Abstract
Conventional brine-based completion fluid are used to control the reservoir pressure after drilling operation. It can be then displaced using HP/HT coiled tubing. Injection of the brine-based completion fluid inside the sandstone formation can significantly reduce the operation expenses. However, depending on the fluid/rock properties and composition, formation damage may occur when the fluid is in contact with sandstone formation. This paper presents laboratory results evaluating the damage that may occur during injection of different completion fluids into sandstone core plugs.
This lab work includes core flood testing to study the effect of injecting the completion fluids on the sandstone rock permeability. XRD was conducted for solid and core plugs analysis. ICP was used to analyze the obtained completion fluid. Zeta potential analysis was performed to assess fluid/rock interactions.
No permeability reduction was observed when completion fluids with pH ≤ 10 were injected into the sandstone core plug. However, a reduction of permeability of 76% was observed after injection of high pH completion fluid no. 3 (pH ≥ 10). Zeta potential experiment showed a stable clay charge and minor disturbance to their structure. Completion fluid no. 3 with polymer-based clay stabilizer caused no damage to the rock.
