CN109946205B - method for testing settling drag coefficient of drill cutting particles - Google Patents
method for testing settling drag coefficient of drill cutting particles Download PDFInfo
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- CN109946205B CN109946205B CN201910187854.8A CN201910187854A CN109946205B CN 109946205 B CN109946205 B CN 109946205B CN 201910187854 A CN201910187854 A CN 201910187854A CN 109946205 B CN109946205 B CN 109946205B
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Abstract
The invention discloses a method for testing a settling drag coefficient of drill cutting particles, which comprises a simulated shaft, a high-speed camera, a data collector and a computer, and comprises the following steps: A. carrying out experiment preparation work, sorting experimental settlement cuttings by using a screen, injecting prepared liquid into a simulation shaft, and standing to prevent bubbles; B. aligning a camera to a simulated shaft, gently placing the selected drilling cutting particles with different meshes on the liquid surface, observing a settling experiment of the drilling cutting particles in the liquid, and collecting an object settling image; C. processing the acquired image, and obtaining the settling speed of drill cutting particles by using a frame difference method; D. calculating a sedimentation drag coefficient according to the sedimentation final speed obtained by the experiment; E. and constructing a new shape description factor to obtain a new sedimentation drag coefficient empirical model. The device and the method provided by the invention can carry out depth analysis on the sedimentation drag coefficient of the rock debris particles with different shapes, and improve the prediction precision.
Description
Technical Field
The invention belongs to the technical field of oil and gas field development, and particularly relates to a method for testing a settling drag coefficient of drill cutting particles.
Background
During drilling, well bore cleaning is one of the major problems affecting efficient and safe drilling. The drill cuttings in the wellbore are distributed in the drilling fluid in the form of particles. The drilling fluid is the continuous phase and the drill cuttings are the discontinuous phase, and the drill cuttings are carried out of the wellbore by the drilling fluid. When the drilling fluid is not enough to provide enough energy to move the drill cuttings, a cuttings bed is formed at the bottom of the well, annular space pressure loss is increased due to the formation of the cuttings bed, high torque and high resistance of a drill string are easily caused, sticking of a drill bit causes the problems of difficult casing running and well cementation, large abrasion of a drilling tool, difficult well descending of a logging instrument and the like, and the safety of drilling is influenced. The problem of forcing to re-drill at a certain block due to the dead drill tool has occurred.
the most critical factor for studying the law of rock debris migration is to obtain the coefficient of the sedimentation drag force, and many studies have been made on the coefficient of the sedimentation drag force by the predecessors, such as the "direct calculation of the coefficient of the drag force of spherical particles" in the treatise of Zhang Qing, where the sedimentation of spherical particles is the basis of studying the sedimentation problem, but the particles most frequently encountered by drill cuttings are non-spherical, which requires that a model of the sedimentation drag force coefficient is provided to be suitable for both spherical particles and non-spherical particles. There are many ways to describe non-spherical particles, such as sphericity, equivalent spherical volume radius, roundness, elongation, and flatness, among others. Based on these description methods, some models of the sedimentation drag coefficient are proposed. Ganser (1993) proposes a method to predict the sedimentation drag coefficients of spherical and aspherical shapes, but does not consider the problem of sedimentation directionality. Gholohossei (2016) proposes a model for predicting the coefficient of drag for settling considering both regular and irregular non-spherical particles, but the calculation of the shape description factor has the problem that the shape of the particles cannot be finely distinguished. Xianzhi Song (2017), although considering the problem of sedimentation directionality, has the problem of over-simplification in the calculation of the projected area and the use of the shape description factor. Therefore, a new shape description factor and accurate directional calculation method are needed to obtain the settling characteristics of the drill cuttings in the well.
Disclosure of Invention
Aiming at the problems, the invention provides a method for testing the sedimentation drag coefficient of drill cutting particles, which can test the sedimentation process and analyze sedimentation, can carry out deep analysis on the sedimentation drag coefficients of the drill cutting particles with different shapes, and improves the prediction precision.
the technical scheme of the invention is as follows:
A testing device for the settling drag coefficient of drill cutting particles comprises a simulation shaft and a data acquisition and analysis module;
The simulation shaft is of a transparent cylindrical structure, and scale marks are stuck to the outer side wall surface of the simulation shaft and are arranged along the longitudinal axis and are vertical to the horizontal direction; a wooden base is fixed at the bottom of the simulation shaft, and a drain valve is arranged at the bottom of the simulation shaft;
the data acquisition and analysis module comprises a high-speed camera, a data collector and a computer; the high-speed camera is arranged right opposite to the simulated shaft, is connected to the data collector through a data line of the high-speed camera, and is connected to the computer through the data line of the data collector.
