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Diagnosis and solution sharing of common faults in core evacuation, pressurization and saturation device
Date: 2025-08-21Read: 1
In the fields of oil and gas exploration and development, unconventional energy research, and geological engineering, the core evacuation and pressure saturation device, as a device that simulates the occurrence state of formation fluids, is responsible for the key task of fully saturating core samples with water or oil. This device removes air from the pores through vacuum degassing, and then applies pressure to fully immerse the liquid into the tiny pores, providing real and reliable initial conditions for subsequent measurements of physical parameters such as permeability, porosity, and relative permeability.
The core evacuation and pressurization saturation device often encounters problems such as insufficient vacuum degree, uneven saturation, and leakage in high-pressure, sealed, and multiphase operating environments. Mastering the diagnosis and solution methods of common faults is the core guarantee for ensuring the accuracy of experimental data.
Problem 1: Low vacuum degree or long evacuation time
Reason: Vacuum pump oil emulsification or insufficient, pipeline joint leakage, vacuum gauge failure, or poor sealing of core clamp.
Solution: Check and replace the clean vacuum pump oil; Inspect the vacuum pipeline, valves, and joints section by section, apply leak detection fluid to check for leaks; Calibrate or replace the vacuum gauge; Ensure that the sealing rings at both ends of the core are intact and tightly pressed.
Problem 2: Low core saturation or internal gas storage
Reason: incomplete evacuation, insufficient saturation pressure, too fast displacement speed, or mismatched wettability.
Solution: Extend the evacuation time (usually ≥ 4 hours) to ensure that the vacuum degree reaches -0.098 MPa or above; Appropriately increase the pressure saturation pressure (up to 2-5 MPa); Adopting a low-speed displacement method to allow the liquid to slowly penetrate; Select the matching wetting phase liquid based on the lithology (such as using water for hydrophilic rock cores and kerosene for oleophilic rock cores).
Problem 3: System pressure cannot be established or pressure maintenance fails
Reason: Failure of the booster pump, leakage in the high-pressure pipeline, internal leakage in the shut-off valve, or damage to the pressure gauge.
Solution: Check if the manual or electric booster pump is working properly; Detect all connection points with soapy water under high pressure; Replace the sealing gasket or valve; Verify the accuracy of the pressure gauge.
Problem 4: Leakage of core gripper or damage to sealing ring
Reason: Aging of sealing ring, improper installation, pressure exceeding the limit, or uneven end face of rock core.
Solution: Regularly replace oil and pressure resistant rubber or PTFE sealing rings; Ensure that the cutting end face of the rock core is flat; Gradually apply pressure according to regulations to avoid impact loads; Check the metal surface of the gripper for scratches or deformation.
Question 5: Liquid leakage or mixing into the vacuum system
Reason: The shut-off valve between the saturation kettle and the vacuum system is not tightly closed, the liquid level is too high, or the operation sequence is incorrect.
Solution: Strictly follow the process of "emptying first, then saturating"; Confirm that the vacuum side valve is closed before saturation; Control the amount of liquid added to avoid flooding the upper end of the rock core.