NO20161040A1

NO20161040A1 - Depth compensated inline active heave compensator

Info

Publication number: NO20161040A1
Application number: NO20161040A
Authority: NO
Inventors: Tord Martinsen; Andre Skare Berg
Original assignee: Safelink As
Priority date: 2016-06-21
Filing date: 2016-06-21
Publication date: 2017-12-22

Abstract

A depth compensated inline active heave compensator comprises a first cylinder having an upper end and a lower end, a first connection means mounted at the upper end of the first cylinder and adapted for connecting the first cylinder to at least one of: a vessel at sea surface or a payload, a first piston located within the first cylinder and adapted for reciprocation with respect thereto, a first piston rod connected to the first piston and extending downwardly therefrom through the lower end of the first cylinder, a second connector means adapted for securing the first piston rod to at least one of: a vessel at the sea surface or a payload, and located at the lower end of the first cylinder, a first volume of hydraulic fluid located between the first piston and the lower end of the first cylinder, a second volume of hydraulic fluid located between the first piston and the upper end of the first cylinder, a second cylinder containing a second piston, a third volume, containing hydraulic fluid, located between the lower end of the second cylinder and the second piston, a fourth volume, containing gas, located between the upper end of the second cylinder and the second piston, effectively pressurizing the third volume and the first volume via conduit means, a sensor, adapted for directly or indirectly measuring movement of the depth compensated inline active heave compensator, a position sensor, adapted for measuring the position of a piston, a means for fluid transportation adapted for applying fluid pressure to the second volume, where the means for fluid transportation is controlled based on sensor measurements, a means for depth compensation, by increasing the pressure in the second volume, where the pressure increase is proportional to the external pressure.A depth compensated inline active heave compensator comprises a first cylinder having an upper end and a lower end, a first connection means mounted at the upper end of the first cylinder and adapted for connecting the first cylinder to at least one of: a vessel at sea surface or a payload, a first piston located within the first cylinder and adapted for reciprocation with respect thereto, a first piston rod connected to the first piston and extending downwardly therefrom through the lower end of the first cylinder, a second connector means adapted for securing the first piston rod to at least one of: a vessel at the sea surface or a payload, and located at the lower end of the first cylinder, a first volume of hydraulic fluid located between the first piston and the lower end of the first cylinder , a second volume of hydraulic fluid located between the first piston and the upper end of the first cylinder, a second cylinder containing a second piston, a third volume, containing hydraul ic fluid, located between the lower end of the second cylinder and the second piston, a fourth volume, containing gas, located between the upper end of the second cylinder and the second piston, effectively pressurizing the third volume and the first volume via conduit means , a sensor, adapted for directly or indirectly measuring movement of the depth compensated inline active heave compensator, a position sensor, adapted for measuring the position of a piston, a means for fluid transportation adapted for applying fluid pressure to the second volume, where the means for fluid transportation is controlled based on sensor measurements, a means for depth compensation, by increasing the pressure in the second volume, where the pressure increase is proportional to the external pressure.

Description

DEPTH COMPENSATED INLINE ACTIVE HEAVE COMPENSATOR

The depth compensated inline active heave compensator (DCIAHC) is an installation tool designed to compensate vertical heave motion during sensitive installation of a payload in an offshore environment. The vertical heave source is typically generated by an installation vessel motion and/or crane tip motion and/or a secondary vessel, such like a barge, but not limited only thereto. The DCIAHC is designed to operate in air or in water. The DCIAHC is an inline tool that combines the principles of spring isolation with active cylinder control in order to generate an efficient compensation effect. The tool can operate like a traditional gas-over-hydraulic fluid springdampening device if the active component fails.

BACKGROUND OF THE INVENTION

Many prior art active heave compensators exist, like the one described in e.g. US 2010/0057279 A1. One of the differences between the prior art and the invention is for example that the DCIAHC is a mobile compensator for inline use with a passive backup system to go subsea with the payload being installed, while traditional active compensators often do not have a passive backup system<and always stay topside on an installation vessel. Prior art depth compensated passive systems>also exist, like US7934561 B2, where the main difference between the invention and the prior art is the fact that the invention is an active compensator while the prior art is a passive compensator, and hence has a different cylinder setup.

The main disadvantages of the prior art (active compensators) are: high capital binding in permanent installed (i.e. not mobile) equipment which is often only needed a few weeks per year, high installation costs, high maintenance costs (especially related to fatigue in steel wire rope), poor splash zone crossing performance due to fast dynamics, poor performance for short wave periods due to fast dynamics, poor resonance protection, high power demand and lack of models for heavy lifts.

The invention has the following advantages compared to the prior art; lower cost for same capacity, as good performance for long wave periods and better performance for short wave periods, excellent splash zone crossing performance, well-suited for resonance protection, reduced wear of the steel wire rope, low energy consumption. However, the compensator uses some of the available lifting height, and it is required to pre-set the compensator before usage. Furthermore, when using a battery pack for the compensator, there could be some limited usable compensation time per lift.

SUMMARY OF THE INVENTION

The main features of the present invention are given in the independent claim. Additional features of the invention are given in the dependent claims.

The DCIAHC can basically be a kind of a passive heave compensator, which traditionally is an inline tool, with an added active component to increase the performance. The energy source for the compensator can be either a battery pack or an energy source on the vessel connected to the compensator via an umbilical. The ideas presented in this application is based on an earlier application, “Inline active heave compensator”, which has more details on adjustment of gas pressure, which is not presented here, but can of course be implemented for the compensator designs shown in the current application as well (for all volumes containing gas).

