CN116483079A - Combined path optimization planning method for offshore floating production oil storage ship - Google Patents
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Abstract
An offshore floating production oil storage ship joint path optimization planning method comprehensively considers the available capacity of shuttle tankers, calculates to obtain an optimal ship type combination, and generates an optimal path of the shuttle tankers according to the crude oil transportation requirements of the FPSO and the optional ship type. Taking the capacity relation between the shuttle tanker and the FPSO into consideration, taking the stock quantity (crude oil reserve) of the FPSO as a key variable, and flexibly planning the transportation path of the shuttle tanker according to the stock level of the FPSO. The invention can select the optimal ship type combination, and minimize the total transport capacity level of the shuttle tanker fleet on the premise of meeting the crude oil transportation requirement. On the basis, the fuel consumption of the unit crude oil is reduced by planning a flexible navigation path.
Description
Technical Field
The invention relates to a technology in the field of shuttle tanker path planning, in particular to a combined path optimization planning method for an offshore floating production oil storage ship (Floating Production Storage and Offloading, FPSO).
Background
Offshore floating production vessels are widely used with the rapid development of deep sea oil recovery. The current FPSOs are mostly applied to shallow sea oil fields, the petroleum exploitation scale is relatively small, and only 1-2 FPSOs are usually matched with shuttle tankers with similar capacities in the same oil field to carry out point-to-point crude oil transportation. In deep sea petroleum enrichment areas, the number of FPSOs planned and commissioned increases rapidly with the rapid expansion of petroleum production scale. Because the performance parameters such as the capacity, the production speed and the like of the FPSO are not standardized at present, the problem that the capacity is difficult to match can occur in the current shuttle tanker configuration along with the continuous development of the FPSO to the deep sea. The current shuttle tanker airlines are in a fixed-period and point-to-point transportation mode, and for a plurality of FPSOs in a sea area in the future, transportation requirements of all FPSOs need to be considered simultaneously, and the current airlines are difficult to meet crude oil transportation tasks of the plurality of FPSOs in the sea area.
Disclosure of Invention
The invention provides a combined path optimization planning method for an offshore floating production oil storage ship, which aims at the defects of the prior art, comprehensively considers the available capacity of a shuttle tanker and ensures that the capacity of the shuttle tanker is utilized to the maximum extent. Maximum utilization of capacity is mainly manifested in two aspects: 1) The optimal ship model combination is solved, and the ship model is selected according to the crude oil transportation requirement and the optional ship model of the FPSO. 2) Generating an optimal path for the shuttle tanker: taking the capacity relation between the shuttle tanker and the FPSO into consideration, taking the stock quantity (crude oil reserve) of the FPSO as a key variable, and flexibly planning the transportation path of the shuttle tanker according to the stock level of the FPSO. The invention can select the optimal ship type combination, and minimize the total transport capacity level of the shuttle tanker fleet on the premise of meeting the crude oil transportation requirement. On the basis, the fuel consumption of the unit crude oil is reduced by planning a flexible navigation path.
The invention is realized by the following technical scheme:
the invention relates to a combined path optimization planning method for an offshore floating production oil storage ship, which comprises the following steps:
step 1) constructing a multi-voyage model, decoupling inventory-paths, describing penalty items of FPSO inventory quantity in different stages by a piecewise linearization method, and specifically comprising the following steps:
1.1 A decision variable comprising a path selection variable of binary and a continuous stop time, speed and transport raw oil variable is established.
1.2 Taking into account the coupling relationship between inventory-berth time-voyage-path, respectively constructing inventory-path, berth time-path and constraint condition between paths based on decision variables, and decoupling the coupling relationship between FPSO inventory and shuttle tanker path, so that the shuttle tanker can berth different FPSOs at different voyages, and the path planning has high flexibility.
1.3 Establishing an optimization objective function with the least shuttle tanker and the least energy consumption of the crude oil in the transportation unit as optimization targets, wherein the objective function is used for limiting the inventory level of the FPSO not to be excessively high, and a piecewise penalty function for limiting the inventory level of the FPSO is added into the objective function.
1.4 The nonlinear navigational speed-time constraint relation and navigational speed-energy consumption corresponding relation of the optimized objective function are subjected to piecewise linearization, linearization errors are set, and a multi-voyage model is realized.
Step 2) solving the multiple voyage model obtained in the step 1 to obtain a planning scheme meeting the FPSO, which specifically comprises the following steps:
2.1 Optional tanker-related parameters, FPSO-related parameters, and planning period length are input as model parameters.
2.2 A solver solution model is invoked to generate a planning scheme meeting the FPSO.
The invention relates to a combined path optimization planning system for an offshore floating production oil storage ship, which realizes the method, and comprises the following steps: the system comprises a parameter input unit, a planning calculation unit and a result evaluation unit, wherein: the parameter input unit collects the selectable tanker related parameters, the FPSO related parameters and the planning period length as model related parameters, the planning calculation unit calculates tanker selection and route arrangement in the planning period length in the model related parameters to obtain decision variables and outputs the decision variables to the result evaluation unit, and the result evaluation unit generates planning results corresponding to the decision variables through the multiple voyage models.
