RU2818628C1 - Method of extracting oil from an oil formation using nanoparticles - Google Patents

Abstract

FIELD: oil industry.

SUBSTANCE: in the method of extracting oil from an oil formation directly at the well before injection into the formation, is dosed into a mixing tank by pumps fresh or mineralized water with total mineralization of up to 300 g/l and a non-ionic high-molecular surfactant alkylphenol with carbon chain length C9-12 – Neonol AF9-12 and at the same time water-insoluble zinc oxide nanoparticles with size of 500 nm of oval or round shape are dosed into the mixing tank using an auger dosing unit for loose reagents with continuous stirring for at least 30 minutes until their uniform distribution. Obtained suspension is pumped into the loading unit of the installation for preparation of solutions from liquid and loose chemical reagents. Then, polyacrylamide is added to the obtained suspension by means of an auger dosing unit for dosing and feeding powdered reagents. to obtain a flooding composition with the following ratio of components, wt. %: Neonol AF9-12 0.1–0.5; said zinc oxide nanoparticles 0.01–0.07; polyacrylamide 0.3–0.7; said water is the rest. Composition for waterflooding is mixed for 10–15 minutes, then it is pumped into the oil formation through an injection well, oil is extracted from production wells.

EFFECT: increasing the efficiency of oil extraction from an oil formation by increasing the surface activity of the oil-displacing composition.

1 cl, 1 dwg, 5 tbl, 1 ex

Description

The invention relates to the oil industry, in particular to methods for extracting oil using nanoparticles from a terrigenous oil reservoir and can be used in the development of oil deposits of viscous and super-viscous oil.

There is a known method for processing an underground well having one or more permeable layers (patent RU No. 2693105, IPC E21B 43/22, C09K 8/84, C09K 8/92, B82Y 99/00, publ. 07/01/2019, Bulletin No. 19), comprising providing a treatment fluid containing water and a plurality of water-dispersible nanoparticles present in the treatment fluid at a concentration of about 0.1 to 5.0 wt. %, introducing the specified medium into the underground formation, so that the nanoparticles form one or more aggregates that clog the pores of the formation and block further flow of fluid in the formation. Water-dispersible nanoparticles contain nanocellulose, rod-shaped nanoparticles, nanotubes or halloysite or combinations thereof.

The disadvantage of the invention is the low degree of oil recovery due to the fact that water-dispersible nanoparticles containing nanocellulose primarily affect water-saturated formations, clogging them, and do not affect oil-saturated formations to displace oil.

There is a known method for developing an oil reservoir with heterogeneous permeability (patent RU No. 2725205, IPC E21B 43/22, C09K 8/88, published June 30, 2020, Bulletin No. 19), which includes pumping two slugs of an aqueous solution into the injection well: the first slug, containing polyacrylamide with a crosslinker, an aqueous solution containing polyacrylamide with a crosslinker is pumped in as the first rim; a composition of chromium acetate and zinc oxide, wt.%, is used as a crosslinker. %:

polyacrylamide 0.51-0.8 chromium acetate 0.04-0.06 zinc oxide 0.04-0.06 water rest

and a second rim containing a solution of a surfactant, which additionally contains polyacrylamide, and as a surfactant the surfactant includes an amphoteric surfactant in the following ratio of components, in wt. %:

polyacrylamide 0.3 amphoteric surfactant 0.3-5.0 water rest

The disadvantage of this method is the low degree of oil recovery associated with the use of a low-effective amphoteric surfactant, as well as the high consumption of reagents used in two slugs.

