Patent Description:
Subsea oil and gas production wells typically require chemical treatment to help ensure the reservoir, production tubing, valves and pipelines remain in optimum condition for well flow and pressure integrity. Chemicals are typically delivered to the production wells thru an umbilical from the host facility to which the production is routed. Current methods require the chemicals to be stored and pressurized at the production host to a pressure exceeding that of the shut in pressure of the reservoir in one case and above flowing pressure of the reservoir in another. Exceeding the production pressure ensures the chemicals are delivered into the wellbore and pipeline system to commingle with the production flow. High pressure chemical delivery requires the delivery conduits in the control umbilical to be rated for these high pressures to both meet the injection pressure requirements locally at the wellsite. Often they are required to be rated for higher pressures to overcome the frictional loss while flowing the chemicals over great distances from the host facility to the subsea well location. Each production reservoir is somewhat unique and requires a variety of chemicals and volumes to be delivered to keep the flow conduits in optimum condition. Corrosion, scale, paraffin, emulsifiers and others are a few of the chemicals used in relatively small volumes to treat the production flow. Some chemicals such as methanol, LDHI, monoethylene glycol are typically delivered in higher volumes to treat the production flow and inhibit the formation of hydrates in the production stream.

Often time flow requirements vary over the course of operating the subsea wells. During startup and shutdown of the wells, higher dosage rates and volumes of these hydrate inhibitors are used to prepare the wells for the flowing and stagnant conditions respectively. Once the wells are flowing and their temperatures are stabilized, the flow rates can sometimes be reduced. Intermittent high rates and volumes of the hydrate inhibitors can drive line sizing in the umbilical to accommodate the worst case scenarios often resulting in an over capacity system design for normal flowing conditions. Many projects suffer an undue economic challenge with large diameter, highly corrosion resistant steel specification, umbilical manufacturing costs as a result. Depending on the overall system level chemical requirements, some umbilicals also exceed total volume and weight requirements of the majority of the available vessels needed to install the umbilical, resulting in further additional costs.

Prior art document <CIT> discloses a method for injecting fluid into an underwater facility. A fluid-storage system includes at least one storage vessel with rigid walls containing a functional fluid which is lowered to the bottom of the water. At least one portion of the functional fluid is injected into the underwater facility. After a time of operation, the fluid-storage system, or a portion thereof, including the storage vessel, is raised back up to the surface.

Prior art document <CIT> discloses a system including a subsea on-site chemical injection management system configured to inject a chemical mixture into a well, wherein the subsea on-site chemical injection management system includes a subsea on-site head tank configured to store a plurality of discrete chemicals, a subsea on-site mixing unit configured to mix one or more of the plurality of discrete chemicals to create one or more chemical mixtures, and a subsea on-site distribution unit configured to distribute the one or more chemical mixtures to the well.

The figures supplied herein illustrate various embodiments of the invention.

In one aspect of the present disclosure there is provided a modular subsea system as in claim <NUM>.

In its various embodiments, the disclosed invention removes chemical delivery conduits from an umbilical, and in some instances eliminates all fluid conduits from the umbilical, and requires only electrical power and/or data delivery to a well site.

In embodiments, subsea fluid storage reservoirs are located on a seafloor adjacent to the well site for low fluid flow requirement chemicals necessary for the well. A subsea pumping system is typically included for boosting the chemical pressure from ambient to that required for injection into the production stream.

In embodiments, low and high flow chemical delivery systems are segregated by use of subsea storage and pressure boosting for the low flow needs and a dedicated flowline from the host facility for the high flow needs. Subsea pressure boosting for the high fluid flow requirements can also be provided for allowing a low pressure flowline to be utilized and minimize cost. The modular approach offered by embodiments of the invention accommodates chemical storage and pumping systems expansion and modification.

In embodiments, integrating the controls and monitoring of both the dual method fluid delivery system and the other subsea production system elements can simplify an umbilical system from a host facility.

Referring to <FIG>, in a first embodiment a modular subsea chemical injection system comprises one or more power and communication umbilical termination modules <NUM> operatively connected to one or more power and communications umbilicals <NUM>, at least one power and communications umbilical <NUM> lacking a chemical delivery conduit; at least one power and communications umbilical terminator <NUM> (not shown in the figures) operatively connected to umbilical <NUM>; one or more power and communications foundation modules <NUM>; one or more fluid storage modules <NUM> operatively in communication with subsea electronics module <NUM> and electrical power distributor <NUM>; one or more pump modules <NUM> operatively in communication with subsea electronics module <NUM> and electrical power distributor <NUM>; and fluid distribution unit <NUM>.