According to the invention a depth compensated inline active heave compensator comprises: a first cylinder having an upper end and a lower end, a first connection means mounted at the upper end of the first cylinder and adapted for connecting the first cylinder to at least one of: a vessel at sea surface or a payload, a first piston located within the first cylinder and adapted for reciprocation<with respect thereto, a first piston rod connected to the first piston and extending downwardly>therefrom through the lower end of the first cylinder, a second connector means adapted for securing the first piston rod to at least one of: a vessel at the sea surface or a payload, and located at the lower end of the first cylinder, a first volume of hydraulic fluid located between the first piston and the lower end of the first cylinder, a second volume of hydraulic fluid located between the first piston and the upper end of the first cylinder, a second cylinder containing a second piston, a third volume, containing hydraulic fluid, located between the lower end of the second cylinder and the second piston, a fourth volume, containing gas, located between the upper end of the second cylinder and the second piston, effectively pressurizing the third volume and the first volume via conduit means, a sensor, adapted for directly or indirectly measuring movement of the depth compensated inline active heave compensator, a position sensor, adapted for measuring the position of a piston, a means for fluid transportation adapted for applying fluid pressure to the second volume, where the means for fluid transportation is controlled based on sensor measurements, a means for depth compensation, by increasing the pressure in the second volume, where the pressure increase is proportional to the external pressure.

BRIEF DESCRIPTION OF THE DRAWINGS

Figure 1-8 are schematic illustrations of eight versions or embodiments of the DCIAHC according to the present invention in which the major component parts of the DCIAHC are specifically identified. The basic concept is to modify a standard passive heave compensator (10+20) with an active element, in this case a pump (70). As most reversible pumps available on the market is low flow, high pressure pumps and the compensators need is the opposite, i.e. high flow and low pressure, a pressure intensifier (30) is used to reduce pressure and increase flow. The source of oil for the pump can either be from an accumulator (60) or from the passive heave compensator part (10+20). Depth compensation is provided with a pressure intensifier principle, either via a ring based cylinder (50) or a standard pressure intensifier (40). The ring based depth compensator has a big advantage as it can serve a dual purpose as both a depth compensator and a flow booster for the pump.

Figure 9 shows a placement of the DCIAHC in a subsea lift, wherein it is located right above a payload, which is symbolized with a rectangle.

DETAILED DESCRIPTION OF THE EMBODIMENTS

Figure 1 illustrates a version or embodiment of a depth compensated inline active heave compensator (DCIAHC (100)). This will now be described in detail. The DCIAHC (100) is normally rigged to a work wire coming from the vessel (102) at either the first connection means (14) or the second connection means (15) and to a payload (101) at either the first connection means (14) or the second connection means (15), i.e. the DCIAHC (100) can be used with the rod pointing down to the seafloor (103) or upwards to the sky. The connection means (14, 15) can be at least one of: a padeye and a clevis, but not limited only thereto. The hydraulic actuator (10) consists of a first cylinder (11) having an upper end and a lower end, a first connection means (15) mounted at the upper end of the first cylinder (11), a first piston (12) located within the first cylinder (11) and adapted for reciprocation with respect thereto, a first piston rod (13) connected to the first piston (12) and extending downwardly therefrom through the lower end of the first cylinder (11), a second connector means (14) adapted for securing the first piston rod (13) to at least one of: the vessel (102) at the sea surface and the payload (101), and located at the lower end of the first cylinder (11). The hydraulic actuator (10) has a first volume of hydraulic fluid (V1) located between the first piston (12) and the lower end of the first cylinder (11) and a second volume of hydraulic fluid (V2) located between the first piston (12) and the upper end of the first cylinder (11). The first gas accumulator (20) consists of a second cylinder (21) containing a second piston (22). The first gas accumulator (20) has a third volume (V3), containing hydraulic fluid, located between the lower end<of the second cylinder (21) and the second piston (22) and a fourth volume (V4), containing gas,>located between the upper end of the second cylinder (21) and the second piston (22), effectively pressurizing the third volume (V3) and the first volume (V1) via conduit means. The pressure intensifier (30), consists of a third cylinder (31), a fourth cylinder (32), a second piston rod (33) and a third piston (34), forming a fifth volume (V5) between one end of the third cylinder (31) and the third piston (34), filled with oil, a sixth volume (V6) between the other end of the third cylinder (31) and the third piston (34), filled with gas and a seventh volume (V7), between the ends of the fourth cylinder (32), filled with oil. The means for fluid transportation (70) is connected between the first volume (V1) and the seventh volume (V7) in such a way that the pressure in the seventh volume (V7) exerted on the second piston rod (33) is converted to a lower pressure in the fifth volume (V5) via the third piston (34), the fifth volume (V5) is in fluid communication with the second volume (V2) via conduit means. A position sensor (16, 23, 35) is adapted for measuring the position of a piston (12, 22, 34). The means for fluid transportation (70) is controlled based on measurements from at least one position sensor (16, 23, 35) and at least one motion sensor (105) and at least one pressure sensor (not shown, to compensate water pressure effects). Adjustment of gas pressure is done via gas transportation means (not shown), which enables adjustment of gas pressure in all<gas volumes.>

