RU2461702C1 - Development method of high-viscous oil deposit (versions) - Google Patents

Abstract

FIELD: oil and gas production.

SUBSTANCE: in method of development of high-viscous oil deposit consisting in pumping of displacement agent through injection well, product extraction through production wells, determination of product water content, use of solution in the course of pumping that reduces oil viscosity at product water content less than 55% as the said solution there used is the solution of non-ionic surfactant AF9-4-6 - NIS AF9-4-6 in hydrocarbon solvent with ratio, vol. %: NIS AF9-4-6 31 - 49, hydrocarbon solvent 51- 69, that is mixed with water before pumping with ratio 1 : 2, note that pumping volume amounts 5-20% of oil volume located in inter-well zone. According to the other version the said method at product water content exceeding 55% as the said solution there used is the solution of NIS AF9-4-6 in hydrocarbon solvent with the following ratio, vol. %: NIS AF9-4-6 31 - 49, hydrocarbon solvent 51- 69, note that pumping volume amounts 5-20% of oil volume located in inter-well zone.

EFFECT: increase of high-viscosity oil extraction efficiency.

2 cl, 4 tbl, 1 ex

Description

The invention relates to the oil industry, in particular to methods for developing deposits of high viscosity oils.

There is a method of developing a reservoir of highly viscous oil, laden with water, including the injection of a gaseous agent and oil production, in order to reduce the viscosity of the oil, the gaseous agent is injected into the aquifer of the reservoir until the mobile water is completely removed, and the production is carried out after the gas is dissolved in oil (a.c No. 620103, IPC Е21В 43/00, 43/18, publ. 27.04.00). It is proposed to use hydrocarbon gas as a gaseous agent. Oil viscosity does not exceed 200 MPa · s.

The disadvantage of this method is the low oil recovery associated with a slight decrease in oil viscosity due to the low rate of penetration of gas into highly viscous oils with a viscosity of more than 200 MPa · s in reservoir conditions. In addition, special equipment is required for the injection of hydrocarbon gases.

A known method of exposure (patent RU No. 2323728, IPC С09К 8/584, publ. 06/27/2008. Bull. No. 18) on the bottom-hole zone of an oil reservoir based on a composition comprising ethoxylated isononylphenols with a degree of ethoxylation of 4-12, a hydrocarbon solvent and as petroleum sulfonate containing the additive C-150, in the following ratio of components:

Additive S-150 2.0-25.0 Oxyethylated isononylphenols with a degree of hydroxyethylation 4-12 1,5-20,0 Hydrocarbon solvent rest.

The composition is prepared by mixing the components to obtain a homogeneous solution. After injection of the solution into the bottomhole zone and / or into the formation when interacting with formation or injected water, a highly viscous emulsion is formed in the washed zones, which increases the filtration resistance in highly permeable water-saturated layers.

The disadvantages of the method are the increased viscosity of the resulting emulsions, low efficiency in the development of deposits of high viscosity oils.

Also known is a method of developing highly viscous oil using hydrocarbon-oxidizing bacteria with nutrient salts in an aqueous solution as a diluent composition (patent RU No. 2195549, IPC EV21/22, publ. 12/27/2002, bull. No. 36) in the following ratio of components, wt. %:

Hydrocarbon oxidizing bacteria 0.05-0.15 Nutrient Salts 0.07-0.3 Water rest.

As hydrocarbon-oxidizing bacteria (DRR), bacteria are used that have the ability to reduce the viscosity of oil and to desulfurize it, for example: Pseudomonas species-45 strain.

The disadvantage of this method is that these hydrocarbon-oxidizing bacteria in the oil refining process primarily consume light components, which are already contained in small amounts in high-viscosity oil, and reduce their content in the oil, which leads to a deterioration in the quality of oil and an increase in its viscosity.

In addition, the method has low efficiency in the development of high viscosity oils, while the known method uses less viscous oils.

The closest in technical essence is the method (prototype) of the production of highly viscous flooded oil (AS 1798487, MPK Е21В 43/22, publ. 02.28.93. Bull. No. 8), which includes reducing the viscosity of the oil-water emulsion by applying a water-depth pump for reception block copolymers of ethylene oxide and propylene in a mixture with a solvent in a ratio of 1: 1. The solvent used is the toluene fraction or nephras A 150/330 or bottoms from the production of butanol.

