Antifreezing flushing solution for cleaning oil-based drilling fluid and application

Abstract

The invention discloses an antifreezing flushing solution for cleaning oil-based drilling fluid. The main agent is composed of a nonionic surfactant, an anionic surfactant and a freezing point lowering agent. The flushing solution for cleaning oil-based drilling fluid provided by the invention effectively solves the problem that a layer of drilling fluid and oil film adhered to a casing wall and well wall after use of oil-based drilling fluid by shale gas horizontal well drilling can result in poor cement sheath interface cementation performance, and can reach the purposes of effective oil film cleaning and interface wetting. In addition, the antifreezing flushing solution still has good fluidity under low temperature (like an environment temperature ranging from 0 to -15DEG C), thus facilitating on-site blending. The antifreezing flushing solution still can perform effective cleaning under low temperature (like an environment temperature ranging from 0 to -15DEG C), and can reach the purposes of effective oil film cleaning and interface wetting.

Description

technical field [0001] The invention relates to oil field cementing technology, in particular to a flushing fluid for cleaning drilling fluid. Background technique [0002] In the drilling process of shale gas horizontal wells, in order to ensure the stability of shale well walls, more than 90% of the wells use oil-based drilling fluid. However, as far as the cementing construction is concerned, the oil-based drilling fluid will stay at the interface and form oil slurry and oil film, which will seriously affect the interface bonding strength of the cement sheath and reduce the sealing quality of the cement sheath. Before operation, a flushing fluid with wetting and reversal effect should be injected to clean the oil slurry, oil film and mud cake adhering to the interface, improve the wetting environment of the annulus interface, and ensure the sealing quality of the cement sheath. [0003] There are many types of flushing fluids currently used in oil-based drilling fluids. ...

AI Technical Summary

Problems solved by technology

The above two flushing fluids are mainly suitable for climate conditions where the ambient temperature is above 0°C. When the ambient temperature is below 0°C, they will lose their fluidity due to wax formation and are not easy to pour. It is difficult to prepare and use the flushing fluid. The use of this type of flushing fluid in cementing construction in alpine regions will be restricted

In addition, there is a document disclosing a main agent and a rinsing solution prepared by adding a suspension stabilizer, a fluid loss reducer, a thickener, a diluent, a viscous lifting agent, a weighting agent, and a pH regulator in parts by weight. Flushing solution composed of water, but its composition is complicated, and its performance is stable in the temperature range of 40-150°C; but when the ambient temperature is below 0°C, the main agent of the flushing solution is solidified, which is difficult to prepare and use, which is not conducive to This type of flushing fluid is used in cementing construction in winter and alpine regions

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