RU2742167C1 - Process liquid for perforation and stopping of wells - Google Patents

Abstract

FIELD: oil and gas production.

SUBSTANCE: invention relates to the field of oil and gas production, in particular to compositions used as process fluids in the development and killing of gas, gas condensate and oil wells, especially at low temperatures and low reservoir pressures, and helping to reduce damage to the reservoir in the process development and repair of wells, reduction of swelling of clay minerals, prevention and dissolution of gas hydrate deposits.A process fluid for perforation, killing and well workover, containing a clay swelling inhibitor, an organic solvent based on monohydric and polyhydric alcohols, a surfactant and water, contains ethanol, or propanol, or methanol as an organic solvent, and mixtures thereof with glycerin and either ethylene glycol or propylene glycol, as clay swelling inhibitors - potassium carbonate or formate or their mixture in a 1: 1 ratio, and as surfactants - benzyldimethylethylammonium chloride, or benzyltrimethylammonium chloride, or triethylbenzyl ammonium chloride, or in the form of a 50% alcohol solution with the following ratio of components, wt.%: clay swelling inhibitor - 2.0-8.0; organic solvent - 15.0-50.0; surfactant - 0.5-3.0; water - the rest.

EFFECT: invention ensures possibility of application in a wide temperature range - from 40 to -40 C with effective use for killing, development and workover of wells.

1 cl, 3 tbl, 1 ex

Description

The invention relates to the field of oil and gas production, in particular, to compositions used as process fluids (TJ) during the development and killing of gas, gas condensate and oil wells, especially at low temperatures and low reservoir pressures, and helping to reduce damage to the reservoir in the process well development and workover, reduction of swelling of clay minerals, prevention and dissolution of gas hydrate deposits.

Known process fluid for perforating and killing wells (see RF patent No. 2115686 on class IPC S09K7 / 02, publ. 20.07.1998) containing masses. %: calcium chloride 1-40; organic solvent, incl. glycerin, 10-50; inhibiting salt, incl. potassium chloride, 1-10; water - the rest.

The disadvantage of this process fluid is that it does not retain the initial permeability of the formation and has significant penetration zones in the near-wellbore zone of the formation after killing the well.

Known process fluid (see RF patent No. 2515626 on class IPC S09K8 / 42, publ. 05/20/2014), including a surfactant (surfactant) complex action SNPKh PKD-515, a weighting agent, a corrosion inhibitor, industrial or sea water, in this case, potassium formate is used as a weighting agent and corrosion inhibitor with the following ratio of components, wt. %: SNPKh PKD - 0.5; potassium formate - 10-50; water - 49.5-89.5.

The disadvantage of this process fluid is that the composition of this process fluid does not allow obtaining systems with a solution density below 1.05 g / cm ³ for use at low reservoir pressures and negative ambient temperatures up to minus 40 ° C, which does not allow use it all year round.

Also known is a process fluid for workover of wells (see RF patent No. 2599395 according to class MPK S09K8 / 42, publ. 10.10.2016), containing polyhydric alcohol (or glycerin, or triethylene glycol, or propylene glycol), an inhibitor and water, while calcium bromide and zinc bromide or iodide are used as inhibitors. The proposed composition makes it possible to obtain process fluids with a density index of 2300-2500 kg / m ³ .

The disadvantage of this process fluid is that its composition does not allow to obtain compositions with a solution density below 1.95 g / cm ³ for operation at low reservoir pressures, and also does not have a positive effect on reducing the swelling of clay rocks and their water saturation.

The closest analogue to the claimed invention is a process fluid for perforating and killing wells (see RF patent No. 2188843 on class IPC E21B43 / 12, publ. 09/10/2002), containing, mass. %: chloride of alkali or alkaline earth metal - 0-50; inhibiting salt (potassium or ammonium chlorides) - 0.1-10; organic solvent (one or polyhydric alcohols, ethers based on them, acetone, hydrocarbons) - 0.1-10; water-soluble surfactant (neonol AF 9-12, OP-10, neftenol VVD or sulfonol) - 0.1-3; water is the rest.

The disadvantage of this process fluid is that the presence in the composition of, in addition to inhibiting salts, chlorides of alkali or alkaline earth metals, within the specified limits of an organic solvent does not allow providing a low density of solutions (<1.1 g / cm ³ ) and its homogeneity in the temperature range up to minus 40 ° C. In addition, the used water-soluble surfactants, lowering the surface tension at the oil-water interface, do not have a hydrophobic effect on the formation and thus do not affect the reduction of clay swelling.

The technical problem of the claimed invention lies in the development of such a composition of the process fluid, which allows it to be used in conditions of low reservoir pressure in a wide temperature range (from +40 to -40 ° C) for efficient killing, development and workover operations.