The disadvantage of this method is the need for constant fishing control. According to the prototype, the density of the studied oils in reservoir conditions is in the range of 808-900 kg / m ³ . According to the existing classification, heavy (highly viscous) oils include oils whose viscosity under reservoir conditions is more than 200 mPa · s and up to 10,000 mPa · s and a density above 900 kg / m ³ . In the proposed method, the density of the developed oils is in the range of 940-965 kg / m ³ in reservoir conditions. Therefore, another disadvantage of this method is the low efficiency in the development of deposits of highly viscous oils with a density in reservoir conditions above 900 kg / m ³ .

The technical task of this invention is to increase the efficiency of extraction of highly viscous oil by significantly reducing the viscosity of oil by injecting a solution that reduces the viscosity of oil.

The task is achieved by a method of developing a highly viscous oil deposit, including injection of a displacing agent through an injection well, product selection through production wells, determination of water cut, and the use of a solution that reduces the viscosity of oil during injection.

New is that at a water content below 55% product as a solution, a viscosity reducing oil, a solution of a nonionic surfactant AF -4-6 ₉ in a hydrocarbon solvent at a ratio,% vol .:

The nonionic surfactant AF ₉ -4-6 31-49 Hydrocarbon solvent 51-69,

which before injection is mixed with water in a ratio of 1: 2, while the injection volume of the specified solution is 5-20% of the volume of oil located in the interwell zone.

The task is achieved by a method of developing a highly viscous oil deposit, including injection of a displacing agent through an injection well, product selection through production wells, determination of water cut, and the use of a solution that reduces the viscosity of oil during injection.

New is that at a water cut greater than 55% as a solution, a viscosity reducing oil, a solution of a nonionic surfactant AF -4-6 ₉ in a hydrocarbon solvent with the following ratio of components,% by vol .:

The nonionic surfactant AF ₉ -4-6 31-49 Hydrocarbon solvent 51-69,

while the injection volume of the specified solution is 5-20% of the volume of oil located in the interwell zone.

The main difficulties in the production of highly viscous oils are associated with their abnormally high viscosities in reservoir conditions. The development methods of high-viscosity (heavy) oils are aimed at reducing their viscosity either by heating the reservoir by pumping coolants (an expensive method) or by injecting agents that reduce the viscosity of oil, for example, hydrocarbon solutions of nonionic surfactants (nonionic surfactants).

The mechanism of action of the hydrocarbon solution of nonionic surfactants on high viscosity oil is that, on the one hand, the solvent, mixed with high viscosity oil, reduces its viscosity, on the other hand, the nonionic surfactant at a certain concentration forms low viscosity direct oil-water emulsions of the type oil in water (m / c), i.e. the external phase (dispersion medium) of these emulsions is water. Such emulsions are characterized by a decrease in viscosity when diluted with water. In addition, as a result of the interaction of two immiscible liquids, such as a hydrocarbon solvent and water in the presence of nonionic surfactants, microemulsions transparent at 8 ° C (m / e) are formed. All these processes contribute to lowering the viscosity of high-viscosity oil due to the combined effects of a hydrocarbon solvent and nonionic surfactants.

As a nonionic surfactant (NSAID), use is made of ethoxylated alkyl phenols with a degree of hydroxyethylation of 4-6 AF ₉ -4, AF ₉ -6 (TU 2483-077-05766801-98) of OAO Nizhnekamskneftekhim. According to their physico-chemical properties of nonionic surfactant AF -4-6 ₉ are predominantly oil-soluble surfactant. They dissolve well in most organic solvents and disperse in water to form emulsions.

Absorbent 50/370 with a density of 0.820 g / cm ^{3 of the} Nizhnekamsk chemical plant (TU 2411-139-05766801-2007), Nefras 150/330 (TU 38.1011049-98), Absorbent A-2 (TU 2411-418- 05742686-98), visbreaking gasoline of TANECO OJSC.

The water used for mixing with a hydrocarbon solution of nonionic surfactants in a ratio of 1: 2 can be both fresh and mineralized with a density of not more than 1120 kg / m ³ .

The laboratory investigation of the influence on the viscosity of high-viscosity oil solutions of nonionic surfactant AF -4-6 ₉ in a hydrocarbon solvent. Laboratory studies were carried out on oils of the Mordovo-Karmalsky field with a density of 945 kg / m ³ and the Ashalchinsky field with a density of 970 kg / m ³ under surface conditions.

