| Title | Quantitative Phase Analysis of HTCC EM Logs |
|---|---|
| Authors | R. Williams |
| Year | 2022 |
| Conference | New Zealand Geothermal Workshop |
| Keywords | Casing, Inspection, Corrosion, Electromagnetic, Quantitative |
| Abstract | MB Century’s High Temperature Casing Condition – Electromagnetic (HTCC-EM) tools assess wellbore casing thickness along with the internal diameter and roughness/cracking of the inside of the casing. The HTCC-EM can operate up to 280°C allowing measurements to be made without the need to quench the well. The HTCC-EM uses three electromagnetic (EM) instruments to perform these assessments: Phase to assess casing thickness, Caliper to assess internal diameter and RI to assess roughness and cracking. The assessments tend to be qualitative because of a range of effects that cannot easily be quantified. Bore field operators prefer quantitative reports of defects in their wells. Quantitative results are easier for making judgements on casing condition and are not influenced by inherent variation in human interpretation. QPA was developed to turn the qualitative metal loss from HTCC-EM logs into quantitative metal loss to satisfy customers’ needs. QPA is limited to the Phase instrument of the HTCC-EM log. It does not consider or attempt to calibrate Caliper or RI instruments. QPA follows on from research dating back to 2011, where some work was done to quantify the Phase instrument. This was used to provide quantitative thickness of casing defects in some specially commissioned reports. These reports were used to help customers manage their fields and have been used for example to prioritize workover activity. Recently a customer had a requirement to report quantitative casing thickness over the whole log. This was achieved by extending the QPA concept – perform QPA of each defect in the well and combine the QPA minimum casing thickness values into a table that formed part of the report. This paper details how QPA works, the accuracy that can be achieved, and the assumptions made. |