Method for determining injected water quality of high water-cut period oilfield based on water quality sensitivity

Abstract

The invention relates to a method for determining the injected water quality of a high water-cut period oilfield based on water quality sensitivity. The method includes the following steps of (1) calculating the pore volume Vphii of a controlled reservoir of each well; (2) calculating the dimensionless injection quantity Qi of each well; (3) calculating the average permeability of the controlled reservoir of each well before water injection development, the permeability water quality sensitivity coefficient thetai of the controlled reservoir of each well under the current injected water quality and the current permeability Ki of the controlled reservoir of each well considering the water injection history; (4) calculating the average permeability of controlled reservoirs of a current waterinjection system; (5) based on water quality recommendation standards, determining which water injection quality should be specifically selected for the current water injection system. The method isbeneficial to solving the contradiction of high water-cut period development and meeting the water injection demand of reservoirs after long-term water injection development, and also has important significance for reducing the energy consumption, saving the cost and adapting to the low-oil-price era.

Description

technical field [0001] The invention belongs to the technical field of water quality selection for sandstone oil reservoir injection in high water cut period, and specifically relates to a water quality decision method in high water cut period based on water quality sensitivity of sandstone permeability. Background technique [0002] As most of my country's major oil fields have been developed by water flooding, they have now entered the stage of high water-cut production. In the process of water flooding development, the quality of injection water will directly affect the development effect of reservoir water flooding and the degree of damage to the reservoir. In high water-cut sandstone reservoirs, long-term water injection, especially substandard water injection, will cause serious clogging of the reservoir, thus causing damage to the permeability of the reservoir. , the impurities in the water fill the pores in the formation; second, the greater the flow rate of the inj...

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Problems solved by technology

[0003] However, in view of the current horizontal and vertical heterogeneity requirements of oil reservoirs, in the existing oilfield water quality recommendation standards, the change law of the permeability retention rate of different reservoirs with different water quality and dimensionless injection volume is not clear, lacking Based on the current recommended water quality standards, a comprehensive analysis of the law of reservoir permeability decay

At the same time, the injection water quality has not been re-selected to control the reservoir permeability of the entire water injection system under the condition of comprehensive consideration of water injection quality and water injection history. There is no clear technical policy limit for decision-making of water injection quality, and there is a lack of a set that is compatible with reservoir development. A dynamic evaluation and decision-making method that can evaluate, constrain, and determine the feasibility of water quality schemes

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