SafeGuard - New well monitoring technology for CCS sites

The Fishbones Jetting/Drilling technology developed by Fishbones AS is proposed to be adapted to serve as a permanent and easily accessed well-based monitoring and early warning system for any or all wells penetrating or surrounding a chosen CO2 sequestration site. For the first time, the Fishbones Jetting/Drilling technology will allow for direct measurement of pore pressure, in-situ stresses, temperature, fluid flow, and deformation of the formations in the near well area without the need for conducting expensive and potentially hazardous well tests. The needles used in Fishbones Jetting/Drilling will be equipped with pore pressure sensors, optic fiber technology, and possibly other load cell equivalent sensors. This project proposal addresses the overall needs in CCS research and innovation of further de-risking CO2 storage and ensuring cost-efficient monitoring of storage containment. Since existing and new wells are identified as the primary containment risk elements. Since these are the most accessible locations for the installation of monitoring devices, we here suggest installing monitoring equipment in the subsurface through well access. In particular, we propose to drill in targeted shale barrier layers, installing Needles at several depths. A corollary of this innovation will also be to assess stresses and pore pressure while drilling new wells. During the first work package, the project team investigated the feasibility of measuring pore pressure in sandstone and shales. Sandstones are more permeable than shales, and pore pressure changes diffuse more quickly through sandstones. The ability to measure pore pressure using needles in sandstone was investigated experimentally using installed needles at various positions in a downscaled well in a sandstone reservoir. The experimentally measured pressure profiles matched theoretical solutions. Additionally, a fracture/leakage path was produced in the wellbore and successfully detected as a perturbation in the measured pressure profile radially outwards from the well. In shale formations, the permeability is low enough that pore pressure, temperature, and stress are highly connected. For example, heating or cooling of the formation will cause a differential expansion of the fluid and rock, altering the pore pressure. A stress increase in the rock will cause compaction of the pore space without the ability of the pore fluid to escape quickly enough, increasing pore pressure. The ability to measure the pore pressure alterations and calculated thermal stresses based on heating or cooling around the well was investigated numerically and experimentally in a similar project. Future tests focus on the measurement of in-situ stress using strain gauges. Results: WP-1 - pore pressure in shales and sandstones Pore pressure measurements inside a shale and sandstone specimen were achieved. It was possible to observe theoretically predicted changes and changes due to fracturing. It seems that the pore pressure measurements allow the detection of fractures and permeability changes. WP-2 - in-situ stress measurement Both radial and axial sensors respond in the expected direction in most cases. The radial load case generated satisfactory results for both rock formations, allowing an absolute calibration of the sensors. For the axial load cases, firmly pronounced post-loading relaxation periods were observed. A possible reason could be the shearing and movement of the Fishbones needle in the engulfed epoxy. The sensor response may give a non-monotonous response, making it impossible to distinguish between loading or unloading load cases for the axial load case. The plasticity and ongoing undrained pore pressure equilibration can be the reason for the lower repeatability of measurements for the shale formation.

With the successful WP-1 and WP-2, the technical base in a laboratory environment was established to take the project to the next phase beyond the current CLIMIT scope. It was verified that attached sensors to a Fishbones needle could pick up readings aligned with the theoretical expectations. The in-situ rock property readings, followed by the data interpretation, can help to create a more accurate leakage detection system for CO2 storage sites.

The Fishbones Jetting/Drilling technology developed by Fishbones AS is proposed to be adapted to serve as permanent and easily accessed well-based monitoring and early warning system for any or all wells penetrating or surrounding a chosen CO2 sequestration site. The Fishbones Jetting/Drilling technology will for the first time allow for direct measurement of pore pressure, in-situ stresses, temperature, fluid flow and deformation of the formations in the near well area, without the need for conducting expensive and potentially hazardous well tests. The needles used in Fishbones Jetting/Drilling will be equipped with pore pressure sensors, optic fibre technology and possibly other load cell equivalent sensors. This project proposal addresses the overall needs in CCS research and innovation of further de-risking CO2 storage and ensuring cost efficient monitoring of storage containment. Since existing and new wells are identified as the main containment risk elements, and since these are the most accessible locations for installation of monitoring devices, we here suggest installation of monitoring equipment in the subsurface through well access. In particular, we propose to drill in targeted shale barrier layers, installing Needles at several depths. A corollary of this innovation will also be to assess stresses and pore pressure while drilling new wells.