CN115964909A - Dynamic characteristic analysis method based on riser-drill rod contact collision effect model - Google Patents
Dynamic characteristic analysis method based on riser-drill rod contact collision effect model Download PDFInfo
- Publication number
- CN115964909A CN115964909A CN202211082928.XA CN202211082928A CN115964909A CN 115964909 A CN115964909 A CN 115964909A CN 202211082928 A CN202211082928 A CN 202211082928A CN 115964909 A CN115964909 A CN 115964909A
- Authority
- CN
- China
- Prior art keywords
- riser
- drill rod
- marine
- marine riser
- drill
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Pending
Links
Images
Classifications
-
- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02T—CLIMATE CHANGE MITIGATION TECHNOLOGIES RELATED TO TRANSPORTATION
- Y02T90/00—Enabling technologies or technologies with a potential or indirect contribution to GHG emissions mitigation
Landscapes
- Earth Drilling (AREA)
Abstract
The invention provides a dynamic characteristic analysis method based on a marine riser-drill rod contact collision effect model. According to the dynamic characteristic analysis method based on the riser-drill rod contact collision action model, provided by the invention, a plurality of iterations are executed, the effective load, the speed, the acceleration and the like are calculated, the motion process of the riser and the drill string after collision is analyzed, and then the dynamic characteristic of the riser is analyzed. The influence of various factors on the dynamic characteristics of the marine riser in the actual operation process is analyzed by the characteristic analysis method, the marine riser is adjusted, and the marine riser is ensured to be in a safety range.
Description
Technical Field
The invention relates to the technical field of deep sea drilling, in particular to a dynamic characteristic analysis method based on a riser-drill rod contact collision effect model.
Background
With the advance of the development of the offshore oil and gas to the deep sea, the marine riser plays an increasingly important role in the development of the offshore oil and gas, is mainly used for connecting a drilling platform and a seabed blowout preventer, and plays roles in isolating the seawater and circulating drilling fluid. The load that the water-proof pipe received during deep water drilling operation is very complicated, takes place to warp under the influence of marine environment load earlier, can contact the collision with inside drilling rod after the deformation, produces the contact force. The drill rod and the marine riser are worn and failed due to the long-term contact effect between the drill rod and the interior of the marine riser, and even equipment can be damaged in serious conditions, so that serious safety accidents are caused.
At present, a contact collision action model between a marine riser and a drill rod is basically perfect at home and abroad, a dynamic model can be established by using a Hamilton principle, then a Hermite cubic interpolation method is used for discretization, a finite element model is established, and finally a Newmark integral method is used for carrying out dynamic response analysis on the model. However, the analysis of the riser-drill string coupled pipe-in-pipe model is still in the initial stage of research, and since the riser swings continuously along with the marine environmental load, the collision boundary of the riser and the drill string is a free movement boundary, and the collision contact is also random contact, so that the collision contact state is difficult to determine. From the existing research situation, a learner proposes to establish a set of collision contact calculation formula for any node of a pipe string by using a collision theory of theoretical mechanics, and assumes an elastic collision recovery coefficient, so that the motion state of any node after collision can be obtained, but the collision force and the collision time cannot be obtained, and the collision of the marine riser and each node of the pipe string are mutually influenced, and the generated collision contact is coupled, so that the collision is difficult to describe by a uniform formula. In summary, the contact collision effect of the marine riser and the inner drill rod is mostly not considered in the prior art, and the prior art is not in line with the actual operation situation, so that on one hand, the drill rod can affect the dynamic response of the marine riser, and on the other hand, the drill rod can cause the wear of the marine riser due to the contact collision with the marine riser.
Disclosure of Invention
Aiming at the problems, the invention provides a dynamic characteristic analysis method based on a riser-drill rod contact collision effect model.
A dynamic characteristic analysis method based on a riser-drill rod contact collision effect model is characterized by comprising the following specific steps of establishing a riser dynamic model considering the drill rod contact collision effect, solving by combining a finite element method and a Newmark-beta method, and further analyzing the dynamic characteristic of a riser, wherein the specific steps comprise:
the method comprises the following steps: inputting basic parameters, setting initial values of drill pipe and marine riser (u) 0 }，
Dividing a time grid and a space grid;
step two: forming a rigidity matrix [ K ], a mass matrix [ M ] and a damping matrix [ C ] of the marine riser and the drill pipe based on the content of the step one;
step three: calculating marine environment load of the marine riser and contact collision force of the drill pipe;
step four: obtaining an effective rigidity matrix of the drill rod according to the drill rod contact impact force calculated in the third step, obtaining an effective rigidity matrix of the marine riser according to the drill rod contact impact force and marine environmental load of the marine riser, and performing triangular decomposition on the effective rigidity matrix of the drill rod and the marine riser;
step five: iterative solution is carried out by using a Newmark-beta method, the time step is selected to be delta t, and parameters gamma and beta are set;
step six: and calculating the effective load at the t + delta t moment, solving the displacement at the t + delta t moment, then solving the speed and the acceleration, and outputting the result.
