Offshore oil and gas seawater lift submersible pumps automated underwater cleaning system

Abstract

An apparatus for automatically spraying a cleaning fluid onto a suction strainer of a submersible pump and a caisson grill of a caisson of an offshore oil and gas facility. The suction strainer includes a cylindrical surface with a cylinder axis parallel to the caisson. The caisson grill includes a downwardly facing planar surface. The apparatus includes a first nozzle ring including a first spray nozzle ring inlet for first hydraulic connection of the cleaning fluid, a first spray nozzle ring outlet for directing the cleaning fluid at the cylindrical surface; a second nozzle ring including a second spray nozzle ring inlet for second hydraulic connection of the cleaning fluid, a second spray nozzle ring outlet for directing the cleaning fluid at the downwardly facing planar surface; and a control system for controlling a supply of cleaning fluid to the first nozzle ring and the second nozzle ring.

Description

FIELD OF THE DISCLOSURE

[0001] Embodiments of the present disclosure generally relate to the maintenance of marine growth on caisson grills and suction strainers to submersible pumps associated with offshore oil and gas platforms.BACKGROUND

[0002] Offshore oil and gas platforms have the unique problem of accumulating marine growth over the life cycle of the facility. Marine growth may host animal or plant life including but not limited to heavy barnacles, seaweed, and algae. Marine growth on offshore equipment, if excessive and not maintained, may cause mechanical integrity issues over the life of the equipment including but not limited to corrosion. One example is with respect to caissons, which are often used to protect the submersible pumps required for produced water handling, fire water systems, and / or other utilities systems. Caissons on offshore platforms are large open-ended cylindrical pipes, mechanically fixed to the platform, and vertically submerged in the seawater. The orifice through which the seawater may enter the open-ended caisson may be referred to as the caisson grill. Caissons are used to protect and house pumps and risers that are connected between the platform and sea floor. Caissons protect the equipment from the force of heavy waves. Because generally seawater may continuously enter the caisson grill for the purpose of feeding a submersible pump housed within the caisson, a caisson grill may require frequent maintenance to remove accumulations of marine growth on the caisson grill and the submersible pump section housed within the caisson.

[0003] Generally, the most common approach to marine growth on caisson grills is to contract with divers to mechanically remove the marine growth. Depending on sea conditions, the age of the platform, and the skill and competence of divers, and frequency of execution, manual marine growth removal may pose personal safety risks too high for offshore oil and gas operators to manage. Therefore, offshore oil and gas operators may instead elect to replace caisson grills earlier than necessary, or may trade the personal safety risk of diving for a reduction in production due to the reduced ability to process produced water, thereby reducing revenue and profit margin.SUMMARY OF THE CLAIMED EMBODIMENTS

[0004] This disclosure presents, in accordance with one or more embodiments, an apparatus for automatically spraying a cleaning fluid onto a suction strainer of a submersible pump and a caisson grill of a caisson of an offshore oil and gas facility, the suction strainer having a cylindrical surface with a cylinder axis parallel to the caisson, and the caisson grill having a downwardly facing planar surface. The apparatus includes a first nozzle ring including a first spray nozzle ring inlet for first hydraulic connection of the cleaning fluid, a first spray nozzle ring outlet for directing the cleaning fluid at the cylindrical surface of the suction strainer; a second nozzle ring including a second spray nozzle ring inlet for second hydraulic connection of the cleaning fluid, a second spray nozzle ring outlet for directing the cleaning fluid at the downwardly facing planar surface of the caisson grill; and a control system for controlling a supply of the cleaning fluid to the first nozzle ring and the second nozzle ring.

[0005] This disclosure presents, in accordance with one or more embodiments, a method for automatically spraying a cleaning fluid from a tank onto a suction strainer of a submersible pump and a caisson grill of a caisson of an offshore oil and gas facility, the suction strainer having a cylindrical surface with a cylinder axis parallel to the caisson, and the caisson grill having a downwardly facing planar surface. The method includes obtaining from a programmable logic controller, a first command to spray the cleaning fluid initiated by a preselected first pressure differential transmitter value; obtaining, from the programmable logic controller, a second command to spray the cleaning fluid initiated by a preselected second pressure differential transmitter value; drawing the cleaning fluid, using an apparatus for spraying the cleaning fluid, from the tank in fluid connection with a pump by turning on the pump of the apparatus to pressurize the cleaning fluid, forming a pressurized cleaning fluid; spraying the pressurized cleaning fluid onto the cylindrical surface of the suction strainer; and spraying the pressurized cleaning fluid onto the downwardly facing planar surface of the caisson grill.