Technical effects
According to the method, a tanker path planning technology taking stock quantity as a core variable is established, a multi-voyage model is established, and the coupling relation between the path and the stock is decoupled, so that the optimal path of the shuttle tanker in the plurality of voyages is solved, and the model solving is accelerated through piecewise linearization of nonlinear parts of the model. Compared with the prior art, the method and the system have the advantages that the transportation route of the tanker is planned in a plurality of voyages, so that the shuttle tanker can carry out flexible path planning according to the stock quantity of each FPSO, and the FPSO with fixed berth is not selected. Compared with a mode of transferring a single fixed FPSO to be served by a single tanker, the provided planning scheme can fully utilize the available capacity of the shuttle tanker and reduce the total capacity requirement under the condition of transporting the same crude oil. On the basis of accomplishing a given crude oil transportation job with minimal capacity, the energy consumption level of the transportation unit crude oil is reduced by path optimization. Compared with a nonlinear model, the linearization method provided by the invention has the advantage that the model solving speed is obviously improved.
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FIG. 1 is a schematic diagram of a FPSO-shuttle tanker joint path plan;
FIG. 2 is a schematic illustration of a multiple voyage model description;
fig. 3 and 4 are schematic views of effects of the embodiments.
Detailed Description
As shown in fig. 1, this embodiment relates to a multi-voyage joint path optimization planning method, which includes:
step 1) establishing a multi-voyage planning model, which specifically comprises the following steps:
1.1 A number of voyage decision variables are established. The decision variables comprising the action space are established by considering a plurality of voyages of the shuttle tanker, the docking sequence of the FPSO and the voyage speed of the shuttle tanker.
The decision variables relate to multiple accesses of the FPSO, multiple voyages of the shuttle tanker and variable voyage speed, and the design of the variables needs to consider the action space, so the design variables are as follows:
node (i, m): is parked mth for FPSO i. In addition, the port node is a special node, the number of stop times is not considered, and the port node is numbered 0.
Path (i, m, j, n): from node (i, m) to node (j, n).
Voyage number (v, k): the kth voyage is performed for tanker v.
Navigational speed s: the voyage interval (including the process of going to and from port) used for the nodes (i, m) to (j, n).
1.2 A path planning constraint condition containing a navigational speed variable is established. Based on the constructed decision variables, a constraint relationship between inventory-path-time-voyage is established.
The constraint conditions include: inventory-path constraints, dock time-path constraints, and path selection constraints. The method comprises the following steps:wherein: />I is the inventory variable of the FPSO, t is the docked time variable of the FPSO, and s is the speed variable of the shuttle tanker.
The inventory-path constraints refer to: the routing of shuttle tankers is directly related to the inventory level of the FPSO. After each time the FPSO is docked by the shuttle tanker, the amount of crude oil stock being offloaded may differ depending on the capacity of the shuttle tanker, and thus will cause a change in the next docking window, thereby affecting the path planning of the shuttle tanker. Depending on the shuttle tanker, the coupling relationship of the inventory variable and path of the FPSO can be expressed as: 1) The stock relationship when FPSOs are parked by different shuttle tankers; 2) The FPSO is related to the inventory of the same shuttle tanker at two successive stops, so inventory-path constraints include in particular:meanwhile, the stock quantity of the FPSO is required to be restrained when the FPSO is stopped for the first time in the planning period, and the stock quantity of the FPSO is restrained to be always lower than the maximum stock quantity of the FPSO, and the stock quantity of the FPSO is restrained when the planning period is finished: /> Wherein: />For the stock quantity, θ, of the node (i, m) at the moment the voyage (v, k) was stopped im,vk Crude oil storage amount extracted when the node (i, m) is stopped by voyage number (v, k), is +.>Production rate of FPSO i (×10) 3 Ton/day),>maximum storage capacity for FPSO i (×10) 3 Ton) of%>O, the moment when the node (i, m) is stopped by the voyage number (v, k) imvk Is a decision variable, i.e., shuttle tanker v is at the kth voyage docking node (i, m). S is S I,VST A set of the order in which FPSOs are docked, or a set of nodes, an element is (i, m) or (j, n). Similarly, S V,VOA For shuttle tankers and voyage collections, the element is (v, k), v represents different shuttle tankers, and similarly, h represents different number of stops, kk represents different voyages. />Representing the stock quantity of the FPSO when it was first docked during the planning period,/for example>Unloading units for shuttle tankersThe crude oil is time-consuming (hours/10) 3 Ton), TW is the duration of the planning period, FI is the stock quantity adjustment coefficient used for restraining the stock quantity allowed by the FPSO at the end of the planning period, and the value is 0,1]Between them.
The parking time-path constraint refers to: the coupling relation between the berthing time and the path of the shuttle tanker is decoupled by respectively constructing different paths under a plurality of voyages. Depending on the shuttle tanker berthing FPSO, the time-path coupling relationship is described from the shuttle tanker perspective and from the FPSO perspective, respectively.