Further, the riser-drill pipe contact collision action model simplifies rigid risers and drill pipe circular tubes into elastic beams, does not consider shear deformation, establishes a two-dimensional coordinate system in the z direction and the y direction, and obtains a motion differential equation and a stress balance equation according to the Lalangbeil principle and an applied force chemical balance analysis, and comprises the following steps:
the differential equation of motion of the marine riser in the y direction is as follows:
the differential equation of the motion of the drill rod in the y direction is as follows:
the stress balance equation of the fluid infinitesimal section in the z direction is as follows:
the stress balance equation of the marine riser micro-element section in the z direction is as follows:
the axial force calculation formula of the marine riser is as follows:
T e ＝T-A i P i +A o P o ＝T top -A i P top (1-2ε)-(m r +m f -ρA o )g(L-z)；
EI and EI' are bending rigidity of the marine riser and the drill rod; m is a unit of f 、m f ' is the fluid quality in the marine riser and drill pipe per unit length, m r 、m p The mass of the marine riser and the drill rod per unit length, V is the fluid velocity in the pipe, F is the environmental load, F c The impact force of the drill pipe and the marine riser is used as c, the structural damping is used as c, the sectional area of the riser is A, and the tension on the section is T; p i 、P o Is the static pressure of the fluid inside and outside the riser, T top Is riser top tension, P top Is the riser top pressure, A i 、A o The internal and external cross-sectional areas of the riser are shown, and epsilon is the Poisson ratio.
Further, a dynamic characteristic analysis method based on a riser-drill pipe contact collision effect model, wherein the calculation of the contact collision force defines the contact collision of the riser and the drill pipe as a concentrated force with small elastic deformation and small contact range, and comprises the following steps:
wherein k is a contact stiffness coefficient,
is the clearance between the drill rod and the water-resisting pipe>
As the relative velocity of the drill pipe and riser, c f Is the crash damping coefficient.
Further, the dynamic characteristic analysis method further comprises a representation of boundary conditions, wherein the boundary conditions comprise a riser boundary condition and a drill pipe boundary condition, and the method comprises the following steps:
the boundary conditions of the marine riser are as follows:
/>
the boundary conditions of the drill rod are as follows:
the EI is the bending stiffness of the riser, and the l is the lengths of the riser and the drill pipe.
Further, the calculation of the marine environmental load adopts a morrison equation, which specifically comprises:
wherein, C D Is the drag coefficient, rho is the sea water density, C M Is a coefficient of the inertial force, and, u x is the horizontal velocity of the wave water particle,
is the horizontal acceleration of the water particles of the wave, A is the projected area per unit height of the cylinder perpendicular to the wave propagation direction, V 0 Is the displacement volume per height of the column, u is the current velocity, and D is the outer diameter of the riser or buoyancy block.
Further, the effective stiffness matrix is expressed as:
[K * ]＝[K]+a 0 [M]+a 1 [C]；
for effective rigidity matrix [ K * ]Performing triangle decomposition, specifically:
[K * ]＝[L][D][L]T；
further, in the step of iterative solution by a Newmark-beta method, a time domain analysis method is adopted to solve the dynamic response of the marine riser, and the method comprises the following steps:
the payload at time t + Δ t satisfies:
the displacement at the moment t + delta t satisfies the following conditions:
the acceleration at time t + Δ t is:
the speed at time t + Δ t is:
wherein the content of the first and second substances,
payload at time t + Δ t;
acceleration->
Displacement u i+1 And speed->
The relationship between them is: />
Calculating integral constant gamma is more than or equal to 0.5, beta =0.25 (0.5 + gamma) 2 。
The invention has the beneficial effects that: the invention provides a dynamic characteristic analysis method based on a marine riser-drill rod contact collision effect model, which establishes a marine riser dynamic model considering the drill rod contact collision effect and solves displacement, speed and acceleration by combining a finite element method with a Newmark-beta method. A plurality of iterative processes are executed in the whole process, the motion process of the marine riser and the drill string after collision is analyzed, and then the dynamic characteristics of the marine riser are analyzed. The influence of various factors on the dynamic characteristics of the marine riser in the actual operation process is analyzed, so that the marine riser is adjusted and is ensured to be in a safety range.
