A kind of selective plugging agent and its application

Abstract

The invention relates to a selective blocking agent. It is characterized in that its components and proportions are as follows according to the mass concentration percentage: polyacrylamide 0.3-2%, cross-linking agent 0.4-1.5%, resorcinol 0.5-1.0%, calcium lignosulfonate 0.5-1.5% , polyvinyl alcohol 0.2-0.5%, acid-base agent 0.2-0.5%, stabilizer 0.8-1.8%, sodium chloride 0.2-0.5%, ammonium chloride 0.8-1.5%, and the balance is water. The selective plugging agent is suitable for selective water plugging of casing damaged wells in low-permeability oilfields without moving strings. The selective plugging agent has the characteristics of good pumpability, strong oil-water selectivity, high plugging rate and erosion resistance, and is suitable for chemical water plugging requirements in low-permeability oilfields.

Description

technical field [0001] The invention relates to a chemical agent in the technical field of petroleum production engineering, in particular to a selective plugging agent and its application in selective water plugging of non-moving pipe strings in casing damaged wells in low-permeability oilfields. Background technique [0002] Oil well water plugging is an important technical measure of "controlling water and stabilizing oil" implemented from production wells. In this process technology, the selectivity of water shutoff agent is the key, especially for low permeability oil fields, the plugging effect of selective water shutoff is the best. At present, although the selective water shutoff technology has been widely used in domestic oilfields and is becoming more and more mature, the mainstream chemical water shutoff system is mainly used in the test of chemical water shutoff technology, and its effective rate is only 50%. The daily oil increase is 0.1t, the average single we...

AI Technical Summary

Problems solved by technology

At present, although selective water shutoff technology has been widely used in domestic oilfields and is becoming more and more mature, the mainstream chemical water shutoff system is mainly used in the test of chemical water shutoff technology, and its effective rate is only 50%. The daily oil increase is 0.1t, the average single well cumulative downflow is 215t, the cumulative oil increase is 25t, and the validity period is 73d. The commonly used mainstream plugging agent system still has the following problems in the application process of low permeability oilfields: 1) High initial viscosity leads to poor pumpability, The injection pressure is too high, causing potential safety hazards; 2) After the plugging agent is injected into the formation, it is easy to completely block the oil-producing layer while blocking the high water-bearing layer, resulting in a "full oil-water plugging" situation; 3) The oil-water selectivity is poor, and the high water-bearing 4) Poor erosion resistance and short validity period

At present, there is no corresponding anti-plugging agent for high water-cut casing damage wells in low-permeability reservoirs

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