Fluid loss control additive for a well drilling fluid.

摘要

The present invention relates to a process for the plugging of a porous formation which may be encountered during the drilling of a well. The process entails plugging of the porous formation by means of a polymeric solution containing pseudo-emulsion spheres. These particles penetrate the pore structure within a formation. Eventually, sufficient numbers of the spheres will accumulate within the pores, blocking further flow through the formation by both the pseudo-emulsion particles and any aqueous solutions. The pseudo-emulsion system is formed by a process which includes the steps of forming a solvent system of an organic liquid and a polar cosolvent, the polar cosolvent being less than 15 weight percent of the solvent system, the viscosity of the solvent system being less than 100 cps; dissolving a neutralized sulfonated polymer in the solvent system to form a solution, the concentration of the neutralized sulfonated polymer in the solution being 0.01 to 0.5 weight percent, the viscosity of the solution being less than 200 cps; and admixing or contacting said solution with 5 to 500 volume percent water, the water being immiscible with the organic liquid and the polar cosolvent wherein neutralized sulfonated polymer transfers from the organic liquid to the water phase, thereby causing the water phase to gel (i.e. thicken).