First, the main cleaning method
1. Mechanical wax removal of the pig
Soft pig pathfinding: Use a soft pig for the first time to detect pipe deformation or blockage and confirm pipeline smoothness.
Mechanical pig scraping: Mechanical pig with steel brush or scraper is used to remove wax and corrosion from the pipe wall through interference design. For example, the Leather Bowl Straight Plate Mixing Pig can carry positioning equipment for precise pigging.
Intelligent pig : integrated detection function, real-time feedback of wax thickness and position on the inner wall of the pipeline, and optimization of cleaning cycle.
Second, Operational procedures and critical control points
1. Preparation before pigging
Check the status of the pig transceiver, valve and instrument to ensure that the seal and function are normal.
The pig interference amount (usually 3%-8% of the pipe inner diameter) is selected according to the degree of wax formation in the pipe.
2. Pigging implementation stage
Process switching: Switching to the sending and receiving process through the forward conveying process to ensure the smooth entry and exit of the pig.
Pressure and temperature monitoring: real-time monitoring of the traveling pressure fluctuation of the pig to avoid jamming; Keep the oil temperature above the wax melting point (e.g. above 40°C) to reduce carryover.
3. Post-pigging treatment
Recover the pig and check for wear, and analyze the composition of the removal to optimize the subsequent cleaning program.
After the resumption of the transfer process, the differential pressure changes are continuously monitored to evaluate the effect of wax removal.
Third,Precautions
1. Safety control: The pigging operation should be equipped with a blowout preventer and an emergency pressure relief device to prevent pipeline overpressure or medium leakage.
2. Environmental protection requirements: The wax-containing sewage generated by cleaning needs to be treated by oil-water separation to avoid environmental pollution.
3. Cycle management: Formulate the cleaning cycle according to the pipeline volume, oil properties and wax formation rate.
Through the above methods, the wax deposition on the inner wall of the pipeline can be effectively removed, the pipeline transportation efficiency can be guaranteed, and the energy consumption can be reduced. The same method can also be used to achieve oil isolation, oil-water isolation, and water caption before the harmless disposal of crude oil pipelines.