The description of the shuttle tanker is as follows: under two consecutive voyages of a single tanker, the sequencing of the docking moments of the shuttle tanker is divided into two cases: i) After the shuttle tanker returns from the FPSO i to the port, a different FPSO is berthed at the next voyage (i.e., node (i, m) →port→node (j.n)); ii) after the shuttle tanker returns from FPSO i to the port, the same FPSO is docked at the next voyage (i.e., node (i, m-1) →port→node (i.m)), specifically:
the description from the perspective of the FPSO refers to: the docking time sequence of the FPSO is discussed in two cases: i) Two different FPSOs are continuously parked on the same tanker; ii) the same FPSO is docked successively by different shuttle tankers, in particular:
in addition, the shuttle tanker first stops the FPSO no earlier than the voyage time from port to FPSO, and the constraint FPSO needs to return to port during planning to complete a complete transportation cycle. The method comprises the following steps:
wherein: />Time consuming unloading of unit crude oil from FPSO i for shuttle tanker v, +.>tvl imjnvks />The time spent from port to node (i, m)/node (i, m) to node (j, n)/node (i, m) to port at the speed of voyage in the s-th interval, respectively. />x imjn,vk,s ，/>For decision variables, the following conditional values are 1 are satisfied: 1) Shuttle tanker v performs the kth voyage. 2) v from port to node (i, m)/from node (i, m) to node (j, n)/from node (i, m) back to port. 3) The tanker v adopts the navigational speed in the s-th linearization interval in the navigation section. SP is the linearized navigational speed interval set, and the element is s.
The path selection constraint refers to: the path selection constraint includes the following aspects: 1) The tanker from the port must be returned to the port; 2) The continuity of the node access order, i.e. the last node must be the starting point of the next node; 3) The number of times FPSO i is accessed increases (m- & gt m+1) in sequence; 4) Tanker v performing the kth voyage, voyage variable z vk Equal to 1; 5) Voyage variable z vk Sequentially increasing the voyage counts in the model; 6) Decision variables for use with tankers when at least 1 of the voyage variables is 1Equal to 1; 7) The same node cannot be accessed repeatedly in a single voyage of one tanker; 8) Binary decision variable O imvk The subscript order of (2) cannot conflict; 9) The stock quantity of the shuttle tanker after exiting the FPSO i should be equal to the stock quantity before docking the FPSO i plus the quantity of crude oil extracted at the FPSO i; 10 The amount of crude oil transported by the shuttle tanker in one voyage should not be higher than its maximum capacity; 11 The amount of crude oil that the shuttle tanker draws at the FPSO i should not be higher than the inventory of the FPSO i itself or the capacity (loadable) remaining from the shuttle tanker.
Wherein: o (O) im,vk Is a boolean variable representing the number of voyage berthing nodes (i, m) of the tanker v at the kth voyage; y is im Is a boolean variable that indicates that FPSO i was docked for the mth time during the planning period; z vk The shuttle tanker v executes the kth voyage in the planning period; />Is a boolean variable indicating that shuttle tanker v is used during the planning period; />f imjn,vk ，/>Is a continuous variable representing the amount of crude oil carried by shuttle tanker v on the kth voyage from port to node (i, m), from node (i, m) to node (i, m), and from node (i, m) back to port, respectively.
1.3 A) constructing an objective function. And setting a corresponding punishment item by taking the total transport capacity and the total oil consumption of the shuttle tanker as objective functions and considering the limitation of the FPSO inventory level.
The decision variables comprise three latitudes of paths (nodes), voyages and voyages, and the increase of the action space leads to the increase of the search space for solving, which is unfavorable for the rapidity of solving. In order to accelerate calculation, the invention adds dimension reduction processing, namely dimension reduction is carried out on the path planning decision variables. Since the speed and the path constraint are not directly related, the speed variable is omitted when the path decision variable is constructed, and meanwhile, the low-dimensional path decision variable is related to the complete path decision variable containing the speed, specifically:wherein: />x imjn,vk ，/>And planning decision variables for paths without considering the navigational speed variables. The purpose of reducing the algorithm search space is achieved by reducing the dimension of part of constraint conditions, so that the calculation is accelerated.
The objective function refers to: targeting minimum capacity and minimum energy consumption, the objective function is constructed as follows: min.f fuel +f operation +f punishment Wherein:
wherein the method comprises the steps of ηv And multiplying the oil tankers with different capacities by corresponding coefficients according to the relation between the navigational speed and the oil consumption of the reference oil tankers to obtain the navigational speed-oil consumption relation. />For rated capacity of tanker v, z vk Is a 0-1 decision variable, i.e. the kth voyage of tanker v is used,/>The stock of crude oil carried by tanker v when the kth voyage returns from node (i, m) to the port. C (C) op And C rent The single-day operation cost and the single-day lease cost of the shuttle tanker are respectively. P (P) ST And P Q Penalty coefficients, respectively, where P ST A punishment item for the residual empty capacity of a single voyage of the tanker encourages the tanker to transport as much crude oil inventory of the FPSO as possible in the single voyage; p (P) Q The inventory penalty term for the FPSO is used to limit the inventory of the FPSO from being too high at any time. f (f) fuel For fuel consumption, a nonlinear relation exists between the fuel consumption and the navigational speed, and the method specifically comprises the following steps: />Wherein omega 1 ，ω 2 ，ω 3 Is a constant coefficient and is related to the model of the tanker.