Drawings
FIG. 1 is a flow chart of a dynamic characteristic analysis method based on a riser-drill pipe contact collision effect model, which is provided by the invention;
FIG. 2 is a schematic diagram of drill pipe-drill pipe contact collision in a dynamic characteristic analysis method based on a riser-drill pipe contact collision effect model according to the present invention;
FIG. 3 is a graph of displacement, bending moment and rotation angle of the dynamic characteristic analysis of the marine riser under different influence factors by the dynamic characteristic analysis method based on the marine riser-drill pipe contact collision effect model provided by the invention;
FIG. 4 is an average displacement difference, collision probability and average collision force diagram of the dynamic characteristic analysis method based on the riser-drill pipe contact collision effect model for the dynamic characteristic analysis of the riser under different influence factors, provided by the invention;
FIG. 5 is a displacement, bending moment and average collision force diagram of the dynamic characteristic analysis of the marine riser under different top tensions by the dynamic characteristic analysis method based on the marine riser-drill rod contact collision effect model provided by the invention;
FIG. 6 is a time history chart of the average displacement difference and the collision force of the dynamic characteristic analysis of the marine riser under different top tension conditions by the dynamic characteristic analysis method based on the marine riser-drill pipe contact collision effect model provided by the invention;
FIG. 7 is a displacement, bending moment and average collision force diagram of the dynamic characteristic analysis of the marine riser under different platform deflection conditions by the dynamic characteristic analysis method based on the marine riser-drill pipe contact collision effect model provided by the invention;
FIG. 8 is a time history chart of the average displacement difference and the collision force of the dynamic characteristic analysis of the marine riser under different platform deflection conditions by the dynamic characteristic analysis method based on the marine riser-drill pipe contact collision effect model provided by the invention;
FIG. 9 is a diagram of displacement, bending moment and average collision force of the dynamic characteristic analysis method based on the riser-drill pipe contact collision effect model for the dynamic characteristic analysis of the riser under different ocean current velocities, according to the embodiment of the invention;
FIG. 10 is a time history chart of displacement difference and collision force of a marine riser dynamic characteristic analysis method based on a marine riser-drill pipe contact collision effect model under different ocean current velocities according to the invention;
FIG. 11 is a displacement, bending moment and average collision force diagram of the dynamic characteristic analysis method of the marine riser under different drilling pressures based on the marine riser-drill pipe contact collision effect model;
FIG. 12 is a time history chart of the average displacement difference and the collision force of the dynamic characteristic analysis method of the marine riser under different drilling pressures based on the marine riser-drill pipe contact collision effect model;
Detailed Description
In order to more clearly understand the technical features, objects, and effects of the present invention, embodiments of the present invention will now be described with reference to the accompanying drawings.
The invention provides a dynamic characteristic analysis method based on a riser-drill rod contact collision effect model, which is characterized in that a riser dynamic model considering the drill rod contact collision effect is established, a finite element method is combined with a Newmark-beta method for solving, and then the dynamic characteristic of a riser is analyzed, as shown in figure 1, the method comprises the following specific steps:
the method comprises the following steps: inputting basic parameters, setting initial values of drill pipe and marine riser (u) 0 }，
Dividing a time grid and a space grid;
step two: forming a rigidity matrix [ K ], a mass matrix [ M ] and a damping matrix [ C ] of the marine riser and the drill pipe based on the content of the step one;
step three: calculating marine environment load of the marine riser and contact collision force of the drill pipe;
step four: obtaining a drill rod effective rigidity matrix according to the drill rod contact collision force calculated in the step three, obtaining a marine riser effective rigidity matrix according to the drill rod contact collision force and marine environmental load of the marine riser, and performing triangular decomposition on the drill rod and the marine riser effective rigidity matrix;
step five: iterative solution is carried out by using a Newmark-beta method, the time step is selected to be delta t, and parameters gamma and beta are set;
step six: and calculating the effective load at the t + delta t moment, solving the displacement at the t + delta t moment, then solving the speed and the acceleration, and outputting the result.
In addition, in this embodiment, the riser-drill pipe contact collision action model simplifies the rigid riser and drill pipe circular pipe into an elastic beam, and the two-dimensional coordinate system in the z direction and the y direction is established without considering shear deformation, and the motion differential equation and the stress balance equation are obtained according to the laranbel principle and the stress chemical balance analysis, and include:
the differential equation of motion of the marine riser in the y direction is as follows:
the differential equation of the motion of the drill rod in the y direction is as follows:
the stress balance equation of the fluid infinitesimal section in the z direction is as follows:
the stress balance equation of the marine riser micro-element section in the z direction is as follows:
the axial force calculation formula of the marine riser is as follows:
T e ＝T-A i P i +A o P o ＝T top -A i P top (1-2ε)-(m r +m f -ρA o )g(L-z)；
EI and EI' are bending rigidity of the marine riser and the drill rod; m is a unit of f 、m f ' is a unit length riserMass of fluid in the drill pipe, m r 、m p The mass of the marine riser and the drill rod per unit length, V is the fluid velocity in the pipe, F is the environmental load, F c The impact force of the drill pipe and the marine riser is used as c, the structural damping is used as c, the sectional area of the riser is A, and the tension on the section is T; p i 、P o Is the static pressure of the fluid inside and outside the riser, T top Is riser top tension, P top Is the riser top pressure, A i 、A o The inner and outer cross-sectional areas of the riser are shown, and the epsilon is the Poisson's ratio.
