-off. Cross-over valves are usually incorporated to allow communication between the production and annulus bores.
Source: API RP 17A, Design and Operation of Subsea Production Systems—General Requirements and Recommendations, Fourth Edition, Reaffirmed 2011. Global Standards
Subsea tree with either multiple or concentric bores and production valves located in the vertical bore of the tree, where the tubing hanger is installed before the tree.
Source: API RP 17G, Recommended Practice for Completion/Workover Risers, Second Edition, July 2006 (Reaffirmed April 2011). Global Standards
Subsea tree with the master valve in the vertical bore of the tree below the side outlet.
Source: API RP 96, Deepwater Well Design and Construction, First Edition, March 2013. Global Standards
Tree with the master valve in the vertical bore of the tree below the side outlet.
Source: API SPEC 17D, Design and Operation of Subsea Production Systems—Subsea Wellhead and Tree Equipment, Upstream Segment, Second Edition May 2011 (Errata September 2011). Global Standards