Figure 2 illustrates a version or embodiment of a depth compensated inline active heave compensator (DCIAHC (100)). This will now be described in detail. The DCIAHC (100) is normally rigged to a work wire coming from the vessel (102) at either the first connection means (14) or the second connection means (15) and to a payload (101) at either the first connection means (14) or the second connection means (15), i.e. the DCIAHC (100) can be used with the rod pointing down to the seafloor (103) or upwards to the sky. The connection means (14, 15) can be at least one of: a padeye and a clevis, but not limited only thereto. The hydraulic actuator (10) consists of a first cylinder (11) having an upper end and a lower end, a first connection means (15) mounted at the upper end of the first cylinder (11), a first piston (12) located within the first cylinder (11) and adapted for reciprocation with respect thereto, a first piston rod (13) connected to the first piston (12) and extending downwardly therefrom through the lower end of the first cylinder (11), a second connector means (14) adapted for securing the first piston rod (13) to at least one of: the vessel (102) at the sea surface and the payload (101), and located at the lower end of the first cylinder (11). The hydraulic actuator (10) has a first volume of hydraulic fluid (V1) located between the first piston (12) and the lower end of the first cylinder (11) and a second volume of hydraulic fluid (V2) located between the first piston (12) and the upper end of the first cylinder (11). The first gas accumulator (20) consists of a second cylinder (21) containing a second piston (22). The first gas accumulator (20) has a third volume (V3), containing hydraulic fluid, located between the lower end of the second cylinder (21) and the second piston (22) and a fourth volume (V4), containing gas,<located between the upper end of the second cylinder (21) and the second piston (22), effectively>pressurizing the third volume (V3) and the first volume (V1) via conduit means. The depth compensator (40) consists of a fifth cylinder (41), a third piston rod (42) exposed to external pressure and a fourth piston (43), forming an eighth volume (V8) between one end of the fifth cylinder (41) and the fourth piston (43), filled with oil, a ninth volume (V9) between the other end of the fifth cylinder (41) and the fourth piston (43), filled with oil. The pressure intensifier (30), consists of a third cylinder (31), a fourth cylinder (32), a second piston rod (33) and a third piston (34), forming a fifth volume (V5) between one end of the third cylinder (31) and the third piston (34), filled with oil, a sixth volume (V6) between the other end of the third cylinder (31) and the third piston (34), filled with gas and a seventh volume (V7), between the ends of the fourth cylinder (32), filled with oil. A conduit means between the second volume (V2) and the ninth volume (V9) allows fluid communication between the respective volumes. A conduit means between the eighth volume (V8) and the fifth volume (V5) allows fluid communication between the respective volumes. The means for fluid transportation (70) is connected between the first volume (V1) and the seventh volume (V7) in such a way that the pressure in the seventh volume (V7) exerted on the second piston rod (33) is converted to a lower pressure in the fifth volume (V5) via the third piston (34). A position sensor (16, 23, 35, 44) is adapted for measuring the position of a piston (12, 22, 34, 43). The means for fluid transportation (70) is controlled based on measurements from at least one position sensor (16, 23, 35, 44) and at least one motion sensor (105). Adjustment of gas pressure is done via gas transportation means (not shown), which enables adjustment of gas pressure in all gas<volumes.>

Figure 3 illustrates a version or embodiment of a depth compensated inline active heave compensator (DCIAHC (100)). This will now be described in detail. The DCIAHC (100) is normally rigged to a work wire coming from the vessel (102) at either the first connection means (14) or the second connection means (15) and to a payload (101) at either the first connection means (14) or the second connection means (15), i.e. the DCIAHC (100) can be used with the rod pointing down to the seafloor (103) or upwards to the sky. The connection means (14, 15) can be at least one of: a padeye and a clevis, but not limited only thereto. The hydraulic actuator (10) consists of a first cylinder (11) having an upper end and a lower end, a first connection means (15) mounted at the upper end of the first cylinder (11), a first piston (12) located within the first cylinder (11) and adapted for reciprocation with respect thereto, a first piston rod (13) connected to the first piston (12) and extending downwardly therefrom through the lower end of the first cylinder (11), a second connector means (14) adapted for securing the first piston rod (13) to at least one of: the vessel (102) at the sea surface and the payload (101), and located at the lower end of the first cylinder (11). The hydraulic actuator (10) has a first volume of hydraulic fluid (V1) located between the first piston (12) and the lower end of the first cylinder (11) and a second volume of hydraulic fluid (V2) located between the first piston (12) and the upper end of the first cylinder (11). The first gas accumulator (20) consists of a second cylinder (21) containing a second piston (22). The first gas accumulator (20) has a third volume (V3), containing hydraulic fluid, located between the lower end of the second cylinder (21) and the second piston (22) and a fourth volume (V4), containing gas,<located between the upper end of the second cylinder (21) and the second piston (22), effectively>pressurizing the third volume (V3) and the first volume (V1) via conduit means. The depth compensator (40) consists of a fifth cylinder (41), a third piston rod (42) exposed to external pressure and a fourth piston (43), forming an eighth volume (V8) between one end of the fifth cylinder (41) and the fourth piston (43), filled with gas, a ninth volume (V9) between the other end of the fifth cylinder (41) and the fourth piston (43), filled with oil. The pressure intensifier (30), consists of a third cylinder (31), a fourth cylinder (32), a second piston rod (33) and a third piston (34), forming a fifth volume (V5) between one end of the third cylinder (31) and the third piston (34), filled with oil, a sixth volume (V6) between the other end of the third cylinder (31) and the third piston (34), filled with oil and a seventh volume (V7), between the ends of the fourth cylinder (32), filled with oil. A conduit means between the second volume (V2) and the fifth volume (V5) allows fluid communication between the respective volumes. A conduit means between the ninth volume (V9) and the sixth volume (V6) allows fluid communication between the respective volumes. The means for fluid transportation (70) is connected between the first volume (V1) and the seventh volume (V7) in such a way that the pressure in the seventh volume (V7) exerted on the second piston rod (33) is converted to a lower pressure in the fifth volume (V5) via the third piston (34). A position sensor (16, 23, 35, 44) is adapted for measuring the position of a piston (12, 22, 34, 43). The means for fluid transportation (70) is controlled based on measurements from at least one position sensor (16, 23, 35, 44) and at least one motion sensor (105). Adjustment of gas pressure is done via gas transportation means (not shown), which enables adjustment of gas pressure in all<gas volumes.>

