Method for determining the operating envelope of a crane or cantilever in a jack-up platform unit, jack-up platform unit

Abstract

By monitoring leg load characteristics during preload application, a method is provided for determining an actual achieved preload value. The method further includes alternatively determining an actual crane or cantilever operating envelope that takes into account the actual achieved preload value. The method further includes taking into account other data such as environmental loads or crane or cantilever movement.

Description

[Technical Field]

[0001] The present invention relates to a jack-up vessel having deck-mounted mission equipment. The mission equipment may be at least one crane or cantilever. The crane may be mounted on a jack-up platform unit and may be movable relative to the deck, e.g., the crane boom angle and / or reach may be changed during operation. The crane may be mounted, for example, on the deck, around a platform, or on a jack house. The cantilever may be movably mounted on the deck and may be movable, for example, between an extended position in which the cantilever extends substantially outside the deck and a retracted position in which the cantilever is substantially above the deck. [Background technology]

[0002] Jack-up platform units or jack-up vessels are well known and generally comprise a floatable hull and a plurality of movable legs. The legs are movable relative to and extendable through the hull. Typically, a jack-up platform unit can have three, four, or six legs. The legs are adjustable between a sailing position in which the legs extend substantially above the hull. In the sailing position, the hull floats on the water surface, and the platform unit can be displaced from one location to another. The legs can also be adjusted to a staging position in which the legs extend substantially below the hull, with the hull at or just above water level. In this position, the legs contact the seabed and rest on and / or in the seabed. In a further operating position, the legs extend substantially below the hull and are fixed to the seabed, while the hull is raised to an operating height above the water surface with sufficient clearance between the water surface and the bottom of the hull, particularly to allow waves to pass underneath. The legs are moved relative to the hull by a jack system.

[0003] Such jack-up platform units can be self-propelled or self-propelled, but can also be towed. Jack-up platform units are often used in offshore operations, for example drilling operations, maintenance operations or wind turbine installation operations. Jack-up platform units often include a crane mounted, for example around one of their legs, for hoisting and / or installation operations.

[0004]

[0003] When the jack-up platform unit is in the installed position, the legs must be lowered to the seabed and firmly installed on the seabed so that the jack-up platform is stable in the operating position and firmly positioned to enable safe operation. To lower the legs firmly onto the seabed, it is common practice to apply a relatively high load, e.g., several thousand tons, to each leg in turn, e.g., one by one or in pairs, while leaving the other legs only lightly loaded; this procedure is often referred to as "preloading."

[0005] Various preloading procedures are possible, with active or passive preloading being the most common, although a combination of active and passive preloading is also possible. In active preloading, a set force is applied continuously to the legs for a predetermined time interval. The application of the active load is repeated until the jack operator, based on his or her experience and expertise, determines that the legs have sufficiently subsided and the foundation is stable. In passive preloading, the force is applied discontinuously to the legs, as opposed to continuously in the active procedure. The discontinuous force is applied repeatedly until the jack operator, based on his or her experience and expertise, determines that the foundation is sufficiently stable. The determination of whether the foundation is stable and the value of the preload relies solely on the expertise and human judgment of the jack operator. There is no reproducible determination of the preload value.

[0006] The jack operator is responsible for the preloading operation and for monitoring that sufficient preload has been applied to the legs and that a stable foundation for the platform unit has been achieved. After this preloading step, the hull is further raised to a desired operating height above sea level, e.g., approximately 10-15 m above sea level, thereby substantially avoiding continued wave impact on the hull. The load on the legs can be made substantially even or uniform before or after further raising of the hull. In this way, it is believed that a relatively stable platform position is established on which operations can be carried out substantially independent of ocean currents and / or wave action.

[0007] During operation, an operator, such as a crane operator or cantilever operator, relies on pre-established procedures and plans, such as a lifting plan, cantilever plan or deck load plan, to ensure that when preload values ​​are not exceeded during operation, the work can be carried out safely without jeopardizing the stability of the platform unit.

[0008] Particularly in the case of offshore wind turbine installation, when the platform is frequently jacked up and down in an installed consecutive construction, there may be time constraints and the operator may not be able to wait long enough to determine whether the applied load has settled to a stable value. Therefore, the safety on which offshore operations on jack-up platform units depend depends on the skill of the jack operator.

