Well cleaning operation process and technical points

Well cleaning is a process in which the well cleaning fluid with certain performance is injected into the wellbore at the ground side, and the dirt such as wax formation, dead oil, rust, and impurities on the wall and tubing are mixed into the well cleaning fluid and brought to the surface.

 Cleaning requirement

1.According to the pipe structure requirements of the construction design, the well cleaning pipe string is lowered to the predetermined depth.

 2.Connect the ground pipeline, test the pressure of the ground pipeline to 1.5 times the pump pressure of the design and construction, and pass the test without puncture or leakage after 5 minutes.

 3.Open casing valve and drive well cleaning fluid. When cleaning the well, pay attention to the change of pump pressure, and the pump pressure should not exceed the starting pressure of oil formation water absorption.The displacement is gradually increased after the outlet discharge is normal, and the displacement is generally controlled at 0.3~0.5m³/min, and all the designed amount of cleaning fluid is driven into the well.

 4.Observe and record pump pressure, displacement, outlet displacement and leakage at any time during well cleaning. When the pump pressure rises and the well is blocked, the pump should be stopped, the cause should be analyzed and dealt with in time, and the pump should not be forced to hold.

 5.After effective plugging measures are taken for serious leakage Wells, well cleaning construction is carried out.

 6.For Wells with serious sand production, the reverse circulation method should be prioritized for well cleaning to maintain no spraying, no leakage and balanced well cleaning. The pipe string should be moved frequently when cleaning the well with positive circulation.

 7.When the pipe string is deepened or lifted up during the washing process, the washing fluid must be circulated for more than two weeks before the pipe string can be moved, and the pipe string is quickly connected until the well is cleaned to the construction design depth.

Technical points

 1.The performance index of well cleaning fluid meets the design requirements.

 2.ensure the import and export liquid measurement accurate.

 3.The depth and operation effect of well cleaning shall meet the requirements of construction design.

 4.minimize the leakage of well cleaning fluid into the formation, reduce the pollution and damage to the formation.

5. after the end of the well cleaning, the relative density of the inlet and outlet of the cleaning fluid should be consistent, and the outlet fluid should be clean and free of impurities and pollution.