Aluminum citrate water-plugging cross-linking agent for oil extraction

Abstract

The invention discloses an aluminum citrate water-plugging cross-linking agent for oil extraction. The aluminum citrate water-plugging cross-linking agent is prepared by the following specific steps: (1) with sodium metaaluminate and citric acid as raw materials, dissolving the citric acid into water, and preparing a 50% citric acid aqueous solution; (2) heating the prepared citric acid aqueous solution to 60-80 DEG C, slowly adding sodium metaaluminate solid under agitation, keeping the solution clear and transparent, and forming an aluminum citrate complex; and (3) adding stronger ammonia water to the aluminum citrate complex obtained from the step (2), adjusting the pH value of the solution to 6.0-8.0, and filtering out insoluble substances so as to obtain the aluminum citrate water-plugging cross-linking agent of which the content of aluminum ions is 30-40g / L. The aluminum citrate water-plugging cross-linking agent has the beneficial effects that the content of the aluminum ions of the aluminum citrate water-plugging cross-linking agent obtained by adopting the method can reach over 30g / L under the environment that the pH value is 6.0-8.0; the content of aluminum is high; and the aluminum citrate water-plugging cross-linking agent is small in corrosivity on equipment, does not contain anions, such as sulfate ions and nitrate ions, which are easy to scale, and is suitable for being crosslinked with polyacrylamide to form a profile control agent.

Description

technical field [0001] The invention relates to a cross-linking agent for petroleum exploitation, in particular to an aluminum citrate water-blocking crosslinking agent for oil exploitation. Background technique [0002] In the process of oil extraction, the low oil recovery rate of crude oil has always been the bottleneck that restricts the efficient utilization of oil. In order to increase oil recovery, water flooding is generally used, but due to the serious heterogeneity of geology, the injected water advances unevenly along the high-permeability layer, resulting in low sweep of the middle-permeability layer and poor oil displacement effect, so profile control and water shutoff must be adopted. There are many ways to improve the absorption profile, usually by means of water plugging and profile control agent to achieve this goal. As a weak gel profile control agent, aluminum citrate / polyacrylamide system is mainly intramolecularly cross-linked. After gelling, the partic...

AI Technical Summary

Problems solved by technology

[0004] The present invention provides an aluminum citrate cross-linking agent that is more environmentally friendly and suitable for use in oil fields in order to solve the shortcomings of the existing aluminum citrate cross-linking agent, such as the generation of harmful substances and the presence of easily scaled anions.