[0009] Furthermore, particularly in jack-up platform units used for wind turbine installation work, a crane for lifting and / or hoisting operations is provided on the jack-up platform, for example, around one of the legs. The maximum crane capacity is determined by the crane's characteristics and specified in the crane operating manual. The crane operator always operates the crane within this specified range. Therefore, the crane operator utilizes the preload value provided by the jack operator. Depending on the jack-up, the operator may overload the leg during operation, even if the preload value provided by the jack system operator is not exceeded. This may threaten the safety and stability of the platform unit. This may result, for example, in the uncontrolled and excessive sinking or penetration of the leg to the seabed, and / or the collapse of the crane, or even the loss of the platform unit. Therefore, it is possible that the crane operator may sometimes leave too much safety margin in one operation and too little safety margin in other operations. This leads to safety risks during operation of the jack-up platform and / or unused crane capacity. Summary of the Invention [Problem to be solved by the invention]

[0010] Therefore, there is a need for safer and more reliable operation of offshore jack-up platform units. [Means for solving the problem]

[0011] Therefore, there is provided a method for determining a crane or cantilever operating envelope for a crane or cantilever mounted on a jack-up platform as set forth in claim 1.

[0012] The method includes the steps of applying a preload to at least one leg of a jack up platform unit, monitoring at least one characteristic of the leg, such as a leg load value and / or a leg penetration value, for a predetermined time interval, monitoring the leg characteristic and / or a slope of the leg characteristic during the time interval, evaluating whether the leg characteristic is stable during the time interval, and repeating the above steps until the leg characteristic is stable, where the leg characteristic remains within a predetermined threshold and the slope of the leg characteristic remains within a predetermined limit during the time interval, wherein an actual achieved preload value is the leg load value associated with the stable leg characteristic thus achieved, and the method further includes the steps of determining an actual crane or cantilever operating envelope for each leg by calculating a leg load capacity based on the actual achieved preload value, and converting the calculated leg load capacity to a crane or cantilever operations capacity.

[0013] Advantageously, determining the amount of crane or cantilever movement is done as a function of the crane or cantilever movement, crane or cantilever loading, e.g. hoist or deck loading, environmental load, crane or cantilever reach, etc. All these parameters can be taken into account together or individually when determining the amount of crane or cantilever movement by converting the calculated leg load capacity into a crane or cantilever movement.

[0014] The leg load value can be considered as the value of the load on the leg and can be monitored, for example, via a jacking system. Naturally, different jacking systems, whether hydraulic, rack and pinion, or electric, have different means of applying and monitoring the leg load value, either directly or indirectly. The leg penetration can be considered as the depth to which the leg is penetrated into the seabed. This can also be referred to as leg subsidence or leg displacement and can be monitored in various ways, directly or indirectly, for example, by measuring the displacement of the leg relative to the hull and by measuring the distance between the hull and the seabed.

[0015] Cranes mounted on jack-up units or cantilevers on decks may typically have operating conditions that cause them to reach outside the hull contour. Such operating conditions may threaten the stability of the jack-up units, especially when inaccurate preload data causes the actual operating conditions to exceed the theoretically determined operating plan. Therefore, more accurate determination of the operating envelope may be relevant for crane or cantilever operations.

[0016] By now determining the actual achieved preload value for the legs in a systematic and objective manner, preferably by using an algorithm executable by a computer program, the jack operator's personal judgment can be made independently of the determination of the actual achieved preload value. This provides a more reliable preload value, resulting in safer operations on the jack-up platform unit. In particular, using the actual achieved preload value to determine the actual crane operating envelope allows for accurate, reliable, and safe crane operations on the jack-up platform unit. Thus, jack operations can be linked and integrated with crane operations, which in turn results in safe crane operations because the actual margin for crane operation can be accurately determined. Similarly, feedback to cantilever operation can also be provided. Therefore, if the crane operator operates the crane within the actual, determined crane operating envelope, the risk of leg and / or platform failure can be avoided. Thus, rather than open-loop conventional methods that rely heavily on human judgment, the theoretically determined operating envelope of the present invention not only more accurately determines the preload, but also provides this precisely defined preload value to the operating envelope, thus providing a more accurate closed-loop method of input, resulting in a more reliable operating envelope and therefore safer operation, with minimal human judgment.

[0017] A leg is considered stable when it is sufficiently submerged on the seabed, in particular when the leg properties are stable during preloading, typically when the difference in leg properties and / or the slope of the leg properties are less than respective predetermined thresholds.

[0018] The leg characteristics are considered unstable if the difference between the leg characteristics and / or the gradient of the leg characteristics are greater than respective predetermined thresholds, in which case the leg is considered not yet stably submerged on the seabed.

