Well-cementing and self-healing cement slurry for oil-gas field

Abstract

The invention relates to well-cementing and self-healing cement slurry for an oil-gas field, which is suitable for the field of oil well cementation. The well-cementing and self-healing cement slurry comprises the following additives percentage by weight: 2-4% of fluid loss agent, 5-40% of self-healing component, 0.2-1.0% of stabilizing agent, 0.5-2.0% of dispersing agent, 0.3-1.0% of de-foaming agent, and 0.03-0.5% of retarding agent by taking the weight of cement as benchmark. A preparation method of the well-cementing and self-healing cement slurry is as follows: controlling the water cement ratio to be 0.44, uniformly mixing the additives at a low shearing speed, weighing a certain amount of cement, adding into slurry preparation liquid, and mixing with API (American petroleum institute) standards to obtain the well-cementing and self-healing cement slurry. The well-cementing and self-healing cement slurry has the characteristics of low water loss, adjustable thickening time, gas channeling prevention and excellent impervious performance and the like, has the functions of crack prevention and self healing, and remarkably improves the mechanical property of the cement.

Description

technical field [0001] The invention belongs to the field of well cementing and cementing in oil fields, and relates to well cementing cement slurry, in particular to a self-healing cement slurry for oil and gas field well cementing. Background technique [0002] In oil and gas well operations, the main purpose of cement slurry is to fill the annular space between the casing and the well wall interface. Its functions are 1. to support and protect the casing, and 2. to separate layers. It will form impermeable cement stone, which can prevent fluids from different layers from crossing each other. [0003] Various operations place certain stresses on the cement over time, and any one of these conditions can also cause damage to the cement sheath. These externally induced cement sheath damages often result in the formation of microannulus that are so small that it is almost impossible to pinpoint their exact location, let alone repair it. But even the smallest micro-annulus is...

AI Technical Summary

Problems solved by technology

These externally induced cement sheath damages often result in the formation of micro-annulus that are so small that it is nearly impossible to pinpoint their exact location, let alone repair them

But even the smallest micro-annulus is enough to become a channel for fluid flow. Under high-energy concentrating flow and strong impact, it will cause the cement sheath to break and form micro-cracks.

All of these may lead to interlayer fluid interflow in the subsequent production process, resulting in greatly reduced seepage reduction and anti-seepage performance

Although cementing experts can use various techniques to enhance the resistance of the cement matrix to various stresses, these techniques will not be effective once the cement sheath is damaged

The existing cement slurry system can not solve the problem of self-healing of micro-cracks well

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