A super-high-density cement slurry stabilizer suitable for ultra-high temperature conditions

Abstract

The invention discloses an ultrahigh-density cement paste stabilizer suitable for an ultrahigh-temperature condition. The stabilizer comprises components in percentage by mass as follows: 20-30% of a nonmetallic oxide, 65-75% of a metallic oxide and 3-5% of asphalt micro powder. The nonmetallic oxide is SiO2 (silicon oxide) in crystalline and amorphous states, and the median particle diameter is smaller than 13-18 mu m; the metallic oxide is a mixture of TiO2 (titanium oxide) and Mn3O4 (manganese oxide) in a mass ratio of 1:4-1:5, and the median particle diameter is smaller than 1.6-2.6 mu m; the asphalt micro powder is rock asphalt, the softening point ranges from 130 DEG C to 160 DEG C, and the median particle diameter is smaller than 18-23 mu m. The stabilizer is slightly tackified at the normal temperature to facilitate preparation of ultrahigh-density cement paste and still has a good suspension characteristic at an ultrahigh temperature to prevent the ultrahigh-density cement paste from settling, so that the requirement of ultrahigh-temperature and ultrahigh-pressure stratum well cementation for oil fields is well met.

Description

technical field [0001] The invention relates to an ultra-high-density cement slurry stabilizer suitable for ultra-high temperature conditions. It can not only increase viscosity at room temperature and is easy to prepare ultra-high-density cement slurry, but also has good suspension characteristics at ultra-high temperatures and maintains ultra-high density. The design performance of high-density cement slurry belongs to a kind of cement additive used in cementing engineering. Background technique [0002] With the depletion of oil and gas resources, the exploration field continues to expand to deep and complex oil and gas reservoirs. There are more and more deep wells and ultra-deep wells. Deep formations require higher and higher cement slurry densities, and the resting temperature at the bottom of the well often exceeds 175°C. Ultra-high temperature and cement slurry density greater than 2.50g / cm 3 Cementing conditions of ultra-high density cement slurry. For example, t...

AI Technical Summary

Problems solved by technology

At present, due to the large density difference between the weighted material and the cement slurry base in the ultra-high-density cement slurry system, there is a phenomenon that the weighted material is easy to sink; at the same time, when the formation temperature is higher than 110°C, in order to prevent the strength of cement stone from fading, If 30% to 40% of quartz sand or quartz powder is added, it is necessary to add weighting materials with higher density and coarser fineness to meet the fluidity requirements of cement slurry mixing and pumping, which makes the weighting materials more likely to occur. settlement

Therefore, it is difficult for ultra-high-density cement slurry to maintain settlement stability under actual conditions, which is the key to restricting the development of ultra-high-density cement slurry technology, which also poses a greater challenge for the development of ultra-high-density cement slurry systems

So far, the main method to solve the stability of ultra-high temperature and ultra-high density cement slurry system is to add high polymer to increase the liquid phase viscosity to increase the suspension force of the weighted material particles, which often occurs when preparing ultra-high density cement slurry. The high consistency of the cement slurry makes it difficult to prepare the ground to meet the design density requirements, and the pumping is also very difficult. However, when the ultra-high-density cement slurry reaches the underground and withstands high and ultra-high temperatures, due to the viscosity-temperature effect of the polymer, it will lose part of its resistance. Increase the suspension force of material particles to cause settlement, lose the design performance of ultra-high-density cement slurry, affect the quality of cementing, and even cause severe settlement to cause "sausage filling" accidents