Well cementation cement paste with high water-cement ratio, low cost and low density and preparation method thereof

Abstract

The invention discloses well cementation cement paste with a high water-cement ratio, low cost and a low density. The well cementation cement paste is prepared from the following raw materials in parts by weight: 40 to 100 parts of oil well cement, 25 to 60 parts of coal ash, 30 to 40 parts of silica fume, 2 to 3 parts of an early strength agent, 2 to 8 parts of a ternary exciting agent, 3 to 3.5parts of a fluid loss agent, 0 to 0.2 part of a dispersing agent, 0.2 part of a defoaming agent and 180 to 272 parts of clean water, wherein the ternary exciting agent is a mixture of soda lime and magnesium sulfate, the mass ratio of the soda lime to the magnesium sulfate is 9 to 1, and the soda lime and the magnesium sulfate are both sieved by a 100-mesh sieve. Meanwhile, the invention further discloses a preparation method of the well cementation cement paste preparation method. The well cementation cement paste has low cost; after the ternary exciting agent is added, the compressive strength is improved, and a requirement of well cementation for the strength of low-density cement paste is met; furthermore, expansibility is improved, cement paste micro annular spaces caused by the inherent shrinkage character are reduced, and the risk of poor wellhole sealing safety is reduced.

Description

technical field [0001] The invention belongs to the technical field of oil and gas well cementing engineering, and in particular relates to a high water-cement ratio low-cost low-density well cementing cement slurry and a preparation method thereof. Background technique [0002] Low-density cement slurry is widely used in the cementing of various low-pressure oil and gas wells that are prone to leakage. Taking the Ordos Basin as an example, because there are many weak formations from top to bottom, more than 90% of the wells need to use low-density cement slurry for cementing. A lot of research has been done on low-density cement slurry at home and abroad, and a series of excellent density-reducing materials such as artificial microbeads and floating beads have been selected, and good results have also been achieved. However, as the international oil price has continued to hover at the middle and low levels in recent years, the pressure to reduce costs and increase efficienc...

AI Technical Summary

Problems solved by technology

At the same time, in order to improve the stability of the slurry under the condition of high water-cement ratio, micro-silicon with a smaller particle size is added to improve the suspension characteristics, forming a ternary system of fly ash-micro-silicon-oil well cement. However, the existing pulverized coal None of the gray activators can make the 1.30-1.35g / cm2 under the condition of high water-cement ratio 3 Density cement slurry strength meets the requirements of cementing industry with high temperature and high pressure (such as 60℃×25MPa) for 24 hours, and normal temperature and pressure for 72 hours. The curing strength is above 3.5MPa.

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