A method and system for determining the optimal position of an offshore drilling platform

Abstract

The present invention discloses a method and system for determining the optimal position of an offshore drilling platform, the method comprising the following steps: obtaining the current state information of the watertight riser and the current position information of the offshore drilling platform, the current state information comprising the upper flexible joint angle, the lower flexible joint angle, the effective bottom tension, the effective top tension and the geometric stiffness coefficient; determining the moving distance and moving angle of the offshore drilling platform according to the current state information of the watertight riser and the current position information of the offshore drilling platform. When the offshore drilling platform moves based on the moving distance and the moving angle, the upper flexible joint angle and the lower flexible joint angle of the watertight riser reach a minimum. The system comprises two inclinometers arranged at the top of the watertight riser and two inclinometers arranged at the bottom; as well as a tensioner arranged at the top of the watertight riser and a blowout preventer arranged at the bottom; the blowout preventer is arranged on the seabed. The present invention can minimize the upper flexible joint angle and the lower flexible joint angle of the watertight riser, thereby improving the safety and integrity of the watertight riser.

Description

Technical Field

[0001] The present application belongs to the field of marine oil and gas exploration and development, and specifically relates to a method and system for determining the optimal position of an offshore drilling platform. Background Art

[0002] As the link between the seabed wellhead and the offshore drilling platform, the riser plays an important role in isolating seawater, guiding drilling tools, circulating drilling fluid, and compensating for the heave and sinking of floating drilling rigs. Regardless of the floating system solution adopted for deep-sea oil and gas exploitation, the riser is an indispensable equipment for offshore oil and gas exploitation, and it is also one of the weak and vulnerable components. Under the combined action of multiple loads such as ocean currents, waves, and the oscillation, drift, and undulating motion of the sea surface platform, the riser in the deepwater environment will not only produce a large displacement, but also will produce alternating stress, induce riser fatigue, reduce the service life of the riser, and even break, causing secondary disasters, causing significant losses to deep-sea oil development.

[0003] In order to ensure the safety and integrity of the riser during its service, the inclination and offset of the riser should be monitored. The offset and inclination can be used to know the state of the offshore drilling platform deviating from the seabed wellhead to ensure that it is within a safe range.

[0004] CN108729862B discloses a robust adaptive three-dimensional vibration suppression method for a marine flexible riser system, including: establishing a three-dimensional dynamic model of the marine flexible riser system; designing a robust adaptive boundary controller based on the three-dimensional dynamic model; wherein the three-dimensional dynamic model is used to analyze the marine flexible riser system; obtaining real-time parameters of the marine flexible riser system; and sending a control command to a drive device based on the robust adaptive boundary controller and the real-time parameters, so that the drive device applies a force to the flexible riser to suppress the vibration of the riser. However, it is not possible to optimize the optimal position of the platform by measuring the angle and position of the up and down tilt, minimize the intermediate deformation of the riser, and increase the service life of the riser. Summary of the invention

[0005] The technical problem to be solved by the present invention is to provide a method and system for determining the optimal position of an offshore drilling platform, which can solve the safety and integrity of a watertight riser and increase the service life of the watertight riser.

[0006] In order to solve the above technical problems, the present invention provides a method for determining the optimal position of an offshore drilling platform, comprising the following steps:

[0007] Acquire current status information of the riser and current position information of the offshore drilling platform, wherein the current status information includes an upper flexible joint angle, a lower flexible joint angle, an effective bottom tension, an effective top tension, and a geometric stiffness coefficient;

[0008] Determine the moving distance and moving angle of the offshore drilling platform according to the current state information of the riser and the current position information of the offshore drilling platform;

[0009] When the offshore drilling platform moves based on the moving distance and the moving angle, the upper flexible joint angle and the lower flexible joint angle of the watertight riser reach the minimum.

[0010] Further, according to the current state information of the riser and the current position information of the offshore drilling platform, the moving distance and the moving angle of the offshore drilling platform are determined;

[0011] The calculation formula for the moving distance and moving angle of the offshore drilling platform is as follows:

[0012]

[0013]

[0014]

[0015] u e =(A T W T WA) -1 A T W T WΘ;

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[0020]

[0021]

[0022]

[0023]

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[0025]

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[0027]

[0028] Where Δu is the moving distance, ξ is the moving angle, T b is the effective bottom tension of the riser, T t is the effective top tension of the riser, α b is the angle of the lower flexible joint of the riser, α t is the upper flexible joint angle of the riser, Q b is the bottom shear force of the riser, Q t is the top shear force of the riser.