The closest is the method for producing hydrocarbon material (patent RU No. 2687412, IPC C09K 8/20, E21B 43/22, C09K 8/60, publ. 05.15.2019, bulletin No. 14), from an underground formation, including the formation of nanoparticles, each of which contains a core containing at least one of the following metals: Mg, Al, Ca, Mn and Zn, and a shell encapsulating the core and containing organic material, combining the nanoparticles with a carrier fluid to obtain a suspension for flooding, pumping the suspension into a subterranean formation containing hydrocarbon material associated with its surfaces to separate it from the surfaces and form an emulsion stabilized by nanoparticles, removing the emulsion from the subterranean formation and modifying at least one of the parameters: temperature, pH value and composition of the emulsion material, after removing the emulsion from a subterranean formation to interact at least a portion of the nanoparticles with the aqueous material to destabilize the emulsion and coalesce the hydrocarbon material. A stabilized emulsion containing a dispersed phase comprising a hydrocarbon material, a continuous phase comprising an aqueous material, and hydrophilic nanoparticles accumulating at an interface between the dispersed phase and the continuous phase, wherein a number of hydrophilic nanoparticles contain a core containing a Mg-Al alloy intended to switching between a first corrosion rate and a second higher corrosion rate as a result of changing at least one property: increasing the temperature of the aqueous material and decreasing the pH value of the aqueous material, and a shell encapsulating the core and containing the polymeric material.

The disadvantage of this method is the low degree of oil recovery since nanoparticles, each of which contains a core containing at least one of the following metals: Mg, Al, Ca, Mn and Zn, which do not have surface activity, are used to form a nanoparticle-stabilized emulsion. The emulsion is pumped out from the underground formation. Since the viscosity of the emulsion is higher than the viscosity of oil, its transportation and subsequent separation into oil and water requires large energy costs.

The technical objective of the invention is to increase the efficiency of the method for extracting oil from an oil reservoir by increasing the surface activity of the oil-displacing composition by introducing nanoparticle additives into the surfactant and reducing material costs.

The technical problem is solved by a method for extracting oil from an oil reservoir using flooding with nanoparticles, which includes obtaining a flooding composition containing nanoparticles and surfactant surfactants, and injecting it into the oil reservoir.

What is new is that directly at the well, before injection into the formation, fresh or mineralized water with a total mineralization of up to 300 g/l and a nonionic high-molecular surfactant alkylphenol with a carbon chain length of C9-12 - Neonol AF9-12 are dosed into the mixing tank by pumps and at the same time into the tank mixtures are dosed using a screw dispenser for bulk reagents, water-insoluble zinc oxide nanoparticles 500 nm in size, oval or round in shape, with continuous stirring for at least 30 minutes until they are evenly distributed, the resulting suspension is pumped into the loading unit of the installation for preparing solutions from liquid and bulk chemical reagents, then polyacrylamide is added to the resulting suspension using a screw doser designed for dosing and supplying powdered reagents, with constant stirring to obtain a composition for flooding with the following ratio of components, wt. %:

Neonol AF9-12 0.1-0.5 Indicated zinc oxide nanoparticles 0.01-0.07 Polyacrylamide 0.3-0.7 Specified water rest,

the flooding composition is stirred for 10-15 minutes, then pumped into the oil reservoir through an injection well, and oil is extracted from production wells.

To implement the method use:

- nonionic high-molecular surfactant alkylphenol with a carbon chain length of C9-12 - neonol AF ₉ -12, produced by OAO Nizhnekamskneftekhim in accordance with TU 2483-077-05766801-98;

- polyacrylamide (PAA) according to TU 2458-024-14023401-2012 with changes. No. 1, 2 or its analogues;

- zinc oxide (nanoparticles) - ZnO (OTs), for which zinc oxide BTsOM is used according to GOST 202-84. Industrial zinc oxide powder has a particle size of about 500 nm, with an oval or round shape. Nanoparticles are insoluble in water, can have both hydrophobic and hydrophilic properties, and have a positive charge.

To prepare an aqueous solution of surfactants, both fresh and mineralized water with a total mineralization of up to 300 g/l are used.

In fig. The dependence of the interfacial tension of surfactant solutions on the concentration of surfactants containing zinc oxide nanoparticles and without nanoparticles is presented.