[0006] This disclosure presents, in accordance with one or more embodiments, a system for automatically spraying a cleaning fluid from a tank onto a suction strainer of a submersible pump and a caisson grill of a caisson of an offshore oil and gas facility, the suction strainer having a cylindrical surface with a cylinder axis parallel to the caisson, and the caisson grill having a downwardly facing planar surface. The system includes a pump including a pump outlet configured to receive the cleaning fluid from the tank into a pump inlet and to pressurize the cleaning fluid to a pressurized cleaning fluid at a preselected pressure; a first nozzle ring including a first spray nozzle ring inlet and a first spray nozzle ring outlet configured to direct the cleaning fluid at the cylindrical surface of the suction strainer; a second nozzle ring including a second spray nozzle ring inlet and a second spray nozzle ring outlet configured to direct the cleaning fluid at the downwardly facing planar surface of the caisson grill. Additionally, the system includes a control system. The control system includes a human machine interface configured for user inputs and a programmable logic controller.

[0007] Other aspects and advantages will be apparent from the following description and the appended claims.BRIEF DESCRIPTION OF DRAWINGS

[0008] FIG. 1 illustrates an apparatus and system according to one or more embodiments disclosed herein.

[0009] FIG. 2 illustrates a method according to one or more embodiments disclosed herein.DETAILED DESCRIPTION

[0010] Caisson grills on any offshore oil and gas platforms or subsea equipment accumulate marine growth over time and require removal. Removal of marine growth is often performed manually by divers thereby increasing personal risk to oil and gas operators. Embodiments disclosed herein provide for methods, systems, and apparatuses for fully automating marine growth removal and obviating the need for diving personnel.

[0011] Embodiments disclosed herein provide for an apparatus, method, and system for automatically spraying a cleaning fluid onto the downwardly facing planar surface of a caisson grill and the cylindrical surface of a suction strainer of a submersible pump of an offshore oil and gas facility. The cylindrical surface of the suction strainer may have a cylinder axis parallel to the caisson. Caisson grills may accumulate marine growth over time due to sea conditions and ecological factors and may require removal during operation on a specified frequency.

[0012] Embodiments disclosed herein describe a system and method to automatically remove marine growth from a caisson grill and suction strainer attached to an offshore oil and gas facility, e.g., an offshore oil and gas seawater lift submersible pumps automated underwater cleaning system, or a “cleaning system.” In one or more embodiments, the system may be automated, e.g., an “automated cleaning system.” The system may include a pump, a first nozzle ring including a first spray nozzle ring outlet, a second nozzle ring including a second spray nozzle ring outlet, and a control system. The first spray nozzle ring inlet may have a hydraulic connection to the cleaning fluid. The second spray nozzle ring inlet may have a hydraulic connection to the cleaning fluid.

[0013] The system may include a programmable logic controller that includes a set of instructions that may be configured to perform a method of removing marine growth. The method of removing marine growth may include obtaining a command to spray pressurized cleaning fluid through both the first spray nozzle ring outlet and the second spray nozzle ring outlet. The method of marine growth removal may include either a mechanical or chemical means removal, or both. The marine growth may be mechanically removed by exposing the marine growth to high pressure cleaning fluid such as water, thereby enabling the marine growth to disintegrate and slough off the caisson grill and suction strainer. The marine growth may be mechanically removed by a cleaning fluid that includes additives such as hypochlorite. In other embodiments, copper sulfate may be used in place of hypochlorite. The marine growth may be chemically removed by exposing the marine growth to a cleaning fluid with a sufficient concentration of hypochlorite to render the marine growth inert and lifeless, thereby enabling the marine growth to disintegrate and slough off the caisson grill and suction strainer. In both means of marine growth removal, the marine growth must disintegrate to a particle size small enough to allow the particles to fall through the caisson grill. A sufficient concentration of hypochlorite in the cleaning fluid may include a concentration of between 0.1 and 1 ppm.

[0014] The command to spray cleaning fluid may be initiated by either a preselected first pressure differential transmitter value or a preselected second pressure differential transmitter value, or both. The apparatus may include a pump for pumping the cleaning fluid from a supply of cleaning fluid such as from a tank or barrel of cleaning fluid. The tank is configured to hold the cleaning fluid and is fluidly connected to the pump. The apparatus may include a first pressure differential transmitter, a second pressure differential transmitter, a human machine interface (HMI), first nozzle ring, a second nozzle ring, a control system, and a programmable logic controller (PLC). The control system includes the human machine interface configured for user inputs, and the control system includes the programmable logic controller.

[0015] FIG. 1 shows an apparatus and system according to one or more embodiments disclosed herein. Enclosures such as caissons form a confined space. The enclosures are typically employed on offshore platforms and act as a protective sheath to enclose a submersible pump, a suction strainer of a submersible pump, and / or a riser, all within the confined space. An enclosure such as a caisson 100 may be fixed to any deck of a platform and extend from above the water line to between 10 m and 50 m below sea level. Pumps housed within offshore oil and gas caissons may include any seawater pumps or submersible pumps that may be required for fire water or utilities systems on the offshore oil and gas platform. A submersible pump assembly 104 may be disposed at an elevation between 10 m and 50 m below sea level and be configured to remove seawater through the submersible pump intake 110 and discharge seawater through the submersible pump discharge 102. The selected length of the caisson associated depth of the submersible pump assembly 104 may depend on the temperature limits of the pump, the caisson, and the conditions of the sea. The deeper the submersion of the caisson and submersible pump assembly 104, the lower the temperature of the seawater.