In this embodiment, the method for analyzing the dynamic characteristics based on the riser-drill pipe contact collision effect model further includes calculating a contact collision force, as shown in fig. 2, the riser-drill pipe contact collision is defined as a concentrated force with small elastic deformation and small contact range, specifically:
wherein k is a contact stiffness coefficient,
is the clearance between the drill rod and the water-resisting pipe>
Is the relative speed of the drill pipe and the riser, c f Is the crash damping coefficient.
In this embodiment, the method for dynamic characteristics analysis further includes representing boundary conditions, where the boundary conditions include a riser boundary condition and a drill pipe boundary condition:
the boundary conditions of the marine riser are as follows:
the boundary conditions of the drill rod are as follows:
wherein, EI is the bending stiffness of the riser, and l is the length of the riser and the drill rod.
In this embodiment, the calculation of the marine environmental load uses the morrison equation, which specifically includes:
wherein, C D Is the drag coefficient, rho is the sea water density, C M Is the coefficient of inertia force, u x Is the horizontal speed of the wave water particle,
is the horizontal acceleration of the water mass point of the wave, A is the projected area per unit height of the cylinder perpendicular to the wave propagation direction, V 0 Is the displacement volume per height of the column, u is the current velocity, and D is the outer diameter of the riser or buoyancy block.
The effective stiffness matrix is expressed as: [ K ] * ]＝[K]+a 0 [M]+a 1 [C]；
For effective rigidity matrix [ K * ]Performing triangle decomposition, specifically: [ K ] * ]＝[L][D][L] T ；
In the iterative solution step of the Newmark-beta method in the embodiment, the finite element method is combined with the Newmark-beta to solve the equation, and the time domain analysis method is adopted to solve the acceleration of the marine riser dynamic response
Displacement u i+1 And speed->
The relationship between them is:
the payload at the time t + delta t satisfies:
the displacement at the moment t + delta t meets the following conditions:
the acceleration at time t + Δ t is:
the speed at time t + Δ t is:
wherein the content of the first and second substances,
calculating integral constant gamma is more than or equal to 0.5, beta =0.25 (0.5 + gamma) 2 。
In a first embodiment, according to the dynamic characteristic analysis method based on the riser-drill pipe contact collision effect model provided by the invention, the dynamic characteristics of the riser under different influence factors are analyzed, and the calculated displacement, speed, acceleration and the like are used for observing the distribution of parameters such as transverse displacement, bending moment, average collision force, average displacement difference, collision force time history and collision probability of the riser, so as to judge the optimal processing mode of the riser under different influence factors. As shown in fig. 3, the displacement, bending moment and corner diagram of the drill pipe and the marine riser can be obtained as follows: the maximum lateral displacement of the riser and the drill pipe occurs in the middle, and the maximum displacement is 35.7m. The drill rod displacement is consistent with the change of the displacement of the marine riser, which indicates that the drill rod and the marine riser are in contact collision, so that the drill rod and the marine riser deform together. Extreme bending moments of the marine riser are generated near the water surface and at the bottom end, the maximum value is 18kN m, the bending moment of the drill rod is smaller than that of the marine riser, and the bending moments of the drill rod and the marine riser are consistent in distribution. Because the top end of the drill rod is fixedly restrained and the bottom end of the drill rod is a free end, the rotating angle of the top end of the drill rod is 0, and the rotating angles of the drill rod and the marine riser tend to be consistent at the bottom end and have the maximum value. As can be seen from fig. 4, the average displacement difference and the collision probability of the drill pipe and the riser can be obtained by a graph: the collision probability of the drill pipe and the left wall surface of the marine riser is increased from the bottom to the top, the collision probability of the right wall surface is gradually reduced from the bottom to the top, and the maximum value of the collision probability and the collision force is shown at the bottom end. The contact force near the bottom end of the riser and the water surface is larger, which indicates that the contact collision of the two places is the most serious, and the distribution is the same as the extreme value distribution of the bending moment of the riser. It can be seen that the drill pipe is in contact with and rubs against the bottom flexible joint for a long time, and the large contact load is very likely to cause abrasion between the drill pipe and the riser wall, which results in the reduction of the service life of the flexible joint and the strength of the riser. When the marine riser displaces, the drill rod is static, the marine riser firstly moves under the action of external load, and then the left wall surface of the marine riser is in contact collision with the drill rod and drives the drill rod to deform together. Therefore, a large collision force is generated at the moment of contact collision, and the movement state of the drill pipe and the riser is gradually stabilized with time, so that the contact collision force is also reduced.
