Abstract: A flowmeter is described which has a retrievable housing conduit which is locatable within a conduit or pipe and which seals against the pipe so that fluid only flows through the housing conduit, and a flow restriction is created within the housing conduit to create a Venturi when in use. At least two spaced pressure measuring stations are provided along the housing conduit, one of the stations located at an unrestricted flow location, the other at a restricted flow location, whereby pressures measured at these stations can be used to calculate fluid flow rates. Embodiments of the invention are described.

Abstract: A subsea navigation system comprising a plurality of spaced antenna means provided on a subsea structure arranged to emit electromagnetic radiation. A detection means is provided on a subsea vehicle for receiving and analyzing the electromagnetic radiation transmitted by the antenna means allowing the subsea vehicle to navigate relative to the subsea structure. Each of the antenna means comprises a cathodic protection anode provided on the subsea structure.

Abstract: An anode monitoring system for monitoring the integrity of anodes 2 provided on a metallic structure such as a pipeline system 1. A signal circuit Sn including the pipeline 1 and one of the anodes 2 is set up and appropriate signals are looked for at a central station 4. Reception of the signal at the central station 4 is dependent on the integrity of the anode 2 under inspection at that time. If the anode 2 is missing or defective the expected signal is not received and thus the fault in the anode 2 can be detected. A notch filter 5 is inserted in series between each anode 2 and the pipeline 1. The filter 5 provides a high impedance which can be signalled across but does not interfere with the cathodic protection system.

Abstract: A ball valve (10) is described which has a ball valve retaining mechanism which, when subject to very slight movement, allows a ball element (20) to be unloaded off a valve seat (48) during rotation, but remain in contact with the valve seat (48) so as to prevent debris ingress between the ball and the valve seat, and to instantaneously reload onto the valve seat upon the event of closure. This instantaneous and automatic redirection of the reaction load path at the occurrence of closure provides an effective seal against high pressure aggressive fluids to prevent fluid escaping beyond the valve components whilst, at the same time, allowing effective rotational movement of the valve to occur without providing rotational reliability. This solution allows conflicting load paths through the valve to be resolved, namely through the trunnion during rotation and through the valve seat during sealing.

Abstract: A well fluid sampling tool (5) having a sample chamber (315) at least partly contained within an at least partially evacuated jacket (160, 165, 170), the outermost wall (160) of the jacket (160, 165, 170) being adjacent to or forming an outermost wall of the tool (5). In such a tool (5) the evacuated jacket (160, 165, 170) acts to maintain the sample as originally retrieved, e.g. in single phase form (at original temperature).

Abstract: An electrical connector system is described for use in subsea environments for providing electrical connection through the wellhead into a tubular element with apertures for carrying electrical cables downhole. The system includes a circumferential electrically conductor ring which is coupled to, and insulated from, a tubular subsea element such as a tubing hanger, by an elastomeric electrically insulating sealing element, surrounding the conductor ring. The conductor ring is coupled to an electrical annular connector and is adapted to receive an electrical connector of a horizontally mounted electrical connector assembly which is hydraulically actuated to penetrate the elastomeric element in the direction transverse to the longitudinal axis of the tubular element to make electrical contact with the conductor ring.

Abstract: A flowmeter used to measure the flow rate of a fluid in a conduit includes a flow restrictor insert. The conduit is coupled to an upstream and downsteam conduit portion and includes three pressure measuring stations axially spaced along the conduit wall. The flow restrictor insert includes two cylindrical portions, the second of which has a diameter larger than the first. The flow restrictor insert is positioned in the flowmeter conduit such that the first cylindrical portion is aligned with the second pressure measuring station and the second cylindrical portion is aligned with the third pressure measuring station. When a fluid flows through the conduit, the flow restrictor insert causes the fluid to diverge around the cylindrical portions thereby creating a venturi effect. The fluid flow rate is calculated from the pressure differentials derived from the data measured at the three pressure measuring stations.

