CN106928956A - A Neutral Hard Scale Softener Used in Three-element Compound Flooding Screw Pump Wells - Google Patents

Abstract

The invention belongs to the technical field of oilfield chemistry, in particular to a neutral hard scale softener used in three-element compound flooding screw pump wells. The invention solves the problem that the screw pump well cannot be pickled after scaling due to excessive corrosion of the scale cleaning agent. The present invention is composed of organic phosphate, organic phosphonate, dispersant, alkali and water, and their percentages by weight are: organic phosphate 10-40%, organic phosphate 2-10%, dispersant 1-5%, alkali 1~3%, water 50~80%. The present invention can be applied to the three-element compound flooding screw pump well to remove scale and jam, completely soften and fall off the scale attached to the screw pump rotor and other parts, and completely remove it. The invention has low corrosion and has no effect on the chrome-plated coating of the screw pump rotor Any damage, the rotor coating will not fall off, the operation will not be lost due to pump leakage, and the production time rate of the screw pump well can be effectively guaranteed.

Description

A Neutral Hard Scale Softener Used in Three-element Compound Flooding Screw Pump Wells

technical field

The invention belongs to the technical field of oilfield chemistry, in particular to a neutral hard scale softener used in three-element compound flooding screw pump wells.

Background technique

In the process of oilfield water injection development, the generation of inorganic scale is a common problem encountered in production. Due to the existence of reservoir heterogeneity, the composition of rock minerals in different underground layers and the properties of fluid in the reservoir are different. When the oil well When underground fluids produced from several different formations are mixed in the wellbore or when the temperature and pressure of various fluids and the concentration of scale-forming ions in the fluid change greatly, it is easy to generate inorganic scale, and these scales will adhere to the Pump barrels, rotors, sucker rods and other parts of screw pump wells cause frequent leakage, rod breakage, and reduced pump efficiency in screw pump wells, which seriously affect the production time rate and increase production costs.

At present, pickling measures are taken to remove scale in ASP flooding oil wells, which has a good scale removal effect on oil wells, but the hydrogen ions in these pickling agents will react quickly with the chrome-plated coating of the screw pump rotor. The chrome-plated coating on the rotor of the screw pump will fall off, and the gap between the stator and the rotor will increase, resulting in a decrease in pump efficiency after pickling and descaling, seriously affecting the recovery efficiency, and even causing the pump to be stuck.

Contents of the invention

The purpose of the present invention is to provide a pump that can effectively soften, shed, and remove the scale attached to the rotor, sucker rod, pump barrel, etc., reduce the number of operations of the screw pump well due to leakage, pump stuck, etc., and prolong the working life of the screw pump well. It is a neutral hard scale softener for ASP flooding screw pump wells with high operating rate.

The present invention is composed of organic phosphate, organic phosphonate, dispersant, alkali and water, and their percentages by weight are: organic phosphate 10-40%, organic phosphate 2-10%, dispersant 1-5%, alkali 1~3%, water 50~80%.

The organic phosphate can be any one of acrylic acid-vinyl alcohol phosphate copolymer, maleic acid-vinyl alcohol phosphate or polyvinyl alcohol phosphate.

The organic phosphonate can be tetrasodium aminotrimethylene phosphonate, potassium aminotrimethylene phosphate, tetrasodium 2-phosphonic acid butane-1,2,4-tricarboxylic acid or ethylenediamine tetramethylene phosphonic acid Any of the pentasodium.

The dispersant can be any one of sodium polyacrylate, sodium polymaleate or hydrolyzed polymaleic anhydride.

Described alkali can be any one in sodium hydroxide, potassium hydroxide, sodium carbonate or potassium carbonate.

Wherein, above-mentioned organophosphate molecular formula is following molecular formula:

Acrylic acid-vinyl alcohol phosphate copolymer molecular formula:

.

.Maleic acid-vinyl alcohol phosphate molecular formula:

Molecular formula of polyvinyl alcohol phosphate:

The scale dissolution mechanism of the present invention is: the phosphoric acid group in organic phosphate or organic phosphate can complex with calcium ions under neutral conditions, improve the hydrophilicity of the scale, improve the permeability, and make a large amount of calcium in the dispersant The carboxyl groups in the scale can further complex with calcium, improve the dispersibility of calcium scale, and finally induce the crystal transformation of inorganic crystalline salts, so that the calcium carbonate crystals in the scale will change from densely packed calcite crystals to loose aragonite crystals. type, so that the scale looses, expands, and falls off from the surface of the mining equipment to achieve the purpose of scale removal.

Compared with the prior art, the present invention has the following advantages:

1) Strong compatibility with the formation, wide adaptability to the temperature, salinity and pH value of the formation, no flocculation and precipitation after mixing with formation fluid;

2) Does not react with reservoir rock minerals in different blocks, static immersion at formation temperature

48 hours, without any erosion and swelling;

3) The dispersion expansion ratio of the ASP flooding well scale sample reaches more than 10 times the volume of the original scale sample;

4) Soaking at formation temperature for 48 hours will not damage the chrome-plated coating of the screw pump rotor, the rotor coating will not fall off, the pump efficiency will not change, and the normal production will not be affected, which can meet the field use requirements of screw pump well descaling;

5) Low corrosion rate, the corrosion rate of N80 test piece at 45°C is lower than 1g/(m ² ·h).