[0016] The caisson 100 may include a caisson grill 136 which may be open-ended at the bottom, rendering the entire caisson open-ended to seawater. The caisson grill may have a downwardly facing planar surface 135 that may be constructed with a plurality of parallel bars, or a plurality of bars arranged in a grid-like pattern that may prevent fish or plant matter from entering the caisson. Although a grid-like pattern of bars is shown on the caisson grill 136, one of ordinary skill in the art would know that any mechanical design that keeps wildlife and plant matter from entering the confined space of the caisson would be sufficient. The caisson grill may have a planar surface downwardly facing the center of the earth, substantially perpendicular to a cylinder axis (e.g., a caisson axis such as an enclosure axis 101) of the caisson 100, as shown in the figure.

[0017] Disposed at an elevation immediately below the submersible pump assembly 104 and upstream of the submersible pump intake 110 may be a first nozzle ring 106 which may include a plurality of nozzles that are part of a first spray nozzle ring outlet 130. The first spray nozzle ring outlet 130 may be configured for directing the cleaning fluid at a cylindrical surface (e.g., a strainer surface 137) of a suction strainer (e.g., a suction strainer 138). The suction strainer may be formed in a cylindrical shape. The suction strainer has an axis such as a cylinder axis (e.g., a strainer axis 139). The suction strainer is shown disposed in the caisson such that the strainer axis 139 is oriented, for example, substantially parallel to the axis of the caisson 100. Although only eleven nozzles are shown in the figure, one of ordinary skill in the art would know that a fewer or greater number of nozzles may be required to mechanically and / or chemically remove any marine growth from the first nozzle ring 106. In accordance with one or more embodiments the nozzles may be cavitation nozzles, fan jet nozzles, any other appropriate types of nozzles, and in any combination. Cavitation nozzles may be selected due to space constraints, e.g., the limited area in the pump suction strainer. A mix of nozzles including fan jet nozzles and cavitation nozzles ensures the efficiency of the system in the marine growth removal process.

[0018] A cleaning fluid may be introduced to the first nozzle ring 106 through a first spray nozzle ring inlet 112 from a fluid conduit (e.g., a high-pressure flexible hose 134). The high-pressure flexible hose may be fluidly connected to a pump 122 configured for pumping cleaning fluid from a cleaning fluid supply of cleaning fluid 125 contained in a vessel such as a tank 124. The tank may be rated for atmospheric pressure and for temperatures up to 150° F. Although not shown in the figure, the tank 124 may include a valve that allows for inbreathing when cleaning fluid is being removed from the tank and a vent that allows for outbreathing when cleaning fluid is being added to the tank. The fluid supply may incorporate a stop valve, a regulating valve, and / or a choke in a cleaner inlet manifold (e.g., a cleaner inlet manifold 142) to control and regulate the incoming flow of the cleaning fluid. The cleaning fluid may then flow through the cleaner inlet manifold and into the pump inlet of the pump.

[0019] The pressurized fluid continues flowing out of the pump outlet and into each of the ring inlets of the nozzle rings. The apparatus and system may include a cleaner output manifold (e.g., a cleaner output manifold 144) configured with valves and chokes to direct the cleaning fluid flow to one nozzle ring at a time or to direct the flow to both nozzle rings. The cleaner output manifold may include choking valves such as metering valves or needle valves to regulate and differentiate the flow between the two rings. The rings, the manifolds, and / or the fluid conduit (e.g., the high-pressure flexible hose 134) may include pressure regulators that are either manual or actuated. Manually-set (manually operated) pressure regulators may be set by an operator directly setting the regulator. Actuated pressure regulators may be coupled to the control system and thereby set by preselected user inputs.

[0020] The pump may be controlled by a programmable logic controller (PLC) (e.g., a PLC 126), which operates on a combination of logic and user inputs from a human machine interface (HMI) (e.g., an HMI 128). The HMI is configured for obtaining user inputs and for receiving user inputs. A control system 127 includes the human machine interface configured for user inputs, and the control system includes the programmable logic controller.

[0021] The spraying of the pressurized cleaning fluid may include the PLC determining a determined pressure of the pressurized cleaning fluid. The spraying includes the PLC comparing the determined pressure with a selected pressure. The selected pressure may be a preselected pressure (e.g., a preselected pump output pressure) of the pressurized cleaning fluid that a user enters into the PLC. The spraying includes the PLC controlling the apparatus in response to a result of the comparing.