Further, the testing device for the settling drag coefficient of the drill cuttings particles is characterized in that the frame rate of the high-speed camera is 100 frames per second, and the high-speed camera is arranged at a position 1 meter away from the simulated well shaft.
Further, a testing arrangement of drill chip granule settlement drag coefficient, the data collector still has wireless transmission module, connects the computer and transmits data through wifi.
further, the computer is used for analyzing and processing image data and simulating the proposed model.
the invention also provides a device and a method for testing the settling drag coefficient of the drill cutting particles, the device for testing the settling drag coefficient of the drill cutting particles is adopted for testing, and the steps are as follows:
A. Carrying out experiment preparation work, and sorting experimental settlement cuttings by using screens with different meshes; injecting prepared liquid into the simulated well bore, and standing for 12 hours to prevent bubbles from being generated;
B. adjusting a camera to completely cover the whole simulated shaft, slightly putting the selected drilling cutting particles with different meshes into the simulated shaft from the liquid surface, observing the sedimentation experiment of the drilling cutting particles in the liquid, collecting the sedimentation image of the object, and repeating the experiment for 3 times by using the same type of particles in each group;
C. Processing the acquired image, and obtaining the settling speed of drill cutting particles by using a frame difference method;
D. Calculating a sedimentation drag coefficient according to the sedimentation final speed obtained by the experiment;
E. and constructing a new shape description factor to obtain a new sedimentation drag coefficient empirical model.
further, the specific steps of the step C are: and continuously recording the positions of the drill cutting particles passing through different scales by using a high-speed camera in front of the simulated shaft, and calculating the settling velocity of the drill cutting particles by using a frame difference method so as to analyze the motion rule of the drill cutting particles in the whole test process.
Further, the specific calculation step in step D is: by utilizing the force balance principle, the calculation formula of the sedimentation drag coefficient is as follows:
in the formula, Cdthe coefficient of the sedimentation drag force is dimensionless; rhopis the density of the granules in kg/m3；ρfIs the density of the granules in kg/m3；deIs the particle equivalent diameter, m; g is the acceleration of gravity, m/s2(ii) a V is the final sedimentation velocity, m/s.
Further, the specific steps of step E are: constructing a new shape description factor, providing a new sedimentation drag coefficient empirical model, and fitting to obtain empirical parameter values considering the shape and the direction;
the fitting uses the following formula:
Wherein Re is the Reynolds number of the particles, and is dimensionless; a. b, c, d and ksare empirical coefficients, obtained by fitting, and are dimensionless.
The invention has the beneficial effects that:
1. By introducing a new particle description equation, a plurality of non-spherical particles can be described, and the projection areas of different sedimentation angles can be accurately calculated.
2. A new shape description factor is provided, so that the shapes of different particles can be effectively distinguished; the influence of the shape and the direction is considered by the adopted sedimentation drag coefficient model, so that the prediction precision of the sedimentation drag coefficient can be improved.
Drawings
FIG. 1 is a schematic diagram of an apparatus for testing the settling drag coefficient of drill cuttings particles in accordance with an embodiment of the present invention;
FIG. 2 is a flow chart of a device and a method for testing the settling drag coefficient of drill cutting particles according to the present invention;
FIG. 3 is a graph of sedimentation drag coefficient versus Reynolds number as experimentally measured for the present invention;
figure 4 is a graph of the analysis of the predicted settling drag coefficient of the present invention compared to an experimentally measured settling drag coefficient.
In the figure:
The system comprises a simulated shaft 1, a high-speed camera 2, a data collector 3, a computer 4, a liquid discharge valve 5 and a base 6.
Detailed Description
the technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the drawings in the embodiments of the present invention, and it is obvious that the described embodiment is only one embodiment of the present invention, and not all embodiments. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the scope of the present invention.
As shown in figure 1, the device for testing the sedimentation drag coefficient of the drill cuttings particles comprises a simulation well bore 1, a high-speed camera 2, a data collector 3 and a computer 4.
the simulated shaft 1 is a cylindrical structure with a closed bottom and an open upper part, is made of transparent materials (such as glass and plastic), and is 1 meter high and 0.2 meter in diameter. The simulated shaft 1 also comprises a drain valve 5 which is positioned on the side surface of the bottom of the simulated shaft. And a ruler 7 (the scale is millimeter) vertical to the horizontal plane is pasted on the simulated shaft 1 along the axial direction of the simulated shaft. The simulation shaft 1 is arranged on the base 6, the base 6 is of a wood structure and is kept horizontal with the bottom of the simulation shaft 1, and the simulation shaft 1 is ensured to be vertical.
