RU2643051C1 - Method for removing liquid from gas and gas-condensate wells - Google Patents

Abstract

FIELD: oil and gas industry.

SUBSTANCE: method for removing liquid from gas and gas-condensate wells involves introducing foaming composition to the well bottom in the form of two types of solid blocks, different in composition, the blocks of the first type contain, wt %: sodium Nitrite 70; sodium chloride 23; nonionic surfactant 5; polyanionic cellulose of high viscosity CMC 0.5; oil-soluble surfactant Sulfonol NP-1 1; complex Trilon B 0.5; the blocks of the second type contain, wt %: sulfamic acid 50; weighting agent- sodium chloride 43; nonionic surfactant 5; high-viscosity PAC 0.5; Sulfonol NP-1 1; Trilon B 0.5, wherein by stoichiometry per 1 part of sodium nitrite in the first step is 1.4 parts of sulfamic acid in the block of the other type.

EFFECT: effective lifting of well fluid from gas and gas-condensate wells.

2 cl, 1 tbl

Description

In gas wells, as they age, water accumulates, preventing the rise of gas. To maximize the life of the well and gas production, it is necessary to remove water from the well or replace it. One of the most cost-effective methods of resuming the free movement of gas is to add a surfactant to the water, which turns the liquid into foam. The formation of foam reduces hydrostatic pressure on the reservoir, increasing well productivity.

Known methods for removing fluid from a well by producing foaming compositions by introducing surfactants into water (Amiyan A.V. Well development using foam systems. - M.: VNIIOENG. - 1984, 25-27). The use of these surfactant input methods is not always effective for well operation at abnormally low values of fluid pressures in reservoirs.

Known foaming composition for removing fluid from gas wells in the following ratio of components, wt. %:

Alkyldimethylamine Oxide CnH2n + 1 (CH3) 2NO, where n = 12-14 31, 47-32, 45 Sodium Alkyl Sulfonate R-SO2ONa 0.9-1.2 Urea 4,5-5,5 Water Rest

(A.S. SU No. 1723090 dated 10/09/1989).

The disadvantage of this composition is the low efficiency of foaming from the bottom of low-temperature gas and gas condensate wells. In addition, working solutions of the specified composition are liquids. The preparation of liquid working solutions is a laborious task, requires the use of large-capacity special equipment and large-capacity tanks.

Currently, the greatest practical interest in terms of saving labor and technical resources are various kinds of solid foaming agents - checkers (rods) - cast or pressed.

Known solid foaming agent for removing liquid formation fluid from gas and gas condensate wells, including an ethoxylated surfactant (Lutensol brand AT 25 or AT 50) and a vinyl-containing polymer (polyvinylpyrrolidone), in the following ratio of ingredients, wt. %:

Lutensol AT 25 or AT 50 40-80 Polyvinylpyrrolidone 20-60

(US Pat. RU 2442814).

Known solid foaming agent for removing liquid from gas and gas condensate wells in the following ratio of ingredients, wt. %:

Urea 27 Ethylene oxide propylene block copolymer (CnH2n + 1O (C3H60) m (C2H4O) pH, where n is the number of carbon atoms in the alkyl radical, equal 5-15 m is the number of moles of ethylene oxide equal to 9-45 p is the number of moles of propylene oxide, equal to 30-180 35.7 Polyvinyl alcohol 2 KSSB 32.6 Water 2

(US Pat. RU No. 2323244).

Known lightweight solid foaming agent for removing liquid from gas and gas condensate wells in the following ratio of ingredients, wt. %:

Powder base (sulfonol, KSSB) 20-80 Based Surfactant polyethylene glycol monoalkylphenol ether based on polymer distillate (OP-7, OP-10) 10-70 Plasticizing additive (CMC, PVA) 1-18 Lightweight additive (expanded polystyrene) 0.3-0.7

(US Pat. RU No. 1710705).

