This paper demonstrates the benefits of using hollow glass microspheres as a low density additive in fluids formulated for use in workover of wells operating under depleted pressure conditions as found in JV “Vietsovpetro” White Tiger (Bach Ho) Oil Fields, Cuu Long Basin in Vietnam. The paper details the requirements on hollow glass microsphere selection process as a function of bottom hole hydrostatic pressure and fluid density. Assessments on cost of fluids of different densities are also made on the basis of microsphere selection and concentration for the workover program in the White Tiger Oil Field. The paper proposes options to bring fluid costs to more economical levels based on microsphere regeneration. Detailed analysis has been made on all operating JV “Vietsovpetro” wells calculating the required amount of microspheres for workover in accordance with the selected grades. The data reported in this paper can be used for mud design and to provide technical support for well workovers whenever low density fluids (less than 1 g/cm3) are considered. In addition to mud properties and formulating practices, the paper also provides useful tips in the preparation, handling, and waste management of low density fluids for workover programs.

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