The essence of the invention

Large-scale industrial application of new “cold” physical and chemical technologies for increasing oil recovery from highly viscous oil deposits, without thermal effects, increasing the oil displacement coefficient while intensifying development, will extend the profitable operation of fields at a late stage of development and involve in the development of fields with hard-to-recover viscous reserves and ultra-viscous oil (SVO).

During the long-term development of an oil field, residual oil located in previously untapped areas also undergoes changes: its density and viscosity increase, and its mobility decreases.

The most common type of chemical method for increasing oil recovery in oil displacement processes is the method of polymer flooding in compositions with various chemical reagents. Adding a surfactant to a polymer solution reduces the interfacial tension between formation oil and formation water, reduces capillary forces, increases oil mobility and oil displacement efficiency.

Table 1 shows the values of interfacial tension (σ) of solutions of PAA polymer in the presence of surfactant AF ₉ -12 of various concentrations in fresh water and mineralized water (d = 1.120 g/cm ³ ) at the interface with kerosene (d = 0.780 g/cm ³ ).

Table 1 - The value of interfacial tension of PAA solutions in the presence of surfactants of different concentrations at the interface with kerosene

Concentration
PAA polymer,
% wt. Concentration Surfactant
AF₉-12,
% wt. Interfacial tension, mN/m Dynamic viscosity, mPa⋅s on fresh per mineral. on
fresh per mineral. 0.1 0.05 5.09 6.92 4.68 3.93 0.1 4.26 5.53 4.94 4.07 0.3 3.27 4.18 5.1 3.85 0.5 3.03 3.59 4.73 3.87 1.0 2.36 3.17 5.07 4.12 0.3 0.05 7.45 8.18 23.85 11.92 0.1 5.87 5.83 22.01 11.58 0.3 4.74 4.32 21.82 11.88 0.5 4.41 3.67 18.25 11.64

Based on the analysis of the data in Table 1, the most optimal concentration range of the surfactant AF ₉ -12 in the PAA solution was established. Since, when the surfactant concentration in the solution decreases from 0.1% to 0.05% (twice), the interfacial tension (σ) at the interface increases from 4.26 mN/m to 5.09 mN/m in fresh water and from 5.53 mN/m to 6.92 mN/m - in mineralized water, (the lower σ, the easier oil comes off from the rock surface), there is a decrease in the surface activity of a PAA solution containing a surfactant at the interface, which, in turn, reduces the efficiency of oil displacement by the composition from the formation.

When the surfactant concentration in the solution increases from 0.5% to 1%, twofold, the surface activity of the solution at the interface increases (σ decreases from 3.03 mN/m to 2.36 mN/m in fresh water, from 3 .59 mN/m to 3.17 mN), i.e. only 1.13-1.28 times, depending on mineralization. In this case, unproductive consumption of surfactants occurs, which generally reduces the efficiency of oil displacement from the reservoir. Consequently, the most optimal concentration of surfactant AF ₉ -12 in a PAA solution is the range from 0.1% to 0.5%.

Since the oil-displacing composition according to this method contains PAA polymer, the optimal concentrations of this reagent were determined. Table 2 shows the values of the dynamic viscosity of polymer solutions measured on a VISCOMETR RM-100 rotational viscometer in the range of PAA concentrations from 0.1% to 0.9% at temperatures of 20°C and 8°C.

Table 2 Dependence of dynamic viscosity of PAA solutions on polymer concentration

PAA polymer concentration,
% wt. Dynamic viscosity of PAA solution at temperature, mPa⋅s 20°C 8°С 0.1 12.87 15.85 0.2 33.62 36.67 0.3 63.50 67.64 0.4 102.2 109.3 0.5 150 158.3 0.6 201.3 209.3 0.7 266.3 285.5 0.8 334.7 346.5 0.9 391.2 419.4

Based on the analysis of the data in Table 2, it was found that the most optimal range of PAA concentration in solution is the range from 0.3% to 0.7%. When the concentration of PAA in the solution decreases below 0.3%, the viscosity of the solution decreases below 40 mPa⋅s, which reduces the efficiency of oil displacement from the reservoir, since this increases the viscosity ratio of super-viscous oil and polymer solution, which leads to early water breakthrough during oil displacement in heterogeneous formations.