[0019] According to the method, at least one leg is preloaded. For a four-legged jack-up platform unit, typically, two diagonally opposite legs are preloaded simultaneously, while the other two legs are unloaded. During preloading, preferably, as much load as possible is applied to the legs. For example, for a 20,000-ton jack-up platform unit, the combined weight of the two legs theoretically results in a preload of 10,000 tons. In practice, this theoretical maximum is never achieved due to friction or other losses, seabed characteristics, environmental loads, etc. The jack operator then attempts to apply as high a load as possible to the leg. This can be done actively, where the jacking system applies such a high load to the leg to be preloaded. Or, this can be done passively, where the jacking system holds the leg to be preloaded while the other legs are released, and the weight of the platform is applied to the leg, thus using gravity for preloading. The method used is independent of the achieved preload value. The actual load on the legs may be monitored via the jack system and provided to the jack operator on the jack operator's operator interface, but may additionally or alternatively be input to the control unit. The decrease in the actual load on the legs over time is observed due to seabed subsidence, friction, hydrodynamics, etc. According to the method, the actual load on the legs is monitored for a predetermined time interval, for example, 30 or 40 minutes. The predetermined time interval may preferably be set by the jack-up platform unit designer, but may also be set by the platform unit operator. During this predetermined time interval, the actual load value on the legs is preferably monitored by the control unit. It is monitored whether the load value on the legs remains above a predetermined threshold and whether the slope of the load value on the legs is less than a predetermined limit. Preferably, the control unit is configured to automatically monitor the load value on the legs. The minimum threshold and maximum slope are advantageously provided by the platform unit designer, but may also be determined by the jack-up platform unit operator.If the drop in leg load value is greater than a predetermined threshold or the slope of the leg load value is too high, the preloading must be repeated. The control unit can provide a warning signal to the jack operator, allowing the jack operator to stop the current preloading and re-preload at least one leg with the same or a slightly higher preload value. By providing a warning signal, visual, audible, or tactile, the operator knows that the preloading step has failed and that the preloading step needs to be repeated with either the same or a higher preload value. The control unit can provide a suggestion or indication of the preload value for the subsequent preloading step. The steps of applying preload and monitoring the load value should be performed until the legs are determined to be stably submerged on the seabed, i.e., until the drop or decrease in the leg load value of the preloaded leg is less than a predetermined threshold and the slope of the load value remains below a maximum predetermined slope limit while the load value is monitored for a predetermined time interval. The actual achieved preload value is then determined as the minimum achieved load value during a predetermined time interval. Preferably, a control unit determines this actual achieved preload value. Once the actual achieved preload value is determined, it can be used to calculate a crane operating envelope for a crane mounted on a jack-up platform unit, for example, around one of the legs. Crane designers also provide crane operating manuals in which the crane operating envelope is defined. However, the crane operating envelope treats the crane as a stationary item, i.e., a static crane operating envelope, and does not take into account that the crane is mounted on a platform unit whose foundation is relatively unpredictable or dynamic. In turn, integrating the actual achieved preload value into the crane operating envelope provides an actual, accurate, and reliable crane operating envelope that takes site-specific conditions into account. For example, after preloading, the loads on the legs can be equalized or evened out, or at least determined relative to the installed load value. The difference between the actual achieved preload value and the installed load value provides the operating load margin and the safety margin.The remaining operating load value can then be used for integration with the theoretical crane operating envelope. Depending on the hoist load, reach, swing angle, and / or boom angle, a particular crane operation may be within the theoretically determined crane operating envelope but outside the operating load margin of the jack-up platform unit, and therefore, it may be unsafe to perform that particular crane operation. An actual crane operating envelope can therefore be determined taking into account the actual achieved preload value as well as the actual crane operation. Advantageously, the actual crane operating envelope can be determined in real time, giving the crane operator a real-time perspective on whether it is safe to perform a particular crane operation. Preferably, this actual crane operating envelope is output to a crane operator display available to the crane operator in his / her cab. The crane operator can then track the operation and operating limits of his / her crane in real time. This is done similarly for the determination of the actual cantilever operating envelope, preferably by outputting the cantilever operating envelope to a cantilever operator display available to the cantilever operator in the operator's cab. The actual cantilever operating envelope may therefore differ from the theoretical cantilever operating envelope in that it takes into account the actual achieved preload values. The theoretical crane or cantilever operating envelope is typically provided by an engineer designing the crane or cantilever, taking into account theoretical values ​​and safety margins.

[0020] The present invention further relates to a system for determining the actual crane operating envelope of a crane on a jack up platform unit.

[0021] Another aspect of the invention relates to a computer program product and / or a non-transitory signal-bearing medium storing a computer program product.

[0022] Further advantageous embodiments are set forth in the dependent claims.