Host facility <NUM> may be operatively connected to power and communications umbilical <NUM>.

In contemplated embodiments, subsea control module (SCM) <NUM> may be present, as more fully described below, where SCM <NUM> may further comprise SCM fluid port <NUM>.

Power and communication umbilical termination module <NUM> comprises electrical power port <NUM> (not shown in the figures) which may comprise low voltage power outlet <NUM>, high voltage power outlet <NUM>, or the like, or a combination thereof. Power and communications umbilical terminator <NUM> may further comprise data communications port <NUM>. If SCM <NUM> is present, power and communications umbilical termination module <NUM> typically further comprises non-integral SCM power and data communications port <NUM> operatively in communication with SCM <NUM>.

At least one power and communications foundation modules <NUM> comprises subsea electronics module <NUM> operatively in communication with power and communications umbilical terminator data communications port <NUM> and electrical power distributor <NUM> operatively in communication with power and communications umbilical terminator electrical power port <NUM>. If SCM <NUM> is present, power and communications foundation module <NUM> may further comprise integral SCM power and data communications port <NUM> operatively in communication with SCM <NUM>.

Fluid storage modules <NUM> typically comprise a plurality of fluid storage bays <NUM>, each fluid storage bay 41adapted to selectively receive a corresponding plurality of fluid storage tanks <NUM>, and at least one fluid storage module fluid port <NUM> in fluid communication with one or more fluid storage tank <NUM>. Not all fluid storage bays 41need to be populated at any given time.

Pump module <NUM> typically comprises a plurality of pump bays <NUM> adapted to selectively receive a corresponding plurality of pumps <NUM>, although not all pump bays <NUM> need to be populated at any given time. At least one pump <NUM> is in fluid communication with at least one fluid storage tank <NUM>. In addition, pump module <NUM> further comprises one or more pump module fluid ports <NUM> in fluid communication with at least one pump <NUM>. In embodiments, one or more high flow fluid ports <NUM> may be present in fluid communication with at least one pump <NUM>.

Fluid distribution unit <NUM> typically comprises at least one distribution fluid port <NUM> in fluid communication with at least one pump module fluid port <NUM>, at least one fluid distribution unit fluid supply port <NUM> in fluid communication with distribution fluid port <NUM>, and fluid metering valve <NUM> disposed intermediate distribution fluid port <NUM> and fluid distribution unit fluid supply port <NUM>. If one or more subsea control modules (SCM) <NUM> are present, each SCM <NUM> is typically in fluid communication with fluid distribution unit fluid supply port <NUM> such as via port <NUM>. In embodiments, each SCM <NUM> is in fluid communication with a separate fluid distribution unit fluid supply port <NUM>.

In contemplated embodiments, subsea processing system <NUM> may be present and in fluid communication with fluid distribution unit fluid supply port <NUM> and/or SCM fluid port <NUM> such as via subsea processing system fluid inlet port <NUM>. Subsea processing system <NUM> may further comprise fluid delivery booster <NUM> which may be in fluid communication with subsea processing system fluid inlet port <NUM>. If host facility <NUM> is present, subsea processing system <NUM> may further comprise at least one subsea processing system fluid outlet port <NUM> in fluid communication with host facility <NUM> and, if fluid delivery booster <NUM> is present, with fluid delivery booster <NUM>.

Referring to <FIG>, in a second embodiment a modular subsea chemical injection system comprises one or more power and communication umbilical termination modules <NUM> operatively connected to one or more power and communications umbilicals <NUM>, at least one power and communications umbilical <NUM> lacking a chemical delivery conduit; at least one power and communications umbilical terminator <NUM> (not shown in the figures) operatively connected to umbilical <NUM>; one or more power and communications foundation modules <NUM>; one or more fluid storage modules <NUM> operatively in communication with subsea electronics module <NUM> and electrical power distributor <NUM>; one or more pump modules <NUM> operatively in communication with subsea electronics module <NUM> and electrical power distributor <NUM>; and fluid distribution unit <NUM>.

Power and communication umbilical termination module <NUM> comprises electrical power port <NUM> (not shown in the figures) which may comprise low voltage power outlet <NUM>, high voltage power outlet <NUM>, or the like, or a combination thereof. Power and communications umbilical termination module <NUM> may further comprise data communications port <NUM>. If SCM <NUM> is present, power and communications umbilical termination module <NUM> typically further comprises non-integral SCM power and data communications port <NUM> operatively in communication with SCM <NUM>.

