Bacterial strain for producing gel breaking enzyme and application thereof

Abstract

The invention relates to a bacterial strain for producing a gel breaking enzyme and an application thereof. The bacterial strain for producing the gel breaking enzyme is the Bacilluslichenformis M1-4 bacterial strain, and the preservation number is CGMCC NO.4511. The M1-4 bacterial strain is used for producing the gel breaking enzyme and preparing a bacteria liquid preparation. The bacterial strain obtained by the invention is high in enzyme production efficiency, and the enzyme output under the industrial fermentation condition is greater than 240 U / ml. The recovery method employed by the invention is relatively high in enzyme yield. The produced fracturing fluid gel breaking enzyme has a high activity within a wide range of temperature and is convenient in operation and less in usage amount. The fracturing fluid gel breaking enzyme has a rapid and even viscosity breaking property which enables the enzyme to completely degrade a guar gum with fewer residues, and the viscosity of a fracturing liquid after gel breaking is less than 5.0 mPa.s. Based on the characteristics of the gel breaking enzyme for cleaning fracturing fluid, the disclosed bacterial strain in the invention can not only be used for the conventional fracturing gel breaker construction operation, but also can be used for a remedial measure of a fracturing operation failure.

Description

technical field [0001] The invention belongs to the technical field of oil field hydraulic fracturing gel breaking, and in particular relates to a bacterial strain for producing gel breaking enzyme and application thereof. Background technique [0002] Hydraulic fracturing is an important technical measure for increasing the production of oil and gas wells and water injection wells. The process is to use fracturing pumps to press the fracturing fluid into the formation at high pressure to form fractures; and use proppant to support the fractures, thereby increasing the conductivity. flow capacity and reduce flow resistance. The national fracturing technology is applied to tens of thousands of wells every year, and the annual oil increase is nearly 10 million tons. The gel-breaking ability of fracturing fluid in the hydraulic fracturing method is the key factor affecting the success of fracturing construction. The gel-breaking effect of fracturing fluid directly affects the ...

AI Technical Summary

Problems solved by technology

However, in practical applications, there are some defects in the oxidative breaker, these defects include: 1. The reaction time and its activity are mainly dependent on the temperature; (the temperature is lower than 50°C, the reaction is very slow; an activator must be added; It decomposes quickly at 93°C, the reaction is not easy to control, and the reaction is rapid, which makes the fracturing fluid degrade in advance and loses the ability to transport proppant, and even leads to the failure of fracturing construction; Any reactant such as pipe material, formation matrix and hydrocarbons reacts to generate pollutants that are incompatible with the formation, causing formation damage; 3. The duration of gel breaking is short, and the oxidized breaker is likely to be consumed before reaching the target fracture 4. Oxidative gel breaking has randomness, resulting in the incomplete degradation of the thickener guava gum chain, and about 20% of the molecular weight is greater than 2.0×10 6 Polymer is substantially undegraded

However, the current production strains of gelatinase have the problem of low production efficiency, and it is urgent to screen out microbial strains with high-efficiency fermentation to produce gelatinase

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