RU2361074C2 - Procedure for development of deposits of high viscous oil (versions) - Google Patents

Abstract

FIELD: oil and gas industry.

SUBSTANCE: invention refers to development of oil deposits and can be implemented for extraction of high viscous oil by means of thermal influence on reservoir. The procedure of development of high viscous oil reservoirs by means of thermal-steam treatment consists in pumping reagent solution with alternating fringes; notably, reagent decomposes under influence of temperature and gives off carbonic dioxide and steam; carbamide is used as said reagent; pumping of said solution is effected via a steam pressure well with not less, than two fringes; upon pumping the whole volume of solution, there is carried out pumping of water in volume 2 m³ exceeding volume of the flow string; further steam is pumped; also the said solution additionally contains ammonium nitrate, ammonium thiothyanic, complex surface active substance - SAS, neftenol BBD or mixture of non-ionogenic SAS - AF9-12 or NP-40, or NP-50 and anionoactive SAS - volgonate or Sulfonal, or NPS-6 at the following ratio of components, wt %: carbamide 15.0-40.0, ammonium nitrate 8.0-20.0, ammonium thiothyanic 0.1-0.5, Neftenol BBD 1.0-5.0, water - the rest or carbamide 15.0-40.0, ammonium nitrate 8.0-20.0, ammonium thiothyanic 0.1-0.5, non-ionogenic SAS 1.0-2.0, anionactive SAS 0.5-1.0, water - the rest; according to another version carbamide is used as the said reagent; pumping of the said solution is effected through a steam-cyclic producing well with not less, than two fringes; upon pumping the last fringe of steam there is carried out pumping of oil fringe; the said well is held for impregnation; further it is started; also the said solution additionally contains ammonium nitrate, ammonium thiothyanic, complex SAS Neftenol BBD or mixture of non-ionogenic SAS - AFD9-12 or NP-40, or NP-50 and anionactive SAS - volgonate or Sulfonal, or NPS-6 at the following ratio, wt %: carbamide 15.0-40.0, ammonium nitrate 8.0-20.0, ammonium thiothyanic 0.1-0.5, Neftenol BBD 1.0-5.0, water - the rest or carbamide 15.0-40.0, ammonium nitrate 8.0-20.0, ammonium thiothyanyc 0.1-0.5, non-ionogenic SAS 1.0-2.0, anionactive SAS 0.5-1.0, water - the rest.

EFFECT: increased efficiency of thermo-steam effect on reservoir of high viscous oil.

2 cl, 2 dwg

Description

The invention relates to the field of oil field development, and in particular to methods for the production of highly viscous oil by thermal action on the reservoir.

A known method for the production of hydrocarbon-containing raw materials - oil, comprising supplying, at least through injection wells, steam, providing heating of the formation, and selection through production wells of hydrocarbon-containing raw materials (SU 933957 A, 07.06.82). But introducing only steam into the formation to reduce the viscosity of oil or bitumen due to an increase in temperature in the formation is not enough. The temperature quickly drops to the initial one and the viscosity of the oil increases.

There is a method of developing an oil deposit, which consists in the fact that when oil is displaced by steam, carbon dioxide is added to it (Effects of CO ₂ addition to steam on recovery of west sak crude oil / Hombrook MW, Dehgham K., Qadur S. Ostermann KD, Ogbe DQ / SPE, Reserrvoir Eng. - 1991 - 6 No. 3, p. 278-286). The main effect of the introduction of the additive is associated with a decrease in the viscosity and density of oil due to the dissolution of carbon dioxide in it in a steam-heated formation. The disadvantage of this method is that the application of the method in the field requires high costs associated with obtaining, transporting and supplying CO ₂ to the injection well.

Also known is a method of cyclic exposure to a bottom-hole zone of a viscous oil formation containing steam and gas, water-soluble gas, and non-condensable gas in a vapor-gas coolant; free oxygen is contained in the gaseous non-condensable phase (US Pat. RF No. 2164289, ЕВВ 43/24). Free oxygen reacts with liquid phase oxidation with formation oil to produce additional heat directly in the formation. However, when the oxygen concentration is higher than optimal due to the oxidation reaction, the formation may overheat to temperatures hazardous to the production casing of the well.

The closest in technical essence to the proposed one is a method of developing hydrocarbon deposits using gas from gasification of coal seams to generate steam, which consists in the fact that steam is pumped through an injection well into an oil reservoir, and a saturated solution of one of carbon dioxide is pumped into this reservoir before steam is injected bicarbonate salts of alkali metals or ammonium. The production of products is carried out through a production well (US Pat. RF №2114988, ЕВВ 43/24). The increase in oil recovery is achieved due to the fact that with increasing temperature the salts decompose with the release of carbon dioxide, which dissolves in the oil and lowers its viscosity.

