Plugging agent for drilling fluid and preparation method of plugging agent

Abstract

The invention discloses a plugging agent for drilling fluid, which can stabilize well walls to reduce leakage of drilling fluid to strata. The plugging agent for drilling fluid comprises the followingcomponents in percentage by mass: 25%-35% of 5# white oil, 25%-35% of natural asphalt and 35%-45% of propylene glycol block polyether. A preparation method of the plugging agent comprises the following steps: adding the 5# white oil into a reaction kettle, sequentially adding the natural asphalt and the propylene glycol block polyether, stirring for 0.8-1.5h, uniformly mixing, and discharging soas to obtain the plugging agent for drilling fluid. The plugging agent for drilling fluid has good plugging effects on different cracks under different temperatures; besides, the preparation method ofthe plugging agent for drilling fluid disclosed by the invention is simple in technology and low in preparation cost.

Description

technical field [0001] The invention relates to the field of plugging agents, in particular to a plugging agent for drilling fluid and a preparation method thereof. Background technique [0002] It is well known that during the drilling process, well collapse, lost circulation and protection of oil and gas layers are the three major technical problems that currently restrict the smooth progress of drilling projects. In order to solve this problem, the drilling fluid is required to have strong plugging performance. In order to prevent the drilling fluid from penetrating into the formation, it is necessary to effectively block the rock pore throats in the formation near the wellbore wall, otherwise it is easy to cause shale hydration and expansion during drilling, causing accidents such as wellbore collapse. [0003] Currently commonly used plugging agents include oxidized asphalt, sulfonated asphalt, natural asphalt and modified asphalt; and the latest invention of nano-bloc...

AI Technical Summary

Problems solved by technology

[0004] At present, asphalt and emulsified paraffin plugging agents are commonly used in drilling projects at home and abroad. The softening point of asphalt materials is very important for the plugging effect at the bottom of the well. It has a strong plugging and stabilizing effect within the softening point, but the temperature exceeds After the softening point, under the action of positive pressure difference, the softened asphalt will flow into the deep rock cracks, so it can no longer play a plugging role. It is difficult to choose asphalt plugging agent for different well depths and temperatures.

[0005] Nano-blocking materials can only be used for nano-scale gaps, and the application area is narrow

[0006] The common cellulose-based plugging agents have large particle sizes, and have a good plugging effect on formations with large fractures and gaps. However, they cannot form a size match with micro-fractures and cannot form a good inner mud cake, so they cannot be used. Effective plugging of micro-fracture formations

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