Cationic chemical plugging agent and preparation method thereof

Abstract

The invention provides a cationic chemical plugging agent including 0.1-5 wt% of a cationic polymer, 1-15 wt% of a filler, 0.1-5 wt% of a crosslinking agent and 1-5 wt% of a rheological modifier, and the weight ratios are based on the total weight of the cationic chemical plugging agent. The cationic polymer is preferably a cationic polyacrylamide, the filler, the crosslinking agent and the rheological modifier are respectively preferably calcium carbonate, hexamethylenetetramine and bentonite. The cationic chemical plugging agent used in oil well leaking stoppage construction is mixed with an anionic drilling fluid in a well section with occurrence of well leakage, and then neutralization reaction and cross-linking reaction are performed, the mixed liquor viscosity increases rapidly, and a space network structure is formed, so that a leakage passage is blocked, the plugging effect is played, and the cationic chemical plugging agent ahs the characteristics of short time plugging consuming and high plugging efficiency.

Description

technical field [0001] The invention relates to the field of petroleum drilling, in particular to a cationic chemical plugging agent and a preparation method thereof. Background technique [0002] Drilling fluid loss (lost circulation) is a ubiquitous petroleum engineering technical problem that has not been completely resolved so far in the process of petroleum drilling. Especially in the drilling construction of deep wells and complex formations, formations with low pressure, fractures and karst caves are often encountered. According to incomplete statistics, the annual cost of dealing with well leakage in my country is as high as 200 million yuan. Therefore, developing a convenient and effective oilfield drilling plugging technology or providing an efficient and practical plugging agent will bring good economic and social benefits. [0003] During the drilling process, when drilling into high-permeability formations, especially formations with developed fractures or lar...

AI Technical Summary

Problems solved by technology

These constructions also have the following problems: first, the cost of urea-formaldehyde resin is high; second, the construction is difficult; third, when the drilling fluid is polluted or the ambient temperature changes, the urea-formaldehyde plugging agent is not easy to consolidate, resulting in a low plugging success rate

[0006] The existing chemical plugging agents have a certain plugging effect in field application, but they often show limitations such as low plugging efficiency, weak plugging strength, and short plugging validity period.

Analysis of the main reason for the low success rate of traditional plugging technology in drilling engineering is that the plugging agent and drilling fluid do not have a synergistic effect, the viscosity changes little after mixing, and the flow resistance of the plugging agent cannot be significantly improved. The plugging agent cannot form a certain volume of retention and solidification, resulting in poor plugging effect

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