In a second embodiment, the dynamic characteristic analysis method based on the riser-drill pipe contact collision effect model provided by the invention is used for analyzing the dynamic characteristic of the riser under different top tensions, as can be seen from the displacement and bending moment diagram in fig. 5, the larger the top tension of the riser is, the smaller the displacement of the riser is, and the smaller the bending moment is. This is because increasing the tension of the riser, equivalent to increasing the bending stiffness, increases the resistance of the riser to deformation, and thus a phenomenon occurs in which the displacement is significantly reduced. From the average collision force and average displacement difference in FIG. 5, it can be seen that: with the increase of the top tension, the contact section of the drill rod and the marine riser is reduced, the collision force is reduced, and the collision probability of the drill rod and the marine riser is reduced. When the top tension is higher, the transverse displacement of the marine riser is smaller, the corner of the flexible joint at the bottom is reduced, and the bending moment is reduced, so that the contact load between the two is reduced. According to the curve of the collision force of the flexible joint at the bottom and the vicinity of the water surface at the upper end (the connecting part of the first buoyancy block and the bare single) along with the time history in the figure 6. As can be seen from the figure, the bottom end collision force continuously changes along with time, the change degree is relatively gentle, and the maximum collision force appears about 20s, which indicates that the drill pipe and the marine riser are always in contact at the bottom end. The marine riser near the water surface is displaced under the action of external load and gradually contacts and collides with the drill rod, the marine riser is in contact and collides with the drill rod for about 0.6s to generate maximum collision force, the marine riser is in contact and collides for about 1.5s for the second time, and the collision force is gradually reduced and tends to be stable along with the time, which indicates that discontinuous intermittent collision is formed near the water surface. This is because the speed of the ocean current near the water surface is high, and the drill pipe and the riser generate a large displacement difference after colliding, so that the drill pipe and the riser frequently contact. Comparing the time histories at the two positions shows that the impact force at the bottom position is influenced more by the top tension than near the water surface. In this embodiment, the following parameters can be obtained by observing and comparing the displacement, bending moment and corner of the drill pipe and the marine riser: in the actual operation process, the deformation resistance of the marine riser can be enhanced by properly increasing the top tension, so that overlarge deformation and bending moment of the marine riser under severe working conditions are prevented, and the frequency of collision between a contact area and contact of the drill rod and the marine riser system is reduced, thereby reducing friction and abrasion between the drill rod and the marine riser system caused by collision. However, in deep water, the axial force is too large due to the increase of the top tension, the stress condition of the riser can be improved by arranging the buoyancy block, and the riser is ensured to be in a safe range.
Similarly, in the third embodiment, the method proposed by the present invention is used to analyze the dynamic characteristics of the riser at different platform offsets, as can be seen from the displacement and bending moment diagram in fig. 7, as the platform offset increases, the transverse displacement and bending moment of the riser increase. Because the top end of the marine riser is connected with the platform and the bottom end of the marine riser is connected with the blowout preventer, when the platform deflects, the top end of the marine riser moves the same distance along with the platform, and the deformation of the marine riser is increased. From the difference between the average collision force in FIG. 7 and the average displacement in FIG. 8, it can be seen that: along with the offset of platform increases, the contact section of drilling rod and riser reduces, and the drilling rod has obvious increase with the contact impact of riser in the bottom position, and is not obvious to the impact near the surface of water influence. The probability of drill pipe to riser collision also increases slightly, indicating that increased platform offset will cause more frequent drill pipe to riser collisions. This is because after the platform takes place the skew, the riser with the drilling rod along with the platform takes place the skew, the drilling rod hugs closely the riser left wall face this moment. When the maximum displacement position of the marine riser rises along with the increase of the offset, the drill rod gradually separates from the left wall surface of the marine riser and gradually contacts and collides with the right wall surface under the action of gravity, and the most direct consequence of the increase of the offset of the platform is that the corner of the bottom end is increased, so that the component of the gravity in the direction of the marine riser at the bottom end is increased, and the contact force is larger. As can be seen from the time histories of the impact forces at the bottom end position and near the water surface of fig. 8, the impact force at the bottom end position increases with increasing platform displacement and varies continuously with time. And according to the displacement difference diagram, the bottom end position is always kept in contact with the marine riser. The collision between the drill rod near the water surface and the marine riser system frequently contacts and collides with each other along with the time, along with the increase of the offset of the platform, the time for the first collision is increased, the maximum contact collision force is reduced, and the collision force tends to be stable after a period of time. The reason is that when the offset is large, the corner of the marine riser near the water surface is small, and the component of the gravity of the drill rod on the marine riser is reduced. Comparing the collision force near the water surface and the bottom end, the collision force near the water surface does not change greatly along with the increase of the platform deviation after the contact collision is stable, which shows that the impact of the platform deviation on the bottom end is larger than that near the water surface. Therefore, under severe sea conditions, the offset of the drilling platform should be controlled within a small range, so as to reduce the transverse displacement and bending moment of the marine riser, facilitate the reduction of the contact force of the flexible joint at the bottom end, and reduce the occurrence of friction and abrasion. If the offset of the platform is too large, the corner of the flexible joint at the bottom end is increased, so that the collision force at the bottom end is increased, the marine riser, the flexible joint and the like are damaged, and the connection must be disconnected.