Specific embodiments: the present invention will be further described below in conjunction with examples: it is made up of organic phosphate, organic phosphonate, dispersant, alkali and water, and their weight percent is: organic phosphate 10～40%, organic phosphate 2-10%, dispersant 1-5%, alkali 1-3%, water 50-80%.

The organic phosphate can be any one of acrylic acid-vinyl alcohol phosphate copolymer, maleic acid-vinyl alcohol phosphate or polyvinyl alcohol phosphate.

The organic phosphonate can be tetrasodium aminotrimethylene phosphonate, potassium aminotrimethylene phosphate, tetrasodium 2-phosphonic acid butane-1,2,4-tricarboxylic acid or ethylenediamine tetramethylene phosphonic acid Any of the pentasodium.

The dispersant can be any one of sodium polyacrylate, sodium polymaleate or hydrolyzed polymaleic anhydride.

Described alkali can be any one in sodium hydroxide, potassium hydroxide, sodium carbonate or potassium carbonate.

The preparation method of the present invention is:

a. Take organic phosphate in a beaker, add water, stir to dissolve.

b. Take the dispersant and add it into the water, stir to dissolve.

c. Mix the above two solutions of a and b, stir evenly, then add organic phosphonate therein, and stir evenly.

d. Take the alkali and add it into water, and after dissolving, use the alkali solution to adjust the solution obtained in step c, and adjust the pH value of the solution to 7.

Embodiment 1: it is made up of acrylic acid-vinyl alcohol phosphate copolymer, tetrasodium aminotrimethylene phosphonate, polysodium maleate, sodium hydroxide, water, and their weight percent is: acrylic acid-vinyl alcohol phosphate copolymer 25%, tetrasodium aminotrimethylene phosphonate 5%, sodium polymaleate 2%, sodium hydroxide 2%, water 66%. This example shows the field test results of neutral hard scale softeners.

This example is used in the screw pump well C271-SP12 of the second class upper return block in the west area of Daqing Oilfield. The current of the screw pump well rises from 51A to 63A due to scale deposition in this well. The current of the oil well recovers after being treated with a neutral hard scale softener Normally reduced to 52A, the oil well produced normally, and no leakage occurred; it was used in the screw pump well N4-10-P3039 in the upper return block in the eastern part of the South Fourth District of Daqing Oilfield. After the treatment, the current dropped from 48A to 37A, and the oil well returned to normal production. A leak occurs. The neutral hard scale softener can make the scale on the pump and oil pipe and other parts soft and fall off without corroding the chrome coating of the screw pump rotor, which meets the field use requirements of the screw pump well for cleaning scale.

Embodiment 2: It is made up of maleic acid-vinyl alcohol phosphate copolymer, 2-phosphonic acid butane-1,2,4-tetrasodium tricarboxylate, sodium polyacrylate, potassium hydroxide, water, their weight The percentages are: maleic acid-vinyl alcohol phosphate copolymer 25%, tetrasodium 2-phosphonic acid butane-1,2,4-tricarboxylate 5%, sodium polyacrylate 2%, potassium hydroxide 3%, water 65%.

Embodiment 3: it is made up of polyvinyl alcohol phosphate copolymer, hydrolyzed polymaleic anhydride, pentasodium ethylenediamine tetramethylene phosphonate, sodium carbonate, water, and their percentage by weight is: polyvinyl alcohol phosphate copolymer 15%, hydrolyzed polymaleic anhydride 1.5%, pentasodium ethylenediamine tetramethylene phosphonate 4%, sodium carbonate 2%, water 77.5%.

Embodiment 4: it is made up of polyvinyl alcohol phosphate copolymer, hydrolyzed polymaleic anhydride, pentasodium ethylenediamine tetramethylene phosphonate, sodium carbonate, water, and their percentage by weight is: polyvinyl alcohol phosphate copolymer 40%, hydrolyzed polymaleic anhydride 3%, pentasodium ethylenediamine tetramethylene phosphonate 8%, sodium hydroxide 3%, water 46%.

Claims (5)

1. a neutral hard scale softening agent for three-way compound flooding screw pump well, is characterized in that: it is made up of organic phosphate, organic phosphonate, dispersant, alkali and water, and their weight percent is: Organic phosphate 10-40%, organic phosphate 2-10%, dispersant 1-5%, alkali 1-3%, water 50-80%. 2. A kind of neutral hard scale softening agent for three-way compound flooding screw pump well according to claim 1, it is characterized in that: described organophosphate can be acrylic acid-vinyl alcohol phosphate copolymer, horse Any one of lactic acid-vinyl alcohol phosphate or polyvinyl alcohol phosphate. 3. A kind of neutral hard scale softening agent for three-way compound flooding screw pump well according to claim 1, it is characterized in that: described organic phosphonate can be tetrasodium aminotrimethylene phosphonate, amino Any one of potassium trimethylene phosphate, tetrasodium 2-butane-1,2,4-tricarboxylate, or pentasodium ethylenediamine tetramethylene phosphonate. 4. A kind of neutral hard scale softening agent for three-way compound flooding screw pump wells according to claim 1, characterized in that: the dispersant can be sodium polyacrylate, sodium polymaleate or hydrolyzed Any one of polymaleic anhydride. 5. A kind of neutral hard scale softening agent for ASP flooding screw pump well according to claim 1, characterized in that: said alkali can be sodium hydroxide, potassium hydroxide, sodium carbonate or carbonic acid any of potassium.