[0029] Δx is the displacement in the X-axis direction, Δy is the displacement in the Y-axis direction, and u e is the weighted equivalent offset, A is the simplified matrix, W is the weighted matrix, Θ is the upper and lower angles, u e is the equivalent offset vector, is the inclination angle between the bottom and the ZX plane, is the inclination angle between the bottom and the ZY plane, is the inclination angle between the top and the ZX plane, is the inclination angle between the top and the ZY plane, x e is the equivalent displacement in the X-axis direction, y e is the equivalent displacement in the Y-axis direction, x b is the bottom displacement in the X-axis direction, y b is the displacement of the bottom Y axis, x t is the top X-axis displacement, y t is the top Y-axis displacement, γ b is the angle between the bottom offset vector and the X axis, γ t is the angle between the top offset vector and the X axis, u b is the bottom offset vector, u t is the top offset vector, u bf is the bottom displacement of the riser caused by external load, u tf is the top displacement of the riser caused by external load, α bo is the lower flexible node angle caused by the displacement of the riser top, α to is the upper flexible node angle caused by the displacement of the riser top, α bf is the lower flexible joint angle of the riser caused by the lateral load, α tf It is the angle of the upper flexible node caused by the lateral load on the riser.

[0030] K T is the geometric stiffness of the riser, T ti , T bi is the top tension and bottom tension of riser segment i, w i is the weight of riser segment i.

[0031] Furthermore, a first inclinometer and a second inclinometer are provided at the top of the riser, and a third inclinometer and a fourth inclinometer are provided at the bottom;

[0032] The upper flexible section angle of the watertight riser is obtained by using the first inclinometer and the second inclinometer; the lower flexible section angle of the watertight riser is obtained by using the third inclinometer and the fourth inclinometer.

[0033] Furthermore, a spatial rectangular coordinate system is established with the bottom of the watertight pipe as the coordinate origin, the z-axis of the spatial rectangular coordinate system is perpendicular to the seabed, the plane formed by the x-axis and y-axis of the spatial rectangular coordinate system is parallel to the seabed, the upper flexible node angle of the watertight pipe is the angle between the top of the watertight pipe and the z-axis, and the lower flexible node angle of the watertight pipe is the angle between the bottom of the watertight pipe and the z-axis.

[0034] Further, the top end of the riser is connected to the tensioner and maintained in a tensioned state;

[0035] Obtaining the effective top tension of the riser through the tensioner;

[0036] The geometric stiffness coefficient of the watertight riser is calculated according to the watertight riser's own characteristics and mud characteristics.

[0037] A system for determining an optimal position of an offshore drilling platform, comprising a riser connecting the offshore drilling platform and a seabed, and further comprising:

[0038] The acquisition module includes a first inclinometer and a second inclinometer arranged at the top of the watertight pipe, a third inclinometer and a fourth inclinometer arranged at the bottom, a tensioner arranged at the top of the watertight pipe, and a blowout preventer arranged at the bottom. The blowout preventer is arranged on the seabed.

[0039] Furthermore, the third inclinometer and the fourth inclinometer are both wirelessly connected to the hydrophone via the underwater beacon.

[0040] Compared with the prior art, the present invention has the following beneficial effects:

[0041] 1. The present invention determines the moving distance and moving angle of the offshore drilling platform according to the current status information of the riser and the current position information of the offshore drilling platform, so as to minimize the upper flexible section angle and the lower flexible section angle of the riser, thereby improving the safety and integrity of the riser.

[0042] 2. The present invention measures the up and down inclination angles and positions of the watertight pipes through inclinometers and tensioners, and optimizes the optimal position of the platform, so that the watertight pipes are in an optimal state, the transverse force at the upper and lower connections is small, the middle deformation of the watertight pipes is minimized, the lateral stress received by the watertight pipes is minimized, and the service life of the watertight pipes is improved.

[0043] 3. The two underwater inclinometers of the present invention, the third inclinometer and the fourth inclinometer, are directly wirelessly connected to the hydrophone through the underwater beacon to transmit the data. Compared with the conventional wired communication with the surface, or the wired communication between the two underwater inclinometers, and then the difference between the two is uploaded wirelessly, the wireless connection method is simple and convenient to install and improves the working efficiency. The underwater signal is transmitted to the hydrophone on the surface through the beacon, and the data is transmitted by wireless communication. The information is easy to obtain and easy to implement. BRIEF DESCRIPTION OF THE DRAWINGS

[0044] Figure 1 The figure is a flow chart of the method of the present invention.

[0045] Figure 2 It is a schematic diagram of the positions of the offshore drilling platform and the riser of the present invention.