Similarly, in the fourth embodiment, the dynamic characteristics of the riser at different current velocities are analyzed by using the method proposed in the present invention, as shown in the displacement, bending moment and average collision force in fig. 9 and the displacement difference in fig. 10: the change of the current speed has no obvious influence on the contact collision position of the marine riser and the drill pipe, but the collision force and the collision probability of the left wall surface and the right wall surface are increased along with the increase of the current speed, which is approximately the same as the distribution rule of the bending moment. According to the ackermann drift theory, the water velocity profile along the water depth is determined by the superficial velocity and increases with increasing water velocity, thereby increasing the ocean current force. Therefore, the current flow rate is increased, the external load of the marine riser and the drill pipe is increased, and the collision is severe. As can be seen from the time history plots at the bottom of fig. 10 and near the water surface, the collision force increases with the flow velocity of the ocean current. The drill rod at the bottom end is always in contact with the marine riser; the first buoyancy block is configured to be in violent contact collision with the connecting part of the bare single, and the maximum collision force is increased along with the increase of the speed of the ocean current, gradually reduced along with the time and tends to be stable. Comparing the change of the collision force between the bottom end and the connecting part of the first buoyancy block and the bare single can see that the influence of the increase of the ocean current speed on the bottom end collision is larger than that of the part near the water surface. It can be found that the influence degree of the current flow velocity on the marine riser dynamic characteristics is greater than the top tension and the platform offset, and the influence of the actual sea condition on the marine riser dynamic characteristics is very important. The increase of the current speed not only increases the contact collision force of the drill pipe and the riser system, but also causes high-frequency contact load between the drill pipe and the riser due to vortex discharge caused by the current, thereby causing severe abrasion. In a sea area with a large ocean current flow velocity, monitoring is enhanced, and a marine riser with a large wall thickness is configured to prevent damage to the marine riser due to abrasion caused by collision.
Similarly, in the fifth embodiment, the dynamic characteristics of the riser at different weight-on-bit are analyzed by using the method provided by the present invention, and as can be seen from the displacement, bending moment, average collision force and average displacement difference at different weight-on-bit in fig. 11 and 12, the weight-on-bit has no significant influence on the displacement and bending moment of the riser. This is because the environmental load on the riser from the seabed to the surface area does not change under the drilling condition, and the deformation and stress of the riser are not changed. The increase in weight on bit slightly reduces the contact area of the drill pipe and the riser, and also reduces the collision force of the drill pipe and the riser at the bottom end, but has little influence on the collision probability between the drill pipe and the riser. Increasing the weight on bit is equivalent to reducing the axial tension of the drill rod, and reducing the deformation resistance of the drill rod, thereby reducing the collision force of the drill rod and the marine riser. As can be seen from the time history of the bottom-end and near-surface impact forces in fig. 12, the bottom-end impact force always keeps the drill pipe in contact with the riser at the bottom end position, and decreases with the increase in the weight on bit. Frequent contact collisions occur near the water surface, and the collision force gradually decreases and stabilizes over time. It can be seen that the change in weight-on-bit has little effect on the impact forces near the water surface. The weight on bit has little effect near the water surface because the axial force of the drill string is greater closer to the water surface than the bottom end position, and the weight on bit is very small relative to the axial force near the water surface, while the bottom end axial force is smaller, and the weight on bit can have a larger effect. Therefore, when drilling operation is carried out, the bottom end is stressed most seriously, the drill rod and the marine riser are often in serious contact collision, and when the drilling pressure is overlarge, attention is paid to preventing abrasion damage caused by the contact collision effect of the drill rod and the marine riser. The weight on bit decreases during tripping, which increases the risk of the drill pipe colliding with the riser system if the drill pipe is lifted hard or the axial force of the drill pipe is increased substantially. Therefore, when the drill bit is pulled out, the drill rod needs to be uniformly and slowly lifted, and the collision is prevented from being greatly changed.
The invention provides a dynamic characteristic analysis method based on a marine riser-drill rod contact collision effect model, which establishes a marine riser dynamic model considering the drill rod contact collision effect and solves displacement, speed and acceleration by combining a finite element method with a Newmark-beta method. A plurality of iterative processes are executed in the whole process, the motion process of the marine riser and the drill string after collision is analyzed, and then the dynamic characteristic of the marine riser is analyzed. The riser is adjusted by analyzing the influence of various factors on the dynamic characteristics of the riser in the actual operation process, so that the riser is ensured to be in a safety range.