According to the first embodiment with a water content below 55% petroleum hydrocarbon solutions of nonionic surfactant AF ₉ -4-6 mixed with water in a ratio of 1: 2 and mixed using a mixer for 5-10 minutes at a speed of 500 rev / min. The concentration of nonionic surfactant AF ₉ -4-6 obtained in solution varies from 31% to 49% by volume. Previous studies have shown that when the concentration of nonionic surfactants in the solution is less than 31% vol. no effective reduction in oil viscosity is achieved. A increase in the concentration of nonionic surfactants in a solution containing water in a ratio of 1: 2, above 49% vol. does not give a multiple increase in process efficiency.

For these same reasons, it was determined upper and lower limits of concentration of hydrocarbon solvent (51-69 vol.%) In a hydrocarbon solution of nonionic surfactant AF ₉ -4-6 diluted with water in a ratio of 1: 2.

The finished solution of nonionic surfactants in a hydrocarbon solvent, mixed with water in a ratio of 1: 2, after mixing on an electric mixer in the form of an emulsion is introduced into high viscosity oil, while the amount (injection volume) of the hydrocarbonic solution of nonionic surfactants can be 5, 10, 15, 20% of the volume oil. The resulting mixture is stirred on an electric mixer for 10 minutes, after which the values of dynamic viscosity are measured at 8 ° C on a Rheomat RM-180 re-viscometer in the speed range 5.4 s ^-1 - 1280 s ^-1 . The temperature of 8 ° C was chosen on the basis that the majority of high-viscosity oil fields are located at a shallow depth and are characterized by a reservoir temperature of 8-10 ° C.

The dynamics of the dynamic viscosity of high-viscosity oil of the Ashalchinskoye field from the concentration of hydrocarbon solution of nonionic surfactants AF ₉ -6 diluted with water in a ratio of 1: 2 at different shear rates is shown in Table 1. The table also shows the magnitude of a multiple decrease in the viscosity of high-viscosity oil after the introduction of a hydrocarbon solution of nonionic surfactants AF ₉ -6 at shear rates of 6.5 s ^-1 and 146 s ^-1 . The shear rate of 6.5 s ^{-1 is} selected from the condition that it is close to shear stresses acting on the fluid in the reservoir conditions, and 146 s ^-1 when the fluid moves in the bottomhole formation zone. In both cases, there is a significant decrease in the initial viscosity of high-viscosity oil. Depending on the content of the hydrocarbon solution of nonionic surfactants in oil and the concentration of nonionic surfactants AF ₉ -6 in the solvent, the viscosity decreases at a speed of 6.5 s ^{-1 by} 1.4-646 times, and at a speed of 146 s ^-1 1080 times.

Using a conductivity meter OK-102/1 (Hungary), the values of electrical conductivity and the type of emulsions obtained were determined. Without nonionic surfactants, water-oil systems are reverse water-in-oil emulsions (v / m), in the presence of nonionic surfactants, the electrical conductivity gradually increases, and then phase inversion occurs, and emulsions become direct oil-in-water (m / v), t. e. the external phase (dispersion medium) of these emulsions is water. Such emulsions are characterized by a decrease in viscosity when diluted with water.

The process of diluting the emulsion with water is not endless, with a certain degree of dilution, the emulsion is destroyed with its separation into highly viscous oil and water. In order to prevent fracture in the formation conditions of low viscosity emulsions based on hydrocarbon solutions of nonionic surfactant and a heavy oil with a water content above 55% the latter serves to pump hydrocarbon solutions of nonionic surfactant AF ₉ -4-6 without introducing additional water. The solution preparation procedure, the viscosity reducing oil (with water content above 55%, i.e., in the second embodiment), is that the nonionic surfactant AF ₉ -4-6 added to the hydrocarbon solvent with concentrations of 31-49 volume percent. In this case, a multiple decrease in the viscosity of high-viscosity oil occurs. The results are shown in table.2.

Similar studies were also carried out in which the following were used as solvent: Nefras 150/330, visbreaking gasoline that did not pass the hydrotreating stage, manufactured by TANECO OJSC (Table 3).

Table 1 The dynamic viscosity of high-viscosity oil of the Ashalchinskoye field with a water content of 38%, containing various amounts of hydrocarbon solution of nonionic surfactants diluted with water in a ratio of 1: 2, at different shear rates Shear rate, s ^-1 The initial viscosity of the oil, MPa · s 15% AF ₉ -6 in r-le 31% AF ₉ -6 in r-le 49% AF ₉ -6 in r-le The size of the rim of the carbohydrate solution of nonionic surfactants in oil,% 5 10 fifteen twenty 5 10 fifteen twenty 5 10 fifteen twenty 5,4 41800 20100 12200 1970 189 7200 1052 1024 76 187 321 708 1750 6.5 40700