[0046] Figure 3 It is a schematic diagram of the structure of the system of the present invention.

[0047] In the figure, 1. offshore drilling platform, 2. riser, 3. seabed, 4. tensioner, 5. first inclinometer, 6. second inclinometer, 7. third inclinometer, 8. fourth inclinometer, 9. blowout preventer, 10. compass. DETAILED DESCRIPTION

[0048] The technical solution of the present application will be described clearly and completely below in conjunction with the accompanying drawings. Obviously, the described embodiments are part of the embodiments of the present application, not all of the embodiments. Based on the embodiments in the present application, all other equivalent transformations obtained by ordinary technicians in the field without creative work are within the scope of protection of the present application.

[0049] like Figure 1 As shown, a method for determining the optimal position of an offshore drilling platform 1 comprises the following steps:

[0050] Step 101, obtaining the current status information of the riser 2 and the current position information of the offshore drilling platform 1.

[0051] Among them, the current state information includes the upper flexible joint angle, the lower flexible joint angle, the effective bottom end tension, the effective top end tension and the geometric stiffness coefficient.

[0052] Specifically, the offshore drilling platform 1 is provided with a GPS device and a compass 10, and the current position information of the offshore drilling platform 1 can be obtained through the GPS device and the compass 10. A first inclinometer 5 and a second inclinometer 6 are installed on the top of the watertight riser 2, and a third inclinometer 7 and a fourth inclinometer 8 are installed on the bottom of the watertight riser 2; accordingly, the upper flexible section angle of the watertight riser 2 can be obtained through the first inclinometer 5 and the second inclinometer 6; the lower flexible section angle of the watertight riser 2 can be obtained through the third inclinometer 7 and the fourth inclinometer 8.

[0053] In this embodiment, a spatial rectangular coordinate system is established with the bottom end of the watertight pipe 2 as the coordinate origin, the z-axis of the spatial rectangular coordinate system is perpendicular to the seabed 3, the plane formed by the x-axis and y-axis of the spatial rectangular coordinate system is parallel to the seabed 3, the upper flexible node angle of the watertight pipe 2 is the angle between the top end of the watertight pipe 2 and the z-axis, and the lower flexible node angle of the watertight pipe 2 is the angle between the bottom end of the watertight pipe 2 and the z-axis.

[0054] like Figure 2 As shown, the top of the riser 2 is connected to the tensioner 4 and maintained in a tensioned state. In the vertical direction, the forces acting on the riser 2 include: (1) the top force of the riser 2, which is equal to the tension of the top tensioner 4; (2) the weight of the riser 2 itself;

[0055] (3) Mud gravity; (4) The tension of the bottom joint of the watertight pipe 2 is equal to the effective bottom tension. The horizontal lateral forces on the watertight pipe 2 include the current force. Among them, the stiffness of the watertight pipe 2 with various muds can be obtained through supplier inquiries. Correspondingly, the effective top tension of the watertight pipe 2 can be obtained through the above-mentioned tensioner 4. The tension of the top tensioner 4, the gravity of the watertight pipe 2, and the gravity of the mud in the watertight pipe 2 are all measured in real time. The effective bottom tension is calculated by measuring the inclination angle between the watertight pipe 2 and the bottom blowout preventer 9. The geometric stiffness coefficient of the watertight pipe 2 is calculated based on the characteristics of the watertight pipe 2 itself and the mud characteristics.

[0056] Step 102, determining the moving distance and moving angle of the offshore drilling platform 1 according to the current status information of the watertight riser 2 and the current position information of the offshore drilling platform 1; wherein, when the offshore drilling platform 1 moves based on the moving distance and the moving angle, the upper flexible joint angle and the lower flexible joint angle of the watertight riser 2 reach the minimum.

[0057] Specifically, the moving distance and moving angle of the offshore drilling platform 1 can be calculated according to the following formula:

[0058]

[0059]

[0060]

[0061] u e =(A T W T WA) -1 A T W T WΘ;

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[0065]

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[0074] Where Δu is the moving distance, ξ is the moving angle, T b is the effective bottom tension of the riser 2, T t is the effective top tension of the watertight pipe 2, α b is the lower flexible joint angle of the watertight pipe 2, α t is the upper flexible joint angle of the watertight pipe 2, Q b is the bottom shear force of the riser 2, Q t is the top shear force of the watertight riser 2.