the high-speed camera 2 is located on the side face of the simulated shaft 1, a lens is vertically opposite to the simulated shaft 1, the distance is preferably 1m, the high-speed camera is used for recording the position of drill cutting particles, and the frame rate of the high-speed camera is 100 frames per second. The high-speed camera comprises a camera support and a light exposure plate, and if needed, a pure-color or self-luminous soft light background plate can be arranged on the other side of the simulated shaft.
the data collector 3 consists of a high-speed data transmission line and a collector and can wirelessly transmit data to the computer 4 (the computer is required to be provided with a wifi module and is in matched connection) through a wifi module (any type wifi module sold in the market can be adopted). The computer 4 is used for image analysis and processing and for simulation of the proposed model.
As shown in fig. 2, a device and a method for testing the settling drag coefficient of drill cuttings particles includes the following steps:
in step 101, experiment preparation is performed to sort the experimental settled drill cuttings with screens of different mesh sizes (the screens can be of various sizes, such as 20 mesh, 40 mesh, 60 mesh, 80 mesh, etc., and the screened drill cuttings are separately stored according to the size specification). Injecting prepared liquid (clear water or drilling mud of different oil field blocks) into the simulated shaft, and standing for 12 hours to prevent bubbles;
In step 102, the viewing range of the camera 2 is adjusted to just cover the whole simulated shaft, and the sorted drill cutting particles with different meshes are put into the simulated shaft in batches according to each single particle, and the sedimentation experiment of the drill cutting particles in the liquid is observed to acquire the image of object sedimentation. In order to make the measurement error small, each group of particles was tested at least 3 times (at most 10 times).
In step 103, the acquired image is processed, and the settling speed of the drill cutting particles is obtained by using a frame difference method.
in step 104, the drag coefficient of settling is calculated from the experimentally obtained final settling velocity. The equivalent diameter of the drill cutting particles is calculated as follows:
In the formula (d)eIs the equivalent spherical diameter of the drill cutting particles, m; vpvolume of drill cutting particles, m3。
The particle reynolds number of the drill cutting particles is calculated as follows:
In the formula, Re is the Reynolds number of the particles and is dimensionless; v is the settling velocity, m/s; μ is the liquid viscosity, Pa · s.
in the formula, Cdthe coefficient of the sedimentation drag force is dimensionless; rhopis the density of the granules in kg/m3；ρfIs the density of the granules in kg/m3；deIs the particle equivalent diameter, m; g is the acceleration of gravity, m/s2(ii) a V is the final sedimentation velocity, m/s.
In step 105, a new shape description factor is constructed, resulting in a new empirical model of the settling drag coefficient. The fitting results in empirical parameter values that take into account shape and orientation. Based on the Ganser (1993) model, the fitting takes the following formula:
Wherein Re is the Reynolds number of the particles, and is dimensionless; a. b, c, d and ksthe empirical coefficient is a drag coefficient, is obtained by fitting and is dimensionless; k is a radical ofsThe calculation formula of (2) is as follows:
ks＝(Fα+Fβ)/2
in the formula, alpha and beta are respectively ksThe empirical coefficients of (3) are obtained by fitting. F is a new shape description factor constructed by the invention, and the calculation formula is as follows:
In the formula, degree of sphericitysurface area of sphere representing the same volume as the particle and surface of the particlethe product ratio is calculated by the formula:
φ＝Ss/Sp
In the formula, SsSurface area of spheres of the same volume as the particles, m3；Spis the surface area of the particle, m3。
psi is a form factor, and the specific expression is as follows:
Where S, L and I are the shortest, longest and middle sides, m, respectively, of the smallest circumscribed cuboid of the particle.
FIG. 3 is a graph of the experimentally measured sedimentation drag coefficient versus Reynolds number for the present invention. An empirical relationship for the drag coefficient can be fit from a plot of reynolds number versus drag coefficient.
Fig. 4 is a comparative analysis chart of the sedimentation drag coefficient predicted by the present invention and the sedimentation drag coefficient actually measured in the experiment, the actually measured value is calculated by the force balance equation in the experiment, and the predicted value is calculated by the proposed drag coefficient prediction model. The obtained prediction result is very consistent with the value range of the actual measurement result, and the relative error is not more than 15%. By adopting the method, the prediction accuracy is greatly improved.
