RU2242494C2 - Reagent for taking away water-condensate mixture from well - Google Patents

Abstract

FIELD: oil and gas production.

SUBSTANCE: polyvinyl alcohol is proposed for taking away water-condensate mixture from wells containing formation water and gas condensate, especially from wells with abnormally low formation pressure.

EFFECT: increased efficiency of removal of water-condensate mixture.

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Description

The present invention relates to the field of gas and gas condensate production, namely, the removal of a water-condensate mixture from wells containing produced water and gas condensate, especially from wells with abnormally low formation pressure.

Known reagent for the removal of fluid from the well containing a surfactant - surfactant - "Progress", manufactured according to TU 38-10719-92 Novocherkassk synthetic products plant [1].

Surfactant “Progress” has the following indicators:

- the color of the aqueous solution with a mass fraction of surfactant 5% optical density, not more than 0.7;

- mass fraction of surfactants (a mixture of secondary sodium alkyl sulfates),% not less than 24.0;

- mass fraction of sodium sulfate,% not more than 3.5;

- mass fraction of non-sulfated hydrocarbons in relation to the active substance,% no more than 0.9;

- mass fraction of isopropyl alcohol,% not more than 3.5;

- the concentration of hydrogen ions - the pH of the commercial product is 7.5-9.0;

- mass fraction of iron,% not more than 0.01;

- density, g / cm ³ - not standardized;

- the mass of surfactant in g, corresponding to 1 cm ³ NaOH solution of concentration C (NaOH) 0.5 mol / dm ³ is not standardized; 0.5 mol / dm ³ - not standardized.

However, when the gas condensate content in the formation fluid is more than 20% by volume, the action of the Progress surfactant deteriorates or completely stops.

The aim of the present invention is to increase the efficiency of the removal of the water-condensate mixture from gas condensate wells, as well as formation fluid with high salinity from gas and gas condensate wells.

This goal is achieved by using the well-known polyvinyl alcohol-PVA - grade 18/11 for the first time for the removal of the water-condensate mixture, which meets the criterion of novelty.

Polyvinyl alcohol - PVA - grades 18/11 are produced according to GOST 10779-78 and are used in engineering in the production of synthetic fibers in the printing industry, as binders and impregnating materials, as an emulsifier and for medical purposes. Non toxic

PVA is soluble in water and insoluble in hydrocarbons, chloroform and ether. PVA is available in the form of a white or slightly yellowish powder and has the following indicators according to GOST 10779-78:

- mass fraction of volatile substances,% no more than 4.0;

- dynamic viscosity of a 4% aqueous solution of Ra · C · 10 ³ = 1 5,0-20,0;

- mass fraction of acetate groups,% - 10.0-14.0;

- an indicator of the concentration of hydrogen ions (pH) of a 4% solution - 5.5 - 7.0.

The use of the well-known PVA grade 18/11 for the removal of a water-condensate mixture became possible due to its property discovered by the authors to foam highly mineralized water and a water-condensate mixture.

Research and field trials have shown that the proposed reagent can be used both in the form of aqueous solutions and in the form of solid rods.

The use of the proposed reagent to remove the water-condensate mixture increases its duration in comparison with the Progress surfactant, which reduces the frequency of reagent injection into the well, that is, the effect of the prolonged action of PVA foaming surfactant takes place.

The validity of the PVA reaches 15 days.

The ability to form a liquid polymer film of PVA on the inner surfaces of lift pipes of a well has the properties of a corrosion inhibitor.

The amount of PVA grade 18/11 introduced into the well is lower than the Progress surfactant, and is determined separately by the well’s operational characteristics.

An example of a specific implementation.

200 ml of a water-condensate mixture and a calculated amount of PVA grade 18/11 are poured into a glass. Instead of PVA, the Progress surfactant is poured into the glass. The resulting mixtures are mixed separately with a mixer of the type “Voronezh” and determine the multiplicity of the foam.

The results are shown in tables 1 and 2.

Processing conditions:

processing temperature, ° С 40

processing time, sec 60

mixing mode, min ^-1 1200

As can be seen from the data obtained, the proposed PVA reagent grade 18/11 when foaming a water-condensate mixture gives a higher foam ratio than the known one.

As can be seen from the data obtained, the proposed reagent surpasses the prototype in terms of foam frequency and applied concentration (Table 1), and in duration of action (Table 2).

The use of the well-known PVA grade 18/11 as a reagent for foaming a water-condensate mixture will increase the efficiency of its removal from the well, reduce operating costs, and also inhibit downhole equipment from corrosion.

Sources of information

1. TU 38.10719-92.

2. GOST 10779 -78.

Claims (1)

The use of polyvinyl alcohol grade 18/11 as a reagent for the removal of water-condensate mixture from the well.