[0075] Δx is the displacement in the X-axis direction, Δy is the displacement in the Y-axis direction, and u e is the weighted equivalent offset, A is the simplified matrix, W is the weighted matrix, Θ is the upper and lower angle value, u e is the equivalent offset vector, is the inclination angle between the bottom and the ZX plane, is the inclination angle between the bottom and the ZY plane, is the inclination angle between the top and the ZX plane, is the inclination angle between the top and the ZY plane, x e is the equivalent displacement in the X-axis direction, y e is the equivalent displacement in the Y-axis direction, x b is the bottom displacement in the X-axis direction, y b is the displacement of the bottom Y axis, x t is the top X-axis displacement, y t is the top Y-axis displacement, γ b is the angle between the bottom offset vector and the X axis, γ t is the angle between the top offset vector and the X axis, u b is the bottom offset vector, u t is the top offset vector, u bf is the bottom displacement of the riser 2 caused by external load, u tf is the top displacement of the riser 2 caused by external load, α bo is the lower flexible node angle caused by the displacement of the top of the riser 2, α to is the upper flexible node angle caused by the displacement of the top of the riser 2, α bf is the lower flexible node angle of the riser 2 caused by the lateral load, α tf It is the upper flexible node angle of the watertight riser 2 caused by the lateral load.

[0076] K T is the geometric stiffness of the riser, T ti , T bi is the top tension and bottom tension of riser segment i, w i is the weight of riser segment i.

[0077] This embodiment determines the moving distance and moving angle of the offshore drilling platform 1 based on the current status information of the watertight riser 2 and the current position information of the offshore drilling platform 1, so that the upper flexible joint angle and the lower flexible joint angle of the watertight riser 2 are minimized, thereby improving the safety and integrity of the watertight riser 2.

[0078] like Figure 3 As shown, a system for determining the optimal position of an offshore drilling platform 1 includes a riser 2 connecting the offshore drilling platform 1 and a seabed 3, and further includes:

[0079] The acquisition module 310 includes a first inclinometer 5 and a second inclinometer 6 disposed at the top of the watertight pipe 2, a third inclinometer 7 and a fourth inclinometer 8 disposed at the bottom; and a tensioner 4 disposed at the top of the watertight pipe 2 and a blowout preventer 9 disposed at the bottom. The upper flexible section angle of the watertight pipe 2 is acquired through the first inclinometer 5 and the second inclinometer 6;

[0080] The angle of the lower flexible section of the watertight riser 2 is obtained by the third inclinometer 7 and the fourth inclinometer 8 .

[0081] The third inclinometer 7 and the fourth inclinometer 8 are both connected to the hydrophone by wireless communication via the underwater beacon.

[0082] The top end of the watertight pipe 2 is connected to the tensioner 4 and maintained in a tensioned state; the effective top tension of the watertight pipe 2 is obtained through the tensioner 4. A blowout preventer 9 is arranged at the bottom end of the watertight pipe 2. The blowout preventer 9 is arranged on the seabed 3.

[0083] The determination module 320 is a computer capable of calculating the moving distance and the moving angle, and is used to determine the moving distance and the moving angle of the offshore drilling platform 1 according to the current state information of the watertight riser 2 and the current position information of the offshore drilling platform 1.

[0084] The installation method of wireless communication of two underwater inclinometers in the present application is simple and convenient, information is easy to obtain, and easy to implement, which reduces the equipment configuration of the existing monitoring system, such as flow meters, strain sensors, communication lines or wireless hydroacoustic beacons.

[0085] It should be noted that, in this article, the terms "include", "comprises" or any other variations thereof are intended to cover non-exclusive inclusion, so that a process, method, article or device including a series of elements includes not only those elements, but also other elements not explicitly listed, or also includes elements inherent to such process, method, article or device. In the absence of further restrictions, an element defined by the sentence "comprises a ..." does not exclude the existence of other identical elements in the process, method, article or device including the element.

[0086] Through the description of the above implementation methods, those skilled in the art can clearly understand that the above-mentioned embodiment methods can be implemented by means of software plus a necessary general hardware platform, and of course by hardware, but in many cases the former is a better implementation method. Based on such an understanding, the technical solution of the present application, or the part that contributes to the prior art, can be embodied in the form of a software product, which is stored in a storage medium (such as ROM / RAM, a magnetic disk, or an optical disk), and includes a number of instructions for a terminal (which can be a mobile phone, a computer, a server, an air conditioner, or a network device, etc.) to execute the methods described in each embodiment of the present application.

[0087] The embodiments of the present application are described above in conjunction with the accompanying drawings, but the present application is not limited to the above-mentioned specific implementation methods. The above-mentioned specific implementation methods are merely illustrative and not restrictive. Under the guidance of the present application, ordinary technicians in this field can also make many forms without departing from the scope of protection of the purpose of the present application and the claims, all of which belong to the scope of protection of the present application.

