Indigenous microorganism activation and exogenous microorganism intensified oil production method in offshore oilfield

Abstract

The invention relates to an indigenous microorganism activation and exogenous microorganism intensified oil production method in an offshore oilfield, which belongs to the technical field of producible oil index improvement, and includes the following steps: firstly, preparation of exogenous microorganism bacterial liquor: beneficial microorganisms separated from an oil deposit stratum are subjected to enrichment culture; secondly, preparation of indigenous microorganism activators: the mass percent of components are: 0.25%-0.5% byproduct molasses in sugar industry, 0.1%-0.2% byproduct corn steep liquor of corn starch, 0.2%-0.4% sodium nitrate and 0.1%-0.3% phosphate; and thirdly, underground activation of an indigenous microflora: the following stages are included: the first stage, exogenous microorganism bacterial solution is injected to improve amount of functional microorganisms and provide nutrition substrates for growth of anaerobic bacteria, and the second stage, indigenous microorganism activators are injected in the anaerobic part of a stratum to improve the oil recovery efficiency. The method has the advantages of simplicity in operation, strong suitability, no harm to an oil-bearing sand, zero pollution, improved recovery efficiency and the like.

Description

technical field [0001] The invention belongs to the technical field of enhanced crude oil recovery, and in particular relates to a method for activating endogenous microorganisms and exogenous microorganisms to enhance oil recovery in offshore oil fields. Background technique [0002] At present, microbial enhanced oil recovery technology is divided into exogenous microbial oil recovery technology and endogenous microbial oil recovery technology. The endogenous microbial oil recovery technology directly uses the existing microbial community in the oil reservoir, and activates the beneficial endogenous microbial community in the oil reservoir by adding nutrient activators. Onshore oilfields generally inject a certain amount of air into the oil reservoir to improve the function. However, in the special environment of offshore oil fields, the injection of air has great potential safety hazards. There is a risk of explosion of flammable mixtures in every link of the air injecti...

AI Technical Summary

Problems solved by technology

The endogenous microbial oil recovery technology directly uses the existing microbial community in the oil reservoir, and activates the beneficial endogenous microbial community in the oil reservoir by adding nutrient activators. Onshore oilfields generally inject a certain amount of air into the oil reservoir to improve the function. However, in the special environment of offshore oil fields, the injection of air has great potential safety hazards

There is a risk of explosion of flammable mixtures in every link of the air injection process, mainly because the injected air contains oxygen, and oxygen reacts with crude oil in the oil reservoir to consume part of the oxygen, but in the case of incomplete oxidation reaction, The light hydrocarbon components in the formation will form a mixed explosive gas with oxygen. When the concentration of the mixed gas reaches the explosive range, an explosion accident will occur under certain conditions; prone to explosion

Once an explosion accident occurs, it will directly lead to the abandonment of production wells and injection wells and the complete destruction of gas injection pipelines, and what’s more, it will cause blowouts and cause greater loss of personnel and property. Therefore, air cannot be injected into microbial oil recovery in offshore oil fields. , there are technical problems such as low oil displacement efficiency of endogenous microorganisms and poor oil displacement effect

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