According to the embodiment, the device and the method for testing the settling drag coefficient of the drill cutting particles, provided by the invention, introduce the hyper-ellipsoid geometric model, and can effectively solve the defect that the conventional settling drag coefficient model is difficult to accurately describe the particle shape. A new shape description factor is constructed, and compared with the existing shape description factor, the shape description factor provided by the invention can accurately distinguish the particle shapes. Conventional shape-describing factors such as the sphericity method, for example, the sphericity of a cylinder (higher than 20 diameters h-20 d) is 0.471, and the sphericity of a disk (higher than 0.1 diameters h-0.1 d) is also 0.471. The method is simple in calculation, and the settling rule of the drill cuttings in the fluid is clarified through analysis of the particle shape and the settling direction. However, it will be appreciated by those skilled in the art that various modifications can be made to the method of the invention without departing from the scope of the invention, to make the prediction of the coefficient of drag of the invention more accurate. The invention is expected to promote the development of the drilling technology in the fields of oil and gas.
although the present invention has been described with reference to a preferred embodiment, it should be understood that various changes, substitutions and alterations can be made herein without departing from the spirit and scope of the invention as defined by the appended claims.
Claims (2)
1. A test method of the settling drag coefficient of drill cutting particles adopts a test device of the settling drag coefficient of drill cutting particles to test, and the structure of the device comprises a simulated shaft and a data acquisition and analysis module;
The simulation shaft is of a transparent cylindrical structure, and scale marks are stuck to the outer side wall surface of the simulation shaft and are arranged along the longitudinal axis and are vertical to the horizontal direction; a wooden base is fixed at the bottom of the simulation shaft, and a drain valve is arranged at the bottom of the simulation shaft;
The data acquisition and analysis module comprises a high-speed camera, a data collector and a computer; the high-speed camera is arranged right opposite to the simulated shaft, is connected to the data collector through a data line of the high-speed camera, and is connected to the computer through the data line of the data collector;
The frame rate of the high-speed camera is 100 frames per second, and the high-speed camera is arranged at a position 1 meter away from the simulated shaft;
The data collector is also provided with a wireless transmission module which is connected with a computer through wifi and transmits data;
the method is characterized by comprising the following specific experimental steps:
A. Carrying out experiment preparation work, and sorting experimental settlement cuttings by using screens with different meshes; injecting prepared liquid into the simulated well bore, and standing for 12 hours to prevent bubbles from being generated;
B. Adjusting a camera to completely cover the whole simulated shaft, slightly putting the selected drilling cutting particles with different meshes into the simulated shaft from the liquid surface, observing the sedimentation experiment of the drilling cutting particles in the liquid, collecting the sedimentation image of the object, and repeating the experiment for 3 times by using the same type of particles in each group;
C. Processing the acquired image, and obtaining the settling speed of drill cutting particles by using a frame difference method;
D. Calculating a sedimentation drag coefficient according to the sedimentation final speed obtained by the experiment;
E. constructing a new shape description factor to obtain a new sedimentation drag coefficient empirical model;
The specific calculation steps of the step D are as follows: by utilizing the force balance principle, the calculation formula of the sedimentation drag coefficient is as follows:
In the formula, Cdthe coefficient of the sedimentation drag force is dimensionless; rhopIs the density of the granules in kg/m3；ρfis the density of the granules in kg/m3；deis the particle equivalent diameter, m; g is the acceleration of gravity, m/s2(ii) a V is the final sedimentation velocity, m/s;
The specific steps of the step E are as follows: constructing a new shape description factor, providing a new sedimentation drag coefficient empirical model, and fitting to obtain empirical parameter values considering the shape and the direction;
the fitting uses the following formula:
wherein Re is the Reynolds number of the particles, and is dimensionless; a. b, c, d and ksIs an empirical coefficient, is obtained by fitting and is dimensionless;
ksthe calculation formula of (2) is as follows:
ks＝(Fα+Fβ)/2
in the formula, alpha and beta are respectively ksThe empirical coefficients of (a) are obtained by fitting; f is a new shape description factor of the structure, and the calculation formula is as follows:
in the formula, degree of sphericityThe ratio of the surface area of the sphere to the surface area of the particle, representing the same volume as the particle, is calculated by the formula:
φ＝Ss/Sp
In the formula, SsSurface area of spheres of the same volume as the particles, m3；SpIs the surface area of the particle, m3；
Psi is a form factor, and the specific expression is as follows:
where S, L and I are the shortest, longest and middle sides, m, respectively, of the smallest circumscribed cuboid of the particle.
2. The method for testing the settling drag coefficient of drill cuttings particles according to claim 1, wherein the specific steps of the step C are as follows: and continuously recording the positions of the drill cutting particles passing through different scales by using a high-speed camera in front of the simulated shaft, and calculating the settling velocity of the drill cutting particles by using a frame difference method so as to analyze the motion rule of the drill cutting particles in the whole test process.
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