9.0 40200 16800 9690 1370 79 5040 833 488 51 103 206 592 1450 16,2 37400 15,000 7240 1160 60 2150 729 375 42 86 172 512 1100 27 34000 13300 4400 977 fifty 1210 628 341 39 78 156 455 995 48.6 31481 12100 2090 899 42 905 511 310 35 78 155 411 855 81 29150 12000 1010 721 35 764 425 300 25 78 155 381 768 146 26990

243 24991 10100 647 592 thirty 452 372 290 25 81 135 320 603 437 23140 9266 540 493 thirty 434 233 290 25 80 130 320 603 729 21426 8501 449 411 thirty 362 194 290 25 80 130 320 605 1280 19839 7799 375 343 thirty 301 161 290 25 77 130 320 605 * - a multiple decrease in viscosity at a shear rate of 6.5 s ^-1 ** - a multiple decrease in viscosity at a shear rate of 146 s ^-1

table 2 The dynamic viscosity of oil containing different amounts of hydrocarbon solution of nonionic surfactants at different shear rates Shear rate, s ¹ The initial viscosity of the oil, MPa · s 15% vol. AF ₉ -6 in r-le (surfactant-15 r-l-85)% vol. 31% vol. AF ₉ -6 in r-le (PAV-25, r-l-75)% vol. 49% vol. AF ₉ -6 in r-le (PAV-49, r-l-51)% vol. The size of the rim of the carbohydrate solution of nonionic surfactants in oil,% 5 10 fifteen twenty 5 10 fifteen twenty 5 10 fifteen twenty 5,4 41800 12800 2980 1200 580 6070 1670 1150 652 127 177 708 1750 6.5 40700 12100 2800 1190 540 5550 1360 1117 494 106 170 681 1600 9.0 40200 10900 2780 1180 525 5200 1140 1080 374 88 165 592 1450 16,2 37400 9420 2600 1170 500 4260 952 844 283 80 160 512 1100 27 34000

48.6 31481 7200 2500 1150 405 1760 621 567 186 78 148 411 855 81 29150 6360 2500 1120 375 1020 518 463 158 78 148 381 768 146 26990

243 24991 4716 2308 1078 256 970 387 345 119 81 145 320 603 437 23140 4136 2219 1057 215 933 337 307 106 80 143 296 590 729 21426 3628 2134 1037 201 897 315 271 99 80 142 274 523 1280 19839 3183 2052 1016 199 854 294 240 97 77 140 254 467 * - a multiple decrease in viscosity at a shear rate of 6.5 s ^-1 ** - a multiple decrease in viscosity at a shear rate of 146 s ^-1

Table 3 Dynamic viscosity of high viscosity oil of the Ashalchinskoye field containing a solution of nonionic surfactants AF ₉ -4 in visbreaking gasoline diluted with water in a ratio of 1: 2 at different shear rates Shear rate, s ^-1 The viscosity of the source oil, MPa · s Dynamic viscosity of oil containing a 31% solution of AF ₉ -4 in visbreaking gasoline in a ratio of 1: 2 with water, MPa · s The size of the rim of the solution in oil (% vol.), 5 10 fifteen twenty 5,4 41800 35100 19400 1750 60 6.5 40700 31500 18600 1480 45 9.0 40200 28500 17300 1250 35 16,2 37400 25500 15500 950 27 27 34000 24100 13700 780 22 48.6 31481 21500 9720 663 19 81 29150 - 3280 561 17 146 26990 - 943 460 fifteen 243 24991 - 810 390 fourteen 437 23140 - 776 335 fourteen 729 21426 - 670 - fourteen 1280 19839 - 503 - fourteen

The effectiveness of the options of the proposed method in comparison with the known method was evaluated in laboratory conditions by comparing the degree of decrease in viscosity of high viscosity oil, the results are presented in table 4. As can be seen from the table, when a hydrocarbon solution of nonionic surfactants AF ₉ -4-6 is introduced into a highly viscous oil at a temperature of 8 ° C, its viscosity decreases in the range from 8 to 44 times, and according to the known method, the oil viscosity decreases by only 6.8-6, 9 times.

Case Study

The field conditions for embodiments of the technology based on the hydrocarbon nonionic surfactant solution requires two types of pumping units 320 and CA-trailers (AC) with a marketable form nonionic surfactant AF and AC ₉ -4-6 with solvent in an amount necessary for the implementation of the technology, the capacity for the preparation of working solution (AC).