[0022] The spraying includes the PLC determining a determined first pressure differential of the suction strainer. The spraying may also include comparing the determined first pressure differential of the suction strainer with a selected first pressure differential. The selected first pressure differential may be a preselected pressure (e.g., a preselected second pressure differential) which a user enters into the PLC. The spraying includes the PLC controlling the apparatus in response to a result of the comparing.

[0023] The spraying includes the PLC determining a determined second pressure differential of the caisson grill. The spraying may also include comparing the determined second pressure differential with the selected second pressure differential. The selected second pressure differential may be a preselected pressure (e.g., a preselected second pressure differential) which a user enters into the PLC. The spraying includes the PLC controlling the apparatus in response to a result of the comparing.

[0024] The system may further include a monitoring subsystem 129 coupled to the control system. The control of the pump by the PLC may include the use of inputs from the monitoring subsystem that are compared with sensor inputs and with user inputs from the HMI. The monitoring subsystem may include one or more sensors such as contamination sensors, pressure transmitters, timers, flow meters, linear transducers, proximity sensors, etc.). The sensors may be configured to measure, for example, suspended solids, pump output pressure, cleaning fluid flowrate, etc. The monitoring subsystem may include a display, such as a display on the HMI. The monitoring subsystem may present system parameters (e.g., a maximum pressure rating, an input voltage parameter, etc.), monitored parameters (e.g., solids contamination, tank fluid supply level, pump enclosure latch closure, etc.), and real-time operational parameters, e.g., parameters detected in real time, such as real-time data for pressure, temperature, and flowrate, including a protection system to provide limit alarm trips, such as level meter trips, and one or more program interlocks.

[0025] The control system may receive from the monitoring subsystem readiness states from which the control system may determine an operational state of the apparatus. For example, the control system may receive a readiness state of the motion detectors (e.g., no motion detected=ready) and of the tank level of the fluid supply (e.g., tank fluid>33 percent full=ready) prior to commencing a pressurization cycle in the workflow. The control system may integrate readiness states from the monitoring subsystem. Readiness states may include confirming function of, for example, level meters, pressure sensors, integrity monitoring systems (such as corrosion monitors), personnel exclusion barrier(s), motion detector(s), proximity sensor(s), and / or camera(s). Readiness states may include confirming function of interlocks such as a closing latch on an enclosure (e.g., latch closed=ready) for the cleaning fluid pump (e.g., the pump 122). A readiness state may include a determination, using the corrosion monitors, that the caisson integrity satisfies a predetermined criteria. For example, corrosion or other monitors may detect holes in the caisson which will cause the hypochlorite to dissipate outside of the caisson. In this case the system readiness state would be caisson integrity holes=not ready.

[0026] The water tank may extract water from any source (e.g., a fire system water header) and inject it with a sufficient concentration of additive such as hypochlorite suitable for eliminating the marine growth. A first level indicating transmitter (LIT) monitors the level of cleaning fluid, e.g., water in the tank. If the water level is low, the cleaning system will be turned off. If the water level is high, a level control valve (LCV) will be shut off. The level control valve LCV moderates the incoming flow from the water source such as the fire system water header.

[0027] The cleaning fluid pump hydraulic downstream circuit may include a pump output duplex strainer and an output pressure differential sensor such as a pressure differential indicator (an output PDI). The output strainer with output PDI may prevent contaminants from the pump being delivered to the flexible pipe and subsequently to the seawater lift pump. The output PDI ensures that the online strainer is operated within an acceptable pressure differential. The cleaning fluid pump hydraulic upstream circuit may include a duplex strainer and a PDI in the hydraulic circuit from the tank to ensure no contaminants from the tank are delivered to the cleaning fluid pump. The PDI ensures that the online strainer is operated within an acceptable pressure differential. A pressure relief valve known as a PZV may be included to ensure that the discharge piping between the cleaning fluid pump output and the flexible pipe is not over pressurized.

[0028] The operational parameters may include those entered by a user in a workflow through HMI. The user may enter into the control system the data required to define the workflow. The workflow may include, for example, a predetermined minimum suspended solids contamination limit. The workflow may include, for example, spray duration for both the first nozzle ring and the second nozzle ring (e.g., the rings) to operate simultaneously, to operate in sequence, or to operate alternately. For example, a user may enter in the HMI a first workflow that includes a preselected duration of five minutes for the PLC to operate the pump to pressurize both rings simultaneously. A user may enter a second workflow for the PLC to operate the first nozzle ring for five minutes and then to operate the second nozzle ring for three minutes. A user may enter a third workflow that includes alternately operating the rings for one minute each for a total of ten minutes, or for one minute for the first nozzle ring and two minutes for the second nozzle ring. The user may enter a fourth workflow that includes a preselected operating pressure for the rings. For example, the user may enter 1200 psi (pounds per square inch) for the first nozzle ring and a pressure of 1000 psi for the second nozzle ring. The user may enter a fifth workflow that includes variations in the pressures and durations.