In the objective function, f operation For operating costs, including vessel rental costs and operating costs for a single voyage. f (f) punishment The punishment term includes utilization punishment of a single voyage of the ship and inventory punishment of the FPSO. Wherein a single voyage utilization penalty term encourages the tanker to return as much crude as possible in one voyage, while the objective of the FPSO inventory penalty is to limit the storage rate of the FPSO to a reasonable interval, leaving some margin to cope with uncertainty factors (weather, vessel failure, etc.) in the actual scenario.
Penalty factor for said inventoryWherein:κ 1 characterizing the maximum fuel consumption from one node to another in order to encourage tankers to stop as early as possible by increasing the speed to prevent overstock when the inventory of the next target FPSO node is high; kappa (kappa) 2 The method is characterized by the loss of stopping production caused by full inventory, and aims to avoid the situation that the inventory of the FPSO is too high when the algorithm plans a path, the continuity of production is higher in priority, and after the penalty term is added, if the current solution causes the capacity of the FPSO at the stopping moment to be too high, the algorithm can reprogram the path by the higher penalty term. Beta oil Is the unit price of crude oil, delta 0 ，δ 1 And obtaining corresponding punishment items after different thresholds are reached for the set segmentation threshold.
1.4 The nonlinear relations of the navigational speed-time and the navigational speed-oil consumption are linearized in a piecewise manner, a mixed integer linear programming model is established, and the solving efficiency is greatly improved while the precision is ensured;
piecewise linearization of the speed-time nonlinear relationship refers to: based on the inverse proportion relation between time and navigational speed, describing the time-navigational speed relation into a relation of a linear inequality group by adopting a piecewise linearization mode, wherein the relation specifically comprises the following steps:wherein:D ij ,D 0j distance of FPSO i/port from FPSOj, +.>spd imjn,vk,s ，/>Slave node at kth voyage for tanker v(i, m) to node (j, n)/port to node (i, m)/node (i, m) to speed within a speed interval s selected within the leg of the port, slope +.>And intercept->The method meets the following conditions:wherein: />v min ,v max The minimum/maximum speed of the shuttle tanker v is respectively, epsilon is the expected maximum linearization error (%), and eta is the required linearization segmentation number calculated according to the linearization error and the speed interval.
The nonlinear relation piecewise linearization of the speed-fuel consumption refers to: for quadratic relation equation between speed of flight and energy consumptionPiecewise linearization is performed. The linearization equation is expressed as:wherein: />And->Coefficients of the quadratic equation of speed-energy consumption, which are piecewise linear equation coefficients, are dependent on shuttle tankers>M is a constant, and its value should be equal to or greater than +.>To ensure the left itemA 0 can be taken.
The piecewise linear equation coefficientAnd->The method is specifically obtained by the following steps: i) Selecting an initial point, such as a minimum navigational speed; ii) calculating the tangential correspondence of the initial point with the minimum speed as the tangential point>iii) Given the linearization error epsilon, calculating the error between the linear equation and the actual curve on the current tangent, calculating the error as the navigation speed spd 'corresponding to epsilon, then (spd',) As the starting point for the next piecewise linear equation; iv) with (spd', ->) As a starting point, a tangent to the next segment of piecewise linearization is calculated. v) repeating steps iii) -iv) until the speed corresponding to the tangent point is greater than the specified maximum speed, the slope of the piecewise linearization equation for the given speed interval is obtained>And intercept->
Wherein the starting point spd min End point spd max And intersection pointThe speed of the voyage is divided into different linearization intervals. Meanwhile, considering the linearization interval of the navigational speed-time, taking the two into a union, namely the final navigational speed linearization interval. Assume that the intersection of the speed-time linearization intervals is denoted as set +.>The intersection points of the navigational speed-energy consumption linearization intervals are expressed as a setThe intersection point set of the final linearization interval is I t ∪I f 。
And 2) inputting user parameters and solving.
2.1 User parameter input. The related parameters of the oil tanker comprise selectable ship types and quantity, capacity of different ship types, throughput speed, oil consumption-navigational speed curve parameters, daily rent and operation maintenance cost (selectable); the FPSO related parameters include FPSO location parameters, capacity, daily throughput, and crude unloading speed. A planning period length parameter is also included.
2.2 A solver is invoked to solve and output a planning result comprising the required ship shape and number, the routing and predicted departure time of each tanker in the planning period and the expected stock change condition of the FPSO.
As shown in fig. 2, the planning result includes: one shuttle tanker parks a plurality of FPSOs to extract crude oil in a planning period; one FPSO can be parked for a plurality of times by different shuttle tankers in a planning period; one shuttle tanker can select different FPSOs to dock at different voyages; each voyage of the shuttle tanker can select departure time from a port according to the stock quantity of the FPSO; shuttle tankers may choose speeds among different nodes.
