Fluid loss agent as well as preparation method and application thereof

Abstract

The invention provides a fluid loss agent as well as a preparation method and application thereof. The preparation method comprises the following steps: mixing a polyether macromonomer, 2-acrylamide-based-2-methyl propanesulfonic acid, N, N-dimethyl acrylamide, binary unsaturated carboxylic acid and water, and stirring to generate a monomer aqueous solution; adjusting the pH value of the monomer aqueous solution to 6-7, heating the monomer aqueous solution to 50-70 DEG C, adding an initiator aqueous solution, and reacting for 2-5 hours to obtain the fluid loss agent. Wherein the mass ratio ofthe polyether macromonomer to the 2-acrylamide-2-methyl propanesulfonic acid to the N, N-dimethyl acrylamide to the binary unsaturated carboxylic acid is (3-15): (35-90): (5-40): (2-10). The fluid loss agent disclosed by the invention can obviously improve the initial rheological property of cement paste and improve the early compressive strength of set cement, so that the cementing quality of anoil-gas well can be effectively improved when the oil-gas well is developed.

Description

technical field [0001] The invention relates to a fluid loss reducer and its preparation method and application, belonging to the technical field of oil and gas well cementing admixtures. Background technique [0002] With the deepening of oil and gas exploration and development, the number of deep and ultra-deep wells is increasing, the downhole geological conditions are becoming more and more complex, and the requirements for cementing quality are getting higher and higher, which brings great challenges to cementing. Cementing refers to the injection of cement before the production of oil and gas wells to achieve the purpose of isolating oil, gas and water layers, preventing inter-formation fluids from crossing each other, and protecting production layers. However, if the cement slurry loses a lot of water during the injection process, the density, thickening time, and rheological properties of the cement slurry will change accordingly, making it difficult or even impossib...

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Problems solved by technology

[0003] The polymer system based on 2-acrylamido-2-methylpropanesulfonic acid (AMPS) has good dehydration performance, excellent temperature resistance, strong salt resistance, and various varieties. It is currently the dehydration reducer research hotspots, but there are still some problems, especially when applied to high-temperature deep wells and small gap cementing.

First of all, this type of fluid loss reducer in China has high molecular weight and high apparent viscosity, and high temperature and high dosage will seriously affect the mixing efficiency of cement slurry powder materials, thereby increasing the difficulty of on-site slurry mixing, especially for low-density cement slurry systems. This phenomenon is more obvious

Secondly, the high-viscosity fluid loss reducer will increase the initial consistency of the cement slurry. In order to obtain good initial rheological properties, it is necessary to add a large amount of dispersant to the system, but this measure will affect the stability of the cement slurry

In addition, in small gap cementing, cement slurry with poor rheological properties will increase the friction of slurry replacement, reduce the displacement efficiency, increase the pump pressure, and even cause cementing accidents

Furthermore, the high-temperature shear thinning and high-temperature dispersion of AMPS polymers cause the cement slurry system to settle at high temperatures, which affects the safety of cementing construction.

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