Experimental research of the impact of filtration processes on the dispersity of emulsion systems with nanoparticles

Hydrocarbon based emulsions are actively used as technological fluids in the processes of oil and gas wells construction, drilling-in, workover, and in the improved oil recovery methods such as intensification of oil production, water shut-off and others [1, 2]. However, the area of effective application of emulsion compositions is determined by their physical properties. Classical hydrocarbon emulsions have low thermal stability and lose aggregative stability in reservoir conditions, due to the coalescence of globules of the dispersed phase, which leads to a decrease in the technological efficiency of their use in high-temperature formations. The authors of the article propose a modification of the emulsion system by the addition of silicon dioxide (SiO2) nanoparticles in order to improve its properties. Previously, the results of experimental studies of thermal stability, which revealed the advantages of modified emulsion system with nanoparticles over classical emulsions were presented. [3]. The comparative analysis of the results of laboratory studies on the emulsion system with nanoparticles dispersity after filtration in porous media using optical microscopy is presented in article. Based on the analysis it was revealed that after filtration in natural rock cores the dispersity of the emulsion system with nanoparticles increased, and that phenomenon might be described by absence of the coalescence in the emulsion, and globules breakdown to smaller size during filtration through the porous media of rock cores from Abdulovskoe and Yugomashevskoe oil-gas fields

Well Killing Technology before Workover Operation in Complicated Conditions

Well killing is an important technological stage before conducting workover operation, one of the tasks of which is to preserve and restore the natural filtration characteristics of the bottomhole formation zone (BFZ). Special attention should be paid to the choice of well killing technologies and development of wells in complicated conditions, which include abnormally low reservoir pressure, high oil-gas ratio and carbonate reservoir type. To preserve the filtration characteristics of the productive formation and prevent fluid losses in producing wells during well killing operation, blocking compositions are used. At the same time, an informed choice of the most effective well killing technologies is required. Consequently, there is a need to conduct laboratory physicochemical and coreflood experiments simulating geological, physical, and technological conditions of field development, as similar as possible to actual reservoir conditions. The article presents the results of experimental studies on the development well killing technologies of producing wells during workover operation in various geological, physical, and technological conditions of oil field development. Physicochemical and coreflood laboratory experiments were carried out with the simulation of the processes of well killing and development of wells in reservoir conditions with the use of modern high-technology equipment in the Enhanced Oil Recovery Laboratory of the Department of Development and Operation of Oil and Gas Fields at St. Petersburg Mining University. As a result of the experimental studies, new compositions of well killing and stimulation fluids were developed, which ensure to prevent fluid loss, gas breakthrough, as well as the preservation, restoration and improvement of the filtration characteristics of the BFZ in the conditions of terrigenous and carbonate reservoirs at different stages of oil field development. It is determined that the developed process fluids, which include surfactants (YALAN-E2 and NG-1), have a hydrophobic effect on the porous medium of reservoir rocks, which ultimately contributes to the preservation, restoration and improvement of the filtration characteristics of the BFZ. The value of the presented research results is relevant for practice and confirmed by the fact that, as a result of field tests of the technology for blocking the BFZ with the composition of inverse water–oil emulsion during well killing before workover operation, an improvement in the efficiency of wells operation was obtained in the form of an increase in their oil production rate by an average of 5–10 m3/day, reducing the time required for the well to start operating up to 1–3 days and reducing the water cut of formation fluid by 20–30%

Well Killing Technology before Workover Operation in Complicated Conditions

Well killing is an important technological stage before conducting workover operation, one of the tasks of which is to preserve and restore the natural filtration characteristics of the bottomhole formation zone (BFZ). Special attention should be paid to the choice of well killing technologies and development of wells in complicated conditions, which include abnormally low reservoir pressure, high oil-gas ratio and carbonate reservoir type. To preserve the filtration characteristics of the productive formation and prevent fluid losses in producing wells during well killing operation, blocking compositions are used. At the same time, an informed choice of the most effective well killing technologies is required. Consequently, there is a need to conduct laboratory physicochemical and coreflood experiments simulating geological, physical, and technological conditions of field development, as similar as possible to actual reservoir conditions. The article presents the results of experimental studies on the development well killing technologies of producing wells during workover operation in various geological, physical, and technological conditions of oil field development. Physicochemical and coreflood laboratory experiments were carried out with the simulation of the processes of well killing and development of wells in reservoir conditions with the use of modern high-technology equipment in the Enhanced Oil Recovery Laboratory of the Department of Development and Operation of Oil and Gas Fields at St. Petersburg Mining University. As a result of the experimental studies, new compositions of well killing and stimulation fluids were developed, which ensure to prevent fluid loss, gas breakthrough, as well as the preservation, restoration and improvement of the filtration characteristics of the BFZ in the conditions of terrigenous and carbonate reservoirs at different stages of oil field development. It is determined that the developed process fluids, which include surfactants (YALAN-E2 and NG-1), have a hydrophobic effect on the porous medium of reservoir rocks, which ultimately contributes to the preservation, restoration and improvement of the filtration characteristics of the BFZ. The value of the presented research results is relevant for practice and confirmed by the fact that, as a result of field tests of the technology for blocking the BFZ with the composition of inverse water–oil emulsion during well killing before workover operation, an improvement in the efficiency of wells operation was obtained in the form of an increase in their oil production rate by an average of 5–10 m3/day, reducing the time required for the well to start operating up to 1–3 days and reducing the water cut of formation fluid by 20–30%