At least one power and communications foundation module30 comprises subsea electronics module <NUM> operatively in communication with power and communications umbilical terminator data communications port <NUM> and electrical power distributor <NUM> operatively in communication with power and communications umbilical terminator electrical power port <NUM>. If SCM <NUM> is present, power and communications foundation module <NUM> may further comprise integral SCM power and data communications port <NUM> operatively in communication with SCM <NUM>.

Fluid storage modules <NUM> typically comprise a plurality of fluid storage bays <NUM>, each fluid storage bay <NUM> adapted to selectively receive a corresponding plurality of fluid storage tanks <NUM>, and at least one fluid storage module fluid port <NUM> in fluid communication with one or more fluid storage tank <NUM>. Not all fluid storage bays 41need to be populated at any given time.

In contemplated embodiments, a single standalone flowline <NUM> (which can be composite, carbon steel, stainless, or the like, or a combination thereof) is connected from surface host <NUM> to subsea fluid distribution unit <NUM>. Chemical startup fluid is pressurized via surface host <NUM> and delivered at the required flow rate to fluid distribution unit <NUM>.

Referring to <FIG>, in a third embodiment a modular subsea chemical injection system comprises one or more power and communication umbilical termination modules <NUM> operatively connected to one or more power and communications umbilicals <NUM>, at least one power and communications umbilical <NUM> lacking a chemical delivery conduit; at least one power and communications umbilical terminator (not shown in the figures) operatively connected to umbilical <NUM>; one or more power and communications foundation modules <NUM>; one or more fluid storage modules <NUM> operatively in communication with subsea electronics module <NUM> and electrical power distributor <NUM>; one or more pump modules <NUM> operatively in communication with subsea electronics module <NUM> and electrical power distributor <NUM>; and fluid distribution unit <NUM>.

At least one power and communications foundation module <NUM> comprises subsea electronics module <NUM> operatively in communication with power and communications umbilical terminator data communications port <NUM> and electrical power distributor <NUM> operatively in communication with power and communications umbilical terminator electrical power port <NUM>. If SCM <NUM> is present, power and communications foundation module <NUM> may further comprise integral SCM power and data communications port <NUM> operatively in communication with SCM <NUM>.

Fluid storage modules <NUM> typically comprise a plurality of fluid storage bays <NUM>, each fluid storage bay <NUM> adapted to selectively receive a corresponding plurality of fluid storage tanks <NUM>, and at least one fluid storage module fluid port <NUM> in fluid communication with one or more fluid storage tank <NUM>. Not all fluid storage bays <NUM> need to be populated at any given time.

In contemplated embodiments, a single standalone flowline <NUM> (which can be composite, carbon steel, stainless, or the like, or a combination thereof) is connected from surface host <NUM> to fluid storage module <NUM>.

Single flowline <NUM> is comprised of low pressure capability designed to aid in refilling fluid storage tanks housing startup chemicals.

Referring to <FIG>, in a further embodiment a modular subsea chemical injection system comprises one or more power and communication umbilical termination modules <NUM> operatively connected to one or more power and communications umbilicals <NUM>, at least one power and communications umbilical <NUM> lacking a chemical delivery conduit; at least one power and communications umbilical terminator <NUM> (not shown in the figures) operatively connected to umbilical <NUM>; one or more power and communications foundation modules <NUM>; one or more fluid storage modules <NUM> operatively in communication with subsea electronics module <NUM> and electrical power distributor <NUM>; one or more pump modules <NUM> operatively in communication with subsea electronics module <NUM> and electrical power distributor <NUM>; and fluid distribution unit <NUM>.

Fluid storage modules <NUM> typically comprise a plurality of fluid storage bays <NUM>, where each fluid storage bay <NUM> is adapted to selectively receive a corresponding plurality of fluid storage tanks <NUM>, and at least one fluid storage module fluid port <NUM> in fluid communication with one or more fluid storage tank <NUM>. Not all fluid storage bays <NUM> need to be populated at any given time.

In contemplated embodiments, a single standalone flowline <NUM> (which can be composite, carbon steel, stainless, or the like, or a combination thereof) is connected from the surface host <NUM> to the electric pump module <NUM>.

Single flowline <NUM> is comprised of low pressure capability designed to deliver required chemical startup flowrates higher than required but at low pressure.

Single or multiple pumps <NUM> take the low pressure supply from the flowline <NUM> and boost the to the required injection pressure.

