Gas expanding agent for cementing medium-temperature and high-temperature wells and application thereof

Abstract

The invention discloses a gas expanding agent for cementing medium-temperature and high-temperature wells and application thereof, and belongs to the technical field of cement admixtures used in the field of cell cementing in an oilfield completion technology. The gas expanding agent comprises the following components in parts by weight: 20-30 parts of a gas generating agent, 5-10 parts of a gas generating aid, 0.5-1.0 part of a foam stabilizer and 40-90 parts of a filler, wherein the gas generating agent is at least one selected from N,N'-dinitrosopentamethyltetramine, azodicarbonamide, barium azodicarboxylate, 4,4'-oxybisbenzenesulfonyl hydrazide and p-toluenesulfonyl hydrazide; the gas generating aid is at least one selected from urea, sodium benzoate, zinc oxide, aluminum oxide and lead oxide. The gas expanding agent can meet requirements of on-site well cementing construction at the circulating temperature of 80-120 DEG C, effectively compensates the pressure loss and the volume shrinkage during cement stone solidification, improves the cement stone cementing quality and improves the anti-gas channeling capacity.

Description

technical field [0001] The invention relates to the technical field of cement admixtures used in the cementing field of oil field completion technology, in particular to a gas expansion agent for medium-high temperature well cementing and its application. Background technique [0002] In oil well cementing construction, good cementation between cement sheath, formation and casing is the basis for effective interlayer isolation. If the interface cementation is poor, it will affect the normal production of oil wells and the implementation of subsequent production stimulation measures. Volume shrinkage of the cement sheath is one of the main causes of poor interlayer isolation or channeling. It has been confirmed that as long as there is a micro-gap of 10 μm at the interface, gas channeling will be induced, and when the micro-gap is 50-70 μm, the cementing quality will be unqualified. With the deepening of oil and gas exploration, the number of high-pressure natural gas wells...

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Problems solved by technology

[0004] In the process of realizing the present invention, the inventors have found that there are at least the following problems in the prior art: the initial gas generation temperature of the existing oil well cement gas expansion agent is relatively low

In the cementing construction in high temperature areas in summer, the expansion agent with a low initial gas generation temperature can react to generate gas when the cement slurry is mixed on the ground, which is prone to gas loss and insufficient expansion rate

At the same time, in a medium-high temperature environment above 80°C, the gas generation rate of this type of expansion agent is too fast, and the reaction rate and gas generation volume are difficult to control, so its application is limited.

In addition, the existing oil well cement gas expansion agent will produce a small amount of CO, NH 3 and other harmful gases, which affect the safety of cementing construction

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