The effectiveness of the use of solutions is much lower than that of solid blowing agents - checkers, it requires the use of special equipment and special injection techniques, as well as large volumes of reagents due to the loss of a chemical substance during foaming. An important feature of solid foaming agents - foam blocks (rods) is the possibility of their use for processing hard-to-reach objects. The use of checkers replaces a special team of workers and equipment. This approach simplifies the use of surfactants and reduces the cost of well operations in general. A disadvantage of the known solid foaming agents is the low efficiency of liquid removal from gas or gas condensate wells in conditions of low gas flow or its complete absence. In this case, the use of foaming checkers is ineffective and inappropriate. A call to the inflow from the formation with subsequent cleaning of the well is possible only in the case of forced foaming using gas-forming compounds.

Known solid foaming agent for removing fluid from the bottom of the well, containing non-ionic surfactants (OP-10 or OP-7), anionic (sulfonol), lignosulfonate (KSSB or SDB, or FHLS), characterized in that when the ratio of OP-10 or OP-7 and sulfonol 3.45: 1, crystalline sulfamic acid and sodium carbonate (potassium or calcium) in the following ratio, wt. %:

OP-10 (OP-7) 34.0-40.0 Sulfonol 9.8-11.6 Crystalline sulfamic acid 11.0-13.0 Sodium carbonate (potassium or calcium) 4,5-6,5 Lignosulfonate (KSSB or SDB, or FHLS) Rest

(US Pat. RU 2223298).

Known foaming agent for cleaning gas wells in the following ratio of ingredients, wt. %:

KSSB powder base 39-49 Surfactant surfactant based on alkyl phenol 50-60 Ammonium tartrate 0.5-0.95 Sodium carbonate 0.05-0.5

(US Pat. RU No. 2173694).

The disadvantage of the above compositions is the lack of foaming due to the high solubility of the resulting carbon dioxide in water. A high foaming effect can be achieved if a relatively inert gas is released with minimal solubility in water.

The closest solution to this problem is a method of removing fluid from the well, including the introduction of a self-generating, foaming composition to the bottom of the well in the form of solid checkers of two types, different in composition: the basis of the checker of one type is alkali metal nitrite, the basis of the other type is sulfamic acid, checkers both types contain a nonionic surfactant, a surfactant and a weighting agent substance - sodium chloride or potassium in an amount providing a density of the blocks of at least 1.8 g / cm ^3, wherein at stoichiometry and 1 part of the alkali metal nitrite in the first checker have 1.14 or 1.4 parts sulfamic acid as another type checker (Pat. RU 2317412).

It is positive that the technology is based on the delivery to the bottom of the well of solid blocks containing nonionic surfactants, the insufficient gas supply to the well is compensated by its generation during a chemical reaction, and nitrogen is released. The generation of nitrogen is preferable to the formation of carbon dioxide, since nitrogen is an inert gas and, most importantly, the solubility of nitrogen in water is much less than the solubility of carbon dioxide (at normal pressure and a temperature of 20 ° C, the solubility of nitrogen is 11 cm ³ in one liter of water, for CO ₂ this figure is 710 cm ³ ). The use of nonionic surfactants provides foaming even in mineralized waters.

The disadvantage of this method is that it does not take into account the quality of the well fluid, namely the presence of hydrocarbon condensate. Hydrocarbons in the reservoir fluid are defoamers, which reduces the efficiency of foam formation and fluid recovery. In addition, in the case of using the blocks according to the above method at temperatures above the melting point of the surfactant, the blocks soften already in the process of falling, this leads to the sticking of the blocks to the surface. All this can lead to blockage of the borehole channel and makes it impossible to reset the checkers in the required calculated quantity.

The objective of the invention is to expand the field of application of foam-generating checkers and increase the efficiency of removal of a water-condensate mixture with a gas condensate content of up to 50% vol.