Figure 4 illustrates a version or embodiment of a depth compensated inline active heave compensator (DCIAHC (100)). This will now be described in detail. The DCIAHC (100) is normally rigged to a work wire coming from the vessel (102) at either the first connection means (14) or the second connection means (15) and to a payload (101) at either the first connection means (14) or the second connection means (15), i.e. the DCIAHC (100) can be used with the rod pointing down to the seafloor (103) or upwards to the sky. The connection means (14, 15) can be at least one of: a padeye and a clevis, but not limited only thereto. The hydraulic actuator (10) consists of a first cylinder (11) having an upper end and a lower end, a first connection means (15) mounted at the upper end of the first cylinder (11), a first piston (12) located within the first cylinder (11) and adapted for reciprocation with respect thereto, a first piston rod (13) connected to the first piston (12) and extending downwardly therefrom through the lower end of the first cylinder (11), a second connector means (14) adapted for securing the first piston rod (13) to at least one of: a vessel (102) at the sea surface or a payload (101), and located at the lower end of the first cylinder (11). The hydraulic actuator (10) has a first volume of hydraulic fluid (V1) located between the first piston (12) and the lower end of the first cylinder (11) and a second volume of hydraulic fluid (V2) located between the first piston (12) and the upper end of the first cylinder (11). The first gas accumulator (20) consists of a second cylinder (21) containing a second piston (22). The first gas accumulator (20) has a third volume (V3), containing hydraulic fluid, located between the lower end of the second cylinder (21) and the second piston (22) and a fourth volume (V4), containing gas, located<between the upper end of the second cylinder (21) and the second piston (22), effectively>pressurizing the third volume (V3) and the first volume (V1) via conduit means. The depth compensator (40) consists of a fifth cylinder (41), a third piston rod (42) exposed to external pressure and a fourth piston (43), forming an eighth volume (V8) between one end of the fifth cylinder (41) and the fourth piston (43), filled with gas, a ninth volume (V9) between the other end of the fifth cylinder (41) and the fourth piston (43), filled with oil. The pressure intensifier (30), consists of a third cylinder (31), a fourth cylinder (32), a second piston rod (33) and a third piston (34), forming a fifth volume (V5) between one end of the third cylinder (31) and the third piston (34), filled with oil, a sixth volume (V6) between the other end of the third cylinder (31) and the third piston (34), filled with oil and a seventh volume (V7), between the ends of the fourth cylinder (32), filled with oil. The second gas accumulator (60) consists of a seventh cylinder (61) and a fifth piston (62) forming a tenth volume (V10) between one end of the seventh cylinder (61) and the fifth piston (62), filled with oil, an eleventh volume (V11) between the other end of the seventh cylinder (61) and the fifth piston (62), filled with gas. A conduit means between the second volume (V2) and the fifth volume (V5) allows fluid communication between the respective volumes. A conduit means between the ninth volume (V9) and the sixth volume (V6) allows fluid communication between the respective volumes. The means for fluid transportation (70) is connected between the tenth volume (V10) and the seventh volume (V7) in such a way that the pressure in the seventh volume (V7) exerted on the second piston rod (33) is converted to a lower pressure in the fifth volume (V5) via the third piston (34). A position sensor (16, 23, 35, 44, 63) is adapted for measuring the position of<a piston (12, 22, 34, 43, 62). The means for fluid transportation (70) is controlled based on>measurements from at least one position sensor (16, 23, 35, 44, 63) and at least one motion sensor (105). Adjustment of gas pressure is done via gas transportation means (not shown), which enables adjustment of gas pressure in all gas volumes.

Figure 5 illustrates a version or embodiment of a depth compensated inline active heave compensator (DCIAHC (100)). This will now be described in detail. The DCIAHC (100) is normally rigged to a work wire coming from the vessel (102) at either the first connection means (14) or the second connection means (15) and to a payload (101) at either the first connection means (14) or the second connection means (15), i.e. the DCIAHC (100) can be used with the rod pointing down to the seafloor (103) or upwards to the sky. The connection means (14, 15) can be at least one of: a padeye and a clevis, but not limited only thereto. The hydraulic actuator (10) consists of a first cylinder (11) having an upper end and a lower end, a first connection means (15) mounted at the upper end of the first cylinder (11), a first piston (12) located within the first cylinder (11) and adapted for reciprocation with respect thereto, a first piston rod (13) connected to the first piston (12) and extending downwardly therefrom through the lower end of the first cylinder (11), a second connector means (14) adapted for securing the first piston rod (13) to at least one of: a vessel (102) at the sea surface or a payload (101), and located at the lower end of the first cylinder (11). The hydraulic actuator (10) has a first volume of hydraulic fluid (V1) located between the first piston (12) and the lower end of the first cylinder (11) and a second volume of hydraulic fluid (V2) located between the first piston (12) and the upper end of the first cylinder (11). The first gas accumulator<(20) consists of a second cylinder (21) containing a second piston (22). The first gas accumulator>(20) has a third volume (V3), containing hydraulic fluid, located between the lower end of the second cylinder (21) and the second piston (22) and a fourth volume (V4), containing gas, located between the upper end of the second cylinder (21) and the second piston (22), effectively pressurizing the third volume (V3) and the first volume (V1) via conduit means. The depth compensator (40) consists of a fifth cylinder (41), a third piston rod (42) exposed to external pressure and a fourth piston (43), forming an eighth volume (V8) between one end of the fifth cylinder (41) and the fourth piston (43), filled with oil, a ninth volume (V9) between the other end of the fifth cylinder (41) and the fourth piston (43), filled with oil. The pressure intensifier (30), consists of a third cylinder (31), a fourth cylinder (32), a second piston rod (33) and a third piston (34), forming a fifth volume (V5) between one end of the third cylinder (31) and the third piston (34), filled with oil, a sixth volume (V6) between the other end of the third cylinder (31) and the third piston (34), filled with gas and a seventh volume (V7), between the ends of the fourth cylinder (32), filled with oil. The second gas accumulator (60) consists of a seventh cylinder (61) and a fifth piston (62) forming a tenth volume (V10) between one end of the seventh cylinder (61) and the fifth piston (62), filled with oil, an eleventh volume (V11) between the other end of the seventh cylinder (61) and the fifth piston (62), filled with gas. A conduit means between the second volume (V2) and the ninth volume (V9) allows fluid communication between the respective volumes. A conduit means between the eighth volume (V8) and the fifth volume (V5) allows fluid communication between the respective volumes. The means for fluid transportation (70) is connected between the tenth volume<(V10) and the seventh volume (V7) in such a way that the pressure in the seventh volume (V7)>exerted on the second piston rod (33) is converted to a lower pressure in the fifth volume (V5) via the third piston (34). A position sensor (16, 23, 35, 44, 63) is adapted for measuring the position of a piston (12, 22, 34, 43, 62). The means for fluid transportation (70) is controlled based on measurements from at least one position sensor (16, 23, 35, 44, 63) and at least one motion sensor (105). Adjustment of gas pressure is done via gas transportation means (not shown), which enables adjustment of gas pressure in all gas volumes.