[0029] The apparatus may, as described above, determine a state of contamination due to fouling as interpreted by pressure differentials across the suction strainer and / or across the caisson grill. The system and apparatus may determine a state of contamination by sensing suspended solids and / or other contamination using contamination sensors. For example, a sand sensor may detect a sand level in the caisson. A solids sensor may detect suspended solids in the seawater within the caisson.

[0030] Likewise additive concentration sensors (e.g., chemical concentration sensors) may be included to determine the chemical concentration of cleaning fluid chemical additives such as hypochlorite, copper sulfate, and other additives. Additive concentration sensors may be configured for monitoring additive concentration data of additives in the cleaning fluid in the tank and / or at the annulus of the caisson. The monitoring subsystem may use additive concentration data from the additive concentration sensors and transmit the data to the HMI. hmm I may compare the monitored concentration data with predetermined concentration parameters and then make a determination to increase or decrease the additive concentration. The system may include an additive supply subsystem that includes an additive supply, e.g., a barrel of additives, hydraulically coupled to the tank through an additive conduit and a series of valves such as those mounted in an additive manifold. The monitoring subsystem may be configured to operate the additive valves. In this manner, the additive concentration may be automatically increased or decreased using the PLC, the HMI, the monitoring subsystem, and an additive supply.

[0031] The apparatus and system may automatically monitor the pressure differentials. As the predetermined pressure differential limit is reached, the system may automatically start the cleaning method. Likewise, the monitoring subsystem may transmit contamination data to the PLC, the HMI, and / or the control system. The transmitted contamination data may be compared with a predetermined contamination level, and then as the predetermined contamination level is reached system may automatically start the cleaning method. In another example, during the cleaning process, the monitoring subsystem may monitor the suspended solids that are removed by the pressurized, sprayed fluid and may send a command to the PLC to continue the cleaning process until the suspended solids are flushed out of the seawater, e.g., until the suspended solids falls below a user-defined threshold. In accordance with one or more embodiments, the apparatus and system may be configured to perform the cleaning processes with the seawater lift pump turned off or simultaneously with the seawater lift pump running.

[0032] Disposed at an elevation (e.g., a first elevation) immediately below the submersible pump intake 110, inside the suction strainer 138, and immediately above the first nozzle ring 106 may be a pressure sensor 116A that may send a first value to a first pressure differential transmitter PDT-1 118. Disposed at an elevation (e.g., a second elevation) immediately below the first nozzle ring 106, outside the suction strainer 138, and inside an annulus 140 may be a pressure sensor 116B that may send a second value to a first pressure differential transmitter PDT-1 118. The first pressure differential transmitter PDT-1 118 may be configured to transmit a pressure differential across the pump strainer. For example, the PDT-1 may transmit the difference in pressure (e.g., a first pressure difference or a pump strainer pressure differential) sensed by pressure sensor 116A and the pressure sensed by pressure sensor 116B. The annulus 140 is the space between the suction strainer and the inner wall of the caisson. In both aforementioned locations, the pressure may be tracked by pressure sensors 116A and 116B.

[0033] The first pressure differential transmitter PDT-1 118 may be designed to capture the pressure differential across the suction strainer to determine the level of fouling on the suction strainer 138 to the submersible pump assembly 104. The pressure sensors, 116A and 116B, may send two separate sensed values to the PDT-1 118. Then, PDT-1 118 may compute the mathematical difference between the two sensed values and transmit the value to the PLC 126. Depending on the difference calculated and whether it falls within the threshold of the preselected first pressure differential transmitter value, the PDT-1 118 may automatically transmit a value that initiates a logic sequence to start the pump 122 and spray cleaning fluid through the first nozzle ring 106.

[0034] In some embodiments, if the method of cleaning is by mechanical removal, the pressure of sprayed cleaning fluid must be high enough to disintegrate, or otherwise remove, the marine growth to a particle size small enough to prevent or mitigate clogging of the flow path of seawater to the submersible pump intake 110. Similarly, in other embodiments, if the method of cleaning is chemical, the concentration of the hypochlorite must be sufficient to disintegrate the marine growth to a particle size small enough to prevent or mitigate clogging of the flow path of seawater to the submersible pump intake 110.