The experimental parameters were set as shown in tables 1 and 2 through specific practical experiments. The model constructed by the invention is solved on an AMD Ryzen 7PRO 4750U (1.70 GHz) 16GB RAM hardware platform by using CPLEX 12.10. The test data obtained by the examples under the above parameter settings are shown in tables 3 and 4. To embody the planning effect of the multiple voyage model, the multiple voyage model is compared with a single voyage model (a traditional transportation model). Where SV-SV represents a single berth-single voyage model, i.e., one FPSO is allowed to be berthed only once during the planning period, and one shuttle tanker has only one voyage during the planning period. Similarly, MV-SV is a multiple berth-multiple voyage model, i.e., the FPSO is allowed to berth multiple times during the planning period. MV-MV is a multiple berth-multiple voyage model. For comparison at the same planning period length, SV-SV was performed 2 times as a comparison with the MV-MV model.
TABLE 1 simulation case A, B Overall arrangement
Table 2 model parameter settings
The result of the example planning is shown in fig. 3, fig. 4, and tables 3 and 4.
Table 3 comparison of case a planning results
Table 4 comparison of case B results
From comparison of the results of case a, it can be seen that the total fuel consumption obtained with the present invention is lower than the planning result using the SV-SV model alone, with the same total capacity demand. Wherein MV-MV-30 saves about 11.14% of total fuel consumption compared to SV-SV-15. This is because in the MV-MV model shuttle tanker a performs only one transport voyage during the planning period, whereas in SV-15 three tankers (a, B, C) perform two voyages during the planning period of 30 days, because path planning cannot be considered cooperatively in multiple voyages, subject to the capacity of the tanker and the time window constraints of the FPSO.
In the comparison case B, since the MV-SV-20 has only a single voyage, three tankers are needed to complete crude oil transportation in the planning period, and the multi-voyage model (MV-MV-20) is adopted, only 2 shuttle tankers are used, so that the transportation requirement can be met by increasing the transportation frequency. At this time, the fuel consumption is slightly increased, but the overall capacity requirement is greatly reduced because one oil tanker is not used. In summary, the planning method provided by the invention can fully utilize the transport capacity of the shuttle tanker, and can reduce the total fuel consumption by reasonably planning the route on the basis of minimizing the transport capacity required by the shuttle tanker.
To verify the effect of path decision variable dimension reduction, a test scenario is set as shown in table 5:
table 5 case C simulation parameters
And comparing the calculation time of the two models before and after the dimension reduction of the decision variable. Test parameters refer to table 2. Both models were performed with the same hardware and software configuration, and the test results are shown in table 6. Compared with the method which does not consider the path decision variable dimension reduction, the method reduces the solving time by about 60 percent. The solution time gap will be more significant if the problem is further scaled up, such as increasing the number of FPSOs, increasing the number of shuttle tankers, etc.
Table 6 case C planning results
To demonstrate the advantages of the flexible choice shuttle tanker of the present invention, simulation case D is set forth in table 7.
TABLE 7 case D simulation parameters
Comparing the planning results of the two cases, when the number of alternative tankers is increased from 4 to 8, the planned total capacity and the fuel consumption are reduced considerably. Although the solution time is increased, a more optimal solution can be obtained.
Table 8 comparison of case D planning results
Compared with the prior art, the method has the technical effects that:
1) The transportation process is optimized through the planning method without equipment transformation, the effect of saving the transportation capacity or the fuel consumption is achieved, and the method has higher feasibility. The traditional multi-node path planning method takes node inventory as a binary variable, only single change of the node inventory is considered, so that the coupling relation between the node inventory change and path planning cannot be reflected, and the traditional path planning method can only optimize the path of a single voyage or a single ship and is possibly not an optimal scheme in a long time scale. The invention relates to the coupling relation between the inventory of the FPSO and the path of the shuttle tanker, and optimizes the path selection problem from a longer time scale, thereby obtaining better optimization results.
2) The safety margin is quantized, and a good balance is achieved between economy and safety. The conventional multi-node path planning method is simple for processing the node time window, and is usually processed by hard constraint, namely, a specified ship has to stop within a specified time, or the safety is only used as one of the objective functions. The capacity margin of the FPSO cannot be quantified by the method, so that reasonable parking time is difficult to determine, planning results are generally conservative, and the available capacity of the FPSO cannot be fully utilized. The invention carries out piecewise linearization processing on the punishment function, and gives the punishment factor actual physical meaning, so that the inventory level of the FPSO and the safety requirement of continuous operation can be well balanced.