The foregoing illustrates and describes the principles and general features of the present invention, together with the advantages thereof. It will be understood by those skilled in the art that the present invention is not limited to the embodiments described above, which are described in the specification and illustrated only to illustrate the principle of the present invention, but that various changes and modifications may be made therein without departing from the spirit and scope of the present invention, which fall within the scope of the invention as claimed. The scope of the invention is defined by the appended claims and equivalents thereof.
Claims (7)
1. A dynamic characteristic analysis method based on a riser-drill rod contact collision effect model is characterized in that the dynamic characteristic analysis method based on the riser-drill rod contact collision effect model is used for solving by establishing a riser dynamic model considering the drill rod contact collision effect and combining a finite element method with a Newmark-beta method, and then analyzing the dynamic characteristic of a riser, and the method comprises the following specific steps:
the method comprises the following steps: inputting basic parameters, setting initial values of drill pipe and marine riser (u) 0 }，
Dividing a time grid and a space grid;
step two: forming a rigidity matrix [ K ], a mass matrix [ M ] and a damping matrix [ C ] of the marine riser and the drill pipe based on the content of the step one;
step three: calculating marine environment load of the marine riser and contact collision force of the drill pipe;
step four: obtaining a drill rod effective rigidity matrix according to the drill rod contact collision force calculated in the step three, obtaining a marine riser effective rigidity matrix according to the drill rod contact collision force and marine environmental load of the marine riser, and performing triangular decomposition on the drill rod and the marine riser effective rigidity matrix;
step five: iterative solution is carried out by using a Newmark-beta method, the time step is selected to be delta t, and parameters gamma and beta are set;
step six: and calculating the effective load at the t + delta t moment, solving the displacement at the t + delta t moment, then solving the speed and the acceleration, and outputting the result.
2. The method of claim 1, wherein the riser-drill pipe contact collision interaction model simplifies rigid risers and drill pipe circular pipes into elastic beams, establishes two-dimensional coordinate systems in the z direction and the y direction without considering shear deformation, and the differential equations of motion and the force balance equations are obtained according to the Ralangbeil principle and the mechanical equilibrium analysis, and comprises:
the differential equation of motion of the marine riser in the y direction is as follows:
the differential equation of the motion of the drill rod in the y direction is as follows:
the stress balance equation of the fluid infinitesimal section in the z direction is as follows:
the stress balance equation of the marine riser micro-element section in the z direction is as follows:
the axial force calculation formula of the marine riser is as follows:
T e ＝T-A i P i +A o P o ＝T top -A i P top (1-2ε)-(m r +m f -ρA o )g(L-z)；
wherein, EI,EI' is the bending rigidity of the riser and the drill rod; m is a unit of f 、m f ' is the fluid quality in the marine riser and drill pipe per unit length, m r 、m p The mass of the marine riser and the drill rod per unit length, V is the fluid velocity in the pipe, F is the environmental load, F c The collision force of the drill pipe and the marine riser is used as c, the structural damping is used as c, the sectional area of the riser is A, and the tension on the section is T; p is i 、P o Is the static pressure of the fluid inside and outside the riser, T top Is riser top tension, P top Is the riser top pressure, A i 、A o The internal and external cross-sectional areas of the riser are shown, and epsilon is the Poisson ratio.
3. The method of claim 1, wherein the calculating of the contact impact force defines the riser-to-drill pipe contact impact as a concentrated force with small elastic deformation and small contact range, and comprises:
wherein k is a contact stiffness coefficient,
is the clearance between the drill rod and the water-resisting pipe>
As the relative velocity of the drill pipe and riser, c f Is the crash damping coefficient.
4. The method of claim 1, further comprising a representation of boundary conditions, wherein the boundary conditions include a riser boundary condition and a drill pipe boundary condition, and the method comprises:
the boundary conditions of the marine riser are as follows:
the boundary conditions of the drill rod are as follows:
wherein, EI is the bending stiffness of the riser, and l is the length of the riser and the drill rod.
5. The method for analyzing the dynamic characteristics based on the riser-drill pipe contact collision effect model according to claim 1, wherein the calculation of the marine environmental load adopts a Morrison equation, which specifically comprises:
wherein, C D Is drag coefficient, rho is sea water density, C M Is the coefficient of inertia force, u x Is the horizontal speed of the water particle of the wave,
is the horizontal acceleration of the water particles of the wave, A is the projected area per unit height of the cylinder perpendicular to the wave propagation direction, V 0 Is the displacement volume per height of the column, u is the current velocity, and D is the outer diameter of the riser or buoyancy block.
