Bacillus subtilis and alkali-resisting and salt-resisting oil field fracturing enzyme and application thereof

Abstract

The invention relates to bacillus subtilis and alkali-resisting and salt-resisting oil field fracturing enzyme and application thereof. A method for preparing the enzyme comprises the steps of: separating the bacillus subtilis BIT09L1 from a deep sea; culturing the bacillus subtilis in a culture medium taking konjak flavor powder and the like as carbon sources; and separating and purifying obtained fermentation liquor to obtain b mannogalactan. The enzyme has 6.0 to 10.0 of tolerance pH value, and 15 to 60 DEG C of temperature. The enzyme can keep the activity over 80 percent at the temperature and in the pH range. The prepared biological enzyme preparation is preserved at the temperature of between 4 and 8 DEG C, and has over 18 months of service life on storage racks. The enzyme has the advantages of simple process, readily available raw materials, easy purification of products, low cost and less pollution. The enzyme preparation has alkali resistance and salt resistance, particularly has high-efficient capacity of breaking the guar gum or modified guar gum of the fracturing fluid for oil fields, has no incompatibility with most chemical agents in the fracturing fluid, and meets the requirements of oil field fracturing engineering.

Description

technical field [0001] The invention belongs to the field of oilfield biotechnology, and in particular uses Bacillus subtilis as a strain to ferment and produce an enzyme gel breaker in oilfield fracturing technology, and degrade colloid or sugar-containing waste liquid containing galactomannan high polymer. Background technique [0002] Oilfield water-based fracturing is one of the most commonly used important means for formation reformation and improvement of formation permeability in the secondary and tertiary oil recovery stages. Through perforation, the formation is torn apart with high-strength vegetable jelly, and proppant, usually quartz sand or ceramsite, is added to the fracture. Plant jelly is usually used to carry these proppants into the ground seam. Natural plant gums such as safflower gum, konjac gum, and cougar gum have been used in my country, but at present, guar collagen powder or its derivatives are mainly used ( Hydroxypropyl Guar Gum HPG, Carboxymethyl ...

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Problems solved by technology

[0007] Some engineering bacteria display can efficiently express the mannanase (Yao Dongsheng et al. publication number: CN1807644; Wang Zhengxiang et al. publication number: CN1699577; Ding Hongbiao et al. publication number: CN1766098; Luo Ke et al. publication number: CN101089185; South publication number: CN101024826; Wu Daopong et al. publication number: CN100999738; Li Defa et al. publication number: CN1834237; Wang Huawei et al. publication number: CN1478887; Ma Yanhe etc. CN1351169; Examples of the use of , limited to the exploratory stage or the pilot level or process research stage

All these patent reports and products that have been applied in the market are used for gel breaking of fracturing fluids, or the dosage is large, the tolerance of electrolytes and chemical additives is poor, and they are greatly affected by pH, and alkaline conditions (pH 9-11) are generally very Difficult to achieve good gel breaking effect, often affected by fungicides, surfactants and other oilfield chemical additives

During the engineering time (1-3 hours) as the temperature rises, the gel breaks ahead of time or the break time is too long, which is difficult to meet the engineering needs

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