[0023] The invention will be further explained with reference to the drawings, which contain figures of exemplary embodiments, in which corresponding elements are indicated with corresponding reference numerals, and in which: [Brief explanation of the drawings]

[0024] [Figure 1] 1 is a flow diagram of a method according to an aspect of the present invention. [Figure 2] 1 is a flow diagram of a method according to an aspect of the present invention using passive preloading. [Figure 3] 1 is a flow diagram of a method according to an aspect of the present invention using active preloading. [Figure 4] 1 is a schematic diagram of a system according to an aspect of the present invention; [Figure 5] FIG. 1 is a schematic diagram of a jack-up platform unit with a crane mounted around one of the legs of the jack-up platform unit. [Figure 6] FIG. 10 is a diagram of a preload step. [Figure 7] FIG. 10 is a schematic diagram of leg load values. [Figure 8a] FIG. 1 is a schematic diagram of a dynamic crane operating envelope. [Figure 8b] FIG. 1 is a schematic diagram of a dynamic crane operating envelope. DETAILED DESCRIPTION OF THE INVENTION

[0025] It should be noted that the drawings depict illustrative embodiments and are not to be construed as limiting and are not to scale.

[0026] FIG. 1 is a flow chart of one embodiment of a method in accordance with the present invention. Method 100 integrates jack system data with crane system data to determine an actual, and sometimes real-time, dynamic crane operating envelope, as well as provide a more accurate determination of the actual achieved preload value on the legs. Method 100 begins a preloading procedure in step 101 by preloading the legs. For some jack-up platform units, preloading occurs simultaneously on two diagonally opposed legs. The preload is a relatively high load, and in some situations, the highest practical load applied to sink the legs to the seabed. Preloading can be active, passive, or a combination active / passive procedure. In step 102, a leg characteristic value is monitored for a predetermined time interval t. The leg characteristic can be, for example, leg load or leg penetration. Then, in step 103, the leg characteristic is monitored for time interval t to determine whether it remains stable, indicating leg stability and ultimately foundation stability. Once the leg characteristics are determined to be stable, a preload value can be established in step 105. The preload value is associated with the leg characteristic value determined to be stable. For each leg, these steps 101, 102, 103, and 105 are repeated until the leg characteristic value is determined to be stable and an associated preload value can be established for each leg (step 106). Once the actual achieved preload values ​​for all legs have been determined, the actual load on each leg can be determined in step 107. The actual load, also referred to as the installation load, can be established only when the platform is jacked up to its operating height. After moving the hull to its operating height, some jack operators can then attempt to distribute the platform load approximately equally among the legs, while other jack operators can leave the load as is. Regardless of which method is used, after moving the hull to its operating height, an installation load value for each leg can be determined in step 107. This is the actual installation load on each leg. Therefore, the actual installation load may vary from one leg to another. The flow diagram does not show the steps between steps 106 and 107 that move the hull into its operational state.

[0027] This installation load value is less than the achieved preload value, and simply put, the difference between the achieved preload value and the installation load for a leg defines the operating margin for the leg, which is determined in step 108. The operating margin for each leg can then be input into the operating margin of the crane or cantilever operating envelope in step 109. The actual crane or cantilever operating envelope is then determined in step 110 using the actual achieved preload value and the actual installation load value, thus obtaining an accurate and reliable crane or cantilever operating envelope.

[0028] Figures 2 and 3 illustrate the method of Figure 1 using passive preloading in Figure 2 and active preloading in Figure 3. Any combination between active and passive preloading is possible. In Figure 2, with passive preloading, the leg characteristic monitored is the leg load value. In Figure 3, the leg characteristic monitored is the leg penetration value. Because the methods are generally similar, Figures 2 and 3 will be described together.

[0029] In step 101, either the preload is applied passively in that the force is applied discontinuously and then the load value is monitored for a predetermined time interval t (step 102 in FIG. 2), or in the other hand the preload is applied actively in that the force is applied continuously and then held at a constant value. Then, in step 102, the leg penetration value is monitored for a predetermined time interval t (step 102 in FIG. 3).

[0030] In step 102 of FIG. 2, the load value of the preloaded leg is monitored for a predetermined time interval, i.e., time t. Time t can be 20 minutes, 30 minutes, or even 50 minutes, and can be set by the jack system operator and / or the jack-up platform unit designer. During time t, it is monitored whether the decrease in the leg load value (ΔLeg Load Value) is greater than a predetermined threshold (question 103), and whether the slope of the decreasing load value (ΔLeg Load Value / Δt) is higher than a predetermined slope limit (question 104). The decrease in the leg load value is the difference between the leg load value at time t and the leg load value at 0 at the start of the monitoring time interval. Similarly, in step 103 of FIG. 3, it is checked whether the increase in the leg penetration value (ΔLeg Penetration Value) is greater than a predetermined threshold, and whether the slope of the leg penetration value (ΔLeg Penetration Value / Δt) is greater than a predetermined limit. If the leg load value decreases too much or the leg penetration value increases too much, this indicates an unstable condition. Alternatively, if the slope of the leg load value or the slope of the leg penetration value is too high, this also indicates an unstable condition. Therefore, in either case, a stable condition has not yet been reached, and the preloading step must be repeated until a stable condition is reached. If the answer to either question 103 or question 104 is "yes," the preloading can be stopped and must be started again from step 101.

