A low-toxic, low-foaming oil-based mud flushing agent for well cementing and its preparation method

Abstract

The invention discloses a low toxicity, low foam, and oil based slurry washing agent for well cementing. The slurry washing agent is mainly prepared from following raw materials in parts by weight: 45to 70 parts of basic oil, 5 to 10 parts of soybean oil fatty acid, and 20 to 30 parts of anacardol surfactant; wherein the anacardol surfactant comprises two anacardol surfactants with different HLBvalues: an anacardol surfactant with an HLB value of 8-9 and an anacardol surfactant with an HLB value of 10-12. The washing agent has a very good flushing effect on oil based slurry and mud cakes. The washing agent can be made into washing solutions with different concentrations and the foaming rate is extremely low. The experiment results show that when the addition amount of the washing agent is 20%, the foaming rate is less than 10%; the washing solution with 10 wt% of the washing agent has maximal washing efficiency close to 98%on a simulated borehole wall, and after washing, the direct cementing degree between the simulated borehole wall and cement paste is high.

Description

technical field [0001] The invention relates to the field of petroleum drilling and cementing, in particular to a low-toxic and low-foaming oil-based mud flushing agent for well cementing and a preparation method thereof. Background technique [0002] The flushing fluid belongs to the pre-cementing fluid, which is used before cementing, mainly for cleaning the oil stain on the well wall and gelling drilling fluid, improving the hydrophilic property of the cementing interface, and increasing the bonding strength between the interface and the cement sheath. And by improving the efficiency of cement slurry replacing drilling fluid, the purpose of improving cementing quality is achieved. [0003] Oil-based drilling fluid has good shale inhibition and excellent lubricity, and is widely used in shale gas wells, long horizontal well sections and other areas, and has achieved good drilling results. However, for well cementing, the oil film and oil-based mud cake formed by the oil-b...

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Problems solved by technology

Commonly used surfactants will kill microorganisms in the environment when they are discharged into the aquatic environment, inhibit the degradation of other toxic substances, and at the same time lead to a decrease in dissolved oxygen in the water, resulting in eutrophication of the water body; surfactants discharged into the soil will affect the growth of soil microorganisms. Effects on growth, thereby affecting soil plant growth and even potential harm to groundwater when migrating downwards

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