Abstract
Novel profile control agents are constantly emerging in the field of enhanced oil recovery, contributing to the extension of a stable production period. However, evaluation performed through conventional core flow experiments is usually inadequate to reveal the in-depth mechanism of profile control agents. Besides, due to different operation and production modes, there is an urgent need for a specific experimental method applicable to horizontal wells in bottom water reservoirs. In this context, this paper describes two models tailored to bottom water reservoirs and investigates the flow characteristics and mechanisms of three water-shutoff agent types. At the pore scale, further study was carried out on the water-shutoff synergism between a gel and an emulsifier. The results show that the gel is present at the edge of the pore body, while the emulsion is blocked in the center of the pore body. Hence, gel that enters a water channel (main flow and accumulation area of emulsion) can cooperate with an emulsion to achieve high-strength water shutoff, making the bottom water that re-invades mainly break through at oil-rich areas. Compared with water shutoff with gel alone (randomly distributed in the breakthrough area), the synergism improves the gel’s ability to select flow channels, inhibits emulsifier channeling, and achieves a remarkable EOR effect.
Highlights
Bottom water reservoirs exist widely in oilfields, mostly developed through horizontal wells
Four types are recognized as agents for water plugging in horizontal wells: (1) a polymer gel system, (2) a surfactant, (3) a precipitate, and (4) a disperse system [6]
This paper describes two types of microfluidic models that could simulate the production characteristics of typical bottom water reservoirs in horizontal wells and covers their use in experiments with three types of plugging agents: polymer gels, polymer microsphere dispersions, and emulsifiers
Summary
Bottom water reservoirs exist widely in oilfields, mostly developed through horizontal wells. Seright et al designed a gel-injection parameter that could be used for water-shutoff treatment in fractured reservoirs through analytical methods [10,11] Disperse systems are another widely applied plugging agent in oilfields, represented by polymer microspheres (particle gel). This paper describes two types of microfluidic models that could simulate the production characteristics of typical bottom water reservoirs in horizontal wells and covers their use in experiments with three types of plugging agents: polymer gels, polymer microsphere dispersions, and emulsifiers. The study of flow characteristics and the mechanism of action is expected to provide a reference for the scientific selection of plugging agents to increase the productivity of horizontal wells in bottom water reservoirs. TThhee ppoollyymmeerr mmiiccrroosspphheerree PPCCSS aanndd eemmuullssiiffiieerr SSCC--ZZ wweerree ppuurrcchhaasseedd ffrroomm BBeeiijjiinngg YYiiddee PPeettrroolleeuumm CCoommppaannyy ((BBeeiijjiinngg,, CChhiinnaa))
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