Figure 6 illustrates a version or embodiment of a depth compensated inline active heave compensator (DCIAHC (100)). This will now be described in detail. The DCIAHC (100) is normally rigged to a work wire coming from the vessel (102) at either the first connection means (14) or the second connection means (15) and to a payload (101) at either the first connection means (14) or the second connection means (15), i.e. the DCIAHC (100) can be used with the rod pointing down to the seafloor (103) or upwards to the sky. The connection means (14, 15) can be at least one of: a padeye and a clevis, but not limited only thereto. The hydraulic actuator (10) consists of a first cylinder (11) having an upper end and a lower end, a first connection means (15) mounted at the upper end of the first cylinder (11), a first piston (12) located within the first cylinder (11) and adapted for reciprocation with respect thereto, a first piston rod (13) connected to the first piston (12) and extending downwardly therefrom through the lower end of the first cylinder (11), a second connector means (14) adapted for securing the first piston rod (13) to at least one of: the vessel (102) at the sea surface and the payload (101), and located at the lower end of the first cylinder<(11). The hydraulic actuator (10) has a first volume of hydraulic fluid (V1) located between the first>piston (12) and the lower end of the first cylinder (11) and a second volume of hydraulic fluid (V2) located between the first piston (12) and the upper end of the first cylinder (11). The first gas accumulator (20) consists of a second cylinder (21) containing a second piston (22). The first gas accumulator (20) has a third volume (V3), containing hydraulic fluid, located between the lower end of the second cylinder (21) and the second piston (22) and a fourth volume (V4), containing gas, located between the upper end of the second cylinder (21) and the second piston (22), effectively pressurizing the third volume (V3) and the first volume (V1) via conduit means. The ring based depth compensator (50) is consists of a sixth cylinder (51), a ring piston (52), a ring piston rod (53) exposed to external pressure, forming a twelfth volume (V12) between one end of the sixth cylinder (51) and the ring piston (52), filled with oil, a thirteenth volume (V13) between the other end of the sixth cylinder (51) and the ring piston (52), the inner diameter of the ring piston rod (53) and the outer diameter of the first cylinder (11), filled with oil or gas, a fourteenth volume (V14) between the other end of the sixth cylinder (51) and the ring piston (52), the outer diameter of the ring piston rod (53) and the inner diameter of the sixth cylinder (51), filled with oil or gas. A conduit means between the second volume (V2) and the twelfth volume (V12) allows fluid communication between the respective volumes. The means for fluid transportation (70) is connected between the thirteenth volume (V13) or the fourteenth volume (V14) and the first volume (V1) in such a way that the pressure in thirteenth volume (V13) or the fourteenth volume (V14) exerted on the ring piston (52) is converted to a lower pressure in the twelfth volume (V12) via the ring piston (52). The means for<fluid transportation (70) is controlled based on measurements from at least one position sensor (16,>23) and at least one motion sensor (105). Adjustment of gas pressure is done via gas transportation means (not shown), which enables adjustment of gas pressure in all gas volumes.

