• properties and applications of the drilling barite

    Drilling Barite heavyweight additive is a barium sulfate material used to weight drilling mud and cement slurries.  Typically, 85 to 90% of barite additive will pass through a 325-mesh sieve. Barite additive is effective at bottomhole temperatures (BHTs) between 80°F and 500°F (27°C and 260°C). A barite additive concentration of 135 lb/sk of cement will provide a maximum slurry weight of 19 lb/gal. Barite additive provide the following benefits: By increasing slurry density, it helps restrain high formation pressures and improve mud displacement. It is applicable in deep, high-temperature wells. The Environmental Protection Agency (EPA) does not classify barite additive as a hazardous waste. Drilling fluids play sophisticated roles in the drilling process: stabilizing the wellbore without damaging the formation, keeping formation fluids at bay, clearing cuttings from the bit face and lubricating the bit and drill-string.

    drilling barite the basic weighting mineral in drilling fluids

    Drilling barite and other Weight materials are compounds that are dissolved or suspended in drilling fluid to increase its density. They are used to control formation pressures and resist the effects of sloughing or heaving shale’s that may be encountered in stressed areas. A critical property differentiating the effectiveness of various wellbore fluids in achieving these functions is density, or mass per unit volume. The wellbore fluid must have sufficient density in order to carry the cuttings to the surface. Drilling barite density also contributes to the stability of the borehole by increasing the pressure exerted by the wellbore fluid onto the surface of the formation down hole. It has been long desired to increase the density of wellbore fluids, and not surprisingly, a variety of methods exist. One method is adding dissolved salts such as sodium chloride, calcium chloride, and calcium bromide in the form of aqueous brine to wellbore fluids. Another method is adding inert, high-density particulates to wellbore fluids to form a suspension of increased density. These inert, high-density particulates often are referred to as “weighting agents” and typically include powdered minerals of barite, calcite, or hematite. Drilling barite in the mud and associated drill cuttings are the largest volume wastes associated with drilling barite of oil and gas wells and often are discharged to the ocean from offshore drilling platforms. Barite (BaSO4) often is added as a weighting agent to drilling mud to counteract pressure in the geologic formations being drilled, preventing a blowout. Some commercial drilling mud barites contain elevated (compared to marine sediments) concentrations of several metals. The metals, if bioavailable, may harm the local marine ecosystem. The bioavailable fraction of metals is the fraction that dissolves from the nearly insoluble, solid barite into seawater or sediment porewater. Barite-seawater and barite-porewater distribution coefficients (Kd) were calculated for determining the predicted environmental concentration (PEC; the bioavailable fraction) of metals from drilling mud barite in the water column and sediments, respectively.

     

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