Water Base Barite Filter Cake Removal Using Non-Corrosive Agents

Abstract

Abstract Barite is one of the most common weighting materials used in drilling fluid for deep oil and gas wells. Consequently, the main source of solids building the filter cake is the weighting material used in drilling fluids ‘Barite particles’. Barite is insoluble in water and acids such as HCl, formic, citric, and acetic acids, as well as the barite has low solubility in chelating agent such as Ethylene Diamine Tetra acetic Acid (EDTA) and Hydroxyethyl Ethylene Diamine Tri Acetic (HEDTA). The present study introduces a new formulation to dissolve the barite filter cake using two types of treatments. The removal treatment consiting EDTA or HEDTA plus converting catalyst. The removal formulation also contains polymer breaker (Enzyme). Solubility tests conducted using industrial barite particles with size ranged from 30 to 60 micron. The solubility experiments were carried at 200 °F for 24 hours. Different concentrations of catalyst were added to select the optimum concentration. The designed formulation was examined to remove filter cake formed by Barite drilling fluid using High Pressure High Temperature cell (HPHT). The result of this study showed that the barite filter removal efficiency of new formulation reached to 90 %. The solubility test results presented that the solubility of barite particles in 20 wt. % EDTA was 60 % in 24 hours at 200 °F. Adding one of the catalyst the solution increased the solubility of barite to 85 %. The second treatment with HEDTA perform 60% removal efficiency in the presence of catalyst. The used treatments were not compatible with the polymer breaker (Enzyme) so the filter cake removal must be two stages. The first stage using 10 wt. % enzyme for 24 hours to break the polymer and the second stage using the designed barite formulation. The investigated formulation that effectively dissolve the barite will change the industrial direction to use the barite as weighting agent because dissolving barite was the most significant limitation of using barite in the drilling fluid.