Figure 7 illustrates a version or embodiment of a depth compensated inline active heave compensator (DCIAHC (100)). This will now be described in detail. The DCIAHC (100) is normally rigged to a work wire coming from the vessel (102) at either the first connection means (14) or the second connection means (15) and to a payload (101) at either the first connection means (14) or the second connection means (15), i.e. the DCIAHC (100) can be used with the rod pointing down to the seafloor (103) or upwards to the sky. The connection means (14, 15) can be at least one of: a padeye and a clevis, but not limited only thereto. The hydraulic actuator (10) consists of a first cylinder (11) having an upper end and a lower end, a first connection means (15) mounted at the upper end of the first cylinder (11), a first piston (12) located within the first cylinder (11) and adapted for reciprocation with respect thereto, a first piston rod (13) connected to the first piston (12) and extending downwardly therefrom through the lower end of the first cylinder (11), a second connector means (14) adapted for securing the first piston rod (13) to at least one of: a vessel (102) at the sea surface or a payload (101), and located at the lower end of the first cylinder (11). The hydraulic actuator (10) has a first volume of hydraulic fluid (V1) located between the first piston (12) and the lower end of the first cylinder (11) and a second volume of hydraulic fluid (V2) located between the first piston (12) and the upper end of the first cylinder (11). The first gas accumulator (20) consists of a second cylinder (21) containing a second piston (22). The first gas accumulator<(20) has a third volume (V3), containing hydraulic fluid, located between the lower end of the>second cylinder (21) and the second piston (22) and a fourth volume (V4), containing gas, located between the upper end of the second cylinder (21) and the second piston (22), effectively pressurizing the third volume (V3) and the first volume (V1) via conduit means. The pressure intensifier (30), consists of a third cylinder (31), a fourth cylinder (32), a second piston rod (33) and a third piston (34), forming a fifth volume (V5) between one end of the third cylinder (31) and the third piston (34), filled with oil, a sixth volume (V6) between the other end of the third cylinder (31) and the third piston (34), filled with gas and a seventh volume (V7), between the ends of the fourth cylinder (32), filled with oil. The ring based depth compensator (50) consists of a sixth cylinder (51), a ring piston (52), a ring piston rod (53) exposed to external pressure, forming a twelfth volume (V12) between one end of the sixth cylinder (51) and the ring piston (52), filled with oil, a thirteenth volume (V13) between the other end of the sixth cylinder (51) and the ring piston (52), the inner diameter of the ring piston rod (53) and the outer diameter of the first cylinder (11), filled with oil or gas, a fourteenth volume (V14) between the other end of the sixth cylinder (51) and the ring piston (52), the outer diameter of the ring piston rod (53) and the inner diameter of the sixth cylinder (51), filled with oil or gas. A conduit means between the second volume (V2) and the twelfth volume (V12) allows fluid communication between the respective volumes. A conduit means between the fifth volume (V5) and the thirteenth volume (V13) or the fourteenth volume (V14) allows fluid communication between the respective volumes. The means for fluid transportation (70) is connected between the first volume (V1) and the seventh volume (V7) in such a way that the<pressure in the seventh volume (V7) exerted on the second piston rod (33) is converted to a lower>pressure in the fifth volume (V5) via the third piston (34). The means for fluid transportation (70) is controlled based on measurements from at least one position sensor (16, 23, 35) and at least one motion sensor (105). Adjustment of gas pressure is done via gas transportation means (not shown), which enables adjustment of gas pressure in all gas volumes.

Figure 8 illustrates a version or embodiment of a depth compensated inline active heave compensator (DCIAHC (100)). This will now be described in detail. The DCIAHC (100) is normally rigged to a work wire coming from the vessel (102) at either the first connection means (14) or the second connection means (15) and to a payload (101) at either the first connection means (14) or the second connection means (15), i.e. the DCIAHC (100) can be used with the rod pointing down to the seafloor (103) or upwards to the sky. The connection means (14, 15) can be at least one of: a padeye and a clevis, but not limited only thereto. The hydraulic actuator (10) consists of a first cylinder (11) having an upper end and a lower end, a first connection means (15) mounted at the upper end of the first cylinder (11), a first piston (12) located within the first cylinder (11) and adapted for reciprocation with respect thereto, a first piston rod (13) connected to the first piston (12) and extending downwardly therefrom through the lower end of the first cylinder (11), a second connector means (14) adapted for securing the first piston rod (13) to at least one of: a vessel (102) at the sea surface or a payload (101), and located at the lower end of the first cylinder (11). The hydraulic actuator (10) has a first volume of hydraulic fluid (V1) located between the first piston (12) and the lower end of the first cylinder (11) and a second volume of hydraulic fluid (V2) located<between the first piston (12) and the upper end of the first cylinder (11). The first gas accumulator>(20) consists of a second cylinder (21) containing a second piston (22). The first gas accumulator (20) has a third volume (V3), containing hydraulic fluid, located between the lower end of the second cylinder (21) and the second piston (22) and a fourth volume (V4), containing gas, located between the upper end of the second cylinder (21) and the second piston (22), effectively pressurizing the third volume (V3) and the first volume (V1) via conduit means. The pressure intensifier (30), consists of a third cylinder (31), a fourth cylinder (32), a second piston rod (33) and a third piston (34), forming a fifth volume (V5) between one end of the third cylinder (31) and the third piston (34), filled with oil, a sixth volume (V6) between the other end of the third cylinder (31) and the third piston (34), filled with gas and a seventh volume (V7), between the ends of the fourth cylinder (32), filled with oil. The ring based depth compensator (50) consists of a sixth cylinder (51), a ring piston (52), a ring piston rod (53) exposed to external pressure, forming a twelfth volume (V12) between one end of the sixth cylinder (51) and the ring piston (52), filled with oil, a thirteenth volume (V13) between the other end of the sixth cylinder (51) and the ring piston (52), the inner diameter of the ring piston rod (53) and the outer diameter of the first cylinder (11), filled with oil or gas, a fourteenth volume (V14) between the other end of the sixth cylinder (51) and the ring piston (52), the outer diameter of the ring piston rod (53) and the inner diameter of the sixth cylinder (51), filled with oil or gas. The second gas accumulator (60), consists of a seventh cylinder (61) and a fifth piston (62) forming a tenth volume (V10) between one end of the seventh cylinder (61) and the fifth piston (62), filled with oil, an eleventh volume (V11) between the other end of the seventh<cylinder (61) and the fifth piston (62), filled with gas. A conduit means between the second volume>(V2) and the twelfth volume (V12) allows fluid communication between the respective volumes. A conduit means between the thirteenth volume (V13) or the fourteenth volume (V14) and the fifth volume (V5), allows fluid communication between the respective volumes. The means for fluid transportation (70) is connected between the tenth volume (V10) and the seventh volume (V7) in such a way that the pressure in the seventh volume (V7) exerted on the second piston rod (33) is converted to a lower pressure in the fifth volume (V5) via the third piston (34). The means for fluid transportation (70) is controlled based on measurements from at least one position sensor (16, 23, 35, 63) and at least one motion sensor (105). Adjustment of gas pressure is done via gas transportation means (not shown), which enables adjustment of gas pressure in all gas volumes.

