A w/o/w active heavy oil plugging agent for oil wells and its preparation method

Abstract

The invention discloses a W / O / W type active viscous oil blocking agent. The blocking agent comprises internal phase water, viscous oil and external phase water. A nonionic surfactant is adopted between the internal phase water and the viscous oil. An ionic surfactant is adopted between the viscous oil and the external phase water. According to the invention, a W / O / W composite structure is adopted, W / O with a relatively large viscosity is coated by the external phase water layer, such that defects in prior arts of high viscosity, high construction pressure and poor selectivity upon an oil-water layer during an active viscous oil blocking agent injection process are overcome. With the blocking agent provided by the invention, the ground fluidity is good, and the injection pressure is low. When the blocking agent enters the stratum, the emulsion is demulsified, and W / O emulsion with a high viscosity is released, such that oil well water exits can be effectively blocked, and defects of existing active viscous oil blocking agents are overcome. The technical scheme provided by the invention is especially suitable for technical features of offshore oilfields.

Description

technical field [0001] The invention relates to an active heavy oil plugging agent for oil wells, in particular to a W / O / W type active heavy oil plugging agent and a preparation method. Background technique [0002] Water production from oil wells is a common problem in oilfield development. The harm caused by the water output of oil wells is very obvious, such as reducing oil production, increasing water production, and increasing the cost of water treatment. In order to solve this problem, people use a variety of blocking agents for water blocking, including: cement, resin, particles, gel, inorganic precipitation, etc. But the plugging agent mentioned above does not have the characteristics of real water blocking and oil blocking. [0003] In order to reduce the damage of plugging agents to oil layers, people have done a lot of work. Among them, heavy oil plugging agents are currently recognized as one of the few selective plugging agents. The use of thick oil plugging ...

AI Technical Summary

Problems solved by technology

Active heavy oil has a high viscosity, generally above 300mPa.s, so during the construction process, the frictional resistance between the heavy oil and the injection pipeline, between the heavy oil and the formation is very large, resulting in high injection pressure on the ground

Second, the active heavy oil plugging agent is an oil-based plugging agent. During the injection process, it will first enter the oil layer or the oil layer with high oil saturation, and the heavy oil plugging agent entering the water outlet layer of the oil well will decrease accordingly, thus affecting the water plugging effect. validity period

It overcomes the shortcomings of the above-mentioned water-in-heavy oil plugging agent to a certain extent, and puts forward the viewpoint of viscosification in the formation, but because the stirring effect provided by the seepage of the oil layer is very weak, it is difficult for the heavy oil to spontaneously form under the formation conditions. It is emulsified into a W / O emulsion. At the same time, the phase inversion agent in this technology is mainly solid particle bentonite. The screen-gravel packing sand control completion method commonly used in heavy oil fields, especially offshore oil fields, cannot pass through granular plugging agents. limited use