The proposed problem is solved by the proposed method for removing liquid from gas and gas condensate wells, including the introduction of a foaming composition to the bottom of the well in the form of solid blocks of two types, different in composition: the base of the first type is sodium nitrite, the basis of the second type is sulfamic acid, both types of checkers contain a non-ionic surfactant surfactant, a weighting agent is sodium chloride, while according to stoichiometry, 1 part of sulfamic acid per 1 part of sodium nitrite in the first checker another type of checker, characterized in that polyanionic cellulose highly viscous (PAC-B), an oil-soluble surfactant — sulfonol NP-1, and complexon — trilon B are added to the checkers of both types in the following ratio of components in each checker,% wt. :

Checker Content The first Second of type of type Sodium nitrite 70 0 Sulfamic acid 0 fifty Sodium chloride 23 43 Nonionic surfactant 5 5 PAC 0.5 0.5 Sulfonol NP-1 one one Trilon-B 0.5 0.5

Additionally, both types of checkers are packaged in water-soluble paper cylinders.

In the presence of hydrocarbons, foaming of the liquid worsens and becomes practically impossible when the hydrocarbon content in the mixture is more than 10-20%. The foaming ability of a non-ionic surfactant type AF9-12, recommended in the method of the prototype, in the well fluid with a high content of hydrocarbons is minimal. In the present invention, a mixture of non-ionic surfactants (neonol) and anionic type (sulfonol) is used, the latter having increased solubility in light oil products. The redistribution of surfactants in the aqueous and hydrocarbon phases provides high foaming of the water-condensate mixture as a whole and provides a more complete removal of fluid from the well. The use in the present invention of a mixture of anionic and nonionic surfactants in a ratio of 1 to 5, with a high content of the latter, minimizes the sensitivity of the system from mineralization of water. Complexon - Trilon B (disodium salt of ethylenediaminetetraacetic acid) is introduced into the composition of the pieces also with the aim of screening the negative effects of hardness salts in the solution and preventing the effect of "salting out" of the anionic surfactant.

Polyanionic cellulose (PAC) serves as a binder, adhesive, provides hardening of the checkers of both types as a whole. In addition, the introduction of a water-soluble polymer - PAC increases the stability of the resulting foam and increases its endurance. Used by the PAC-B method, it is a thermostable substance resistant to water mineralization.

In order to eliminate the effect of “sticking”, the pressed pieces are additionally packaged in paper cylinders of water-soluble paper. For packaging checkers by the present method, water-soluble paper Aquasol (USA) is used. It is possible to use water soluble paper from any other manufacturer.

The effectiveness of the invention was evaluated in laboratory conditions by the volume of the removed fluid with different salinity and gas condensate content. The tests were carried out at room temperature; model waters containing calcium, sodium, and magnesium ions were used.

The following reagents were used for research: sodium nitrite (GOST 4144-79), sulfamic acid (TU 2121-400-0576-3441-2002), non-ionic surfactant Af9-12 (TU 38-507-63-171-91), sulfonol- NP-1 (TU 2484-004-8482528-99), sodium chloride (GOST 4233-77), Trilon B (GOST 10652-73), PAC-V polyanionic cellulose (TU2231-015-32957739-00) (see table )

The results of laboratory studies showed a more complete removal of the borehole fluid containing gas condensate, by checkers according to the claimed method in comparison with the prototype.

The application of the proposed method can improve the efficiency of removing well fluid with high salinity and gas condensate content up to 50% under conditions of abnormally low reservoir pressures and complete self-capping of the well.

Claims (3)

1. The method of removing liquid from gas and gas condensate wells, including the introduction of a foaming composition to the bottom of the well in the form of solid blocks of two types, different in composition: the basis of the first type of checkers is sodium nitrite, the basis of the second type is sulfamic acid, both types of checkers contain nonionic surfactant surfactant, weighting agent - sodium chloride, while stoichiometry per 1 part of sodium nitrite in the first piece contains 1.4 parts of sulfamic acid in a piece of another type, characterized in that o additionally, high viscosity polyanionic cellulose (PAC-V), oil-soluble surfactant Sulfonol NP-1 and complexon Trilon B in the following ratio of components in each dye, wt.% are added to both types of checkers:

2. The method according to p. 1, characterized in that the checkers of both types are additionally packed in cylinders of water-soluble paper.