An increase in the concentration of PAA in the solution above 0.7%, at which the viscosity of the solution becomes above 300 mPa⋅s, leads to problems when pumping the solution into the well, especially if the well has an injectivity below 200 m ³ /day.

The above data show that for more complete extraction of residual oil, it is not enough to displace it only with water or a surfactant with a polymer.

Recently, nanosuspensions, which are water-based suspensions, the dispersed component of which are nanoparticles (NPs), have been used to extract hard-to-recover oil reserves.

The use of nanoparticles improves oil displacement through several mechanisms of action, which include: 1) changing the wettability of the rock, 2) creating disjoining pressure between oil droplets and the rock surface, 3) clogging pore channels, 4) reducing interfacial tension between oil and the injected liquid, 5) inhibition of asphaltene precipitation. In addition, nanoparticles can be used to reduce the viscosity of heavy and viscous oil.

In order to study the effect of nanoparticles on the surface activity of surfactant solutions AF ₉ -12, the properties of these solutions were studied in the presence of zinc oxide (ZnO) nanoparticles, which were introduced into surfactant solutions with continuous uniform stirring. The effect of nanoparticles on the surface activity of a solution of surfactant AF ₉ -12 at the interface with a hydrocarbon liquid, for which kerosene was used, was studied.

Quantitative changes in the value of interfacial tension of surfactant solutions AF ₉ -12 at the interface with kerosene on a stalagmometer are presented in Table 3.

Table 3 - Interfacial tension of 0.1% surfactant solutions containing and without zinc oxide nanoparticles at the border with kerosene

Additive ZnO,
% wt. The value of interfacial tension of AF solutions _{is 9} -12, mN/m fresh mineralized 0 2.42 2.86 0.01 2.37(2.06%) 2.8(2.1%) 0.03 2.27(6.2%) 2.62(8.4%)

The interfacial tension of a 0.1% solution of AF ₉ -12 in fresh water at the interface with kerosene decreased by 6.2% when ZnO nanoparticles were introduced into the solution at a concentration of 0.01% in fresh water and by 2.1% in mineralized water. A further increase in the concentration of ZnO nanoparticles to 0.03% in fresh water led to a decrease in interfacial tension to 2.27 mN/m, and in mineralized water it decreased to 2.62 mN/m, i.e. decreased by 6.2 - 8.4% compared to a solution not containing ZnO nanoparticles. A small addition of zinc oxide nanoparticles leads to a reduction in the consumption of expensive surfactants by further reducing the interfacial tension at the interface between two immiscible liquids.

In fig. The dependence of the interfacial tension of surfactant solutions on the concentration of AP ₉ -12, containing and not containing zinc oxide nanoparticles, at the boundary with Ashalcha oil, measured on an optical device (Dataphysics, Germany) using the hanging drop method, is presented. For clarity, the concentration of surfactant AF ₉ -12 in solutions varied from 0.1% to 0.4%, the concentration of nanoparticles in surfactant solutions was 0.03%, 0.05%, 0.07%.

Table 4 shows the values of interfacial tension σ, and in parentheses it is indicated how many times the interfacial tension of the surfactant solution decreased when zinc oxide nanoparticles were introduced into it.

The interfacial tension of surfactant solutions containing 0.03% zinc oxide nanoparticles at the interface with oil was most effectively reduced. Other concentrations of NPs also work, reducing the value of σ to a slightly lesser extent relative to a surfactant solution that does not contain nanoparticles.

