HIGH-PRESSURE/HIGH TEMPERATURE SOLIDS-FREE FLUID SYSTEM FOR DRILLING, COMPLETING AND REPAIRING OIL AND GAS WELLS

摘要

The present invention relates to the composition, preparation method and useof asolids-free drilling fluid system formulated with a mixture of divalent heavybrines, which isresistant to high pressures and high temperatures, which system can be usedfor drilling,completing and repairing oil wells and, more specifically, for drilling,completing andrepairing the productive area of offshore, onshore and lake-based wells thatproducehydrocarbons (crude oil, gas and mixtures of oil/gas and condensates). Saidsystem hasthe special feature that it significantly reduces productive-formationpermeability damageas it uses mixtures of different salts of water-soluble divalent metals toprovide the featuresof density, polymers and special additives to provide the system with thephysicochemicalproperties that any fluid for drilling, completing and repairing wellsrequires in order to fulfillthe functions thereof and, above all, to provide heat resistance up to200°C, providinglubrication and inhibiting hydration of any clays present in the productiveformation pores.A main feature of the present invention is that the composition that embedsthedrilling/completing/repairing of oil wells fluid contains synthetic polymersand biopolymers,for enhancing viscosity and controlling filtration losses, that do not requirelarge amountsof time, high shear speeds or heating for hydration thereof in divalent metalsalt derivedsimple or binary brines.