Squeeze Cementing Job Evaluation
Post-squeeze evaluation protocols will depend on what the purpose of the job was and also what subsequent operations are to be performed on the well. The first step is usually to check the well for the presence of cement nodes that extend into the casing and are capable of restricting passage of downhole tools, and also to check the rathole below the perforations for remaining cement.
Evaluation options can include a temperature log to confirm the location of injected cement or an acoustic log to evaluate the effectiveness of a squeeze to repair a void behind pipe.
The most common tests are positive or negative pressure tests. If the squeeze cementing is successful, no fluid should be taken or released by the formation.
- The positive pressure test determines if fluid can still be injected into the squeezed formation by pumping into the well using the rig or cementing pumps. In some production wells, it may be impractical to unload the wellbore without returning the well to production. In these cases, a positive pressure test that does not exceed formation-fracture pressure should be conducted after cement has set and, if required, after drillout.
- The negative pressure test determines if fluid flows from the formation in response to a pressure differential by swabbing the well. Another option for negative pressure testing is by circulating a lighter fluid down the tubing and then closing the circulation ports above the packer. The pressure differential should be less than or equal to the expected drawdown pressure under producing conditions.
In squeeze jobs where cement is drilled out, the way the cement drills is an indication of success. If it drills hard all the way, chances are the squeeze job is successful. Soft spots or voids usually indicate an unsuccessful job.
