Fractured Carbonate Formation Plugging Agent

Abstract

The invention relates to a fractured carbonatite formation plugging agent. The plugging agent is prepared by adding the following components by weight into 100 mL of raw drilling fluid: 9 to 25 grams of walnut shell, 1 to 5 grams of FCL fiber, 4 to 10 grams of Neotoy fiber, 6 to 15 grams of synergist SQD-98, 1 to 2 grams of sawdust, and 1 to 2 grams of cottonseed hull. The plugging agent can effectively plug cracks with a width of 2 to 4 mm in the fractured carbonatite formation. The leakage of the plugging agent is very little during the plugging process. The cement in the crack opening and in the crack is compact, the cracks can be rapidly sealed, and the borne pressure can reach 15 MPa or more.

Description

technical field [0001] The invention relates to a plugging agent in the drilling process of fractured carbonate rock oil and gas fields, in particular to a high-efficiency plugging agent for fractured leakage formations. Background technique [0002] Fractures are well developed in carbonate formations. For oil and gas development, the existence of fractures is convenient for oil and gas extraction, but for drilling, the presence of fractures will narrow the mud density window, and narrow mud density windows often cause serious lost circulation problems. Cause a large amount of mud to leak into the formation. During on-site construction, it is also difficult to deal with the leakage of fractured carbonate rock formations, showing the situation of repeated plugging and repeated leakage, and there is a relatively high occurrence rate in some well areas, and its manifestation is that the leakage formation can be temporarily blocked , but it is difficult to improve the pressure...

AI Technical Summary

Problems solved by technology

When directly using plant fibers such as cottonseed hulls for plugging, due to the inherent characteristics of these fibers: too light specific gravity, easy to knot, poor fluidity, unable to form effective support and other factors, the plugging effect is not very good during use, and the pressure bearing capacity is weak. ; while only using granule or powder plugging agent, the phenomenon of "sealing the door" (the plugging agent cannot enter the leaky layer) and "regurgitation" (leakage after plugging) occurs, and, for cracks with a large opening There are certain limitations in use, and it is impossible to effectively seal; to use bridging agent mud and gel mud to plug leaks, it is necessary to prepare dozens or even hundreds of cubic meters of this kind of mud, and the original mud has been changed after use. Due to its high cost and difficult preparation, chemically synthesized composite plugging agents are not widely used on site.

[0004] In fractured carbonate rock formations, the mud density window is narrow, which is likely to cause serious lost circulation problems, resulting in a large amount of mud leakage into the formation

At present, some of the plugging agents for fractured carbonate rock formations have poor field practical effect and insufficient pressure bearing capacity; some have limitations in use and are not suitable for widespread promotion; Difficult to maintain; some have high configuration costs and are not applicable on site