an alternative to cabr 2 Strong inhibition and low corrosion brine completion fluid and preparation method thereof

Abstract

The invention discloses strong-inhibition low-corrosion brine completion fluid capable of replacing CaBr2, and a preparation method thereof. The alkaline completion fluid comprises the following components in percentage by mass: 50 to 80 percent of composite potassium salt, 1 to 3 percent of hydrophobic modified sodium alginate, 1 to 2 percent of a clay anti-swelling agent, 1.5 to 2 percent of a filtrate reducer, 2 to 5 percent of a corrosion inhibitor and the balance of water. The novel strong-inhibition low-corrosion brine completion fluid capable of replacing CaBr2 brine completion fluid with the density being 1.70 g / cm<3> is prepared by adopting the hydrophobic modified sodium alginate as a completion fluid tackifier and adopting the clay anti-swelling agent, the filtrate reducer and the corrosion inhibitor for the first time; in addition, the preparation method is simple and safe, and has extremely good industrial prospect.

Description

technical field [0001] The invention relates to the technical field of brine completion fluid, in particular to a CaBr substitute 2 Strong inhibition and low corrosion brine completion fluid and preparation method thereof. Background technique [0002] Completion fluid is the working fluid used in the well completion process. Its main functions are to balance formation pressure, carry suspended solid particles, and improve reservoir protection capabilities. The use of inferior completion fluids can reduce well productivity by more than 30%, causing formation damage. [0003] CaBr 2 As a commonly used well killing fluid system, brine completion fluid has the advantages of moderate price, and the density of saturated solution can reach 1.70g / cm3 after complete dissolution 3 about. But CaBr 2 There are also many disadvantages in brine completion fluid: 1) During construction in winter, due to the low outdoor temperature (below 10°C), the physical and chemical properties o...

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Problems solved by technology

But CaBr 2 There are also many disadvantages in brine completion fluid: 1) During construction in winter, due to the low outdoor temperature (below 10°C), the physical and chemical properties of CaBr make CaBr 2 The dissolution rate is slow, the solid phase content increases, and the density of the brine solution is difficult to meet the requirements, and sometimes the density can only reach 1.45g / cm 3 left and right; 2) due to poor solubility, insoluble particles of inorganic salts precipitate and invade the formation, resulting in pore blockage; 3) due to CaBr 2 For divalent metal salt, Ca 2+ Salt meets CO 3 2- , SO 4 2- etc. prone to scaling, not environmentally friendly, and damaging to the reservoir; 4) CaBr 2 The brine completion fluid is highly corrosive to the casing, and after a long time, there is a potential danger; 5) The completion fluid system itself lacks performance, which makes the cemented particles loose and then dissolves, dissolves or recrystallizes minerals, and particles migrate and minerals Precipitation, causing rock damage to the reservoir

After the reservoir is damaged, first, it is easy to reduce the production capacity of the oil reservoir, and in severe cases, it will completely lose the oil production capacity, resulting in huge economic losses in the oil field; second, it is very difficult to restore to the original level, and of course the cost is also very expensive

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