3) And a linearization method and a dimension reduction method of a high-dimension decision variable are designed, so that a solving process is accelerated. The linearization process is to perform piecewise linearization on the nonlinear relations of navigational speed-time and navigational speed-energy consumption, and convert the original nonlinear programming model into linear programming so that the solver can solve efficiently. The dimension reduction method is characterized in that in the constraint condition of path planning, the constraint relation among Boolean variables is considered to be irrelevant to the value of the navigational speed, so that in the constraint condition related to path selection, the dimension reduction processing is carried out on the path planning, the action space of the navigational speed variables is eliminated, the search space of the problem is effectively reduced, and under the same parameter setting, the solving time is shortened compared with a planning model without dimension reduction.
The foregoing embodiments may be partially modified in numerous ways by those skilled in the art without departing from the principles and spirit of the invention, the scope of which is defined in the claims and not by the foregoing embodiments, and all such implementations are within the scope of the invention.
Claims (6)
1. The combined path optimization planning method for the offshore floating production oil storage ship is characterized by comprising the following steps of:
step 1) constructing a multi-voyage model, decoupling inventory-paths, describing penalty items of FPSO inventory quantity in different stages by a piecewise linearization method, and specifically comprising the following steps:
1.1 A decision variable comprising a path selection variable of binary values and a continuous parking time, speed and transportation crude oil variable is established;
1.2 Taking the coupling relation between inventory-berthing time and navigational speed-paths into consideration, respectively constructing inventory-paths, berthing time-paths and constraint conditions among paths based on decision variables, and decoupling the coupling relation between FPSO inventory and shuttle tanker paths so that the shuttle tankers berth different FPSOs at different navigational times;
1.3 Establishing an optimization objective function with the least shuttle tanker and the lowest energy consumption of crude oil in a transportation unit as optimization targets, wherein the objective function is used for limiting the inventory level of the FPSO not to be excessively high, and a segmentation penalty function for limiting the inventory level of the FPSO is added into the objective function;
1.4 The nonlinear navigational speed-time constraint relation and navigational speed-energy consumption corresponding relation of the optimized objective function are subjected to piecewise linearization, linearization errors are set, and a multi-voyage model is realized;
step 2) solving the multiple voyage model obtained in the step 1 to obtain a planning scheme meeting the FPSO, which specifically comprises the following steps:
2.1 Inputting optional tanker related parameters, FPSO related parameters and planning period length as model parameters;
2.2 A solver solution model is invoked to generate a planning scheme meeting the FPSO.
2. The method for joint path optimization planning of an offshore floating production storage vessel according to claim 1, wherein the decision variables relate to multiple accesses of the FPSO, multiple voyages of the shuttle tanker and variable voyages, and the design of the variables requires consideration of the motion space, and the method comprises the steps of:
node (i, m): for the FPSOi to be parked for the mth time, the port node is a special node, the number of times of parking is not considered, and the number is 0;
path (i, m, j, n): from node (i, m) to node (j, n);
voyage number (v, k): carrying out the kth voyage for the tanker v;
navigational speed s: for the voyage interval used from node (i, m) to node (j, n).
3. The method for optimizing and planning the joint path of the offshore floating production storage ship according to claim 1, wherein the constraint condition comprises: inventory-path constraints, dock-time-path constraints, and path selection constraints; the method comprises the following steps: wherein: />x is a path selection variable of the shuttle tanker, i is an inventory variable of the FPSO, t is a berthed time variable of the FPSO, and s is a speed variable of the shuttle tanker;
the inventory-path constraints refer to: the shuttle tanker's routing is directly related to the FPSO inventory level; after each time the FPSO is stopped by the shuttle tanker, the unloaded stock of crude oil can be different according to the transport capacity of the shuttle tanker, so that the time window for the next stop is changed, and the path planning of the shuttle tanker is affected;
the coupling relation between the inventory variable and the path of the FPSO comprises: 1) The stock relationship when FPSOs are parked by different shuttle tankers; 2) The inventory-path constraints of the FPSO by the inventory relationship of the same shuttle tanker at two successive stops include:meanwhile, the stock quantity of the FPSO is required to be restrained when the FPSO is stopped for the first time in the planning period, and the stock quantity of the FPSO is restrained to be always lower than the maximum stock quantity of the FPSO, and the stock quantity of the FPSO is restrained when the planning period is finished: />
