Medium-high temperature oil reservoir phenolic gel self-degradation temporary plugging agent and preparation method thereof

Abstract

The invention relates to a medium-high temperature oil reservoir phenolic gel self-degradation temporary plugging agent and a preparation method thereof. The temporary plugging agent is prepared fromthe following components in percentage by mass: 2 to 2.5 percent of low molecular weight polymer, 0.2 to 0.25 percent of phenolic cross-linking agent, 0.2 to 0.6 percent of aldehyde cross-linking agent, 0.05 percent of stabilizer, 0.1 percent of catalyst, 0.5 to 2 percent of gel breaker and the balance of water, wherein the sum of the mass percent of all the components is 100 percent. The gel temporary plugging agent provided by the invention can meet the requirements that the oil reservoir temperature is 60-100 DEG C, the plugging time is adjustable within 120-168h, and the gel breaking timeis adjustable within 168-240h; the plugging rate of a rock core reaches 98% or above, the permeability damage rate after gel breaking is 10% or below, a high-permeability layer of a target stratum canbe effectively plugged, flowback is easy after automatic gel breaking, damage to the stratum is extremely small, and the plugging agent can be suitable for most conventional oil reservoirs and has good field application value.

Description

Technical field: [0001] The invention relates to a phenolic gel self-degradation temporary plugging agent for medium-high temperature oil reservoirs and a preparation method thereof, belonging to the technical field of oil field chemistry. Background technique: [0002] my country is one of the countries with a relatively high proportion of oilfields developed by water flooding in the world, and oilfields developed by waterflooding play an important role in my country's oil development. With the continuous long-term development of water flooding oilfields, after entering the middle and late stage of development, the phenomenon of uneven water flooding has become more and more serious, and the comprehensive water cut has risen. In order to increase the production of oil wells, fracturing or other profile control and water shutoff operations will be carried out on oil fields with development prospects to develop crude oil in medium and low permeability layers. However, due to...

AI Technical Summary

Problems solved by technology

This kind of oxidative breaker has certain defects in the application process: (1) it reacts quickly under high temperature conditions, so that the temporary plugging agent is degraded in advance; under low temperature conditions, the breakage is slow and incomplete

(2) It is a universal reactant, which can react with most of the reactants encountered, such as pipes, formation matrix and hydroxyls, etc., thereby generating pollutants and causing formation damage; (3) Ammonium persulfate is a kind of persulfate Oxides, storage, use, etc. have potential safety hazards

However, this patent document uses inorganic acid as a gel breaker, and the temporary plugging agent breaks the gel incompletely, and this temporary plugging agent is not suitable for plugging regulation in reservoirs with a temperature exceeding 90°C

[0004] There are some deficiencies in the above and existing related patents: the cost of the polymer is high, it is greatly affected by the reservoir temperature, and the gel breaker ammonium persulfate is added, etc. Oxide, oilfield site construction is complex, causing formation damage

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