Method for treating awste water for oil field tertiary oil production prepared polymer solution

Abstract

The treating process of oil field waste water for compounding tertiary oil production polymer solution includes aeration of waste water in aeration tank with air compressor to aerate from the bottom of the tank; filtering to eliminate three-valent iron ion and other harmful two-valent metal ion, with the three-valent iron being eliminated as ferric hydroxide with manganese sand; and treatment in oxygen eliminating apparatus. The treated waste water may be used directly in compounding polymer solution injected to stratum for displacing oil. The polymer solution compounded with the treated waste water has higher viscosity than that compounded with clear water and thus higher oil recovering rate. The present invention can eliminate environmental pollution caused by oil field waste water and make full use of water resource.

Description

technical field [0001] The invention belongs to a technology for enhancing oil recovery, and in particular relates to a method for treating sewage used for preparing polymer solution in oilfield tertiary oil recovery by using oilfield output sewage instead of clear water to prepare polymer. Background technique [0002] Most of the oil reservoirs in my country belong to continental deposits, and the reservoir heterogeneity is serious. After water flooding development, due to serious fingering of injected water, the sweep efficiency of water flooding is low, and the development effect is poor. According to the calibration results of the recovery rate of onshore water-flooded oilfields organized by the former China National Petroleum Corporation Development Bureau, the recovery rate is only 35%. Under the current situation that my country's reserve resources are very scarce, how to extract nearly two-thirds of the remaining underground resources as much as possible is a strate...

AI Technical Summary

Problems solved by technology

However, due to the serious shortage of fresh water resources in most oil fields in my country, the continuous application of the mature clear water polymer flooding technology to improve oil recovery is limited, and there are also serious problems in the treatment and discharge of sewage produced by oil wells, and the use of sewage instead of clear water to prepare polymers One of the most serious problems brought by the solution is the degradation of the polymer by various complex chemical components in the sewage. The most important thing is that the sewage contains the active substance ferrous ions (Fe 2+ ) leads to a substantial decrease in the viscosity of the polymer solution

The simple method of oxygen waterfall in sewage can oxidize ferrous ions to ferric ions, temporarily relieve Fe 2+ Degradation of polymers, but the underground oil reservoir is a high-temperature and high-pressure reducing environment. After the ferrous ions in the sewage are oxidized, they remain in the sewage in the form of ferric iron and are injected into the underground oil reservoir. In the reducing environment It is reduced to ferrous ions, which degrades the polymer twice in the oil layer (reduces the viscosity of the polymer solution). Therefore, the sewage produced in the oil field seriously restricts the application of polymer flooding EOR technology