Startup chemicals are delivered via the pumps <NUM> to the port <NUM> to the fluid distribution unit <NUM> to service the wells during startup and shutdown.

Each pump <NUM> is typically configured to be self-contained and isolatable from the remaining pumps <NUM> of the predetermined set of individual pumps <NUM> and to be selectively removable from the bays <NUM>. Moreover, each pump <NUM> typically comprises storage tank <NUM>, low flow fluid pump <NUM> in fluid communication with storage tank <NUM>, and fluid pump controller in communication with umbilical <NUM>. Each of storage tank <NUM>, low flow fluid pump <NUM>, and fluid pump controller <NUM> may be scalable. Storage tank <NUM> may comprise a multi-fluid storage tank. In such configurations, multi-fluid storage tank <NUM> may further comprise a multi-fluid storage tank which is refillable or replacable subsea.

One or more pumps <NUM> may further comprise a pump designed to deliver fluid to multiple wells distributed via subsea manifold.

Each pump <NUM> is typically configured to be selectively removable from housing <NUM> such as via a remotely operated vehicle (ROV), an autonomous underwater vehicle (AUV), a crane assist, or the like, or a combination thereof.

Pump module <NUM> typically comprises pump module housing comprising a plurality of pump receivers pump fluid inlet in fluid communication with modular subsea chemical injection skid pump fluid outlet a predetermined set of low flow fluid pumps, each low flow fluid pump configured to be received into a pump receiver of the plurality of pump receivers ; and fluid pump controller in communication with umbilical signal conduit. Each low flow fluid pump is typically in fluid communication with pump fluid inlet and pump fluid outlet. High flow chemical flowline may be present and in fluid communication with pump module.

In further contemplated embodiments, referring generally to <FIG> a system for delivering fluids subsea comprises umbilical termination assembly <NUM> designed to break out power cable or electrical umbilical into motive power source, communication pathway which may be bidirectional to provide both feedback to surface location and/or to receive commands/data from surface location, and low voltage power source to supply low voltage to the field.

Modular electric/power distribution module <NUM> designed to be retrievable and comprises subsea electronics housing <NUM>. In embodiments, electric/power distribution module <NUM> comprises subsea transformer <NUM> to step down voltage to usable motive power levels for and distribute electrical signals to the various other modules.

Switchgear <NUM> is housed in subsea electronics housing <NUM> and configured for control and protection of electrical components.

Distribution panels/equipment <NUM> is housed in subsea electronics housing <NUM> and usable to deliver signals and power to other various modules.

Mudmat <NUM> is sized to contain and support numerous electrical components. Mudmat <NUM> is typically sized to contain and support numerous pump modules and may comprise additional slots for expansion if needed.

Subsea electronics module <NUM> is designed to control components and data exchange throughout predetermined components of the system for delivering fluids subsea and typically comprises controls for automatic fail safe state should a loss of power, communications, and/or controls occur. It also typically receives and collects data/information from all individual modules within the system such as system pressure, valve position, cycle counter, RPM, flow rate, linear position, stroke rate, chemical leak detect, water detection, ground fault monitoring, voltage, and/or current. In embodiments, subsea electronics module <NUM> receives commands such as via a topside communication link and relays controls and commands to appropriate modules. In certain embodiments the system for delivering fluids subsea may comprise one or more redundant and/or secondary communication links.

Modular fluid storage module <NUM> is configured to contain a variety of fluids utilized in subsea production activities and comprises frame <NUM> designed to be delivered and retrieved subsea.

Frame <NUM> may be locked in place via locking pins <NUM>. One or more indicators <NUM> may be present to aid in confirm positioning of modular fluid storage module <NUM>. Frame <NUM> typically comprises ROV interface <NUM> which comprises one or more subsea interconnects <NUM> for a predetermined set of connections, by way of example and not limitation comprising low voltage power, data communications, hydraulic connections for suction and discharge, stab plate and connector connectors, instrument and visual indicators designed to relay information topside about the condition of the system, leak detection, and/or level indication. In addition, module <NUM>, which comprises control valves, may be used to isolate the system for delivering fluids subsea via topside communication or manually via an ROV.

A predetermined number of storage modules <NUM> are disposed within frame <NUM> and utilized for storage of low flow fluids. Over pressure relief device <NUM> may be present and disposed within a hydraulic circuit and usable to provide system relief due to under pressure within the hydraulic circuit.

One or more chemical tanks <NUM> may be removably disposed in storage modules <NUM>, each of which may comprise a bladder is designed to be a form of secondary containment.