[0035] Disposed at an elevation below the first nozzle ring 106 and suction strainer 138 may be the second nozzle ring 108, which may include a plurality of nozzles that are part of the second spray nozzle ring outlet 132. The second nozzle ring has a second spray nozzle ring inlet. The second spray nozzle ring inlet is configured for second hydraulic connection of the cleaning fluid. The second nozzle ring outlet is configured for directing the cleaning fluid at the downwardly facing planar surface of the caisson grill. Although only eight nozzles are shown in the figure, one of ordinary skill in the art would know that a fewer or greater number of nozzles may be required to remove any marine growth from the second nozzle ring 108. Like the first nozzle ring 106, a cleaning fluid may be introduced to the second nozzle ring 108 through a second spray nozzle ring inlet 114 from the high-pressure flexible hose 134, fluidly connected to a pump 122 controlled by the PLC 126 to pump cleaning fluid from tank 124. The apparatus may have a control system for controlling the supply of the cleaning fluid to the first nozzle ring and to the second nozzle ring.

[0036] Similar to the first pressure differential transmitter PDT-1 118, the second pressure differential transmitter PDT-2 120 may be configured to calculate and transmit the difference in pressure sensed at two separate elevations. Disposed at an elevation (e.g., a third elevation) immediately above the second nozzle ring 108 may be a pressure sensor 116C that may send a first value to a second pressure differential transmitter PDT-2 120. Disposed at an elevation (e.g., a fourth elevation) immediately below the second nozzle ring 108 and caisson grill 136 may be a pressure sensor 116D that may send a second value to a second pressure differential transmitter PDT-2 120. The second pressure differential transmitter PDT-2 120 may be configured to transmit a pressure differential across the caisson grill. For example, the PDT-2 may transmit the difference in pressure (e.g., a second pressure difference or a caisson grill pressure differential) sensed by pressure sensor 116C and the pressure sensed by pressure sensor 116D. In both aforementioned locations, the pressure may be sensed by pressure sensors 116C and 116D.

[0037] The second pressure differential transmitter PDT-2 120 may be designed to capture the pressure differential across the caisson grill to determine the level of fouling on the caisson grill 136. The pressure sensors, 116C and 116D, may send two separate sensed values to the PDT-2 120. Then, PDT-2 120 may compute the mathematical difference between the two sensed values and transmit the value to the PLC 126. Similar to PDT-1 118, depending on the difference calculated and whether it falls within the threshold of the preselected second pressure differential transmitter value, the PDT-2 120 may automatically transmit a value that initiates a logic sequence to start the pump 122, thereby spraying fluid onto the downwardly facing planar surface of the caisson grill.

[0038] In this manner, the system is configured to detect excessive marine growth at the suction strainer and / or at the caisson grill. The system is configured for continuous monitoring of the pressure differential on the pump suction strainer and caisson grill. After the system detects the buildup and is activated, it will extract water containing a sufficient concentration of hypochlorite from the water storage tank which will then be pressurized and pumped using a pump such as a positive displacement pump powered by an electric motor. The system may be configured for automatic activation based on a timer. The system may activate when the automatic timer expires. For example, the timer may be set for single cycle, e.g., one event set at a user-entered predetermined date and time such as Tuesday 10:00 a.m. for a duration of ten minutes, or, for example, fifteen minutes after the user sets the timer. The timer may be set for repeated, automatic cycling, e.g., repeated events set at a user-entered predetermined regularly repeating date and time such as daily at 10:00 a.m. for ten minutes. The system may be manually operated by a user setting the system to activate, thus turning on the pump for a duration or until the system is turned off. The system may be set up for any combination of regular times and durations.

[0039] In accordance with one or more embodiments, once the system has been running and discharging the water for a set duration, e.g., ten minutes, the system will be automatically turned off as the cleaning process has been complete. The system is configured to turn off before the timer expires in the event that the pressure differential across the suction strainer or across the caisson grill drops down to acceptable limit. The system monitors the water tank level. The system will automatically shut off when the water tank level transmitter reads below a user-defined set limit known as, for example, a low-low level. Likewise, in the event that the water tank level transmitter reads a high-high level, a tank inlet level control valve, e.g., the LCV providing water to the tank will be closed to prevent overflowing.

[0040] FIG. 2 shows a method 200 for automatically spraying a cleaning fluid from a tank onto a caisson grill and a suction strainer of a submersible pump of an offshore oil and gas facility. First, under step 204, the method includes obtaining from a PLC 126 a command to spray the cleaning fluid. The command to spray a cleaning fluid may be initiated by a preselected first pressure differential transmitter value transmitted by PDT-1 118. The first pressure differential transmitter value may not be high enough to start pump 122 and spray cleaning fluid through the first spray nozzle ring outlet 130 because the pressure differential across the suction strainer 138 may be too low. In that case, step 206 may obtain, from a PLC 126, a command to spray the cleaning fluid initiated by a preselected second pressure differential transmitter value.

[0041] Thus, the second pressure differential transmitter value transmitted by PDT-2 120 may initiate a command to spray the cleaning fluid through the second nozzle ring 108 and the second spray nozzle ring outlet 132. Either the first pressure differential transmitter value, or the second pressure differential transmitter value, or both may initiate the PLC 126 to execute step 208, which is to draw the cleaning fluid, using an apparatus according to FIG. 1 for spraying the cleaning fluid, from the tank fluidly connected using a fluid connection to a pump inlet 121 with a pump 122. Next, in order to draw fluid under step 208, step 210 requires turning on the pump 122 of the apparatus to pressurize the cleaning fluid thereby forming a pressurized cleaning fluid coming out of the pump at a pump outlet 123.

