Biodegradable water-swelling plugging agent and preparation method thereof

Abstract

The invention discloses a biodegradable water-swelling plugging agent and a preparation method thereof. The biodegradable water-swelling plugging agent is prepared from the following raw materials inparts by weight: 30-80 parts of acrylic acid, 0 to 40 parts of acrylamide, 0 to 20 parts of 2-acrylamide-2-methyl propanesulfonic acid, 0.1 to 0.35 part of an initiator, 30 to 65 parts of a neutralizer, 0.1 to 0.35 part of a reducing agent, 0.2 to 0.5 part of a cross-linking agent, 3-10 parts of enteromorpha prolifera powder, 30 to 50 parts of bentonite, 50 to 120 parts of water, 0 to 20 parts ofnut shells, 0-10 parts of mica and 0-10 parts of vermiculite. The prepared water-swelling plugging agent is stable in structure, high in strength and good in viscoelasticity, still has good expansioncapacity and anti-pressure capacity in a high-temperature and high-pressure environment at the bottom of a well, is good in plugging effect, can be completely biodegraded in a soil environment, and isfriendly to the environment.

Description

technical field [0001] The invention belongs to the technical field of geological drilling and oil drilling plugging operations, and in particular relates to a biodegradable water-absorbing swelling plugging agent and a preparation method thereof. Background technique [0002] Lost circulation is a downhole complex situation in which the working fluid leaks into the formation in drilling engineering, and it is one of the most common and frequently encountered complex problems in drilling operations. Because the downhole complex situation caused by lost circulation is very harmful to the drilling and completion construction, the lost circulation has always been a matter of great concern to the petroleum engineering circles at home and abroad. In the drilling operation, once leakage occurs, not only the drilling time will be delayed, the drilling fluid will be lost, the oil and gas layers will be damaged, and the normal progress of the geological logging work will be affected,...

AI Technical Summary

Problems solved by technology

At present, the most commonly used plugging technology at home and abroad is mainly the bridge plugging technology, but this type of plugging technology mainly has the following defects: 1. The fracture opening of the formation is often not accurately grasped. 1. When the concentration depends more on field experience, it is often prone to repeated leakage, resulting in huge losses of manpower, material resources and financial resources; Stable plugging; Third, the plugging material has poor deformability and is easy to plug on the fracture surface, and cannot penetrate deep into the formation to plug

[0004] At present, the most widely used water-absorbing polymer is polyacrylamide, but its water-absorbing speed is too fast, and when it is used for plugging operations, it is easy to cause pumping difficulties and affect the performance of drilling fluids. Unable to enter the leakage layer, resulting in weakened plugging effect

In some large fractures and high permeability formations, the strength of the water-absorbent resin cannot meet the plugging requirements, so using the polymer gel system alone for plugging operations is not ideal, and the degradation rate of polyacrylamide is slow and takes a long time , Excessive use will cause adverse effects on the environment

At present, there are also attempts to use self-degradation plugging agents prepared by the polymerization of acrylic acid monomers and starch. Although this type of plugging agent can be degraded naturally, on the one hand, it is easy to cause pumping difficulties due to the fast water absorption speed when used in plugging operations. On the other hand, its strength is low, its compression and expansion properties are poor, and the plugging effect is not good.