To implement the process options, for example, on a site of a highly viscous oil reservoir, consisting of one injection well (in the center) through which the displacing agent is injected, and five production wells located at a distance of about 50-100 m from this injection well and of which selection of products is carried out, the water content of the extracted products is determined.

The water content of the product is 38%. As water cut below 55% (first embodiment), as the solution viscosity reducing oil solution of nonionic surfactant used AF -4-6 ₉ in a hydrocarbon solvent, mixed with water in a ratio of 1: 2. Next, the required amount of reagents for the preparation of a solution of nonionic surfactants in a hydrocarbon solvent is calculated. For this, we initially calculate the volume of oil enclosed in the cylinder of the reservoir around the injection well, according to the formula:

where Vн is the volume of oil, m ³ ;

π - constant = 3.14;

R is the distance between the injection and producing wells, m;

h - oil saturated formation thickness, m;

S - oil saturation, d.ed .;

m - porosity, d.ed.

The required volume of injection of hydrocarbon solution of nonionic surfactants is 5-20% of the volume of oil Vn.

At R = 50 m, h = 6 m, S = 0.65, m = 0.22 Vn is 3367.7 m ³ . The volume of the rim of the solution is 15% V _H of the volume of oil, therefore, the volume of the hydrocarbon solution of nonionic surfactants is 505 m ³ (respectively Vnpav = 42 m ³ , Vp-la = 126 m ³ and water with a ratio of 1: 2 Vv = 337 m ³ ) . Moreover, their concentration in the solution is,% vol., Nonionic surfactants - 8.3, solvent - 25, water - the rest. The method can also be implemented through a production well, while similar calculations of the required volumes of reagents are carried out.

Preparation of 1 m ^{3 of a} 35% solution of nonionic surfactants in a solvent is carried out as follows: a pump unit from AC with a commercial form of nonionic surfactants AF ₉ -6 delivers 350 l of AF ₉ -6, from AC with a solvent of 650 l of absorbent 50/370 into a container (AC) for preparation of the working solution, then 2 m ^{3 of} water from the water conduit is fed (1: 2 ratio). For 20-30 minutes everything is mixed at the maximum possible capacity of the pumping unit according to the scheme: capacity for the preparation of working solution (AC) - pumping unit - capacity for the preparation of working solution (AC). The emulsion obtained from the tank for preparing the working solution is pumped into the well by the second pumping unit.

According to the second option, when the water content of the product (equal to 65%), i.e. above 55%, hydrocarbon solution of nonionic surfactants not diluted with water is injected. For the preparation of 1 m ³ 35% vol. a solution of nonionic surfactants in a hydrocarbon solvent is supplied to the AC for the preparation of a working solution of 350 l (35% vol.) of nonionic surfactants AF ₉ -4 and 650 l (65% vol.) of absorbent 50/370. For 20-30 minutes everything is mixed, the solution is pumped into the well. Since the concentration of nonionic surfactants is high in solution, it will be sufficient to inject a rim of a smaller size, for example 5% of Vn. After injection of the rim of the hydrocarbon solution of nonionic surfactants, water flooding is carried out in the usual mode.

The use of variants of the proposed method in the development of deposits of high viscosity oils increases the efficiency of extraction of high viscosity oil by significantly reducing the viscosity of the oil by injecting a solution that reduces the viscosity of the oil.

Claims (2)

1. A method of developing a reservoir of high-viscosity oil, including injecting a displacing agent through an injection well, selecting products through production wells, determining the water content of the product, using a solution to reduce the viscosity of the oil when injecting, characterized in that when the water content of the product is below 55% as a solution, it reduces oil viscosity, use a solution of non-ionic surfactant AF9-4-6 - nonionic surfactants AF9-4-6 in a hydrocarbon solvent at their ratio, vol.%:
Nonionic surfactant AF ₉ -4-6 31-49 Hydrocarbon solvent 51-69,
which before injection is mixed with water in a ratio of 1: 2, while the injection volume is 5-20% of the volume of oil located in the interwell zone. 2. A method of developing a reservoir of high-viscosity oil, including pumping a displacing agent through an injection well, selecting products through production wells, determining water cut, using a solution to lower the oil viscosity when pumping, characterized in that when the water cut is higher than 55%, the solution reduces oil viscosity, use a solution of nonionic surfactants AF9-4-6 in a hydrocarbon solvent in the following ratio of components, vol.%:
Nonionic surfactant AF ₉ -4-6 31-49 Hydrocarbon solvent 51-69,
wherein the injection volume of said solution is 5-20% of the volume of oil located in the interwell zone.