However, methods for developing oil deposits of highly viscous oils using steam and heat exposure, which make it possible to increase the oil recovery coefficient only by reducing the viscosity of oil, are not effective enough. By such methods, only that part of the oil that is in the cracks and pores can be selected, and the film oil due to the large adhesion to the formation rock is not selected.

The objective of the invention is to increase the efficiency of the steam and thermal effects on the reservoir of highly viscous oil by increasing the oil recovery coefficient not only by reducing the viscosity of the oil, but also due to a more complete extraction of oil from the reservoir.

The technical result is achieved by the method of developing deposits of high-viscosity oils by means of steam and heat treatment, including, according to claim 1, injection of alternating rims of a solution based on a reagent, decomposed under the influence of temperature, decomposing with the release of carbon dioxide, and steam, carbamide is used as the specified reagent, injection of this solution is carried out through steam injection well with at least two rims; after pumping the entire specified solution, water is pumped in a volume exceeding 2 m ³ volume per pine-compressor pipes, then steam, followed by production through the production well. In the case of the paracyclic action according to claim 2, a solution based on a reagent, decomposed under the influence of temperature decomposing with the release of carbon dioxide, is injected into alternating rims into the well, and urea is used as the indicated reagent, the solution is injected through the parocyclic well by at least two rims, after the last rim of steam has been injected, the rim of oil is injected, the indicated well for impregnation is maintained, then put into operation.

The solution is recommended to be injected with at least two rims. The urea-based solution additionally contains ammonium nitrate, thiocyanate and at least one component from the group: complex surfactant Neftenol VVD or a mixture of non-ionic surfactants (ethoxylated alkylphenol neonol AF9-12 or ethoxylated nonylphenol NP-40, or NP-50) and anionic (alkanesulfonate, for example volgonate, or alkylaryl sulfonate, for example sulfonol, or ethoxylated nonylphenol sulfonated NPS-6) in the following proportions, wt.%:

Urea 15.0-40.0 Ammonium nitrate 8.0-20.0 Ammonium Rodanisty 0.1-0.5 Neftenol VVD 1.0-5.0 Water Rest or Urea 15.0-40.0 Ammonium nitrate 8.0-20.0 Ammonium Rodanisty 0.1-0.5 Nonionic surfactant (AF9-12 or NP-40, or NP-50) 1.0 - 2.0 Anionic surfactant (alkanesulfonate, for example, volgonate or alkylarylsulfonate, for example, sulfonol, or NPS-6) 0.5-1.0 Water Rest

In the reservoir, under the influence of the high temperature of the injected steam, urea is hydrolyzed to form carbon dioxide and ammonia. Carbon dioxide, unlike ammonia, is much more soluble in oil than in water. Therefore, in the oil-water system, the oil phase will be enriched in carbon dioxide, the aqueous phase will be enriched with ammonia, which with ammonium nitrate forms an alkaline system with a maximum buffer capacity in the pH range 9.0 ÷ 10.5. The dissolution of carbon dioxide in oil leads to a decrease in its viscosity. Carbon dioxide and ammonia in the vapor phase contribute to the preservation of the vapor-gas mixture at a temperature below the vapor condensation temperature, increase the efficiency of the process of transporting oil components by the distillation mechanism. Carbon dioxide and ammonia reduce the swelling of clay minerals of the reservoir rock and thereby contribute to maintaining the initial permeability of the formation. The ammonia buffer system formed during the dissolution of ammonia in an aqueous solution of ammonium salts plays the same role. In addition, due to its alkalinity, pH 9 ÷ 10.5 and the presence of surfactants, it contributes to the intensification of countercurrent impregnation and oil displacement. A surfactant together with an alkaline buffer system contributes to the destruction, thinning of highly viscous layers or films formed at the boundaries: oil - water - rock, which worsen the filtration of liquids in the reservoir and reduce the completeness of oil recovery. When oil is displaced by a urea-based solution by reducing viscosity and improving wetting ability, the mobility of the filtered fluid increases by 1.5-6 times, the increase in oil displacement coefficient is 10-20%, the residual oil saturation is significantly reduced, which leads to stabilization or reduction of water cut in production wells and increase oil production. The ammonium salt, which is part of the solution, is also an indicator tracer.

The implementation of the method in an industrial environment is as follows.