[0031] By monitoring whether the leg characteristics become stable, it is possible to detect when the leg preload value settles to a specific value. In particular, a leg characteristic value that is a decrease in load value or an increase in penetration value indicates leg subsidence. The slope or gradient of the decrease in load value or increase in leg penetration value indicates the rate of leg subsidence. If the load value at the leg decreases too rapidly or the leg penetration value increases too rapidly, this indicates that the leg has not yet stably sunk to the seabed. The decrease in load value or increase in leg penetration at the leg when preload is applied may be due to seabed characteristics, such as mud being different from sand or rock, friction, environmental loads, etc. If the answers to both questions 103 and 104 are "no," the leg has stably sunk to the seabed, and the actual achieved preload value can be determined in step 105. The actual achieved preload value at the leg is considered to be the minimum achieved load value during time t. The actual achieved leg penetration value is related to and therefore indirectly indicates the actual achieved preload. In contrast to traditional preloading, where the applied preload is often treated as the preload value, this method now allows an actual achieved preload value to be established for each leg. Preloading and determining the actual achieved preload value should be performed for each leg or pair of legs until an actual achieved preload value is established for each leg of the jack-up platform unit. This is shown in step 106. After completing preloading, some crane operators may then perform platform load equalization across the legs of the platform unit, also known as leg load equalization. With this method, this is no longer strictly necessary. It is possible that some legs may remain heavier loaded than others. After applying the preload and moving the vessel to its operating height above sea level, the crane operator can apply additional loads to two diagonally opposite legs to create additional torque on the vessel. Thus, after applying the preload and further moving the vessel to its operating height, the actual load on each leg may be determined in step 107. This actual load is called the installation load value.Again, the step of moving the hull to its operating height between steps 106 and 107 is not shown. This installed load value is less than the achieved preload value. Briefly, the difference between the achieved preload value and, for example, the installed leg load value is the operating load margin of the leg, as described in connection with FIG. 7, and is determined in step 108. This operating load margin may be determined based on the installed leg load value after preload application and jacking the hull to the operating position, advantageously taking into account a safety factor. In this case, the operating load margin is a static value. Alternatively, the operating load margin may be determined based on the actual measured leg load value, as measured by the jacking system or any other measuring unit on the leg. In this case, the operating load margin is a dynamic value that changes during operation of the platform unit. This operating load margin may then be integrated into the crane or cantilever operating envelope, resulting in an integrated crane or cantilever operating envelope that takes into account the additional loads that a single leg can bear. This is done in step 109. A particular crane operation with a particular hoist load, reach, swing angle, and / or boom angle may impose such a high load on a single leg that the leg load may be higher than the actual achieved preload value, and therefore the entire operating load margin may be used for that crane operation. In this case, the crane can no longer operate safely, even if the particular crane operation itself is within the static crane operating envelope. The static crane operating envelope is an operating condition or range given by the crane designer and typically does not take into account that the crane is attached to a dynamic foundation, i.e., a jack-up platform unit. A similar condition may be a cantilever operation with a large cantilever extension and / or heavy cantilever loads. A jack-up platform unit, even if stably lowered to the seabed, should still be considered a dynamic foundation, as opposed to a static foundation on land, due to the operations performed on the platform unit, wind and / or wave loads, seabed characteristics, etc.Thus, in step 110, an actual crane operating envelope for a particular crane operation can be determined using the hoist load, reach, swing angle, and / or boom angle. This gives the crane operator an even more reliable view of what they can do with the crane. Furthermore, the actual crane operating envelope is preferably adapted in real time, so that as the crane swings, for example, the envelope adapts and is provided to the crane operator, allowing them to instantly assess whether their operation is still safe. This is a significant advantage for the crane operator, as it allows them to monitor and assess the safety of the operation during the operation. In prior art operations, the crane operator does not have an integrated crane operating envelope that integrates the actual achieved preload value. In prior art operations, the crane operator may have a preload value, which is often an applied preload value rather than an actual achieved preload value, but has no information about the actual leg load. Similarly, in step 110, an actual cantilever operating envelope can be determined, possibly in real time, that takes into account actual platform conditions, environmental conditions, cantilever reach, and / or cantilever load application. This also provides advantages to the cantilever operator.

