The invention relates to the introduction of pressurized fluid, e.g. acid, into a subsea well directly from a vessel (33). A fluid injection assembly (20) is fitted to the top of a subsea Xmas tree (3), the assembly (20) including fail safe closed valve (21) which is controlled via a hydraulic line (31) from the vessel. The hose and assembly and valve are designed with an internal bore allowing a large diameter ball to be dropped (required for acid stimulation). The subsea subsea control module (8) on the Xmas tree is controlled from the producing platform.

Without limitation, embodiments of the present invention relates to an offshore wellhead platform (100), the offshore wellhead platform (100) comprising a configurable support structure (200) for supporting upper parts of a plurality of conductors (210) through which one or more well processing tasks can be performed, wherein the configurable support structure (200) further provides a first position (150) and a second position (160) for the conductors (210), and the offshore wellhead platform (100) allows movement of an upper part of a conductor (210) between its first (150) and second position (160). In this way, efficiency when processing a plurality of wells is provided since repositioning of the well center is not needed or needed significantly less. Effectively, the wells are brought to the well center so-to-speak instead of the well center needing to be moved to each well.

This invention relates to oil and gas exploration and comprises a direct connection system referred to as a Lower Riser Termination Assembly (LRTA), between risers made of composite material and horizontal lines installed on the seabed (flowlines). The system is applicable to a hybrid riser and its construction method allows cost reduction and system assembly/installation time optimization. The LRTA connection system is applicable to both rigid and flexible flowlines without need for any intermediate connection section/equipment between these and the risers.

Another important feature of the presented system is the fact that its construction allows free vertical expansion of the risers along the entire structure.

In addition, while, in the state of the art, the conventional methods require a large assembly and construction area, in the construction method developed for this system, the required area is significantly reduced, approximately 10 times smaller than that required for known construction methods.

A drilling riser running system includes a water filling system and a pressure testing system that can fill and pressure test auxiliary lines of the riser system, while simultaneously running a riser joint.

A drilling riser running system includes an automated self-aligning system that can detect and correct when two riser joints are not properly aligned prior to contact between the joints. The system can also include a counter-weight load compensating system that can detect contact between riser joints when they are mis-aligned and reduce the effective load to reduce likelihood of damage resulting from the contact.

A workover unit for lowering an irregularly shaped production string into a live well includes a traveling assembly and stationary assembly movable relative to each other. The traveling assembly may include a traveling static annular BOP configured to seal around the production string during the lowering. The traveling assembly may include a reciprocating riser connected to the traveling annular BOP. The traveling assembly may include traveling slips configured to grip the production string during the lowering. The stationary assembly may include a dynamic BOP configured to seal around the reciprocating riser during the lowering. The stationary assembly may include a reciprocating jack configured to lower the traveling assembly. The stationary assembly may include a lower static annular BOP configured to seal around the production string when the traveling assembly is moved relative to the production string.

A thread compensator for performing casing running operations. An example method may include visually ascertaining operational parameters of a thread compensator displayed on a video output device. The thread compensator may be connected between a top drive and a travelling block, and a casing running tool may be connected to the top drive. The operational parameters may include the height that the top drive is lifted by the thread compensator and force applied to casing by the top drive. The method may further comprise manually controlling well construction equipment to perform casing running operations based on the ascertained operational parameters.

An offloading system for conveying hydrocarbons from a buoyancy-supported subsea riser to a surface tanker vessel comprises a flexible hose that hangs from the riser structure in a U-shape having first and second limbs. An upper end of the first limb communicates with the riser and an upper end of the second limb terminates in a pulling head for connecting the hose to the tanker. A clump weight acts on a lowermost bend of the hose between the limbs to maintain tension in the limbs. A subsurface holder fixed to the riser structure is arranged to hold the pulling head against the tension in the second limb of the hose when the system is in a standby state. The holder is offset laterally from a central longitudinal axis of the riser structure and a counterweight is positioned to a side of that axis opposed to the holder.

A mobile offshore drilling unit is converted to provide drilling, completion and workover access to multiple dry tree wells from a drilling derrick to allow production and export of oil and gas from high pressure, high temperature reservoirs in deep offshore waters. Existing practice has been for the drilling derrick on a production platform supporting dry tree wells to be moved over a fixed well slot. The present invention provides a movable wellbay that supports multiple top-tensioned subsea well tieback risers, which may be positioned directly below the derrick's rotary table and/or beneath another operating device. The use of top-tensioned subsea well tieback risers supported by the movable wellbay allows the converted facility to drill, complete, maintain, improve and produce from subsea wells through dry trees.

A pipeline bundle for a riser tower or tie-back is manufactured offshore by suspending the bundle from an installation vessel, adding structural core sections successively to an upper end of the suspended bundle, lowering the bundle after adding each successive core section, and feeding one or more lengths of flowline pipe beside the core sections for incorporation into the bundle. The flowline pipe is coiled on a reel or carousel as a full-length piece before being uncoiled progressively as core sections are added to the lengthening bundle. The flowline pipe is then engaged with guide frames and/or buoyancy blocks supported by the core sections, by movement in a radially-inward direction through a radially-outer opening in a retainer formation. The opening is then closed to hold the flowline pipe in the retainer formation.