A polymer for oil recovery in high-temperature and high-salt reservoirs, its preparation method and application

Abstract

The invention provides a polymer for oil recovery of high-temperature and high-salt oil reservoirs, a preparation method and application thereof. The polymer for oil recovery of high-temperature and high-salt reservoirs includes the following raw material components: organic carboxylic acid monomers containing acrylimide groups, acrylamide monomers, N-alkyl substituted acrylamide sulfonic acid monomers, ethylene-containing Aniline-based polyol monomers. The polymer provided by the invention has low initial viscosity, good pumping performance, excellent temperature resistance and salt resistance, good compatibility with surfactants, and the interfacial tension of the formed poly-surface binary composite system can still reach an ultra-low interface after 3 months Tension 10 ‑3 mN / m; act on high temperature (86~120℃) or high salt (>40000mg L ‑1 , Ca 2+ , Mg 2+ >2000mg·L ‑1 ) reservoirs, the effective stability period is long and the oil displacement effect is good, which can significantly improve the development status of oilfields and provide an effective solution for further improving the recovery of high-temperature and high-salt reservoirs.

Description

technical field [0001] The invention belongs to the technical field of oil exploitation, and in particular relates to a polymer for oil recovery in high-temperature and high-salt oil reservoirs, a preparation method and application thereof. Background technique [0002] With the in-depth exploration and development of major domestic oil fields, the difficulty of mining has gradually increased, and most of them have entered the stage of high water-cut mining. In order to tap the residual oil and residual oil in the reservoir more efficiently, the polymer flooding tertiary oil recovery technology came into being. Field tests and industrial promotion and application have been carried out in Daqing, Dagang, Henan, Shengli, Xinjiang and other oilfields successively. Significant economic benefits have been achieved. [0003] Polymer flooding mainly increases the viscosity of the injected formation fluid, changes the oil-water mobility ratio, forces the subsequent liquid flow to c...

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Problems solved by technology

However, there are some insurmountable shortcomings in actual production and application: under high temperature conditions, the polymer will undergo obvious thermal degradation, lose its original stability, and the oil displacement effect will be greatly weakened; the high-salt environment is not conducive to the dissolution of the polymer and water With the prolongation of the aging time, the degree of hydrolysis of the polymer increases, and it is easy to precipitate under the action of high-valent metal ions such as calcium and magnesium, and loses the ability to displace oil. The field test research shows that the apparent viscosity of the polymer before and after being injected into the pump The decline rate of the chemical agent reaches about 15% to 35%. In addition, the polymer will be adsorbed and retained in the near-wellbore area, which will greatly increase the pumping pressure of the subsequent agent and increase the production cost.

[0004] In view of the limitations of the performance of existing industrialized polymers, which cannot meet the requirements of enhanced oil recovery in oil fields, it is urgent to modify existing polymers and introduce various functional monomers with different structures into the polymer main chain through copolymerization. Change the intra-molecular and intermolecular interactions, and develop a new type of polymer for oil recovery in high-temperature and high-salt reservoirs that has good viscosity-increasing performance, excellent temperature and salt resistance, and can be widely used in the field of oil production

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