The technical result consists in the development of the composition of the process fluid having a density value in the range of 0.9-1.1 g / cm ³ while ensuring the necessary fire safety of the composition in accordance with GOST 6356-75. An additional result is an inhibiting and dissolving effect on gas hydrate deposits.

To solve a technical problem and a technical result, a process fluid for perforating, killing and repairing wells containing a clay swelling inhibitor, an organic solvent based on monohydric and polyhydric alcohols, a surfactant and water, according to the invention, contains ethanol or propanol as an organic solvent, or methanol, as well as their mixtures with glycerin and either with ethylene glycol or with propylene glycol, as clay swelling inhibitors - potassium carbonate or formate or their mixtures in a 1: 1 ratio, and as surfactants - benzyldimethylethylammonium chloride or benzyltrimethylammonium chloride or triethylbenzylammonium chloride or cetyltrimethylammonium chloride in the form of a 50% alcohol solution with the following ratio of components, wt%:

clay swelling inhibitor 2.0-8.0 organic solvent 15.0-50.0 surface-active substance 0.5-3.0 water rest

The organic solvent in the specified quantitative ratio (15-50%) provides the required density of the process fluid, homogeneity of solutions in the temperature range from -40 to +40 ° C and the flash point of the system ≥ + 20 ° C.

A decrease in the solvent content of less than 15.0% leads to liquid crystallization at -20 ° C (Table 1), and exceeding its amount of more than 50.0% does not provide the set value of the flash point (<+20 ° C).

Table 1

Composition and technological parameters of the process fluid

Composition of the composition, wt% Density, g / cm ³ Crystallization temperature, ° С Flash point, ° С By prototype: CaCl ₂ - 7.05
NH ₄ Cl - 2.35
Solvent - 0.3
Surfactant - 0.05
Water - 90.25 1.40 -fifteen 63 Developed composition No. 1 Organic solvent - 12:
(Propanol-1 - 2
Ethylene glycol - 5
Glycerin - 5)
Clay Swelling Inhibitor - 3
(Potassium carbonate)
Cationic surfactant - 1.0
(Alkyltrimethylammonium chloride C ₁₂ - C ₁₄ , 50% alcohol solution)
Water is the rest 1.05 -20 35 Developed composition No. 2 Organic solvent - 25
(Ethanol - 15
Ethylene glycol - 5
Glycerin - 5)
Clay Swelling Inhibitor - 3
(Potassium formate - 1.5
Potassium carbonate - 1.5)
Cationic surfactant - 1.0
(Cetyltrimethylammonium chloride, 50% alcohol solution)
Water is the rest 1.00 ≤-40 25 Developed composition No. 3 Organic solvent - 45
(Ethanol - 30
Ethylene glycol - 10
Glycerin - 5)
Clay Swelling Inhibitor - 3
(Potassium formate)
Cationic surfactant - 1.0
(Alkylbenzyldimethylammonium chloride C ₁₂ - C ₁₄ , 50% alcohol solution)
Water is the rest 0.98 ≤-40 22 Developed composition No. 4 Organic solvent - 55
(Ethanol - 40
Ethylene glycol - 5
Glycerin - 10)
Clay Swelling Inhibitor - 3
(Potassium formate)
Cationic surfactant - 1.0
(Alkylbenzyldimethylammonium chloride C ₁₈ - C ₁₆ , 50% alcohol solution)
Water is the rest 0.95 ≤-40 eighteen

The clay swelling inhibitor prevents the swelling of clay minerals of the rock of different composition or clay particles of the drilling mud, thus, providing a sparing effect on the reservoir properties of the formation during development, perforation and killing of wells (see, for example, Shadymukhamedov S.A., Smykov Yu. V., Vakhitov T.M., Safuanova R.M. Analysis of modern technical and technological solutions for killing and flushing wells // Investigated in Russia: electron. Journal 2008. No. 68. P. 724-736. URL .: http : //zhurnal.ape.relarn.ru/articles/2008/068.pdf .). With a decrease in the content of the swelling inhibitor of less than 2%, no significant effect on the swelling of clays is observed, with an increase in the content of the swelling inhibitor of clays above 8%, the achieved inhibitor efficiency remains, but the density of the process fluid exceeds 1.1 g / cm ³ .

