Wellbore shielding (WBS) technology can help isolate the hydrocarbon formation from wellbore pressure, allowing successful placement of cement barriers. Knowledge of actual frac and pore pressure gradients is critical during the cement-design phase of well planning. Unfortunately, in exploration wells, engineers may have to estimate frac and pore pressure gradients. Cement circulation can fail due to uncertainties in these estimates. If errors in the engineering estimates cause lost circulation, at minimum the casing will not be supported. Resulting situations will require costly remedial work and, in the worst case, skidding and redrilling of the well.
This article explains how a WBS spacer incorporates technology that deposits a micron-thin barrier on the inside face of the wellbore. This deposited barrier, to an extent, isolates the formation from the full wellbore equivalent circulating density (ECD). Typically, in situations where lost circulation events occur due to an increase in cement-related ECD, WBS technology contributes to maintaining or regaining full circulation.