6. The method of claim 1, wherein the effective stiffness matrix is expressed by the following expression:
[K * ]＝[K]+a 0 [M]+a 1 [C]；
for effective rigidity matrix [ K * ]Performing triangle decomposition, specifically:
[K * ]＝[L][D][L] T 。
7. the method for analyzing the dynamic characteristics based on the riser-drill rod contact collision effect model according to claim 1, wherein in the step of solving the Newmark-beta iteratively, a time domain analysis method is adopted to solve the riser dynamic response, and the method comprises the following steps:
the payload at time t + Δ t satisfies:
the displacement at the moment t + delta t meets the following conditions:
the acceleration at time t + Δ t is:
the speed at time t + Δ t is:
wherein [ K ] * ]＝[L][D][L] T In order to be an effective stiffness matrix,
acceleration->
Displacement u i+1 And speed->
The relationship between them is: />
Calculating integral constant gamma is more than or equal to 0.5, beta =0.25 (0.5 + gamma) 2 。/>
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202211082928.XA CN115964909A (en) | 2022-09-05 | 2022-09-05 | Dynamic characteristic analysis method based on riser-drill rod contact collision effect model |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202211082928.XA CN115964909A (en) | 2022-09-05 | 2022-09-05 | Dynamic characteristic analysis method based on riser-drill rod contact collision effect model |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CN115964909A true CN115964909A (en) | 2023-04-14 |
Family
ID=87356750
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CN202211082928.XA Pending CN115964909A (en) | 2022-09-05 | 2022-09-05 | Dynamic characteristic analysis method based on riser-drill rod contact collision effect model |
Country Status (1)
| Country | Link |
|---|---|
| CN (1) | CN115964909A (en) |
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN117113777A (en) * | 2023-09-08 | 2023-11-24 | 武汉理工大学 | Drill string vortex-induced vibration calculation method considering internal flow |
-
2022
- 2022-09-05 CN CN202211082928.XA patent/CN115964909A/en active Pending
Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN117113777A (en) * | 2023-09-08 | 2023-11-24 | 武汉理工大学 | Drill string vortex-induced vibration calculation method considering internal flow |
| CN117113777B (en) * | 2023-09-08 | 2024-04-09 | 武汉理工大学 | Drill string vortex-induced vibration calculation method considering internal flow |
Similar Documents
| Publication | Publication Date | Title |
|---|---|---|
| Burke | An analysis of marine risers for deep water | |
| Raman-Nair et al. | Three-dimensional dynamics of a flexible marine riser undergoing large elastic deformations | |
| CN115964909A (en) | Dynamic characteristic analysis method based on riser-drill rod contact collision effect model | |
| Qin et al. | Nonlinear dynamic characteristics of the drill-string for deep-water and ultra-deep water drilling | |
| Yang et al. | Full time-domain nonlinear coupled dynamic analysis of a truss spar and its mooring/riser system in irregular wave | |
| Li et al. | Dynamic analysis of a deepwater drilling riser with a new hang-off system | |
| CN110344819A (en) | A kind of high temperature and pressure high gas rate well completion tubular column vibration prediction method | |
| CN102252897B (en) | Analysis method of deepwater jack tension riser bending vibration | |
| Mao et al. | Dynamic characteristic analysis of riser considering drilling pipe contact collision | |
| CN113343544B (en) | Mechanical analysis method for lowering coiled tubing into horizontal well | |
| CN102354333A (en) | Method for analyzing out-of-plane motion of steel catenary riser | |
| CN105675255A (en) | Pool simulation experiment system for platform marine riser coupling | |
| Wang et al. | Analysis of marine risers subjected to shoal/deep water in the installation process | |
| Zhao et al. | Dynamic stability of a stepped drillstring conveying drilling fluid | |
| Lou et al. | Experimental and numerical study of dynamic performance of CVAR subjected to regular wave and platform motion | |
| CN109522509B (en) | Stability judgment method for offshore shallow water region bare suspended pipeline | |
| Pavlou | Flow-riser interaction in deep-sea mining: an analytic approach for multi-layered FRP risers | |
| Allen et al. | VIV suppression device development and the perils of Reynolds number | |
| Zhou et al. | Dynamic analysis of drill string in" pipe in pipe" structure while deep water drilling | |
| Jensen et al. | Modelling and control of offshore marine pipeline during pipelay | |
| Patrikalakis et al. | Vortex-induced response of a flexible cylinder in a constant current | |
| Wodtke et al. | FEM calculations in analysis of steel subsea water injection flowlines designing process | |
| Mao et al. | Dynamic analysis of a drilling string for deepwater riserless drilling with vortex-induced vibration considered | |
| Hansen-Zahl et al. | Effect of damping on VIV response in umbilicals and flexible risers | |
| Ormberg et al. | Coupled analysis of offshore floating systems |
Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| PB01 | Publication | ||
| PB01 | Publication | ||
| SE01 | Entry into force of request for substantive examination | ||
| SE01 | Entry into force of request for substantive examination |