Case study of the cementing phase of an observation well at the Pembina Cardium CO2 monitoring pilot, Alberta, Canada

The Pembina field was chosen from several fields within Alberta, Canada, for a geological carbon dioxide (CO2) storage pilot study, in which the injection of CO2 was combined with enhanced oil recovery (EOR). As part of the project, an existing wellbore within the study area was used as a dedicated observation well. The design and initial results during cementing of this observation well are reviewed. The experience of implementing monitoring technologies was analyzed in order to assess existing knowledge for deploying downhole instrumentation used for monitoring and verification of CO2 movements in the subsurface. Analysis indicates that the observation well allows direct monitoring and measurements at reservoir level of multiple variables through geophysical, geochemical, and geomechanical instrumentation, as well as the opportunity to carry out wellbore integrity studies under in situ conditions. A post-cement job and completion analysis that couples downhole measurements and analytical simulation was conducted to improve future installations. Results verified that equivalent circulation density profiles, and minimum and maximum flow rates during placement should be determined prior cementing operations to avoid influx or fracturing in pre-cased observation wells. Results also indicate that pressure signatures during cement circulation are dominated by fluid density, volume, and rate, and not by sensor assemble geometries used to diagnose the operation. Downhole pressure gauges captured the dynamics of cement displacement and were key elements during post-cement job review and assessments of future well integrity. The experience and analyses gained from the installation of this observation well provide valuable insight for CO2 geological storage monitoring and risk/performance assessment.

.Figure optionsDownload as PowerPoint slideResearch highlights▶ Downhole pressure gauges capture the dynamics of cement displacement. They are key to a post-cement job review and future well integrity assessment. ▶ Case study of direct monitoring and measurement of large varieties of parameters and properties at the reservoir level. ▶ Density, volumes, and flow rate have a large impact on cement circulation pressures.