[0032] 4 shows a schematic diagram of a system 200 according to the present invention, comprising a jack system 201 and a crane system 202 in communication with a control unit 203. The jack system 201 is arranged to jack up and down an associated leg relative to the hull of the jack-up platform unit and to hold the leg in a position. The jack system 201 is operated by a jack operator who provides input to the jack system 201 via a jack operator user interface 204. The jack system 201 receives input data from the jack operator user interface 204 and can also provide data, e.g., measured load data, to the jack operator user interface 204. The jack operator user interface 204 can be a display and / or a control panel through which the operator provides input, e.g., a load to be set, to the jack system. Data from the jack system 201, such as the measured load, leg position, etc., may be shown to the jack operator on the display of the jack operator user interface 204. The jack system 201 may be arranged to measure the load on the leg. Alternatively, a separate load measuring unit may be provided on the leg to determine the actual load on the leg.

[0033] The crane system 202 communicates with a control unit 203 and is operated by a crane operator from a crane cab. The crane operator has at his disposal a crane operator user interface 205 through which he can control crane operations. The crane system 202 receives input data from the crane operator user interface 205 but can also provide crane data to the crane operator user interface 205. The crane operator interface 205 can include one or more displays on which crane operation data, e.g., hoist load, reach, swing angle, or boom angle, is displayed. The crane operator interface 205 can further include an operator panel with, e.g., one or more joysticks, for providing commands to the crane system 202.

[0034] According to the present invention, the control unit 203 communicates with the jack system 201, the jack operator user interface 204, the crane system 202, and the crane operator user interface 205. The control unit 203 receives data from the jack system 201, particularly measured leg load data. The measured leg load data is input to the control unit 203, particularly to a first sub-control unit 206 configured to determine an actual achieved preload value at the leg. The actual achieved preload value, once determined, can be fed back to the jack operator user interface 204. Further, according to the present invention, the actual achieved preload value is input to a second sub-control unit 207. The second sub-control unit 207 is configured to determine an actual, i.e., dynamic, crane operating envelope. The actual crane operating envelope takes into account the actual achieved preload value to determine the crane operating envelope. The actual crane operating envelope can be obtained by using the actual hoist load and / or reach and / or swing angle and / or boom angle and by using actual crane data. Advantageously, the crane operating envelope may be calculated in real time, providing the crane operator with a real-time envelope on which they can base their crane operations. More advantageously, the actual crane operating envelope is calculated using the actual measured leg loads, and therefore the second secondary control unit 207 may also be in communication with the jacking system 201 to receive the actual measured leg loads. The crane operating envelope thus determined may be fed back to the crane operator, and in particular to the crane operator user interface 205, whereby the actual crane operating envelope may be displayed to the crane operator.

[0035] FIG. 5 shows a schematic diagram of a jack-up platform unit 300 having a hull 301 and four legs 302. The legs 302 are adjustable relative to the hull 301. The drawing shows the jack-up platform 300 in an operational state, with the hull 301 at an operational height above sea level. The four legs 302 are lowered to the seabed. Each leg 302 is equipped with a jack system 201 that moves the leg up and down. The jack system 201 is operated by a jack operator from a jack cab with a jack operator interface. A crane 303 is positioned around one of the legs for offshore heavy lifting operations, such as wind turbine installation operations. The crane 303 is operated by a crane operator in a crane cab with a crane operator user interface. As explained above, the jack system 201 and the crane system 202 communicate with the control unit 203 to determine the actual crane operating envelope using the actual achieved preload value.

[0036] FIG. 6 shows a schematic diagram of measured leg load data during a preloading step. Here, the preloading step for a four-legged platform unit is shown. Starting with the four legs on the ground (position 401), a high load (applied preload value 410) is applied to two diagonally opposite legs (lines 402 and 403), while the other pair of legs is substantially unloaded. Over a predetermined time interval, e.g., 30 minutes, the decrease in the measured load values ​​of the legs, as indicated by lines 402 and 403, is monitored. It is monitored whether the decrease in the measured load values ​​remains above a predetermined load threshold Lt. Furthermore, it is monitored whether the slope or gradient g of the leg load value lines 402 and 403 is less than a preset limit gl. In this embodiment, the leg load values ​​of the legs, as indicated by lines 402 and 403, satisfy both requirements, and the two legs are said to be stably submerged relative to the seabed. The actual achieved preload value is then determined as the minimum of lines 402, 403, which are load values ​​412, 413, respectively. Then, in the next preloading step, the preloading is repeated for the other two legs by applying preload value 420 to them. The measured preload slowly decreases as shown by lines 404, 405. However, when the decrease in leg load value is less than a predetermined threshold and the slope is less than the slope limit, the minimum achieved value is determined as the actual achieved preload value 414, 415.

