Analysis of problems in the use of vibrating screen:

1. Short service life of vibrating screen

The main reasons for the rapid damage of screen mesh are clay accumulation, wrong rotation direction of motor, loose fit between screen mesh and screen frame, and poor screen mesh quality.

(1) The amplitude of clay accumulation vibration is too small, which is difficult to screen under the condition of polymer drilling fluid, and can not effectively overcome the viscosity of drilling cuttings (clay), resulting in the accumulation of drilling cuttings on the screen and rapid damage to the screen.

resolvent:

① Increase the vibration amplitude;

② Flush the screen and drilling cuttings with sprayed water to reduce the viscosity of drilling cuttings, but this method is only suitable for occasions where water is allowed to be added;

③ Adjust the angle of the screen at the end of the sand discharge port downward, which is conducive to the removal of rock debris by gravity, but may lead to slurry loss;


④ Change the mesh size of the screen or adjust the flow rate of the single screen. * The flow stop of the drilling fluid is close to the screen outlet, allowing the drilling cuttings to be discharged smoothly under the lubrication of the drilling fluid.

2. Motor steering error

During the commissioning of the motor steering, the field operator, based on the previous experience in the use of single shaft shale shaker or linear screen, believed that it was OK as long as the drilling cuttings went forward, but this method was not applicable to the translational elliptical shale shaker. If the motor rotates inwards by mistake, the ejection angle is 45 ° forward, but the drilling cuttings have the force to roll backward. At this time, the drilling cuttings move forward much slower, stay on the screen for a long time, and even cause the drilling cuttings cannot be discharged.

resolvent:

① When the screen box is running, press the stop button of the electric control box. At this time, the vibrating screen will stop slowly. Observe the elliptical track formed by the small points on the side plate when the vibrating screen is running. Rolling towards the sand outlet is the correct turning direction;

② Remove the cover of the vibrator and check whether the eccentric block rotates outward;

③ Replace any two phase lines in the incoming power supply of the electric cabinet, and sprinkle some sand on the screen. The one with faster sand discharge speed is the right direction.

3. The screen mesh and screen frame do not fit tightly, and the screen mesh cannot be contacted reliably after the rubber strip supporting the screen mesh is worn; The screen is not properly tightened.

Solution: Replace the worn rubber strip, so that the screen mesh can be reasonably tightened.

4. Poor screen mesh quality The screen mesh generally has the upper screen layer and the lower stress layer. It is required that these two layers should closely fit. If the screen mesh pre tensioning process is poor, when the stress layer at the bottom of the screen mesh is tensioned, the screen layer is not tensioned, and the throwing force of drilling cuttings is greatly reduced during operation, so the drilling cuttings cannot be screened and discharged smoothly.

Solution: Replace the qualified and high-quality screen.

5. Bleeding

The reasons for shale shaker mud loss are: high solid content, high viscosity and dispersed drilling cuttings in drilling fluid; The vibrating screen has small vibrating force, high mesh number and small screen area; The direction and position of the liquid inlet of the shale shaker are inappropriate during on-site installation. It is analyzed from the following aspects:

(1) The rapid drilling of the surface layer will produce a large amount of solid phase, occupying the effective screen area, so the fine screen cannot be used in the shallow well section.

(2) The medicine added in the drilling fluid was not fully dissolved and was pasted on the sieve screen. It should be used after the drug is fully dissolved.

(3) When drilling to loose sand bearing strata or quicksand layers, sand particles are easy to get stuck in the screen mesh hole, causing screen plugging. Therefore, it is necessary to test several screens with different mesh sizes to reduce screen plugging.

(4) The greater the vibration amplitude, the greater the processing capacity; The greater the viscosity of drilling fluid, the smaller the treatment capacity; The smaller the density, the smaller the treatment capacity.

(5) The drilling fluid returned from the wellhead flows into the liquid inlet bin of the shale shaker from the elevated slot through the diversion slot. After buffering, it flows evenly to the shale shaker with hook screen structure at the head end of the screen. The screen surface on both sides of the screen *. The drilling fluid is easy to flow to both sides and escape. Therefore, the drilling fluid should enter the screen frame from the middle.

6. Motor fixing bolt broken

The fixed bolts of the motor are broken, which is generally caused by the looseness during the vibration process due to insufficient bolt tightening force, or the insufficient strength of fasteners, and sundries between the bottom surface of the motor and the base plate surface.

resolvent:

① High strength bolts of grade 10.9 and nuts of grade 10 shall be used, and high strength flat gaskets with hardness greater than 45 HRC shall be used;

② Tighten the motor bolts according to the correct installation sequence;

③ The torque shall be selected according to 70% of the bolt breaking strength. Under strong vibration, the contact surface of the motor and the base plate is forced to deform, resulting in a gap. Therefore, a torque wrench must be used to re tighten the motor fixing bolts; ④ The joint surface between the motor bottom and the base plate is uneven or has sundries. Although the bolts reach the tightening torque, the joint surface will produce small gaps in a short time. Not only will severe impact loads be generated between the motor and the base plate, but also the motor will slide horizontally, which is easy to cut the bolts.

7. Electrical fault

(1) Improper setting of the overheat relay of the electric control box will also cause the vibration motor to start but trip frequently. Generally, the actual working current of the 1.86kW motor is about 2.2 A, so it is reasonable to set the current setting value at 3~4 A.

(2) Mechanical problems can also cause the overheating relay to act, such as the loosening of motor fixing bolts, resulting in unbalanced load, and failure of the bearing of the vibrating motor.

8. Cracking of screen box side plate

When the connection part between the vibration shaft and the side plate is cracked, first check whether the rotation direction of the motor and the installation method of the eccentric block are correct. When the screen box is operated in a correct way, the force on the side plate of the screen box is not large, and the repair welding of the cracked part can be used normally.