DEVELOPMENT OF SELECTIVE GROUTING COMPOSITIONS BASED ON BITUMINOUS EMULSIONS FOR WATER INSULATION WORKS

Abstract

To increase the efficiency of water inflow isolation in oil wells, selective grouting compositions are preferred. The use of selective isolation methods provides for selective clogging of water inflow channels while maintaining the permeability of oil-saturated reservoir intervals. The mechanism of selectivity realization for different groups of grouting compositions is shown. It is noted that the selectivity of the action of these compositions is significantly affected by the permeability heterogeneity of the formation. In this case, the water primarily flows through the high-permeable interlayers, where the grouting composition will be pumped in a larger volume than in the low-permeable interlayer during water insulation works. In this paper, we continue to study selective grouting compositions that clog the pore space with a material that is subsequently soluble in oil and insoluble in water. The possibility of using bitumen emulsions, including commercially available road emulsions, is analyzed. The use of bituminous emulsions as water-insulating compositions has a number of advantages: due to the low viscosity of the direct emulsion, it easily penetrates into the porous medium. At the same time, bituminous emulsions have high thermal stability. The resulting bitumen film is impervious to water and is sufficiently resistant to aggressive media (acids and alkalis). The objects of the study were used bitumen road emulsion cationic grade EBDK B-52 and acrylic dispersions, which were intended to increase the adhesion of bitumen to the surface of rock and metal. Commercially produced reagents of the Lacroten brands (E-081, E-31, E-082, E-43), Lacryl 4443 were used as acrylic dispersions. Studies of bituminous emulsions and acrylic dispersions for adhesion to the surface of metal, carbonate and terrigenous rocks have been carried out, from which it follows that acrylic dispersions with a low pH (3.0-3.6) are an effective means of processing samples. Filtration studies indicate the selective properties of the bitumen emulsion. When injecting B-52 bitumen emulsion for both the bulk model and the ideal crack model, there is a general tendency to reduce water permeability: 32.8 % for the bulk model and 33.6 % for the ideal crack model. When conducting filtration studies with the initial injection of acrylic dispersion followed by injection of the emulsion, in all experiments, filtration attenuation is observed in both the water-saturated and oil-saturated reservoir models. According to the results of the conducted studies, for the isolation of water-saturated interlayers, it is proposed to carry out works according to the scheme of selective isolation using bituminous emulsion B-52; and when carrying out works on the elimination of behind-the-casing flows, disconnecting water-filled layers and eliminating the leakage of production columns in the coupling joints, sequential injection of acrylic dispersion and bituminous emulsion is provided.