Paper: Low Density Completion Slurries Developed For Partially Depleted Reservoirs

Cementing production casing in partially depleted reservoirs is a common problem in the Permian Basin. The industry is continually looking for alternative slurry designs to lower annular pressures during cementing while maintaining the material properties needed for stimulation and zonal isolation. In order to be viable, the resulting technology must decrease density while preserving compressive strength, fluid loss and free water properties of the cement. Cement slurries using foam or hollow spheres are capable of meeting these requirements. The additional equipment and material cost required usually prevent these systems from being economical when mixed between 13.5 and 14 ppg (lbigal). Recent technical developments have lead to the creation of slurries weighing 13.8 ppg containing 60% pozzolan and 40% API cement. These economical slurries exhibit mechanical properties comparable to standard API slurries having much higher densities. Laboratory testing and bond logs are presented and compared along with recommended applications.