Table 4 - Interfacial tension of surfactant solutions at the boundary with oil

AF9-12 concentration, wt.% Interfacial tension of surfactant solutions containing ZnO nanoparticles at the interface with oil, mN/m 0 0.03 0.05 0.07 0.1 1.6 1.1(1.45) 1.16(1.38) 1.25(1.28) 0.2 1.01 0.74(1.36) 0.77(1.31) 0.95(1.06) 0.3 0.78 0.62(1.26) 0.67(1.16) 0.71(1.1) 0.4 0.62 0.51(1.22) 0.56(1.11) 0.60(1.03)

The smallest decrease in interfacial tension is observed in surfactant solutions with the addition of 0.07% ZnO. This can be explained by the fact that at a concentration of 0.07%, zinc oxide nanoparticles dispersed in a surfactant solution begin to aggregate (stick together), which leads to a reduction in the contact area between the surfactant and nanoparticles. Therefore, further increasing the concentration of zinc oxide nanoparticles in a surfactant solution is not advisable.

According to the proposed method, directly at the well, before injection into the formation, fresh or mineralized water with a total mineralization of up to 300 g/l and a nonionic high-molecular surfactant alkylphenol with a carbon chain length of C9-12 - Neonol AF9-12 are dosed into the mixing tank by pumps and at the same time dosed into the mixing tank using a screw dispenser for bulk reagents, water-insoluble zinc oxide nanoparticles 500 nm in size, oval or round in shape, with continuous stirring for at least 30 minutes until they are evenly distributed, the resulting suspension is pumped into the loading unit of an installation for preparing solutions from liquid and bulk chemical reagents , then polyacrylamide is added to the resulting suspension with a screw doser designed for dosing and supplying powdered reagents with constant stirring to obtain a composition for flooding with the following ratio of components, wt. %: Neonol AF9-12 0.1-0.5, specified zinc oxide nanoparticles 0.01-0.07, polyacrylamide 0.3-0.7, specified water - the rest, the composition for flooding is stirred for 10-15 minutes ., then pumped into the oil reservoir through an injection well, and oil is extracted from production wells.

Preliminary introduction of AF ₉ -12 nanoparticles into the surfactant solution according to the proposed method, which use zinc oxide nanoparticles, makes it possible to enhance the surface activity of the solution and increase the displacing ability of the surfactant-polymer composition.

Filtration experiments to determine the efficiency of EHV displacement by oil-displacing compositions were carried out using a bulk reservoir model made of stainless steel, which is a pipe within a pipe with a length of 0.5 m and an internal diameter of 8.8 mm.

The results of filtration experiments to determine the oil displacement coefficient when injecting compositions containing nanoparticles at temperatures of 8°C and 20°C are presented in Table 5.

A temperature of 8°C is typical for many super-viscous oil deposits, i.e., experiments conducted at this temperature are close to the reservoir conditions of EHV deposits, and at 20°C - to the conditions of conventional terrigenous reservoirs.

Table 5 shows: the change in pressure during injection of the oil-displacing slug; primary - Kvyt(p) and final Kvyt(k) oil displacement coefficients for each experiment, as well as the reduced oil displacement coefficient (PKut.). The reduced oil displacement coefficient, which is equal to the ratio of the final oil displacement coefficient to the injection pressure drop, i.e. Kvyt(k)/ΔР, is used for comparative analysis of the efficiency of oil displacement by different compositions. The higher the given oil displacement coefficient, the higher the efficiency of the oil extraction process.

Table 5 - Results of filtration experiments on oil displacement from the reservoir model at temperatures of 20°C and 8°C.

