During the plugging and fracturing in oil wells, polymer has to be added into the working fluid as a thickener to improve blocking strengths or sand-carrying performance and reduce the amount of fluid loss. However, because of construction or polymer itself, polymer blocking or its liquid water residue clogging happens in the formation, which affects operation results. Therefore we must remove the blockage, restore formation permeability and improve construction effect.

To solve this problem, the polymer blocking remover was a developed polymer blocking remover, which has achieved good results in both laboratory evaluation and field application. Neither vegetable gum as fracturing fluid nor PAM used for plugging modulation or EOR can be a water-soluble polymer. If the chain is interrupted or completely cleaved, the polymer can turn into low-viscosity materials or full liquid water. According to this principle, we combined a variety of additives, which can turn polymers into liquid water and dissolve the residue generated by polymers hence release the blocking.

1. Performance Indicators:

(1) Appearance: Pale yellow or light red liquid

(2) Density: 1.0g/cm³（25℃）

(3) Dispersion: miscible in water or salt solution in any proportion

(4) Vegetable Gum Cake Elimination performance: With ordinary fracturing breaking-gel-to-water liquid (unfiltered and residue is retained) through the core, the permeability dropped down to 1/4 to 1/2 of the original. With the help of this blocking remover, the permeability returned to 85% of the original, which was increased by 0.6 to 1.0 times compared with the permeability after injury.

(5) Breaking-gel-to-water Performance for PAM Crosslinked Fluid: Prepare an aqueous solution. Add chromium salt crosslinker to form a gel and take about 200g gel. With 200ml blocking remover stirred at 80℃ for 30min, the gel turns into aqueous solution.

(6) Corrosion Inhibition Performance: Corrosion Rate≤5g/m²•h（90℃, atmospheric pressure, with 1% corrosion inhibitor for 4h）

(7) Surface Tension: ≤30 mN/m

2. Usage:

Wash the well completely. Prepare the blocking remover into a 1: 3 or 1: 5 solutions, where corrosion inhibitor is added by 1 to 2%. Pump the solution in place of active water, shut for 2 to 4 hours, put spray, drain, wash well and then get down to production.