In the previous article, we discussed the main causes of sucker rod pump failure and how to diagnose pumping well failures. This article will detail common troubleshooting methods for pumping wells and the steps for analyzing abnormal wells. Without further ado, let's take a look.
III. Common Troubleshooting Methods for Pumping Wells:
1. Casing Pressurization Method:
This method is suitable for resolving problems where a floating or fixed valve is stuck on its seat and cannot be opened.
Specific Procedure: Check the tightness of the wellhead pipeline connections and connect the pressure-holding pipeline. Then, use a pump truck to pump oil or gas into the annular space of the casing to increase pressure. Simultaneously, start the pump. When the pressure reaches 3-5 MPa, the fixed valve of the pump can be opened.
2. Piston Removal Method:
Lift the polishing rod, remove the piston from the working cylinder, and move it up and down for 0.5 to 1 hour. Then, replace the piston in the working cylinder. This will remove the stuck piston. 3. Bare rod fastening method: When the thread of the bare rod or 1~2 sucker rods below the bare rod is disengaged, it is generally manifested as a large difference in the upper and lower strokes of the pumping unit's suspension load, and the oil well will not produce oil. The sucker rod fastening operation is as follows: (1) Stop the donkey head at the bottom dead center. (2) Close the back pressure valve and vent the wellhead. (3) Remove the bare rod sealing box and remove the sealing ring. (4) First tighten the lifting ring or coupling on the bare rod, then loosen the square clip of the bare rod on the rope hanger and lower the bare rod for fastening. There are two methods for fastening: manual fastening and power fastening. (5) Check the anti-collision distance, add the sealing ring, open the back pressure valve, and start pumping. 4. Pump collision method: The pump collision method is to adjust the pump's anti-surge distance to zero or a negative value. When the piston reaches the bottom dead center, it collides with the fixed valve cover, generating an impact force, which shakes off the sand deposited on the fixed valve and the floating valve, so that the valve ball and the valve seat are sealed. This method is a commonly used method to remove minor sand jams in shallow wells (within 1000m). Operation steps: (1) Stop the sucker rod near the bottom dead center and use a square clip to lock the light rod at the sealing box, turn the pump, and unload the sucker rod load. (2) Mark the light rod under the rope hanger. (3) Loosen the square clip on the rope hanger. Slowly release the brake. When the mark under the rope hanger is approximately larger than the original anti-surge distance during upward movement, tighten the brake and re-lock the square clip on the rope hanger. (4) Release the brake, remove the square clip on the sealing box, and start the pumping unit to make the plunger and the fixed valve collide 3 to 5 times.
(5) After the collision, re-align the anti-surge distance.
(6) Start the pumping unit and check whether the anti-surge distance is appropriate.
5. Well washing method:
Well washing is the main method to solve oil well failures. It is suitable for sucker rod pump valve sand, wax stuck, pump down oil inlet equipment blockage, etc.
Well washing precautions:
(1) The well washing fluid should be determined according to the liquid conditions in the well. Oil wells without water or with water content below 20% should use crude oil as well washing fluid, and well water with water content greater than 20% should use well washing fluid.
(2) The temperature requirement of the well washing fluid is 70~80℃, and the outlet temperature is not lower than 60℃.
(3) Reverse circulation well washing is used during flushing. The amount of well washing fluid used is not less than 2 times the wellbore volume. The displacement is gradually increased from small to large, generally 15~30m³/h.
(4) During the well washing process, if the donkey head is found to be running slowly during the up and down strokes, it means that there is wax stuck. The displacement should be increased and it is strictly forbidden to stop the machine.
(5) The current should be measured before and after the well washing. The current should return to normal level after the well washing.
Well selection principles:
(1) Well washing should be carried out according to the wax deposition cycle of the oil well.
(2) Wells with reduced production or increased load due to wax deposition must be washed in time.
(3) Wells that are judged to be pump leakage after pressure buildup should be washed.
(4) Wells with sand stuck in the pump should be washed.
(5) Wells that are judged to be partially blocked in the oil inlet should be washed in time.
IV. Analysis steps for abnormal wells:
1. Ground fault analysis:
1) Analysis of the working condition of the pumping well：
(1) Listen for abnormal noises from the various operating parts of the pumping unit. If there are any, they should be handled in time.
(2) Check whether the fixing screws are loose. If they are loose, they should be tightened in time.
(3) Check the rod, gearbox, and motor for heat. If the rod is hot, it means the seal is too tight; if the gearbox is hot, it means there is too much oil; if the motor is hot, it means the load is too large or there is a fault inside the motor.
(4) Check whether the power supply voltage and distribution box are normal.
2) Wellhead process analysis Check whether the gate valves at the wellhead are opening normally and whether there is oil or gas leakage at the wellhead.
3) Process analysis from the wellhead to the well group
(1) Check whether the pipeline from the wellhead to the well group is blocked or leaking. Blockage: wellhead back pressure increases; leakage: wellhead back pressure decreases.
(2) Check whether the metering room process is correct and whether the metering is accurate. (Note: For most oil and gas fields, metering rooms have become history. Remote digital instruments have officially replaced metering room processes. This requires a timely understanding of the situation of individual wells and tracking and analysis of production changes.)
(3) Check whether the temperature of the oil pipeline and the heating pipeline is normal.
2. Wellbore analysis:
(1) Based on the pressure buildup and the indicator diagram, analyze and determine whether the fixed valve and the floating valve are leaking.
(2) Based on the changes in load, current and the indicator diagram, determine whether the oil well is waxing.
(3) Based on the gas production and the indicator diagram, analyze whether it is affected by gas.
(4) Based on the indicator diagram, current, load and changes in production, determine whether the pump is disconnected or the rod is broken.
(5) Based on the indicator diagram, pressure buildup and dynamic liquid level, analyze whether the oil pipe is disconnected and leaking.
(6) Based on the dynamic liquid level, pressure buildup and the indicator diagram, analyze whether the oil inlet is blocked or the liquid supply is insufficient.
3. Reservoir analysis:
Analyze the changes in formation pressure and the injection-production relationship.
V. Common Problems and Solutions for Pumping Unit Lubrication:
Pumping units are powered by an electric motor, which converts the motor's high-speed rotation into low-speed rotation on the output shaft via a reduction gear mechanism. The reduction gear mechanism plays a crucial role throughout its operation. Its complex internal structure, heavy loads, and high torque output make it a crucial component in mechanical oil production. Ensuring long-term, efficient, and stable operation requires the proper functioning of the lubrication system, which is crucial for the performance of the equipment. During field operations, reduction gear lubrication failures are a prominent issue, hindering the daily work of equipment personnel. This article proposes feasible solutions from the perspectives of equipment performance analysis and improved management. Beam pumping units are crucial equipment in oilfield production. While their types and models vary, their main structural components share a fundamentally similar operating principle. They consist of four main components: the beam-connecting-rod crank mechanism, the reduction gear mechanism, the power unit, and the auxiliary device. The pumping unit reduction gear box, as a key component of the pumping equipment, is the most critical part, enduring high torque and speed during operation. Oil leakage often occurs due to factors such as long-term wear, fatigue, aging, manufacturing quality and on-site management. The lubrication of the reduction mechanism is very important. If the lubrication is poor, a series of faults such as bearing burning and gear wear may occur. This is the main cause of damage to the reduction mechanism and will cause many problems to oil field production and on-site management.