Temperature-resistant and salt-tolerant foaming agent system for thermal recovery of heavy oil reservoir and preparation method

Abstract

The invention relates to the technical field of heavy oil recovery, in particular to a foam agent system used for switching water drive into steam drive of a heavy oil reservoir or steam huff and puff to improve the oil recovery efficiency. According to the technical scheme, the temperature-resistant and salt-tolerant foaming agent system for thermal recovery of the heavy oil reservoir is characterized by comprising a foaming agent base, a foam stabilizer, a foam fixing agent, a foam promoter, an alkali substance, inorganic salt and a solvent. The foaming agent system can resist the temperature of 350 DEG C and has good thermal stability and better foamability; the foaming agent base in the system is lower than the critical micelle concentration and can produce more foam, the apparent viscosity is substantially increased, and the cost is saved; the foaming agent system has better solubility, causes little damage to formation and is environment-friendly.

Description

technical field [0001] The invention relates to the technical field of heavy oil recovery, in particular to a foaming agent system used for water flooding of heavy oil reservoirs followed by steam flooding or steam huff and puff to enhance oil recovery. Background technique [0002] Heavy oil, also known as heavy crude oil or high-viscosity crude oil, has the characteristics of large specificity and high viscosity, which brings a series of problems to mining and transportation. For heavy oil production, foam flooding is an economical and efficient oil recovery technology to enhance heavy oil recovery. In the process of oil displacement, commonly used non-condensable gases include carbon dioxide, nitrogen, air, and flue gas. When the non-condensable gas contacts crude oil, it can form a miscible state, which can displace crude oil with a very high recovery rate. . However, during the steam flooding process, due to the low viscosity and strong fluidity of the steam (gas) its...

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Problems solved by technology

However, during the steam flooding process, due to the low viscosity and strong fluidity of the steam (gas) itself, most of the steam channeled along the large pores, resulting in serious viscous fingering and ineffective steam channeling, making the entire reservoir Steam cannot be well utilized, wasting a lot of resources, and at the same time, the adverse effects of reservoirs with poor heterogeneity will be more serious, resulting in low sweep efficiency

There are also many problems in the process of chemical flooding, such as surfactant flooding and polymer flooding: when surfactant flooding, two types of emulsions are formed, water-in-oil and oil-in-water, Then wrapping, carrying and transporting, this requires a large volume of surfactant, which is an uneconomical mining method; in the process of using polymer flooding, the polymer reduces the viscosity of the displacement fluid by increasing the viscosity of the displacement fluid. The flow rate of crude oil is beneficial to improve sweep efficiency and oil recovery. However, in heavy oil reservoirs, crude oil viscosity is high, and a large amount of polymer is needed to increase sweep efficiency. At the same time, polymer is not very good Through the low permeability zone in the oil layer, therefore, it is also an uneconomical method to exploit heavy oil reservoirs by chemical flooding

However, these structures are unstable in high-salinity and high-temperature formations and are prone to rupture; there are other factors that lead to the instability of the foam, such as the absorption of rock surface and crude oil, and the repulsion of the electric double layer of the foam liquid film. Force, water loss of liquid film, capillary suction, foam surface elasticity, steric resistance and apparent viscosity of liquid film, etc., will directly or indirectly result in low effective concentration of blowing agent, weak compressive capacity of foam, etc., causing the total volume of foam to decrease, Cannot achieve the purpose of blocking large pores

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