Development of Hollow Glass Sphere blended fluid system for Workover Programs in Subhydrostatic Wells

Due to ever increasing numbers of sub-hydrostatic wells, work-over activities are, often, highly susceptible to fluid losses resulting in formation damage and poor well productivity. To address this need a new water base workover fluid formulation with specific density lower than 1.0 sg (8.34 ppg) has been developed after a series of experiments by using light weight Hollow Glass Spheres (HGS) with other chemical additives.

This paper describes a low densityHollow Glass Sphere blended fluid system which is customized with Hollow Glass Spheres(HGS) as density reducing agent, Potassium Chloride (KCl) brine as the base fluid,XC Polymer as viscosifier, fluid loss additive and thermo stability agent to facilitate the stability of formulation at ambient as well as elevated temperature.

The innovative workover fluid systemin lab studies has shown excellent rheological properties, stability up to 20 hrs.attemperatures 90ºC and it imparts low formation damage/fluid invasion in the pay sand due to its low specific gravity ranging between 0.67-0.81. Economically, it is viable due to its reusability at different wells.It is also non- hazardous, non-corrosive,non-residual, and prevents fish eye formation by forming a clean homogeneous fluid.The application of low density fluid in sub-hydrostatic wells during workover operation is expected to control fluid loss and will result in enhance productivity.