[0037] Using the determined actual achieved preload values, an operating margin for each leg can be determined. This is shown in FIG. 7 for the four legs 302-1, 302-2, 302-3, and 302-4 of a four-legged platform unit. Actual achieved preload values ​​412, 414, 413, and 415 are the top line per leg. A safety factor is applied to the actual achieved preload values, resulting in factored preload values ​​412f, 413f, 414f, and 415f. After preloading, when the hull is raised to its operating height, the total platform weight is distributed across the four legs, resulting in installed load values ​​512, 513, 514, and 515 per leg. The difference between the factored preload values ​​and the installed leg loads, i.e., the gap in this illustration, is the operating margin available for operations such as crane operations on the platform unit. Such a diagram can be calculated by the control unit and fed back to the jack operator, and in particular to the jack operator user interface, so that the jack operator has reliable information about the leg operating margin.

[0038] FIG. 8 illustrates a crane operating envelope, with reach plotted on the horizontal axis and primary hoist load plotted on the vertical axis in FIG. 8a. In this diagram, the maximum crane rated load is plotted as line 601. This gives the maximum rated load of the crane as if the crane were on a static foundation and therefore does not take into account the dynamic foundation of the crane on the platform unit. Also plotted on the diagram is the base rated load as line 602. This is, in fact, an operating margin identified using actual achieved preload values. In this example, it can be seen that a portion of base rated load line 602 falls below crane rated line 601, thus reducing the actual safe crane operating envelope. Thus, the maximum rated load of the crane is determined by portion 602a of the base rated load and portion 601a of the crane rated load. The actual working load of the crane is represented by point 603. During operation, point 603, the actual crane working load, moves within the diagram. Advantageously, line 602 is calculated in real time using actual crane data as well as actual measured leg loads. Thus, as point 603 moves, line 602 can shift as well. FIG. 8b is an alternative representation of a crane operating envelope, including the outline of jack-up platform unit 300, including legs 302 and crane 303 around one leg. The crane operating envelope is here indicated by inner boundary 605, which indicates the minimum reach of the hoist load, and outer boundary 606. Outer boundary 606 gives the maximum reach of the hoist load, taking into account the actual achieved preload value and the operating leg load margin. In this example, it can be seen that a portion of outer boundary 606 (portion 606a) has been cut away. This corresponds to portion 602a in FIG. 8a, which limits the maximum crane load rating. The crane operator thus knows that movement of the hoist load beyond the outer boundary is unsafe for the foundation and for the platform unit. Furthermore, these boundaries are calculated in real time and provided to the crane operator in real time on the crane operator interface.Thus, by combining and integrating the actual achieved preload value, the actual measured leg load and the crane operating envelope, a dynamic and preferably real-time crane operating envelope is obtained, thereby enabling safer and more stable crane operation.

[0039] In Figures 4-8, a crane example is shown, but all are equally applicable to cantilevers and cantilever operation, and wherever crane is mentioned, cantilever should be read. Additionally, in Figures 4-8, the method is described using passive preloading, but as described with respect to Figure 3, the method is equally applicable to active preloading or any combination thereof. A method is provided for determining an actual achieved preload value by monitoring leg load characteristics during preloading. The method further includes determining an actual crane or cantilever operating envelope by instead taking into account the actual achieved preload value. The method further includes taking into account other data, such as environmental loads or crane or cantilever movement.

[0040] For clarity and conciseness of description, features are described herein as part of the same or separate embodiments, but it will be understood that the scope of the present invention may include embodiments having all or any combination of the described features. In view of this passage, it will be apparent to one skilled in the art that variations of the claims of the application may be combined with other features described in the present application of the application, particularly with features described in the dependent claims. The illustrated embodiments may be understood to have the same or similar components except where they are described as different.

