Zwitterionic Hydrophobic Association Polymer Fluid Loss Control Agent Resistant to Ultra-high Temperature and Compound Salt and Preparation Method thereof

Abstract

The invention relates to an ultrahigh-temperature-resistant and complex-salt-resistant amphoteric ion hydrophobic association polymer filter loss reducer and a preparation method thereof. The filter loss reducer is a multipolymer with amphoteric ion hydrophobic association characteristic and is generated by performing polymerization reaction on hydrophobic alkylamide, strong hydrophilic anion alkenyl sulfonate and strong hydrophilic cationic alkenyl quaternary ammonium through a water-soluble azo initiator in an aqueous solution, wherein the generated multipolymer molecular chain contains about 2,000 to 4,000 structural units, and the weight-average molecular weight range is 1,320,000 to 2,100,000. The multipolymer filter loss reducer has high compatibility in an ultrahigh-temperature water-based drilling fluid well completion fluid, can obviously reduce the filter loss quantity of the drilling fluid well completion fluid under the ultrahigh-temperature environment, has temperature resistance capable of reaching 248 DEG C, saturated sodium chloride resistance and excellent complex salt resistance, and can obviously reduce the filter loss quantity in the water-based high-temperaturedrilling fluid with the chloridion concentration higher than 100,000 ppm, calcium ion concentration higher than 5,000 ppm and magnesium ion concentration higher than 5,000 pmm and invaded with acidicgas.

Description

Technical field: [0001] The invention relates to an amphoteric ion hydrophobic association polymer filtrate reducer that is resistant to ultra-high temperature and compound salt and a preparation method thereof, and belongs to drilling fluid and oil and gas drilling engineering, exploration and development of deep earth resources, and geothermal well drilling engineering. Completion fluid technology field. Background technique: [0002] With the in-depth development of oil and gas exploration and development in the world and the continuous progress of oil and gas resource exploration and development technology, oil and gas exploration and development areas are gradually developing towards ultra-deep layers. In addition, with the continuous advancement of major deep-earth projects such as my country's deep resource exploration, continental scientific drilling projects, and deep earth exploration programs, the geological design well depth in drilling projects has also increase...

AI Technical Summary

Problems solved by technology

The physical and chemical properties of water as the continuous phase of water-based drilling fluid are not considered. Changes in ultra-high temperature and high pressure environments. With the gradual increase of temperature and pressure, water gradually becomes subcritical water, and the dielectric constant of water continues to decrease , indicating that the polarity of water is gradually weakened. Therefore, subcritical water can gradually have a certain solubility for neutral polar and non-polar organic compounds. At the same time, polymer treatment agents with strong hydrophilicity may not be able to It is completely dissolved in subcritical water, leading to the occurrence of thermally induced phase separation; in addition, the hydrogen bonding of water gradually weakens with the gradual increase of temperature and pressure, the surface tension of water also gradually decreases, and the ion content of water The constant increases gradually

Therefore, when designing the molecular structure of polymer fluid loss control agents similar to those in the above-mentioned similar patent documents, the influence of changes in water in ultra-high temperature and high pressure environments is usually ignored, so that the current fluid loss control agents can be used in ultra-high temperature and high pressure environments. The effect under the condition is not ideal, and even can not reach the effect of field application

In addition, the current anti-high temperature and anti-salt polymer fluid loss reducers are generally able to resist saturation of sodium chloride, but the ability to resist high-valent metal cations is often weak, and the ability to resist hydrogen sulfide is also weak. When the conditions are low, the fluid loss control agents currently used are less effective

Finally, the initiators commonly used in the above-mentioned patent documents are persulfate and sodium bisulfite. The traditional oxidation-reduction initiation system has a low initiation efficiency for the reaction system, and the conversion rate of the product is also relatively low. The corresponding reaction conditions are relatively harsh

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