The rim of the solutions can be injected either into steam injection wells during stationary steam-thermal treatment of the formation, or into production wells during the steam-cycle treatment. In the implementation of the process using standard oilfield equipment.

The solution is prepared as follows: a certain volume of water is supplied to the mixer tank, a nonionic surfactant — a complex surfactant Neftenol VVD or ethoxylated alkylphenol neonol AF9-12 or ethoxylated nonylphenol NP-40, or ethoxylated nonylphenol NP-50, an anionic surfactant — for example, alkanesulfonate or alkylaryl sulfonate, for example sulfonol, or ethoxylated nonylphenol sulfonated NPS-6, urea and ammonium nitrate. Using pumps, they are mixed until they are completely dissolved by circulating the mixture in the system: pump - mixer - pump. The prepared solution is pumped from the mixer tank to the storage tank and pumped (AN-700, CA-320, etc.) to the wells.

Alternating injection of rims is carried out in steam injection wells or in groups of steam injection wells: a urea-based solution, then steam, after the steam rim, again the solution rim and again steam, etc., production is taken through production wells. A carbamide-based solution is recommended to be injected with at least two rims. After the completion of the injection of the entire volume of the solution into the steam injection well, it is necessary to pump water in a volume exceeding by 2 m ^{3 the} volume of tubing (tubing), and then continue the injection of steam.

Alternating edges of the urea-based solution are injected into the steam-producing producing wells. A carbamide-based solution is recommended to be injected with at least two rims. After the steam injection is completed, a rim of oil is pumped into the well and left to impregnate, and then the well is put into operation.

The effectiveness of the application of this method for the development of high-viscosity oil deposits is evaluated by the results of pilot tests at the Usinskoye field of LUKOIL-Komi LLC and the high-viscosity oil field Liaohe (China). In September 2002, a urea-based solution was injected into steam injection wells 4029, 4040 and 4596 at the PTV-3 steam and heat treatment section of the Permocarbon deposit of the Usinsk deposit. The injection volume per well amounted to 88 tons, the total injection volume for all wells was 264 tons. A urea-based solution was prepared as follows: to prepare 5.0 tons of solution, 3.345 tons of water was fed into the mixer tank, 0.1 tons of nonionic surfactant neonol AF9 -12, loaded with 0.05 tons of volgonate, 1.0 tons of urea, 0.5 tons of ammonium nitrate and 5.0 kg of ammonium thiocyanate. Using pumps, they were mixed until they were completely dissolved by circulating the mixture in a pump-mixer-pump system. A prepared solution containing 20 wt.% Urea, 10 wt.% Ammonium nitrate, 2.0 wt.% Non-ionic surfactant neonol AF9-12, 1.0 wt.% Volgonate, 0.1 wt.% Ammonium thiocyanate and water - the rest , from the mixer tank was pumped into the storage tank. Ready solution pumping unit (AN-700, CA-320, etc.) was pumped into the wells. The injection of the solution into the steam injection well was carried out with rims of 30 and 58 tons, after each portion of the solution water was pumped into the well with a volume exceeding 2 m ^{3 the} volume of the tubing, and then steam was injected. After the second rim of the solution, steam was pumped in accordance with the accepted technological regime of development, production was produced through production wells.

Steam injection wells 4040, 4029 and 4596 had a high injection rate before injection (800-1000 m ³ / day in water at an injection pressure of 0). In the process of injection, the injectivity has not changed.

Efficiency analysis was carried out on the basis of production data for production wells of three experimental sites with injection wells 4040, 4029 and 4956, Fig.1. Production wells respond by reducing water cut by 5–40%, on average by 10–20%, increasing oil production rates in pilot plots by 31–49%, and by an average of 40%, which indicates a high oil-displacing effect of the method and an increase in liquid production rates by 4-25%, on average by 5-10%, which indicates the intensification of development. Additional oil production for the period from September 2002 to February 2004 inclusive amounted to: in the pilot section with a steam injection well 4029–11.3 thousand tons, with a steam injection well 4040–14.0 thousand tons and with a steam injection well 4596–19.1 thousand tons , in total 44.3 thousand tons, or 14.7 thousand tons of additionally extracted oil per 1 well treatment.

