Oil well plugging removal method

Abstract

The invention discloses a blockage removal method for an oil well. An oil pipe is arranged in the oil well, and an annular space formed by the oil pipe and the well wall is internally provided with asleeve pipe. The method includes the following steps that a polymer neutral blockage removal agent is prepared; the prepared polymer neutral blockage removal agent is put into an inlet of the oil pipefor the first time, hot water with the temperature of 70 DEG C is added in an inlet of the sleeve pipe, the inlet of the oil pipe and the inlet of the sleeve pipe are closed, and the wellhead of theoil well is covered by insulating cotton; after being closed for 12 hours, the inlet of the oil pipe and the inlet of the sleeve pipe open again, the inlet of the sleeve pipe is then closed after hotwater with the temperature of 80 DEG C is added in the sleeve pipe for replacing original water, the prepared polymer neutral blockage removal agent is poured in the inlet of the oil pipe for the second time, and meanwhile mixed gas of carbon dioxide and nitrogen with the pressure of 2.0 MPa is continuously injected in the oil pipe. The method can effectively remove stratum blockage objects in theoil well, does not cause corrosion and damage to the stratum, equipment and pipelines, and also does not affect subsequent dehydration of crude oil.

Description

technical field [0001] The invention relates to a blocking removal method. More specifically, the present invention relates to a method for unblocking an oil well, which belongs to the field of petrochemical technology. Background technique [0002] As an important non-renewable chemical energy, petroleum has an important impact on the national economy and national security. Relying on natural energy consumption (with a recovery rate of 5% to 10%) is called primary oil recovery, and artificial water (gas) injection Reservoir pressure (recovery rate of 30-40%) is called secondary oil recovery, but as the oilfield enters the late development stage with high water cut, the remaining recoverable reserves are getting smaller and smaller, and the decline in oil production is becoming more and more serious. Tertiary oil recovery The new method is an important measure to increase recoverable reserves. Polymer flooding is one of the very important methods of enhancing oil recovery....

AI Technical Summary

Problems solved by technology

Polymer flooding is one of the very important methods of enhancing oil recovery. During polymer flooding, a certain amount of polyacrylamide or biopolymer xanthan gum with high relative molecular weight is added to the injected water. However, the polymer flooding The substance itself is difficult to decompose. After a long time, a large amount of polymers will accumulate in the formation, which will cause the formation to be blocked, and the liquid will form a lying well, which will seriously affect the production.

[0003] At present, in order to solve the above problems, polymer deblocking agents are generally used to degrade a large number of polymers accumulated in the formation. Most of the existing polymer deblocking agents are strong oxidants. The main principle is that strong oxidants can completely oxidize and decompose the main chain of polymers. Break the long chains of macromolecules into multiple short chains of small molecules, reduce the viscosity of polymers and improve the fluidity of polymer solutions, thereby reducing or removing polymer clogging, but strong oxidants can seriously damage the formation and greatly enhance water flow channels Make the water content of oil production rise rapidly, or be a strong acid plugging removal agent. Acidizing plugging removal is to improve the formation permeability by means of the chemical dissolution of inorganic acids and organic acids on formation rocks and blockages and the hydraulic action of acidizing pressure, but strong acid plugging removal After the agent is used, the strong acid will flow back into the wellbore, causing serious corrosion to the oil casing and lifting equipment