Development and application of self-synchronous linear vibrating screen

At present, most of the vibrating screens used in China are single-axis inertial vibrating screens, and their motion trajectories are circular or quasi-circular.The screen has a simple structure, but its screening efficiency is low, the service life of the screen is short, and the drilling fluid loss is large.Since the early 1970s, self-synchronous linear vibrating screens have been tested and studied, but due to the unreasonable overall layout of the vibrating screen, the fixing method of the screen, the performance of the elastomer and the motor, etc., the screen is bulky, the performance is unstable, and the service life of the screen is short. So far, no economical and practical self-synchronous linear vibrating screen has been launched.Foreign countries have done a lot of work on self-synchronous linear vibrating screens, and several companies have launched self-synchronous linear vibrating screens one after another, such as Derrick in the United Kingdom and KEM-TRON in the United States.Self-synchronous linear vibrating screens have become essential equipment when bidding for foreign drilling. Most of the linear screens currently used in China are imported screens, which are mainly used in offshore drilling platforms and land deep well fleets. Judging from the application effect, the purification effect and treatment capacity of drilling fluid can basically meet the design requirements, but the screens are replaced frequently and imported screens are expensive.Therefore, it is urgent to develop a high-performance and long-life self-synchronous linear vibrating screen suitable for the current domestic drilling situation.The Yellow River Drilling Company adopts composite elastic elements to improve the screening effect, and has carried out structural transformation of the vibrating screen in many aspects to improve the working performance of the self-synchronous linear vibrating screen. 1. Working principle The dual-motor self-synchronous exciter device is shown in Figure 1.

The masses of the two eccentric rotors are m1 and m2, respectively, driven by two motors, and rotate in the opposite direction around the O1 and O2 points on the box M with a radius of r and a speed of N. The centrifugal force is F, and the reaction force of the support spring is S1 and S2.To make a linear vibration of the screen box, first m1=m2, n1=n2=n, r1=r2=r, that is, the centrifugal force F1=F2=F.　　As can be seen from Figure 1, at any position, the centrifugal force of the eccentric rotor cancels each other in the horizontal direction.Therefore, every time the rotor rotates, a reciprocating excitation force is generated in the vertical direction, causing the screen box to move in a reciprocating linear motion. If the characteristics of the two motors in the system are the same, the stiffness and damping of each fulcrum are equal, and there is no phase difference when starting again, then the two eccentric blocks will operate synchronously under ideal conditions.In actual work, synchronous operation can not be achieved at any time. Since the two exciters are installed on a base at a certain angle, their initial phase angles are not equal due to gravity. After starting, there will be a phase difference. At this time, although the centrifugal force generated by m1 and m2 is equal, due to the different angles from the vertical direction, the forces in the horizontal and vertical directions are different, which will inevitably produce an unbalanced force that causes the screen box to move and swing on the support spring. It is this kind of movement and swing that makes m1 and m2 follow each other, due to the existence of inertial forces. , So that the phase difference is gradually reduced, and finally the phase difference is zero, reaching a stable state, and achieving the ideal synchronization state.

2. Structural characteristics and performance parameters

2. 1 structure

The structure of the self-synchronous linear vibrating screen is shown in Figure 2.

　In Figure 2, the current sharing adjustment structure is composed of a diversion blade and a current sharing plate. The middle of the screen box is the frame structure of the beam. The exciter sits in the middle of the beam at a certain angle. The front end of the screen box is equipped with an angle adjustment mechanism on the left and right sides to meet the requirements of different screening particles and displacement. A single-layer prestressed hook-edge screen is used. The horizontal 6 pressure plates and the longitudinal compression frame are fixed in both directions. The pressure plate and the screen box are connected with special anti-release bolts. The bolts and the pressure plate are inserted and then rotated 90°, which is conducive to the replacement of the screen. The trajectory of the equipment is linear. The double screen juxtaposition structure (spare) has the advantages of high screening efficiency, large processing capacity, ultra-fine screen can be used, and long service life of the screen.2. 2 Characteristics (1). The trajectory of the screen box is straight, so the movement of drill cutters on the screen surface is regular, and the chip removal is smooth; the angle of the screen box is adjustable, which is used for different screening particles, and the screening effect is good.(2) The drilling fluid adjustment and flow sharing structure are adopted to reduce the erosion of the screen.(3) The use of prestressed screen and two-way screen fixing mechanism, the replacement of the screen is convenient and fast, while extending the service life of the screen; you can use ultra-fine screens above 200 mesh, which do not paste the screen and do not run drilling fluid.(4) Use special springs, which are safe, durable and low noise.

