How the Innovative Tri-Axial Geophones Helped to Pinpoint the Source of Slow Building B and C Annulus Pressures

Well integrity assessment is a challenging task that is dependent on continuous technology enhancements, multiple data integration and careful interpretation. Not all challenges may demand immediate intervention and thus have a potential of long-term damage to both the well bore and the reservoir. One such challenge is fluid migration between two reservoirs – either behind the completion or through the damaged completion. In some cases, these fluids may find a way to surface and result in sustained annulus pressures (SAP) at the well head. In some extreme cases, these fluids may even bypass the wellbore and leak to surface. Detecting the exact location of the source(s) of fluid entries and then tracing their path has always been a challenge. While fast building annulus leakage has been historically detected with traditional temperature surveys, a more informative and interpretative approach was taken in spectral noise logging technology. The challenge however remains for slow building leaks for which higher sensitivity sensors are required. Recently, an innovative Tri-Axial Geophones (TAG) based logging technology was introduced and mobilized across several fields to detect sources(s) of slow building Casing-Casing well head annulus pressure in addition to checking the hydraulic isolation of various reservoir layers and aquifers.