Working in conjunction with the Division of Oil, Gas, and Geothermal Resources, or DOGGR,
SoCalGas is diligently testing every well at our Aliso Canyon Storage Facility.
Using a rigorous Two-Phase Well Testing Procedure ensures that every storage well in our system
is operating safely, now and into the future.
Natural gas storage wells consist of two layers of cement bonded to steel casing.
The surface casing supports the well while the permanent Well Production Casing runs
from the surface down to the natural gas storage reservoir.
Steel Tubing sits inside the Well Production Casing from the surface to the Liner, which
is the transition into the natural gas storage reservoir.
At the bottom of the casing, a Packer seals the well and helps preserve pressure.
Once the well is sealed, the tubing is used to inject or withdraw natural gas.
Next, is a review of the DOGGR-approved Two-Phase Well Testing Procedure.
Phase One consists of temperature and noise tests.
During the temperature test, a thermometer is lowered down the well on a weighted wire
through the tubing to test for temperature variations.
A temperature drop could indicate a leak.
The noise test is conducted as the wire is pulled back to the surface using a sensitive
microphone to record and listen for sound frequency changes that might indicate a leak.
If the well does not pass Phase One testing, the well is idled, repaired, or permanently abandoned.
If the well passes Phase One testing, Phase Two testing for integrity and pressure begins.
Phase Two testing starts when a Workover Rig is moved onto the wellhead, allowing the inspection
crew to install equipment that provides pressure control of the well during the six-step testing procedure.
Next, the interior steel tubing along with the existing Packer are pulled from the well.
They are replaced with temporary tubing known as Work String and a retrievable Bridge Plug
at the bottom of the well just above the Liner.
The Ultrasonic Imaging Test uses sound waves to measure the thickness of the casing and
cement quality to verify the pressure the pipe can withstand.
This test runs concurrently with the Cement Bond Test, which uses sound waves to measure
the quality of the adhesion between the casing and the cement, as well as the cement and
the surrounding rock formation.
The Magnetic Flux Leakage Test creates a magnetic field to measure for any pitting in the
steel casing and the thickness of the steel.
The Multi-Arm Caliper Test measures the internal diameter of the steel casing while searching
for changes in the wall integrity.
If the well passes all previous tests, the final two-stage pressure test begins.
The two-stage Hydro Pressure Tests begin when fluid is pumped into the well and pressurized
above the maximum operating pressure to ensure that the casing is secure.
After the first pressure test, the Bridge Plug is removed and new Tubing is installed
along with a new Packer.
The second pressure test is performed.
Conducting two separate pressure tests provides extra assurance of the well’s integrity.
After all testing has been performed the fluid is removed.
If the well does not pass the pressure test, it is either idled, repaired, or permanently abandoned.
If the well completes all tests and is approved, it will be put back into service once the
entire facility has completed the DOGGR Well Testing Procedure.
Natural gas can be injected or withdrawn only through the inner tubing for added safety.
Finally, all Aliso Canyon facility wells will be monitored continually for pressure changes
and scanned daily with an infrared camera, resulting in a daily log of each well.
Multi-stage well testing offers the soundest approach to maintaining the ongoing integrity of our wells.
SoCalGas is committed to the safety of our customers, our employees, and the communities we serve.