[0042] Under step 212, the pressurized cleaning fluid may be sprayed onto the planar surface of the caisson grill 136 to remove marine growth and onto the cylindrical surface. Under step 214, the pressurized cleaning fluid may be sprayed onto the cylindrical surface of the suction strainer 138. If either the PDT-1 118 or the PDT-2 120 (or both) initiate a command to spray the cleaning fluid, cleaning fluid may be sprayed through both the first spray nozzle ring outlet 130 and the second spray nozzle ring outlet 132.

[0043] In summary, embodiments disclosed herein provide for an apparatus, method, and system for automatically spraying a cleaning fluid onto a caisson grill and a suction strainer of a submersible pump of an offshore oil and gas facility. The apparatus, method and system are all intended to automatically remove accumulated marine growth from the downwardly facing planar surface of the caisson grill and the cylindrical surface of the suction strainer upon a preselected first pressure differential value or a preselected second pressure differential value high enough to initiate a command to spray cleaning fluid.

[0044] The embodiments disclosed herein provide for an apparatus, method, and system that automatically sprays cleaning fluid onto a caisson grill and a suction strainer, uniquely obviating the need for diving personnel and decreasing personal safety risks posed to offshore oil and gas operators. For example, diving personnel (divers) will not be needed to assess the marine growth buildup nor for underwater cleaning in possibly hazardous environments, such as underwater manual jetting operations. Using this system, various forms of marine growth occurring at the seawater lift pump suction strainer and at the caisson grill will be minimized. This will ensure that the seawater lift submersible pump system can sustain normal operation and flows. The pump flooded suction will result in motor casing sufficient cooling thereby keeping the winding temperatures within an acceptable limit. The overall reliability of the system will be increased which may result in the avoidance of the massive costs of having to remove the whole pump-motor assembly system and overhauling it due to the deficiency of a hypochlorite or other additive system.

[0045] Finally, it is to be understood that the configurations described above, along with the specific examples and uses are only illustrations of the application of the principles in the present invention. Numerous modifications and variants of the arrangements may be made by those skilled in the art without departing from the spirit and scope of the present disclosure and the appended claims are intended to include such modifications. Thus, while the present invention has been described above with particularity, it will be apparent to those of ordinary skill in the art that numerous modifications, including but not limited to, variations in assembly, size, materials, form, function, and operation may be used without departing from the principles and concepts set forth herein.

[0046] Unless defined otherwise, all technical and scientific terms used have the same meaning as commonly understood by one of ordinary skill in the art to which these systems, apparatuses, methods, processes and compositions belong.

[0047] The singular forms “a,”“an,” and “the” include plural referents, unless the context clearly dictates otherwise.

[0048] As used here and in the appended claims, the words “comprise,”“has,” and “include” and all grammatical variations thereof are each intended to have an open, non-limiting meaning that does not exclude additional elements or steps.

[0049] “Optionally” means that the subsequently described event or circumstances may or may not occur. The description includes instances where the event or circumstance occurs and instances where it does not occur.

[0050] When the word “approximately” or “about” are used, this term may mean that there can be a variance in value of up to ±10%, of up to 5%, of up to 2%, of up to 1%, of up to 0.5%, of up to 0.1%, or up to 0.01%.

[0051] Ranges may be expressed as from about one particular value to about another particular value, inclusive. When such a range is expressed, it is to be understood that another embodiment is from the one particular value to the other particular value, along with all particular values and combinations thereof within the range.

[0052] While the disclosure includes a limited number of embodiments, those skilled in the art, having benefit of this disclosure, will appreciate that other embodiments may be devised which do not depart from the scope of the present disclosure. Accordingly, the scope should be limited only by the attached claims.

Claims

1. An apparatus for automatically spraying a cleaning fluid onto a suction strainer of a submersible pump and a caisson grill of a caisson of an offshore oil and gas facility, the suction strainer having a cylindrical surface with a cylinder axis parallel to the caisson, and the caisson grill having a downwardly facing planar surface, the apparatus comprising:a first nozzle ring comprising a first spray nozzle ring inlet for first hydraulic connection of the cleaning fluid, a first spray nozzle ring outlet for directing the cleaning fluid at the cylindrical surface of the suction strainer;a second nozzle ring comprising a second spray nozzle ring inlet for second hydraulic connection of the cleaning fluid, a second spray nozzle ring outlet for directing the cleaning fluid at the downwardly facing planar surface of the caisson grill; anda control system for controlling a supply of the cleaning fluid to the first nozzle ring and the second nozzle ring.

