Plugging agent for drilling fluid and preparation method thereof

Abstract

The invention discloses a plugging agent for drilling fluid and a preparation method thereof. The plugging agent is prepared from the following components in parts by weight: 100 parts of matrix asphalt, 10-40 parts of a microcapsule modifier, 1-20 parts of a dispersing agent, 5-20 parts of a curing agent, 0.5-5 parts of an accelerant and 100-200 parts of water. The plugging agent can effectively reside at entrances of malignant leakage strata such as large cracks and karst caves to form solid sealing, and particularly, the retention plugging capacity and the water washing resistance are improved at high temperature and high pressure, so that the plugging success rate is increased.

Description

technical field [0001] The invention relates to the field of oil drilling plugging, in particular to a plugging agent for drilling fluid and its preparation. Background technique [0002] In the oil and gas drilling process, lost circulation is a ubiquitous and often encountered complex problem. Downhole accidents caused by lost circulation are extremely harmful to drilling and completion, and have always been an urgent problem to be solved in the field of petroleum engineering. During drilling operations, once lost circulation occurs, it will not only delay time, lose drilling fluid, and damage oil and gas layers, but also may cause well wall instability, leading to a series of complex situations and accidents such as well collapse, pipe sticking, and blowout, and even lead to wellbore failure. scrapped, resulting in significant economic losses. [0003] Especially in the process of drilling deep oil and gas wells in alpine areas, the number of large fractures and karst-v...

AI Technical Summary

Problems solved by technology

Although compared with the previous patent, the plugging ability has been improved, but there are also problems such as the formation fluid is easily diluted by the formation fluid, and the cementation strength of the diluted plugging material will be greatly reduced, resulting in a decrease in the retention capacity.

[0006] CN102618230A discloses a controllable cross-linked gel water plugging and leakage plugging material for oil and gas fields. The plugging material is first made of water-absorbing resin by reacting organic monomers in an aqueous solution with an initiator, and then continues to react repeatedly in the oil phase. The particles obtained by wrapping are added into the HPAM aqueous solution for cross-linking reaction to obtain an immobile gel, which can plug fracture-type and karst-cavity formations. poor sex

[0007] CN110003864A discloses a plugging agent in drilling fluid and its preparation method. The method uses resin as the main agent and adopts a latent curing agent with microcapsule structure. The core layer is an amine curing agent, and the wall layer is a high-toughness engineering Plastic polymers, this method can solve the contradiction between the long construction period and fast curing of the plugging resin, but due to the use of high-tough engineering plastic polymers in this method, if the thickness of the capsule wall is not well controlled, the capsule wall will be difficult to break during use Or it cannot be completely broken, so that the curing agent cannot fully react with the resin, affecting the curing effect

In addition, since the main agent is resin, the cured product has high hardness, poor viscoelasticity, poor adaptability to different cracks and hole sizes, and it is difficult to achieve a good plugging effect

[0008] At present, although a large number of researches on plugging materials have been carried out for the leakage of large fractures and caves, there are still problems such as poor retention ability of plugging materials in the leakage channel, weak resistance to water dilution, weak scouring ability, and low plugging strength.

Especially under the condition of high temperature use, the success rate of leak plugging of large cracks and karst caves is very low, and the loss is serious