Abstract: A fluid-tight coupling (2) for connecting opposite ends of the pipe section (4, 6) to provide a fluid-tight AI seal is described. The fluid-tight seal between the upper and lower tubular sections is provided by an upper and a lower metal-to-metal seal produced respectively between a lower sealing surface (10) of the upper pipe section (4) and an upper sealing surface (12) of an annular interface member (8) and an upper sealing surface (14) of the lower section (6) and a lower sealing surface (16) of the annular interface member (8). The metal-to-metal seals are produced and maintained by a collar (20) arranged coaxially about the coupling region of the tubular sections.

Abstract: A Christmas tree (16) is based on a dual bore sub-sea test tree. The Christmas tree consists of a Christmas tree housing (56), which connects to a wellhead (44), a Christmas tree valve block assembly (62) disposed in the housing (56) and a tree cap (84) which connects to the housing (56) and valve block assembly (62). In a preferred embodiment the valve block assembly (62) has a main production bore (70) with two valves (72,74) in series and two auxiliary bores (76,96). One auxiliary bore (96) has a valve (98) for facilitating control of the annulus bore (96) whereas the other annulus bore (76) has no valve and provides a pathway for an electrical submersible cable (66) to a pump. The valves (72,74,98) are actuatable via control from an umbilical (94) and provide the facility to seal the production and annulus access bores to meet statutory requirements. A tubing hanger is not required.

Abstract: A bore selection apparatus (38) is described for facilitating access from a single bore riser to a production bore (34,34a) or annulus bore (36, 36a) without using a wireline-run whipstock. The bore selector apparatus disposed within the bore of a BOP stack (12) and which can be coupled between casing or tubing and a sub-sea test tree. The bore selector apparatus (38) can be actuated from the surface or from an ROV to provide a coupling between the tubing bore (44) and the production bore (34, 34a) or between the tubing bore (44) and the smaller annulus bore (36, 36a).

Abstract: A wellhead cap assembly (10) includes a high security barrier (16) for installation onto a wellhead (12) containing any leakage safely and for permitting the installation of a subsea xmas tree onto the wellhead (12) whilst, simultaneously, providing means for containing full pressure control during rectification of the leak. The barrier (16) is provided by an internal tree cap which allows pressure between the top of the tubing hanger (34) and the underside of the tree cap (16) to be monitored by pressure monitoring means (20) via a port (29) in the assembly (10) and, in addition, in the event the presence of well bore fluids is detected indicating that leakage has occurred, the cap assembly allows intervention in order to rectify the leakage.

Abstract: A single bore riser system is disclosed which is based on a dual bore completion tree. An eccentric offset sub is coupled to the top of the tree and which can be sealed by BOP pipe rams. The completion tree has a main bore and an auxiliary bore with ball valves located in the respective bores. A remotely actuatable annulus plug is located in the bottom of the annulus bore and is moveable between a first position allowing fluid flow through the annulus bore and a second position sealing the annulus bore to provide control of various operations. Embodiments of the invention are described.

Abstract: An improved sub-sea Xmas tree consists of a wellhead connector, a cylindrical structural housing and a tree cap mounted on top of the housing. A dual bore sub-sea completion test tree is disposed in the housing and it has a main production bore with serial ball valves for controlling fluid flow in the production flow path of an annuus bore with a ball valve therein. The ball valves are independently and remotely actuatable by a remotely operated vehicle (ROV) override system to control communication through the Xmas tree and to comply with various regulatory standards. A cross-over valve is provided between the main bore and the annulus bore to allow fluid passage for well kill operations.

Abstract: Apparatus for enabling electric signals to be transmitted between a device such as a sonde (46) positioned inside a tubing (38) of a well (30) and a region outside the tubing. In a preferred embodiment the apparatus comprises a transmitter coil (58) in the sonde (46) and a receiver coil (42) coupled to the tubing (38). The sonde (46) is coupled via wireline (48) to the surface and the receiver coil (42) is also coupled to the surface via a permanently installed cable (44). At least one measurement instrument (56) is located in the sonde such that measurement signals passed to said transmitter (58) are coupled to said receiver coil (42) and to the surface. The transmitter and receiver permit bidirectional communication and electrical power can be transmitted from the surface via said permanently installed cable such that single-phase or multi-phase power can be transmitted to drive downhole equipment, which may be coupled to the sonde.