2. The apparatus of claim 1 further comprising a pump fluidly connected to a tank configured to hold the cleaning fluid.

3. The apparatus of claim 1 further comprising:a first pressure differential transmitter for transmitting a first pressure difference sensed by a first plurality of pressure sensors disposed at a first elevation immediately inside the suction strainer and above the first nozzle ring, and disposed at a second elevation inside an annulus and below the first nozzle ring;a second pressure differential transmitter for transmitting a second pressure difference sensed by a second plurality of pressure sensors disposed at a third elevation immediately above the caisson grill and at a fourth elevation below the caisson grill;a human machine interface configured for receiving user inputs; anda programmable logic controller.

4. A method for automatically spraying a cleaning fluid from a tank onto a suction strainer of a submersible pump and a caisson grill of a caisson of an offshore oil and gas facility, the suction strainer having a cylindrical surface with a cylinder axis parallel to the caisson, and the caisson grill having a downwardly facing planar surface, the method comprising:obtaining, from a programmable logic controller, a first command to spray the cleaning fluid initiated by a preselected first pressure differential transmitter value;obtaining, from the programmable logic controller, a second command to spray the cleaning fluid initiated by a preselected second pressure differential transmitter value;drawing the cleaning fluid, using an apparatus for spraying the cleaning fluid, from the tank in fluid connection with a pump by turning on the pump of the apparatus to pressurize the cleaning fluid, forming a pressurized cleaning fluid;spraying the pressurized cleaning fluid onto the cylindrical surface of the suction strainer; andspraying the pressurized cleaning fluid onto the downwardly facing planar surface of the caisson grill.

5. The method of claim 4, wherein the spraying of the pressurized cleaning fluid further comprises a user entering into the programmable logic controller, a selected pressure of the pressurized cleaning fluid.

6. The method of claim 5, wherein the spraying of the pressurized cleaning fluid further comprises determining, using the programmable logic controller, a determined pressure of the pressurized cleaning fluid.

7. The method of claim 6,wherein the spraying of the pressurized cleaning fluid further comprises comparing, using the programmable logic controller, the determined pressure with the selected pressure and controlling the apparatus in response to a result of the comparing.

8. The method of claim 4, wherein the spraying of the pressurized cleaning fluid further comprises a user entering into the programmable logic controller, a selected first pressure differential of the suction strainer.

9. The method of claim 8,wherein the spraying of the pressurized cleaning fluid further comprises determining, using the programmable logic controller, a determined first pressure differential of the suction strainer.

10. The method of claim 9,wherein the spraying of the pressurized cleaning fluid further comprises comparing, using the programmable logic controller, the determined first pressure differential with theselected first pressure differential and controlling the apparatus in response to a result of the comparing.

11. The method of claim 4, wherein the spraying of the cleaning fluid further comprises a userentering into the programmable logic controller, a selected second pressure differential of the caisson grill.

12. The method of claim 11,wherein the spraying of the pressurized cleaning fluid further comprises determining, using the programmable logic controller, a determined second pressure differential of the caisson grill.

13. The method of claim 12,wherein the spraying of the pressurized cleaning fluid further comprises comparing, using the programmable logic controller, the determined second pressure differential with the selected second pressure differential and controlling the apparatus in response to a result of the comparing.

14. A system for automatically spraying a cleaning fluid from a tank onto a suction strainer of a submersible pump and a caisson grill of a caisson of an offshore oil and gas facility, the suction strainer having a cylindrical surface with a cylinder axis parallel to the caisson, and the caisson grill having a downwardly facing planar surface, the system comprising:a pump comprising a pump outlet configured to receive the cleaning fluid from the tank into a pump inlet and to pressurize the cleaning fluid to a pressurized cleaning fluid at a preselected pressure;a first nozzle ring comprising a first spray nozzle ring inlet and a first spray nozzle ring outlet configured to direct the cleaning fluid at the cylindrical surface of the suction strainer;a second nozzle ring comprising a second spray nozzle ring inlet and a second spray nozzle ring outlet configured to direct the cleaning fluid at the downwardly facing planar surface of the caisson grill; anda control system comprising:a human machine interface configured for user inputs; anda programmable logic controller.

15. The system of claim 14, wherein the programmable logic controller comprises a set of instructions configured to perform a method comprising:obtain a first command to spray the cleaning fluid initiated by a preselected first pressure differential transmitter value;obtain a second command to spray the cleaning fluid initiated by a preselected second pressure differential transmitter value;turn on the pump to pressurize the cleaning fluid to the pressurized cleaning fluid at thepreselected pressure;spray the pressurized cleaning fluid through the first spray nozzle ring outlet onto the cylindrical surface of the suction strainer; andspray the pressurized cleaning fluid through the second spray nozzle ring outlet onto the downwardly facing planar surface of the caisson grill.

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