Identify, Remediate and Verify Cross Sectional Cement Barriers for Permanent Well P&A

Abstract

Abstract The expectation for well barriers lasting for eternity and the need to reduce the cost on post-abandonment monitoring are a function of the abandonment method employed. As it currently stands, there exists a comprehensive set of guidelines and procedures that are intended to provide for permanent plug and abandon of wells, however we are proposing a 3-step workflow (IRV) to Identify areas of localized leaks with fluid/gas movements in A/B annulus by using a passive acoustic tool. Then to Remediate the well leaking section by setting a cross-sectional cement plug to create a rock-to-rock barrier, and finally to Verify the barrier by listening to potential liquid/gas leaks above the cement plug. A permanent well abandonment dictates that there should be zero leakage to surface, but the current barrier philosophy is not sufficient to confirm it, as the procedure is to verify the placement of cement by a bond log, but not to evaluate for possible fluid/gas flow paths. On barriers, there is a dispensation that the length may be reduced from 50m to 30m if that is verified by a bond log. The value proposition for our workflow is to focus on the condition of the barrier, and to make emphasis on its ability to resist leakage. Traditional barrier evaluation is based on a subjective interpretation of the response from an active acoustic logging tool. The "quality" of the cement is inferred from evaluating the response of sonic or ultrasonic measurements. The flaw in this approach is that there may be cases where an annular barrier conforms to location, length, and quality of cement but still exhibits annular pressure build-up. The uniqueness of this IRV workflow is to Identify the leakage in A or B annulus by listening to the noise events created by the leakage, then Remediate the well with a cross sectional cement barrier to finally, Verify the barrier with high-definition noise detection tools. The concept was tested by measuring cement sealing quality at DrillWell and P&A Innovation Programs, showing that the newest design of passive acoustic tools can detect flow of both liquid and gas down to extremely low levels. The well leakage was repaired by using the perf, wash and cement technique and injecting cement during a project test at NORCE in 2020-2021 called the PERFORM Project. Since then, several services have been successfully achieved. In conclusion, the system is ready for deployment of the workflow for Identifying Sustainable annulus pressure (SAP) using the passive acoustic tool and mapping both gas and liquid annular flows, from within production tubing, then to repair the SAP by using the Perf, Wash, Cement technique to finally verifying the cement barrier integrity with the acoustic listening tool.