Table 1

Claims

1. Depth compensated inline active heave compensator (100) comprising:

a first cylinder (11) having an upper end and a lower end;

a first connection means (15) mounted at the upper end of the first cylinder (11) and adapted for connecting the first cylinder (11) to at least one of: a vessel (102) at sea surface or a payload (101);

a first piston (12) located within the first cylinder (11) and adapted for reciprocation with respect thereto;

a first piston rod (13) connected to the first piston (12) and extending downwardly therefrom through the lower end of the first cylinder (11);

a second connector means (14) adapted for securing the first piston rod (13) to at least one of: a vessel (102) at the sea surface or a payload (101), and located at the lower end of the first cylinder (11);

<a first volume of hydraulic fluid (V1) located between the first piston (12) and the lower end>of the first cylinder (11);

a second volume of hydraulic fluid (V2) located between the first piston (12) and the upper end of the first cylinder (11);

a second cylinder (21) containing a second piston (22);

a third volume (V3), containing hydraulic fluid, located between the lower end of the second cylinder (21) and the second piston (22);

a fourth volume (V4), containing gas, located between the upper end of the second cylinder (21) and the second piston (22), effectively pressurizing the third volume (V3) and the first volume (V1) via conduit means;

a sensor (105), adapted for directly or indirectly measuring movement of the depth compensated inline active heave compensator (100);

a position sensor (16, 23), adapted for measuring the position of a piston (12, 22);

a means for fluid transportation (70) adapted for applying fluid pressure to the second volume (V2), where the means for fluid transportation (70) is controlled based on sensor (105, 16, 23) measurements;

a means for depth compensation, by increasing the pressure in the second volume (V2), where the pressure increase is proportional to the external pressure.

2. Depth compensated inline active heave compensator (100) according to claim 1, further comprising:

a pressure intensifier (30), consisting of a third cylinder (31), a fourth cylinder (32), a second piston rod (33) and a third piston (34), forming a fifth volume (V5) between one end of the third cylinder (31) and the third piston (34), filled with oil, a sixth volume (V6) between the other end of the third cylinder (31) and the third piston (34), filled with gas and a seventh volume (V7), between the ends of the fourth cylinder (32), filled with oil, wherein the means for fluid transportation (70) is connected between the first volume (V1) and the seventh volume (V7) in such a way that the pressure in the seventh volume (V7) exerted on the second piston rod (33) is converted to a lower pressure in the fifth volume (V5) via the third piston (34), the fifth volume (V5) is in fluid communication with the second volume (V2) via conduit means;

a position sensor (16, 23, 35), adapted for measuring the position of a piston (12, 22, 34).

3. Depth compensated inline active heave compensator (100) according to claim 1, further comprising:

a depth compensator (40) is the specific means for depth compensation, consisting of a fifth cylinder (41), a third piston rod (42) exposed to external pressure and a fourth piston (43), forming an eighth volume (V8) between one end of the fifth cylinder (41) and the fourth piston (43), filled with oil, a ninth volume (V9) between the other end of the fifth cylinder (41) and the fourth piston (43), filled with oil;

a pressure intensifier (30), consisting of a third cylinder (31), a fourth cylinder (32), a second piston rod (33) and a third piston (34), forming a fifth volume (V5) between one end of the third cylinder (31) and the third piston (34), filled with oil, a sixth volume (V6) between the other end of the third cylinder (31) and the third piston (34), filled with gas and a seventh volume (V7), between the ends of the fourth cylinder (32), filled with oil;

a conduit means between the second volume (V2) and the ninth volume (V9), allowing fluid communication between the respective volumes;

a conduit means between the eighth volume (V8) and the fifth volume (V5), allowing fluid communication between the respective volumes;

wherein the means for fluid transportation (70) is connected between the first volume (V1) and the seventh volume (V7) in such a way that the pressure in the seventh volume (V7) exerted on the second piston rod (33) is converted to a lower pressure in the fifth volume<(V5) via the third piston (34);>

a position sensor (16, 23, 35, 44), adapted for measuring the position of a piston (12, 22, 34, 35).

4. Depth compensated inline active heave compensator (100) according to claim 1, further comprising:

a depth compensator (40) is the specific means for depth compensation, consisting of a fifth cylinder (41), a third piston rod (42) exposed to external pressure and a fourth piston (43), forming an eighth volume (V8) between one end of the fifth cylinder (41) and the fourth piston (43), filled with gas, a ninth volume (V9) between the other end of the fifth cylinder (41) and the fourth piston (43), filled with oil;

a pressure intensifier (30), consisting of a third cylinder (31), a fourth cylinder (32), a second piston rod (33) and a third piston (34), forming a fifth volume (V5) between one end of the third cylinder (31) and the third piston (34), filled with oil, a sixth volume (V6) between the other end of the third cylinder (31) and the third piston (34), filled with oil and a seventh volume (V7), between the ends of the fourth cylinder (32), filled with oil;

a conduit means between the second volume (V2) and the fifth volume (V5), allowing fluid communication between the respective volumes;