Electric pump module <NUM> is utilized for delivery of flow assurance chemicals via subsea stored chemicals or boosting for high flow line, and comprises one or more pumps <NUM>, which may comprise a positive displacement pump modified for subsea use, removably disposed in pump storage <NUM>. Pumps <NUM> are typically disposed within frame <NUM> and sized to distribute low flow, high pressure inhibitor type chemicals to a multitude of wells or sized to deliver low flow, high pressure inhibitor type chemicals to a single well. In certain embodiments, a single motor drives a single pump or a series of pump. Pump <NUM> may be rated for metering or dosing. Flow rate can be adjusted via a VFD or a metering valve. As with other modules, electric pump module <NUM> may comprise an adjustable device for the regulation of system pressure, one or more devices for system relief of over pressure within the hydraulic circuit, and/or one or more a devices for system relief due to under pressure within the hydraulic circuit.

Components of electric pump module <NUM> are typically housed in frame <NUM> which is designed to be delivered and retrieved subsea. Frame <NUM> may be locked in place via locking pins and comprise indicator to aid in confirming position. Frame <NUM> may further comprise an ROV interface with subsea interconnects for low voltage power, data communciations, motive power, hydraulic connections for suction and discharge, and/or stab plate and connector connections. Electric pump module <NUM> components may be protected via subsea compensation and may further comprise one or more control valves which can isolate system via topside communication or manually via an ROV.

In the operation of exemplary embodiments, the overall cost from both a manufacturing and installation perspective of fluids subsea may be minimized by using one or more of the disclosed systems and providing umbilical <NUM> that lacks a chemical delivery conduit; locating a subsea fluid storage reservoir such as <NUM> on a seafloor adjacent to a well site, where subsea fluid storage reservoir <NUM> is configured to provide low flow requirement fluids necessary for the well; and segregating low and high flow chemical delivery systems by use of subsea storage and pressure boosting for the low flow needs and a dedicated flowline from the host facility for the high flow needs.

In embodiments, all fluid conduits may be eliminated from umbilical <NUM> and only electrical power needs to be delivered to the well site. In those embodiments with boosters, fluid pressure may be boosted subsea from the subsea storage reservoir for high flow chemical requirements such as boosting the chemical fluid pressure from ambient to that required for injection into the production stream. In certain embodiments, a low pressure flowline may be utilized to minimize cost.

As used herein, a "host" can be defined as a floating deepwater production facility, a permanently fixed structure, an unmanned floating control buoy, or the like.

Claim 1:
A modular subsea chemical injection system, comprising:
a. a power and communications terminator (<NUM>) configured to be operatively connected to an umbilical (<NUM>) that lacks a chemical delivery conduit;
b. a power and communications terminator (<NUM>) configured to be operatively connected to the umbilical, the power and communications terminator comprising a data communications port (<NUM>) and an electrical power port (<NUM>);
c. a power and communications module (<NUM>), comprising:
i. a subsea electronics module (<NUM>) operatively in communication with the power and communications umbilical terminator data communications port; and
ii. an electrical power distributor (<NUM>) operatively in communication with the power and communications umbilical terminator electrical power port;
d. a fluid storage module (<NUM>) operatively in communication with the subsea electronics module and the electrical power distributor, the fluid storage module comprising:
i. a plurality of fluid storage bays (<NUM>) adapted to selectively receive a corresponding plurality of high fluid flow and/or low fluid flow fluid storage units (<NUM>); and
ii. a fluid storage module fluid port (<NUM>) in fluid communication with the plurality of high fluid flow and/or low fluid flow fluid storage bays (<NUM>);
e. a pump module (<NUM>) operatively in communication with the subsea electronics module and the electrical power distributor, the pump module comprising:
i. a plurality of pump bays (<NUM>) adapted to selectively receive a corresponding plurality of pumps (<NUM>), at least one pump being in fluid communication with the fluid storage module fluid port (<NUM>);
ii. a fluid port (<NUM>) in fluid communication with the plurality of pump bays (<NUM>); and
iii. a pump module fluid port (<NUM>) in fluid communication with the plurality of pump bays (<NUM>); and
f. a fluid distribution unit (<NUM>), comprising:
i. a distribution fluid port (<NUM>) in fluid communication with the pump module fluid port (<NUM>);
ii. a fluid distribution unit fluid supply port (<NUM>) in fluid communication with the distribution fluid port (<NUM>); and
iii. a fluid metering valve (<NUM>) disposed intermediate the distribution fluid port (<NUM>) and the fluid distribution unit fluid supply port (<NUM>).