'Shielding' spacer prevents cement-imperiling losses

摘要

Protective membrane supports a high-pressure differential. Cement bond integrity and zonal isolation can be compromised when severe losses are encountered during cementing operations. When casing is landed in mechanically weak and/or depleted reservoirs, resultant narrow fracture gradient windows and higher cementing equivalent circulating densities (ECDs) can break down the formation. The combination of existing and induced losses invariably requires costly remedial cementing to ensure zonal isolation.