In September-October 2003, pilot tests were successfully carried out to improve the steam cycle effect on the high-viscosity oil deposit of the Liaohe field (China). 60 and 80 tons of solution, 2.5 thousand tons of steam and 10 tons of oil were pumped into two steam cyclic production wells 3-2 and 5-2. The solution was prepared at an acid station in a container with a capacity of 60 m ³ with a paddle mixer (~ 20 rpm) at 60 ° C. To prepare 50 tons of urea-based solution, 24.95 tons of water was poured into the mixer tank, then 750 kg of non-ionic surfactant NP-40, 250 kg of anionic surfactant NPS-6, 16 tons of urea, 8 tons of ammonium nitrate and 50 kg of rhodanum ammonium were poured. Using a paddle mixer they were mixed until completely dissolved. The prepared solution containing 32 wt.% Urea, 16 wt.% Ammonium nitrate, 1.5 wt.% NP-40, 0.5 wt.% NPS-6, 0.1 wt.% Rhodanist ammonium and water - the rest, were pumped from the mixer tank to the storage tank and the pumping unit were pumped into the wells. First, 15 tons of solution were pumped into well 3-2, then 300 tons of steam, then a second rim of the solution was pumped 45 tons and then 2200 tons of steam. After steam, a rim of oil was pumped into the production well 3-2 and the well left for impregnation. After 7 days, oil production began. The first rim of the solution was injected into the well 5-2, 20 tons, then 300 tons of steam, the second rim of the solution was 60 tons and then 2200 tons of steam. After that, a rim of oil was pumped into the production well 5-2 and the well left for soaking for 14 days, then oil production from the production well was started.

Data on the operation of wells 3-2 of the Huangsilin region of the Liaohe field after injection of steam with a urea-based solution is shown in FIG. 2. A decrease in the viscosity of the produced oil by 3 times was observed, a decrease in the pour point from +6 ÷ + 10 ° С to -4 ÷ -16 ° С, the duration of the oil production period increased by several months compared with the steam injection cycle. In the 3-2 well for the period from October 2003 to March 2005 inclusive, oil production was 874 tons, 2.3 times higher than in the previous cycle, where only steam (375 tons) was injected. In the well 5-2 from October 2003 to January 2005 inclusive, oil production amounted to 1387 tons, while in the previous cycle, where only steam was injected - 786 tons, the increase in oil production was 76%.

Thus, the results of the analysis of the current development status of the pilot sections of the permocarbon deposits of high-viscosity oil of the Usinsky field and the Liaohe field, developed using steam and heat treatment, before and after the application of this method showed its effectiveness to increase oil recovery and intensify development.

Claims (2)

1. A method of developing deposits of high-viscosity oils by means of steam and heat exposure, including the injection of alternating rims of a reagent solution under the action of temperature decomposing with the release of carbon dioxide, and steam, characterized in that carbamide is used as the specified reagent, the solution is injected through a steam injection well of at least than two rims, after pumping the entire specified solution, water is pumped in a volume exceeding 2 m ^{3 the} volume of tubing, eat steam, while this solution additionally contains ammonium nitrate, thiocyanate ammonium, a complex surfactant - surfactant Neftenol VVD, or a mixture of nonionic surfactant - AF9-12, or NP-40, or NP-50 and anionic surfactant - volgonate or sulfonol , or NPS-6 in the following ratio, wt.%:
Urea 15.0-40.0 Ammonium nitrate 8.0-20.0 Ammonium Rodanisty 0.1-0.5 Neftenol VVD 1.0-5.0 Water Rest
or
Urea 15.0-40.0 Ammonium nitrate 8.0-20.0 Ammonium Rodanisty 0.1-0.5 Nonionic surfactant 1.0-2.0 Anionic surfactant 0.5-1.0 Water Rest 2. A method for developing deposits of high-viscosity oils by means of steam and heat exposure, including the injection of alternating rims of a reagent solution under the action of temperature decomposing with the release of carbon dioxide, and steam, characterized in that carbamide is used as the specified reagent, the solution is injected through a non-steam producing well less than two rims, after the last rim of steam has been injected, the rim of oil is injected, the indicated well is maintained for impregnation, they put it into operation, while this solution additionally contains ammonium nitrate, thiocyanate ammonia, a complex surfactant - surfactant Neftenol VVD, or a mixture of nonionic surfactant - AF9-12, or NP-40, or NP-50 and anionic surfactant - volgonate or sulfonol, or NPS-6 in the following ratios, wt.%:
Urea 15.0-40.0 Ammonium nitrate 8.0-20.0 Ammonium Rodanisty 0.1-0.5 Neftenol VVD 1.0-5.0 Water Rest
or
Urea 15.0-40.0 Ammonium nitrate 8.0-20.0 Ammonium Rodanisty 0.1-0.5 Nonionic surfactant 1.0-2.0 Anionic surfactant 0.5-1.0 Water Rest

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