[0041] In the claims, any reference signs placed in parentheses shall not be construed as limiting the claim. The word "comprising" does not exclude the presence of functions or steps other than those listed in a claim. Moreover, the words "a" and "an" shall not be construed as being limited to "one" only, but are rather used to mean "at least one" and do not exclude a plurality. The fact that certain measures are recited in mutually different claims does not indicate that a combination of these measures cannot be used to advantage. Many variations will be apparent to those skilled in the art. All variations are understood to be included within the scope of the present invention, as defined in the following claims. [Explanation of symbols]

[0042] 100 ways 200 systems 201 Jack System 202 Crane System 203 Control Unit 204 Jack Operator User Interface 205 Crane Operator User Interface 206 First Sub-Control Unit 207 Second Sub-Control Unit 300 Jack-up platform unit 301 Hull 302, 302-1, 302-2, 302-3, 302-4 Legs 303 Crane

Claims

1. 1. A method for determining a crane or cantilever operating envelope for a crane or cantilever mounted on a jack-up platform unit, comprising: - preloading at least one leg of said jack-up platform unit; - monitoring at least one characteristic of said leg, such as a leg load value and / or a leg penetration value, during a predetermined time interval; - monitoring said leg characteristic and / or the gradient of said leg characteristic during said time interval; - evaluating whether said leg characteristics are stable during said time interval; repeating the above steps until said leg body characteristic is stable, where said leg body characteristic remains within a predetermined threshold and said gradient of said leg body characteristic remains within a predetermined limit during said time interval; wherein the actual achieved preload value is the leg load value associated with the stable leg characteristic thus achieved, and the method further comprises: - for each leg, determining an actual crane or cantilever operating envelope by calculating a leg load capacity based on said actual achieved preload value, and converting the calculated leg load capacity into a crane or cantilever operating amount.

2. 2. The method of claim 1, further comprising determining the amount of crane or cantilever movement in response to at least crane or cantilever movement, and / or crane or cantilever load application, and / or environmental load.

3. 3. The method of claim 1, wherein the step of evaluating whether the leg body characteristic is stable comprises the step of evaluating a difference in the leg body characteristic value relative to a predetermined threshold and / or the step of evaluating the gradient of the leg body characteristic relative to a predetermined limit.

4. 4. The method of claim 1, wherein the step of evaluating whether the leg characteristic is stable includes, if the leg characteristic is a leg load value, evaluating whether a decrease in the leg load value at the leg remains below a predetermined threshold and whether the slope of the leg load value at the leg is less than a predetermined limit.

5. 4. The method of claim 1, wherein the step of evaluating whether the leg characteristic is stable includes, if the leg characteristic is a leg penetration value, evaluating whether an increase in the leg penetration value remains below a predetermined threshold and whether the slope of the leg penetration value for the leg is less than a predetermined limit.

6. 6. The method according to claim 1, further comprising the step of providing a warning signal if the monitored leg body characteristic values ​​of the leg are assessed to be unstable because the difference in the leg body characteristics and / or the gradient of the leg body characteristics are greater than respective predetermined thresholds.

7. 7. The method according to any one of claims 1 to 6, wherein the step of determining the actual crane or cantilever operating envelope is performed in real time using actual crane or cantilever parameters such as hoist load and / or crane reach and / or swing angle and / or boom angle and / or cantilever reach.

8. - providing a control unit configured to receive the monitored values ​​of the leg body characteristic of the leg during a predetermined time interval, and configured to monitor during said time interval whether the leg body characteristic is stable.

8. The method of claim 1, further comprising:

9. The method described in claim 8, wherein the control unit is configured to provide a warning signal when the leg body characteristics of the leg body are assessed as unstable.

10. The method of claim 8, wherein the control unit is configured to determine the actual crane or cantilever operating envelope by calculating the leg load capacity for each leg based on the achieved preload value and converting the calculated leg load capacity into a crane or cantilever operating amount depending on crane or cantilever parameters such as hoist load and / or crane reach and / or slewing angle and / or boom angle and / or cantilever reach.

11. 1. A system for determining an actual crane or cantilever operating envelope for a crane or cantilever on a jack-up platform unit, comprising: a jack-up system arranged to move and load associated legs relative to the hull of the jack-up platform unit; - a crane or cantilever system operated by a crane or cantilever operator; a control unit configured to receive monitored leg characteristic values ​​of said leg during preloading, said control unit further configured to monitor whether said leg characteristic values ​​remain stable for a predetermined time interval; Equipped with the jack-up system and the crane or cantilever system are in communication with the control unit; The control unit is configured to: - for each leg, determining an actual crane or cantilever operating envelope by calculating leg load capacities based on said actual achieved preload values, and converting the calculated leg load capacities into crane or cantilever operating quantities; The system further configured to:

12. The system of claim 11 , wherein the control unit is further configured to perform any of the remaining steps of the method of any one of claims 1 to 10 .

13. 13. The system of claim 11 or 12, further comprising a crane operator display arranged to receive actual crane motion envelope data from the control unit, and / or a cantilever operator display arranged to receive actual cantilever motion envelope data from the control unit.

14. A computer program product comprising software executing on one or more processing engines to perform any of the methods of claims 1 to 10.

15. A non-transitory signal storage medium storing the computer program product of claim 14.

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