<a conduit means between the ninth volume (V9) and the sixth volume (V6), allowing fluid>communication between the respective volumes;

wherein the means for fluid transportation (70) is connected between the first volume (V1) and the seventh volume (V7) in such a way that the pressure in the seventh volume (V7) exerted on the second piston rod (33) is converted to a lower pressure in the fifth volume (V5) via the third piston (34);

5. Depth compensated inline active heave compensator (100) according to claim 1, further comprising:

a pressure intensifier (30), consisting of a third cylinder (31), a fourth cylinder (32), a second piston rod (33) and a third piston (34), forming a fifth volume (V5) between one end of the third cylinder (31) and the third piston (34), filled with oil, a sixth volume (V6) between the other end of the third cylinder (31) and the third piston (34), filled with oil and a<seventh volume (V7), between the ends of the fourth cylinder (32), filled with oil;>

a second gas accumulator (60), consisting of a seventh cylinder (61) and a fifth piston (62) forming a tenth volume (V10) between one end of the seventh cylinder (61) and the fifth piston (62), filled with oil, an eleventh volume (V11) between the other end of the seventh cylinder (61) and the fifth piston (62), filled with gas;

a conduit means between the ninth volume (V9) and the sixth volume (V6), allowing fluid communication between the respective volumes;

wherein the means for fluid transportation (70) is connected between the tenth volume (V10) and the seventh volume (V7) in such a way that the pressure in the seventh volume (V7) exerted on the second piston rod (33) is converted to a lower pressure in the fifth volume (V5) via the third piston (34);

a position sensor (16, 23, 35, 44, 63), adapted for measuring the position of a piston (12, 22, 34, 35, 63).

6. Depth compensated inline active heave compensator (100) according to claim 1, further comprising:

a depth compensator (40) is the specific means for depth compensation, consisting of a<fifth cylinder (41), a third piston rod (42) exposed to external pressure and a fourth piston>(43), forming an eighth volume (V8) between one end of the fifth cylinder (41) and the fourth piston (43), filled with oil, a ninth volume (V9) between the other end of the fifth cylinder (41) and the fourth piston (43), filled with oil;

wherein the means for fluid transportation (70) is connected between the tenth volume (V10) and the seventh volume (V7) in such a way that the pressure in the seventh volume (V7) exerted on the second piston rod (33) is converted to a lower pressure in the fifth<volume (V5) via the third piston (34);>

7. Depth compensated inline active heave compensator (100) according to claim 1, further comprising:

a ring based depth compensator (50) is the specific means for depth compensation, consisting of a sixth cylinder (51), a ring piston (52), a ring piston rod (53) exposed to external pressure, forming a twelfth volume (V12) between one end of the sixth cylinder (51) and the ring piston (52), filled with oil, a thirteenth volume (V13) between the other end of the sixth cylinder (51) and the ring piston (52), the inner diameter of the ring piston rod (53) and the outer diameter of the first cylinder (11), filled with oil or gas, a fourteenth volume (V14) between the other end of the sixth cylinder (51) and the ring piston (52), the outer diameter of the ring piston rod (53) and the inner diameter of the sixth cylinder (51), filled with oil or gas;

a conduit means between the second volume (V2) and the twelfth volume (V12), allowing fluid communication between the respective volumes;

wherein the means for fluid transportation (70) is connected between the thirteenth volume<(V13) or the fourteenth volume (V14) and the first volume (V1) in such a way that the>pressure in thirteenth volume (V13) or the fourteenth volume (V14) exerted on the ring piston (52) is converted to a lower pressure in the twelfth volume (V12) via the ring piston (52);

a position sensor (16, 23), adapted for measuring the position of a piston (12, 22).

8. Depth compensated inline active heave compensator (100) according to claim 1, further comprising:

a pressure intensifier (30), consisting of a third cylinder (31), a fourth cylinder (32), a second piston rod (33) and a third piston (34), forming a fifth volume (V5) between one end of the third cylinder (31) and the third piston (34), filled with oil, a sixth volume (V6)<between the other end of the third cylinder (31) and the third piston (34), filled with gas and>a seventh volume (V7), between the ends of the fourth cylinder (32), filled with oil;

a conduit means between the thirteenth volume (V13) or the fourteenth volume (V14) and the fifth volume (V5), allowing fluid communication between the respective volumes; wherein the means for fluid transportation (70) is connected between the first volume (V1) and the seventh volume (V7) in such a way that the pressure in the seventh volume (V7) exerted on the second piston rod (33) is converted to a lower pressure in the fifth volume (V5) via the third piston (34);

9. Depth compensated inline active heave compensator (100) according to claim 1, further comprising:

a conduit means between the thirteenth volume (V13) or the fourteenth volume (V14) and the fifth volume (V5), allowing fluid communication between the respective volumes; wherein the means for fluid transportation (70) is connected between the tenth volume (V10) and the seventh volume (V7) in such a way that the pressure in the seventh volume (V7) exerted on the second piston rod (33) is converted to a lower pressure in the fifth volume (V5) via the third piston (34).

10. Depth compensated inline active heave compensator (100) according to any one of claims 1-9, wherein at least one of the cylinders is constituted of a predetermined number of cylinders arranged in a parallel connection in order to increase the effective volume of at least one volume of the gas and/or hydraulic fluid volumes.

<11. Depth compensated inline active heave compensator (100) according to any one of claims>1-10, wherein a means for gas transportation is used to transport gas between at least one gas volume and another gas volume and/or the surroundings.

12. Depth compensated inline active heave compensator (100) according to any one of claims 1 and 7-11, wherein the ring based depth compensator (50) is not concentric with the hydraulic actuator (10), i.e. it can be placed anywhere in the compensator design, e.g. concentric with another cylinder.

13. Depth compensated inline active heave compensator (100) according to any one of claims 1-12, wherein oil is replaced by any fluid.