Inhibitory properties were assessed by the impregnation of a liquid into plastic clay samples in a test medium (Table 2). Moreover, the relative increase in mass in% was determined as:

∆m = (m2-m1) ∙ 100% / m1,

where m2 is the mass of the sample held for 7 days. in the test environment;

m1 is the mass of the original sample.

table 2

Information on the inhibitory power of the tested formulations

No. Composition Relative increase in sample weight after 7 days, ∆m,% one Water, 100% 97 2 Water, 99%, HCOOK, 1% 86 3 Water, 98%, HCOOK, 2% 54 4 Water, 97%, HCOOK, 3% 20 five Water, 95%, HCOOK, 5% 19 6 Water, 91%, HCOOK, 9% 19

Cationic surfactants reduce the surface tension, facilitating the removal of the process fluid from the porous medium of the reservoir after its application (see, for example, "Development of oil fields using surfactants" / GA Babalyan, AB Tumasyan, B.I. Levy et al. - M .: Nedra. 1983. pp. 47-50.). When the content of the cationic surfactant is below 0.5%, a decrease in the surface tension is not ensured, the use of a concentration of more than 3% is meaningless, since there is no further decrease in the surface tension (Table 3). Also used cationic surfactants have a hydrophobic effect on the surface of a porous medium (see, for example, Holmberg K., Jensson B., Kronberg B., Lindman B. - Surfactants and polymers in aqueous solutions M .: Binom. Knowledge laboratory. 2007. S.327.), Thereby inhibiting the swelling of clays (see Demakhin S.A., Demakhin A.G. The use of water repellents in oil and gas production. Saratov. 2016).

Table 3

Influence of the concentration (in commercial form) of cationic surfactants on the change in interfacial tension at the "process liquid-oil" interface

(oil density 0.854 g / cm ³ )

Interfacial tension mN / m at chemical reagent concentration, wt% 0 0.3 0.5 1.0 2.0 3.0 3.5 24.0 0.1 0.041 0.027 0.021 0.020 0.020

The information provided on the composition and properties of the developed process fluid indicates that the achieved indicators give it a new set of properties that provide the necessary impact on the reservoir. The solvent provides high solubility to the used inhibitor and cationic surfactant, which gives the solutions the necessary surfactant and solubilizing properties in a wide temperature range in the presence of the required density and fire safety of the systems used.

The process fluid is obtained as follows.

A predetermined amount of reagents is sequentially introduced into a reactor with a stirring device: water, then a clay swelling inhibitor, a single or multicomponent organic solvent (low-boiling solvents are introduced first), a cationic surfactant. After the introduction of the components, the composition is mixed for 30 minutes until complete homogenization.

The efficiency of using the developed process fluid is illustrated by the following example.

Example. The botuobinsky reservoir of the Chayandinsky oil and gas condensate field contains minerals with an increased content of clay cement. Productive formations are characterized by low reservoir pressures and low reservoir temperatures. Killing a well in winter with ambient temperatures up to ≤-40 ° C is extremely difficult, since a solution with a density of 1.05 g / cm ³ freezes and requires continuous heating. This leads to very high costs for heating and killing the well. During killing, the water-salt solution leads to swelling of the clay component of the reservoir and the well does not reach the design gas flow rate. In order to reduce the cost of work and improve the manufacturability of the killing process, it was proposed to use a new process fluid.

The process fluid contained: 51% water, 3.0% potassium formate, 45% organic solvent, including 30% ethanol, 10% ethylene glycol, 5% glycerin, 1% cationic surfactant (Alkylbenzyldimethylammonium chloride C12 - C14, 50% alcohol solution ). The resulting process fluid had the following indicators: density 0.98 g / cm ³ ; crystallization temperature ≤-40 ° С; flash point 22 ° C.

Then the process fluid was pumped into circulation into a gas well with a volume of 30 m ³ until it was completely filled. After that, work was carried out to open the productive formation and develop the well. After the development work, the well reached the design gas flow rate of up to 450 thousand m ³ / day, which indicates an improvement in the condition of the bottomhole formation zone due to the reduction of clay swelling and accelerated removal of the kill fluid from the porous space of the formation.

Thus, the inventive process fluid provides effective killing and development of the well, its accelerated reaching the mode, reduces the cost of development and repair of the well, and provides the possibility of carrying out work in the winter.

Claims (2)

Process fluid for perforating and killing wells containing a clay swelling inhibitor, an organic solvent based on monohydric and polyhydric alcohols, a surfactant and water, characterized in that it contains ethanol, or propanol, or methanol as an organic solvent, as well as mixtures with glycerin and either ethylene glycol or propylene glycol, as clay swelling inhibitors - potassium carbonate or formate or mixtures thereof in a 1: 1 ratio, and as surfactants - benzyldimethylethylammonium chloride, or benzyltrimethylammonium chloride, or triethylbenzyl ammonium , or cetyltrimethylammonium chloride in the form of a 50% alcohol solution with the following ratio of components, wt%: clay swelling inhibitor 2.0-8.0 organic solvent 15.0-50.0 surface-active substance 0.5-3.0 water rest