Non-cross-linked gel plugging system

Abstract

The invention provides a non-cross-linked gel plugging system which comprises a non-cross-linked polymer and an aqueous solution, wherein the mass of the non-cross-linked polymer is 0.5%-5.0% of the mass of the non-cross-linked gel plugging system. Compared with the prior art, the non-cross-linked polymer in the non-cross-linked gel plugging system provided by the invention can form a gel in the manner of physical cross-linking; the gel has difficulty in being mixed with oil, gas and water, has a better pumping performance, can easily enter into a crack and can automatically fix; the formation fluid can be fully discharged; the gel can effectively occupy and fill the seam and hole spaces of the underground leakage layer; a 'sectional plug' capable of fully isolating the formation fluid from the well hole is formed in the stratum, has a certain static yield stress and elasticity and is capable of regulating the starting pressure gradient; the gel plugging system provided by the invention can be independently used and can be used together with the other additives; different injection manners can be taken for solving various well leakage problems.

Description

Technical field [0001] The invention belongs to the field of petroleum exploitation, and specifically relates to a non-crosslinked gel plugging system. Background technique [0002] Lost circulation is a type of working fluids including mud, cement slurry, completion fluid and other fluids that leak into the formation under the action of pressure difference during special downhole operations such as drilling, cementing, testing or workover. Phenomenon is one of the most common and common technical problems in underground engineering. [0003] According to the leakage rate, leakage can be divided into micro leakage, small leakage, medium leakage, large leakage, and malignant leakage. Among them, malignant leakage is the most serious and difficult to solve. The malignant leakage of complex formations mainly includes: leakage of fractures with inflow and outflow, and repeated leakage at multiple points at random in low-pressure-bearing formations. Such leakage has a high rate of leak...

AI Technical Summary

Problems solved by technology

However, because the plugging agent used is easy to be diluted by water, it is not easy to accumulate in the leakage layer, and it is not easy to form the slug required for plugging, so the plugging effect is not good, and the success rate of plugging is low.