Liquid-Bead Solution for Lightweight Cement Slurries

Abstract

Design, execution, and evaluation of cement operations using a new liquid-bead cement system helped achieve the necessary top of cement for development wells in Brunei. Glass beads are a common lightweight material used within the oil industry to generate low-density slurry designs with competent compressive strength development. For Brunei offshore operations, using dry beads poses many challenges, such as rig silo management, quality control of blends, and waste. A new approach has been proposed using a liquid-bead system to produce lightweight cement slurries by adding beads stabilized within a fluid as another liquid additive to help reduce the need for dry bulk blending of beads. Planning, execution, and post-operation evaluation methods were developed for this new approach. The liquid beads can be added to cement slurries using liquid additive pumps. For Brunei's operation, a mobile injection skid was developed to inject liquid beads at a predetermined rate into the suction header of the cement unit triplex pump while the base slurry is being mixed and pumped at a predetermined rate on the fly. Extensive laboratory tests were performed on the liquid slurry and the final set product to demonstrate the liquid-bead influence on cement properties compared to a dry-blend bead design. To validate this technology, a field mixing trial was performed at the rigsite. Cement evaluation with conventional logging tools poses an additional challenge for beaded slurries. To evaluate cement placement, a bond log post-process analysis was performed. The first Brunei offshore trial operation, executed during April 2018, was a 9 5/8-in. production casing where 13 m3 of a liquid-bead cement slurry design was mixed, pumped, and successfully placed within the annulus. Laboratory testing validations and injection skid and post-operation cement evaluations are discussed.