，
Wherein: />For the stock quantity, θ, of the node (i, m) at the moment the voyage (v, k) was stopped im,vk Crude oil storage amount extracted when the node (i, m) is stopped by voyage number (v, k), is +.>Production rate of FPSOi (. Times.10) 3 Ton/day),>maximum storage capacity for FPSOi (×10) 3 Ton) of%>O, the moment when the node (i, m) is stopped by the voyage number (v, k) imvk Is a decision variable, namely, shuttle tanker v stops at the kth voyage stop node (i, m); s is S I,VST For a set of FPSO parked orders, or a set of nodes, the element is (i, m) or (j, n), S V,VOA For shuttle tankers and voyage sets, the elements are (v, k), v represents different shuttle tankers, and similarly, h represents different number of stops, kk represents different voyages; />Representing the stock quantity of the FPSO when it was first docked during the planning period,/for example>Time consuming unloading of unit crude oil to port for shuttle tankers (hours/10 3 Ton), TW is the duration of the planning period, FI is the stock quantity adjustment coefficient used for restraining the stock quantity allowed by the FPSO at the end of the planning period, and the value is 0,1]Between them;
the parking time-path constraint refers to: decoupling the coupling relation between the berthing time and the path of the shuttle tanker by respectively constructing different paths under a plurality of voyages; the time-path coupling relationship is described from the shuttle tanker and from the FPSO perspective, respectively, according to the shuttle tanker docking FPSO;
the description of the shuttle tanker is as follows: under two consecutive voyages of a single tanker, the sequencing of the docking moments of the shuttle tanker is divided into two cases: i) After the shuttle tanker returns from the FPSO to the port, it stops at a different FPSO (i.e., node (i, m) →port→node (j.n)) at the next voyage; ii) after the shuttle tanker returns from the FPSO to the port, the same FPSO is docked at the next voyage (i.e., node (i, m-1) →port→node (i.m)), specifically:
the description from the perspective of the FPSO refers to: the docking time sequence of the FPSO is discussed in two cases: i) Two different FPSOs are continuously parked on the same tanker; ii) the same FPSO is docked successively by different shuttle tankers, in particular:
the time for the shuttle tanker to stop the FPSO for the first time is not earlier than the sailing time from the port to the FPSO, and the FPSO is constrained to return to the port in the planning period, so that a complete transport cycle is completed, specifically: wherein: />Time consuming unloading of unit crude oil from FPSOi for shuttle tanker v, +.>The time spent from port to node (i, m)/node (i, m) to node (j, n)/node (i, m) to port at the speed of voyage in the s-th interval, respectively; />x imjn,vk,s ，/>For decision variables, the following conditional values are 1 are satisfied: 1) Shuttle tanker v performs the kth voyage; 2) v from port to node (i, m)/from node (i, m) to node (j, n)/from node (i, m) back to port; 3) The voyage speed of the oil tanker v in the s linear interval is adopted in the voyage section; SP is a linearized navigational speed interval set, and the element is s;
the path selection constraint includes: 1) The tanker from the port must be returned to the port; 2) The continuity of the node access order, i.e. the last node must be the starting point of the next node; 3) The number of times FPSOi is accessed increases (m- & gt m+1) in sequence; 4) Tanker v performing the kth voyage, voyage variable z vk Equal to 1; 5) Voyage variable z vk Sequentially increasing the voyage counts in the model; 6) Decision variables for use with tankers when at least 1 of the voyage variables is 1Equal to 1; 7) The same node cannot be accessed repeatedly in a single voyage of one tanker; 8) Binary decision variable O imvk The subscript order of (2) cannot conflict; 9) The stock quantity of the shuttle tanker after exiting the FPSOi should be equal to the stock quantity before the FPSOi is stopped plus the quantity of crude oil extracted at the FPSOi; 10 The amount of crude oil transported by the shuttle tanker in one voyage should not be higher than its maximum capacity; 11 The amount of crude oil extracted by the shuttle tanker at the fpso should not be higher than the inventory of the fpso itself or the capacity (loadable) remaining by the shuttle tanker, specifically:
wherein: o (O) im,vk Is a boolean variable representing the number of voyage berthing nodes (i, m) of the tanker v at the kth voyage; y is im Is a boolean variable that indicates that the fpso was docked for the mth time during the programming period; z vk The shuttle tanker v executes the kth voyage in the planning period; />Is a boolean variable indicating that shuttle tanker v is used during the planning period; />f imjn,vk ，/>Is a continuous variable representing the amount of crude oil carried by shuttle tanker v on the kth voyage from port to node (i, m), from node (i, m) to node (i, m), and from node (i, m) back to port, respectively.
