Self-cementing leaking stoppage agent and leaking stoppage method

Abstract

The invention discloses a self-cementing leaking stoppage agent and a leaking stoppage method. The self-cementing leaking stoppage agent is prepared from the following ingredients in percentage by mass: 25 to 35 percent of acrylamide monomers, 0.1 to 0.5 percent of cross-linking agents, 0.2 to 0.5 percent of sodium carbonate, 20 to 25 percent of bentonite, 2 to 5 percent of high-molecular polymers, 3 to 5 percent of pre-cross-linking gel particles, 30 to 35 percent of fine-mesh calcium carbonate, 5 to 8 percent of fiber and 0.1 to 0.5 percent of initiators; the raw materials are uniformly mixed, and the self-cementing leaking stoppage agent is obtained. The self-cementing leaking stoppage agent has the advantages that the formation temperature is used, so that a polymerization reaction is taken among molecules; a rubber plug with certain water absorption expansion performance and compressive strength is formed, so that a leakage layer is blocked.

Description

technical field [0001] The invention relates to the technical field of plugging in drilling engineering, in particular to a self-cementing plugging agent and a plugging method. Background technique [0002] Lost circulation is a common downhole complex situation in oil and gas drilling operations. Lost circulation can occur in shallow, middle and deep formations, and can also occur in formations of different geological ages, and it is possible in formations of various lithologies Appear. Due to the different types of well leakage, there are many restrictive factors, and because the plugging technology is relatively targeted, so far it is difficult to have a general model for leak prevention and plugging. At present, the commonly used bridging and plugging materials have many limitations in dealing with large fractures, large pores, and malignant leakage under harsh conditions such as large amounts of formation water, especially formation water with high salinity. Bridging ...

AI Technical Summary

Problems solved by technology

Bridging plugging materials have poor deformability or no deformability. If the plugging material is slightly larger than the size of the pores and cracks in the leakage zone or does not match the shape of the pores and cracks in the leakage zone, it will not easily enter the leakage zone. Accumulation is formed on the surface of the leakage layer, which can easily lead to poor plugging effect or repeated leakage after plugging

The current pre-crosslinked gel plugging materials have deficiencies in the plugging process: 1) The internal structure of the system is loose and lacks uniform structural integrity, which leads to insufficient compressive strength of the material itself and no cementation with the leaky layer. The scouring of drilling fluid is easy to lose along the leakage channel, resulting in a low success rate; 2) Once the conventional gel is formed, the viscosity of the system will not change, and its overall compressive strength is basically constant and does not change with time. The strength increase in the later stage is extremely limited, and the probability of re-leakage increases with the repeated scouring of drilling fluid during the later stage of drilling

Although this patent discloses the chain polymerization of acrylamide and condenses into a hard solid, which is cemented together with the rock of the leakage layer to enhance the leakage plugging effect, but the cotton silk and wood flour in this patent have poor temperature resistance and are long-term. Under the action of high temperature in the stratum over time, cotton silk and wood powder are easy to deteriorate and their strength is reduced, which will lead to leakage again.

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