Claims

1. A method for determining the optimal position of an offshore drilling platform, characterized in that: The following steps are involved: Acquire current status information of the riser and current position information of the offshore drilling platform, wherein the current status information includes an upper flexible joint angle, a lower flexible joint angle, an effective bottom tension, an effective top tension, and a geometric stiffness coefficient; Determine the moving distance and moving angle of the offshore drilling platform according to the current state information of the riser and the current position information of the offshore drilling platform; When the offshore drilling platform moves based on the moving distance and the moving angle, the upper flexible joint angle and the lower flexible joint angle of the riser reach a minimum; Determine the moving distance and moving angle of the offshore drilling platform according to the current state information of the riser and the current position information of the offshore drilling platform; The calculation formula for the moving distance and moving angle of the offshore drilling platform is as follows: u e =(A T W T WA) -1 A T W T WΘ; Where Δu is the moving distance, ξ is the moving angle, T b is the effective bottom tension of the riser, T t is the effective top tension of the riser, α b is the lower flexible joint angle of the riser, α t is the upper flexible joint angle of the riser, Q b is the bottom shear force of the riser, Q t is the top shear force of the riser; Δx is the displacement in the X-axis direction, Δy is the displacement in the Y-axis direction, and u e is the weighted equivalent offset, A is the simplified matrix, W is the weighted matrix, Θ is the upper and lower angles, u e is the equivalent offset vector, is the inclination angle between the bottom and the ZX plane, is the inclination angle between the bottom and the ZY plane, is the inclination angle between the top and the ZX plane, is the inclination angle between the top and the ZY plane, x e is the equivalent displacement in the X-axis direction, y e is the equivalent displacement in the Y-axis direction, x b is the bottom displacement in the X-axis direction, y b is the displacement of the bottom Y axis, x t is the top X-axis displacement, y t is the top Y-axis displacement, γ b is the angle between the bottom offset vector and the X axis, γ t is the angle between the top offset vector and the X axis, u b is the bottom offset vector, u t is the top offset vector, u bf is the bottom displacement of the riser caused by external load, u tf is the top displacement of the riser caused by external load, α bo is the lower flexible node angle caused by the displacement of the riser top, α to is the upper flexible node angle caused by the displacement of the top of the riser, α bf is the lower flexible node angle of the riser caused by the lateral load, α tf is the upper flexible node angle of the riser caused by the lateral load; K T is the geometric stiffness of the riser, T ti , T bi is the top tension and bottom tension of riser segment i, w i is the weight of riser segment i.

2. A method for determining the optimal position of an offshore drilling platform according to claim 1, characterized in that: The top of the watertight riser is provided with a first inclinometer and a second inclinometer, and the bottom is provided with a third inclinometer and a fourth inclinometer; The upper flexible section angle of the watertight riser is obtained by using the first inclinometer and the second inclinometer; the lower flexible section angle of the watertight riser is obtained by using the third inclinometer and the fourth inclinometer.

3. A method for determining the optimal position of an offshore drilling platform according to claim 2, characterized in that: A spatial rectangular coordinate system is established with the bottom of the watertight riser as the coordinate origin, the z-axis of the spatial rectangular coordinate system is perpendicular to the seabed, the plane formed by the x-axis and y-axis of the spatial rectangular coordinate system is parallel to the seabed, the upper flexible node angle of the watertight riser is the angle between the top of the watertight riser and the z-axis, and the lower flexible node angle of the watertight riser is the angle between the bottom of the watertight riser and the z-axis.

4. A method for determining the optimal position of an offshore drilling platform according to claim 1, characterized in that: The top end of the riser is connected to the tensioner and maintained in a tensioned state; Obtaining the effective top tension of the riser through the tensioner; The geometric stiffness coefficient of the watertight riser is calculated according to the watertight riser's own characteristics and mud characteristics.

5. A system for implementing the method for determining the optimal position of an offshore drilling platform according to any one of claims 1 to 4, comprising a watertight pipe connecting the offshore drilling platform and the seabed, characterized in that: Also includes: An acquisition module includes a first inclinometer and a second inclinometer disposed on the top of the riser, and a third inclinometer and a fourth inclinometer disposed on the bottom; As well as a tensioner set at the top of the watertight pipe and a blowout preventer set at the bottom; the blowout preventer is set on the seabed.

6. The system according to claim 5, characterized in that: The third inclinometer and the fourth inclinometer are both wirelessly connected to the hydrophone via the underwater beacon.

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