4. The method for optimizing and planning the joint path of the offshore floating production oil storage ship according to claim 1, wherein the decision variables comprise three latitudes of paths (nodes), voyages and voyages, and the increase of the action space leads to the increase of the search space of the solution, which is unfavorable for the rapidity of the solution; in order to accelerate calculation, the invention adds dimension reduction processing, namely dimension reduction is carried out on the path planning decision variables; since the speed and the path constraint are not directly related, the speed variable is omitted when the path decision variable is constructed, and meanwhile, the low-dimensional path decision variable is related to the complete path decision variable containing the speed, specifically:wherein: />x imjn,vk ，/>Planning decision variables for paths without considering navigational speed variables; the purpose of reducing the algorithm search space is achieved by reducing the dimension of part of constraint conditions, so that the calculation is accelerated;
the objective function refers to: targeting minimum capacity and minimum energy consumption, the objective function is constructed as follows: min.f fuel +f operation +f punishment Wherein: wherein eta v The oil consumption coefficient of the shuttle oil tanker v is obtained by multiplying oil tankers with different capacities by corresponding coefficients according to the relation between the navigational speed and the oil consumption of the reference oil tankers, and the navigational speed-oil consumption relation is simplified; />For rated capacity of tanker v, z vk Is a 0-1 decision variable, i.e. the kth voyage of tanker v is used,/>The stock of crude oil carried for the tanker v when the kth voyage returns from node (i, m) to the port; c (C) op And C rent The single-day operation cost and the single-day lease cost of the shuttle tanker are respectively; p (P) ST And P Q Penalty coefficients, respectively, where P ST A punishment item for the residual empty capacity of a single voyage of the tanker encourages the tanker to transport as much crude oil inventory of the FPSO as possible in the single voyage; p (P) Q A stock quantity penalty term for the FPSO for limiting the stock quantity of the FPSO from being too high at any time; f (f) fuel For fuel consumption, a nonlinear relation exists between the fuel consumption and the navigational speed, and the method specifically comprises the following steps: /> Wherein omega 1 ，+ 2 ，ω 3 Is a constant coefficient and is related to the model of the tanker; f (f) operation For operating costs, including vessel rental costs and single voyage operating costs; f (f) punishment For penalty term, including single voyage of shipUtilization penalty of (1) and inventory penalty of FPSO; wherein a single voyage utilization penalty term encourages the tanker to return as much crude oil as possible in one voyage, and the objective of the inventory penalty of the FPSO is to limit the storage rate of the FPSO to remain in a reasonable interval, leaving a margin to cope with uncertainty factors in the actual scenario;
penalty factor for said inventoryWherein:κ 1 characterizing the maximum fuel consumption from one node to another in order to encourage tankers to stop as early as possible by increasing the speed to prevent overstock when the inventory of the next target FPSO node is high; kappa (kappa) 2 Representing the production stopping loss caused by full inventory, wherein the aim is to avoid the condition that the inventory of the FPSO is too high when the algorithm plans the path, the continuity of production is higher priority, and after the penalty term is added, if the current solution causes the capacity of the FPSO at the stopping moment to be too high, the higher penalty term causes the algorithm to re-plan the path; beta oil Is the unit price of crude oil, delta 0 ，δ 1 And obtaining corresponding punishment items after different thresholds are reached for the set segmentation threshold.
5. The method for optimizing and planning the joint path of the offshore floating production storage ship according to claim 1, wherein the piecewise linearization of the speed-time nonlinear relationship is as follows: based on the inverse proportion relation between time and navigational speed, describing the time-navigational speed relation into a relation of a linear inequality group by adopting a piecewise linearization mode, wherein the relation specifically comprises the following steps:wherein: />SP＝{s 1 ,s 2 ,...s η }，D ij ,D 0j Distance of FPSOi/port from FPSOj, +.>spd imjn,vk,s ，/>For the voyage of the tanker v in the voyage interval s selected in the voyage section from node (i, m) to node (j, n)/port to node (i, m)/node (i, m) to port, slope +.>And intercept->Meet the requirements of->Wherein:v min ,v max the minimum/maximum navigational speed of the shuttle tanker v is respectively, epsilon is the expected maximum linearization error (%), and eta is the required linearization segmentation number calculated according to the linearization error and the navigational speed interval;
the nonlinear relation piecewise linearization of the speed-fuel consumption refers to: for quadratic relation equation between speed of flight and energy consumptionPerforming piecewise linearization; the linearization equation is expressed as:wherein: />And->Is piecewise linear equation coefficient, dependent on shuttle oilCoefficients of the quadratic equation of the speed of the wheel and the energy consumption +.>M is a constant, and its value should be equal to or greater than +.>To ensure that the left item above can get 0;
the piecewise linear equation coefficientAnd->The method is specifically obtained by the following steps: i) Selecting an initial point, such as a minimum navigational speed; ii) calculating the tangential correspondence of the initial point with the minimum speed as the tangential point>iii) Given linearization error epsilon, calculating the error between the linear equation and the actual curve on the current tangent, and calculating the error as the navigational speed spd' corresponding to epsilonAs the starting point for the next piecewise linear equation; iv) with +.>Calculating a tangent line of the next segment of piecewise linearization as a starting point; v) repeating steps iii) -iv) until the speed corresponding to the tangent point is greater than the specified maximum speed, the slope of the piecewise linearization equation for the given speed interval is obtained>And intercept->Wherein the starting point spd min End point spd max And intersection->Dividing the navigational speed into different linearization sections; taking the linearization interval of the navigational speed-time into consideration, and taking the two intervals as a union, namely the final navigational speed linearization interval; assume that the intersection points of the speed-time linearization intervals are represented as a setThe intersection of the speed-energy consumption linearization intervals is denoted as set +.>The intersection point set of the final linearization interval is I t ∪I f 。
6. A system for implementing the joint path optimization planning method of an offshore floating production storage vessel according to any one of claims 1-5, comprising: an offshore floating production storage vessel joint path optimization planning system comprising: the system comprises a parameter input unit, a planning calculation unit and a result evaluation unit, wherein: the parameter input unit collects the selectable tanker related parameters, the FPSO related parameters and the planning period length as model related parameters, the planning calculation unit calculates tanker selection and route arrangement in the planning period length in the model related parameters to obtain decision variables and outputs the decision variables to the result evaluation unit, and the result evaluation unit generates planning results corresponding to the decision variables through the multiple voyage models.
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