A low-temperature cement early strength agent for well cementing and cement containing it

Abstract

The invention discloses a low-temperature cement early strength agent used for well cementation and cement containing the low-temperature cement early strength agent and relates to the technical fieldof cement additives. The low-temperature cement early strength agent is prepared from, by weight, 23-27 parts of sodium sulfate, 5-7 parts of sodium nitrate, 3-5 parts of ferrous sulfate, 0.2-0.3 part of diethanol amine, 0.4-0.5 part of triethanolamine, 1.0-1.3 parts of water reducer, 2-2.5 parts of micro-fine mica powder, 0.3-0.5 part of lithium carbonate and 0.8-1.0 part of talcum powder. The early strength agent has excellent low-temperature early strength and compressive strength, is capable of meeting the requirements for low-temperature deepwater well cementation, the time for waiting for cementation is shortened, the working efficiency and the safety are improved. The early strength agent is a chloride-free early strength agent, and in use, the early strength agent is good in flowability, the flash cementation phenomenon does not occur, and the early strength agent has no corrosive effect on a casing.

Description

technical field [0001] The invention relates to the technical field of cement admixtures, in particular to a low-temperature cement early strength agent for well cementing and cement containing the same. Background technique [0002] Oil well cement is specially used in the cementing engineering of oil well and gas well, also known as plugging cement. Its main function is to cement and seal the casing and the surrounding rock formations, to isolate the oil, gas and water layers in the formation, and to prevent crosstalk, so as to form a well-isolated oil flow channel from the oil layer to the ground in the well. The basic requirements of oil well cement are: the cement slurry should have a certain fluidity and suitable density during the well injection process; after the cement slurry is injected into the well, it should set quickly and reach a considerable strength in a short period of time; the hardened cement slurry should It should have good stability, impermeability an...

AI Technical Summary

Problems solved by technology

Commonly used early strength agents include inorganic strong electrolytes and water-soluble organic electrolytes. Inorganic strong electrolytes mainly include chloride salts, sulfates and nitrates. Calcium chloride is a commonly used chloride salt early strength agent. Calcium tends to increase the yield value of cement slurry, and even flash coagulation, so that the cement slurry cannot be pumped. In addition, it will increase the volume shrinkage of cement stone, increase the permeability and reduce the ability to resist sulfate corrosion; sulfate Early-strength accelerators are easy to cause corrosion to cement stones and affect the durability of cement stones; triethanolamine is a commonly used organic early-strength agent, but when the concentration is too high, it will retard the cement slurry, and the mechanism of action has not yet been unified

Single-component accelerators have many disadvantages and cannot meet the needs of accelerators in oilfield cementing. The current research trend is multi-directional to the development of composite accelerators.

However, the early strength performance of the existing composite early strength agents is not satisfactory. The development of new low temperature early strength agents is of great significance for the exploration and development of offshore oil and gas resources under harsh conditions such as low temperature and shallow flow.

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