Abstract: A lightweight intervention system is described for use with single bore and dual bore intervention operations and which can be used with both horizontal trees and conventional trees and with wellheads without trees mounted thereon. The system is based on a two-part intervention apparatus; the lower part provides the pressure control and consists of an xmas tree or wellhead connector and structural housing in which a sub-sea test tree is located and is coupled to the xmas tree and an upper part, a disconnectable section, attaches to the lower part and consists of a sub-sea test tree latch housed within an xmas tree connector and additional pressure control equipment as required. This general structure can be configured in various ways to create different embodiments for use with horizontal trees and conventional trees which have a single through-bore requirement and a dual bore requirement respectively.

Abstract: A lightweight intervention apparatus is described for use with a single bore intervention operation and which is suitable for use with a sub-sea horizontal tree with a tree cap and integral ball valve. The lightweight intervention apparatus is adapted to be coupled to the horizontal tree and that when so coupled the integral ball valve within the tree can be actuated via the intervention apparatus and cycled between an open and a closed position. The annulus line within the horizontal tree is adapted to be coupled through the lightweight intervention apparatus to a separate annulus line such that the annulus line is separate from the main bore to facilitate control of the annulus for certain well functions. A significant advantage of this arrangement is that the internal diameter of the main bore is not reduced in any way by apparatus or equipment for separating the annulus line from the main bore so that full bore diameter may be used.

Abstract: A dual bore riser system is described which includes a conventional monobore riser (12) for production access and an independent coil tubing (14) disposed in parallel with the monobore riser (12) for providing annular access. The monobore riser includes discrete A joints of tubing, casing or drill pipe and the coil tubing riser may be any suitable size but is normally between 23/8" and 27/8" outside diameter. The standard monobore riser (12) and coil tubing riser (14) is fed from a coiled tubing reel (78), which is conventional, via a sheave (80) and straightening rollers into the well with the tubing riser. The coiled tubing is clamped to the tubing riser by clamps (16) at intervals along its length corresponding to a joint every 30 ft. The upper end of the landing spool adaptor (28) receives the tubing (14) and also contains a termination for the coiled tubing which is typically a swage device (32). The 5".times.

Abstract: A safety valve for use with horizontal subsea trees as described which uses a two-part (10, 12) safety valve system. The first part (10) containing a valve mechanism (16, 18, 22, 26) remains in the wellhead and is normally biased to a closed position. The valve mechanism (16, 18, 22, 26) remains in the wellhead at all times during production and can be actuated to an open position by latching in a second part (12) which contains control cables (58) and a moveable valve actuator (62, 70, 40, 26) operable from the surface during workover to actuate the valve (18) in the wellhead portion (10) open. This provides for greater safety during the workover phase in comparison to a wire set plug and allows safer re-entry to the well.

Abstract: A well testing system is described which comprises a ball valve (10) having a plurality of fluid lines coupled thereto (20a, 20b, 20 c). The ball valve (10) is located between a process fluid flow line (16) and a vent line (18) with each fluid line (20a, 20b, 20c) being coupled to a respective piece of well-test equipment rated at a certain pressure value. Pressure relief means (22a, 22b, 22c) are located in each fluid line (20a, 20b, 22c) between the piece of equipment and said valve (10) and each pressure relief means (22a, 22b, 22c) is operable when the in-line fluid pressure exceeds a predetermined value to pass said fluid to said ball valve(10).

Abstract: An apparatus for burning crude oil has a conduit (12) without a flow restriction orifice and which receives oil to be burned. The conduit (12) has a plurality of inclined nozzles (28) which are also arranged about the longitudinal axis of the bore (30) so as to be substantially tangential to the interior surface. A supply of high velocity air is passed through an inlet manifold (32) and inside a housing (18) surrounding the conduit (12) in the vicinity of the nozzles (28) where it passes through the nozzles (28) into the bore (30) of the conduit (12). The high velocity air breaks the fuel up into particles and pounds the particles with an angular velocity causing the particles to swirl or rotate as a fine mist in one direction about the longitudinal axis at the outlet (16).