Storable Liquid-Bead System as Lightweight Additives for Oilwell Cementing

Abstract

Hollow-glass microspheres (beads) are widely used during oilwell cementing operations to produce lightweight cement slurries; this paper discusses a new method of blending hollow-glass beads into cement slurries by creating a storable liquid suspension of hollow-glass microspheres (liquid beads). This new method enables efficient delivery of lightweight cement slurries in offshore and remote locations by eliminating bulk-blending logistics. The concept of liquid beads is not new; however, earlier attempts to develop liquid beads or similar products generally failed to address the storability problem. The buoyancy force tends to lift the beads to the surface of the suspension, forming a gel or crust and causing the mixture to lose flowability within a relatively short period of time. A special chemical-additive package developed in this study significantly extends the storability of liquid beads. This paper compares the gelation time of different liquid-bead formulas and evaluates the performance of cement slurries prepared with liquid beads. Laboratory test data show that the chemical-additive package developed in this study can extend the storage time (shelf life) of liquid beads from a few hours to at least one month without reagitation at room temperature; the shelf life can be further extended to at least one year with regular reagitation of the mixture. Cement slurries prepared with dry-blended beads and those prepared with liquid beads exhibit similar performance in terms of laboratory test results, such as free fluid, fluid loss, thickening time, and hydration kinetics. The liquid-bead system developed can be produced with cement batch mixers for field use and remain stable in tote tanks for at least several months with regular recirculation. Liquid beads can be added to cement slurries through liquid-additive pumps during a cementing operation. A novel liquid-bead product that can be stored for extended periods of time without separation is presented here along with necessary laboratory testing, actual field applications, and field-application case histories using liquid beads to produce low-density cement slurries.

Shale Cuttings Addition to Wellbore Cement and Their Effect on Unconfined Compressive Strength

“…Blast furnace slag formed during the manufacturing of iron has been shown to aid in preventing gas migration, setting time, and bonding [23,24]. Glass microspheres are a type of pozzalanic material that is used to lower the density of cement but have many drawbacks such as their cost, separation tendencies, and the tendency to be crushed under pressure [25][26][27].…”