2, 3 performance parameters

3. On-site test situation

3. After the successful trial production of the prototype of the 45-X9 well in Camp 1, the test was first carried out in the 45-X9 well in Camp 1. The well is a directional well with a depth of 2500m. When the vibrating screen was first used, the depth of the well was 780m. The lithology of the formation is mainly mudstone, and the viscosity of the drilling fluid is up to 50s.The vibrating screen has been in operation for a total of 210h from the beginning of use to the completion of the well. The lower layer replaces 5 pieces of screen, 2 pieces of 60 mesh, and 3 pieces of 40 mesh. The average use time is 42h. The replaced screens are mainly 2# screens, and the screens of 1# and 3# screens are well used.The upper layer uses 2 pieces of 175 mesh screens, which are not damaged.The vibrating screen is running smoothly, and the angle adjustment and current sharing adjustment mechanism are operating normally.This proves that the basic structure of the vibrating screen is feasible and can use a fine screen.The problem is that the screen has a short service life.After analysis, the main reason is that the overall rigidity of the screen box is not enough, and the vibration of the screen and the screen box cannot be completely synchronized.3. 2 The second test of the King 24-X30 well vibrating screen was carried out in the King 24-X30 directional well. After drilling at a depth of 2325m, the vibrating screen was used at a depth of 750m. It operated for a total of 192h and replaced 3 pieces of 40 mesh screens. The drilling fluid density is 1.15~1.22g/cm3, the highest viscosity is 55s, the screen is used for an average of 64h, and other components are operating normally, proving that the improvement of the vibrating screen has seen results.Two of the reasons for the broken screen this time were due to human factors, that is, the fixing screws of the screen were loose and not found in time, which caused the sand to accumulate and caused early damage to the screen.Through the tests of the two wells, it was found that the details of the installation of the vibrating screen in the drilling fluid inlet device, the fixing of the screen, and the rigidity of the screen box still need to be improved. For this reason, a double screen was re-installed, and a single-layer screen was used. The screen has a two-way fixing mechanism, and a combined buffer box.3. 3 angle 5-X281 well vibrating screen is improved at angle 5- The X281 directional well was tested, and the drilling depth was 2560m. The small cycle started from 750m, and the upper formation was mainly mudstone.The viscosity of the drilling fluid is up to 60s, the vibrating screen runs for 130h, and a 60 mesh hook-edge screen is used. The screen is not replaced, the drilling fluid is not run, and the screen is not sticky.Due to the poor oil and gas display, after filling the well, the vibrating screen was used again for 120h, and the screen was used for a total of 250h without damage.After that, the vibrating screen was used in well 9-16 in Guangbei. The screen was used for 168h, the 1# screen was used for a total of 418h, and the 2# screen was used for 380h.Use 102h in the wide 3-oblique 28 well sieve, and it works normally.As of October 2002, more than 80 sets of self-synchronous linear vibrating screens have been used in Shengli, North China, Daqing, Liaohe and other oil fields, including 64 sets in Shengli Oilfield, which have been used in more than 1,000 wells, including 38 horizontal wells, 6 scientific test wells, and 62 directional wells. The Xuegu-1 and Xuegu-2 wells in cooperation with Chevron in Shengli Oilfield have been applied and have been highly praised.Compared with the old-fashioned vibrating screen, the average drilling cost per well is about 14,000 yuan.4. Conclusion (1). The trajectory of the self-synchronous linear vibrating screen is easy to realize, and it has the advantages of simple structure, reliable work, high efficiency, and long life.(2) The overall layout of the self-synchronous linear vibrating screen is reasonable, the size is small, the structure is compact, and it is easy to transport and install.(3) The self-synchronous linear vibrating screen can use ultra-fine screens of more than 200 meshes, and the drilling fluid purification effect is high. It creates conditions for drilling to provide high-quality and low-solid-phase drilling fluid, and at the same time can reduce downhole accidents.(4) The vibrating screen uses special springs, which have low noise and are conducive to the health of engineers.

Reference document

[1], Gong Wei'an.Drilling fluid solid phase control technology and equipment.Beijing: Petroleum Industry Press, 1995-04[2], Shen Hong.Manual of Mechanical Engineering.Beijing: Machinery Industry Press, 1983-11

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