Well cementing slurry capable of preventing CO2 and H2S corrosion

Abstract

The invention relates to well cementing slurry capable of preventing CO2 and H2S corrosion. The well cementing slurry comprises water and cement, wherein the mass ratio of the water to the cement is (0.40-0.50):1, and the cement comprises G-grade high-sulfate-resistance oil well cement, micro-cement, a dispersing agent, a fluid loss agent, micro-silicon, fly ash, an expanding agent, latex, water-soluble resin, an early strength agent, retarder and a defoaming agent. The well cementing slurry is excellent in CO2 and H2S corrosion resistance, capable of effectively resisting the corrosion of CO2 and H2S, capable of protecting underground tools such as sleeves to the maximum degree, and especially applicable to the well cementing of a high-CO2 and high-H2S acid oil-gas field.

Description

technical field [0001] The invention belongs to the technical field of preparation of petrochemical products, and relates to a 2 、H 2 Cement slurry formula in the cementing process of sour oil and gas fields such as S. Background technique [0002] With the deepening of exploration and development of oil and gas resources, many 2 、H 2 The oil and gas resources of S have been brought into the focus of development, and there are more and more acid oil and gas fields. The cement sheath is in direct contact with the formation environment, and acts as the first protective barrier for oil and gas wells to seal the formation. in CO 2 、H 2 Under the combined influence of corrosive media such as S and groundwater, the cementing components in the cement stone will decrease continuously, and the permeability will increase, resulting in a decrease in its compressive strength or even no strength at all. If the performance of the cement sheath deteriorates, it will gradually lose i...

AI Technical Summary

Problems solved by technology

in CO 2 、H 2 Under the joint influence of corrosive media such as S and groundwater, the cement components in the cement stone will continue to decrease, and the permeability will increase, resulting in a decrease in its compressive strength or even no strength at all.

The performance of the cement sheath deteriorates, which will gradually lose the protective effect on the casing, water and gas channeling will occur, and the casing will be completely in the corrosive medium, which will greatly shorten the life of the oil and gas well and affect the normal production

At present, cement extrusion is usually used at home and abroad to block the cement stone corrosion channel, but cement extrusion requires professional equipment, which is expensive and risky

Adding corrosion inhibitors to the wellbore can also alleviate the corrosion problem to a certain extent, but it needs to be added continuously for a long time, which is time-consuming and labor-intensive. In the long run, the cost is not low, and the channeling problem cannot be solved fundamentally, and the symptoms are not cured.

In recent years, scholars at home and abroad have conducted a lot of research on the anti-corrosion cement slurry system, most of which focus on the density of cement slurry and latex cement system. Although these two methods can alleviate the corrosion of cement stone to a certain extent, But the effect is not obvious, and in the environment of complex strata, the cement slurry technology that can effectively seal the strata for a long time is still rare so far.

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