No.
experience Researched
compositions t of experiment, ° Pressure during composite injection ΔР, MPa Primary Kvyt (p). oil water, % Gain ΔKw. oil composition, % Final Kvyt (k) oil,% Given. Pkvyt. Oil,
%/MPa The dynamic viscosity of oil is 160 mPa s and the density is 922 kg/m ³ at 20°C. 1 0.3% PAA+0.1% AF ₉ -12+0.01% ZnO 20 0.9 11.07 32.75 43.82 48.69 2 0.3% PAA+0.3% AF ₉ -12 0.9 9.38 29.44 38.82 43.13 3 0.3% PAA+0.3% AF ₉ -12+0.03% ZnO 0.9 12.47 37.41 49.88 55.42 The dynamic viscosity of oil is 9900 mPa⋅s and the density is 963 kg/m ³ at 8°C 4 0.4% PAA+0.4% AF ₉ -12 8 1.10 0 26.96 26.96 24.51 5 0.4% PAA+0.4% AF ₉ -12+0.04% ZnO 1.15 0 29.49 29.49 33.91 6 0.7% PAA+0.5% AF ₉ -12+0.07% ZnO 1.25 0 33.07 33.07 27.56 7 (Prototype)
0.3% PAA+3.0% BETAPAV 20 0.9 9.98 13.6 23.58 26.2

It is obvious that at a temperature of 20°C the efficiency of oil displacement by a surfactant-polymer composition containing and without nanoparticles is much higher than at a temperature of 8°C.

The introduction of 0.03% ZnO into a 0.3% solution of AF ₉ -12 and its further mixing with 0.3% PAA (experiment 3, table 5) led to an increase in the final oil displacement efficiency by 11.06% at 20°C relative to composition that does not contain zinc oxide nanoparticles (experiment 2, table 5), and relative to the prototype (experiment 7, table 5), which includes an amphoteric surfactant that does not contain nanoparticles, and the concentration of BETAPAV is 30 times higher than the concentration of AF ₉ -12 .

Even the composition containing minimal concentrations of the reagents included in its composition turned out to be more effective in displacing oil (experiment 1, table 5) than the prototype composition, KV(k) are, respectively, 43.82% and 23.58%.

Oil displacement at 8°C is complicated by the fact that more viscous oil was used in these experiments. The introduction of 0.04% zinc oxide nanoparticles into the composition led to an increase in the final oil displacement coefficient by 3.32% (experiment 5, table 5).

An example of a specific implementation.

The proposed method is carried out using standard (existing) oilfield equipment that provides transportation, preparation (mixing) and injection of aqueous solutions into the well: a complex for preparing solutions from liquid and bulk chemical reagents KUDR-8 or analogues; pumping units type ANTs-320 according to TU 26-02-30

Well 1 develops an oil reservoir 5 m thick with a porosity of 20%. The well's injectivity is 350 m ³ /day at a pressure on the water pipeline of 8.0 MPa.

The method is implemented through injection wells. Aqueous solutions are prepared directly at the well before injection into the formation by mixing the components on the KUDR-8 installation.

Water and surfactant AF ₉ -12 are dosed into the container for liquid reagents by pumps at a flow rate that provides the required concentrations of the components in the working solution.

Simultaneously with the dosage of surfactant AF ₉ -12, zinc oxide is dosed into the mixing container using a screw doser for bulk reagents with constant stirring for at least 30 minutes.

After this, the resulting suspension is pumped into the loading unit of the KUDR installation, equipped with a screw dispenser designed for dosing and supplying powdered reagents. PAA is supplied from the hopper by a screw dispenser at a flow rate that provides the required concentrations into the jet apparatus, with constant stirring. The composition is mixed for 10-15 minutes and pumped into the well.

A solution is prepared in water with a density of 1100 kg/m ³ of the following composition: a) surfactant AF ₉ -12 with a concentration in the composition of 0.3 wt. %; b) zinc oxide with a concentration in the composition of 0.03 wt. %. After mixing these reagents, PAA polymer powder is introduced with a concentration in the composition of 0.3 wt. %, water - the rest (corresponds to experiment 3, table 5).

The consumption of reagents per 1 m ³ of water is surfactant - 3.3 kg, OC - 0.33 kg, PAA - 3.3 kg.

A composition with a volume of 300 m ³ is pumped in, after which the well switches to normal operation. A month later, the average flow rate from the surrounding production wells increased from 8.5 tons/day to 10.5 tons/day. The increase in the average daily flow rate was 2 tons/day.

The results obtained show that there was an increase in oil recovery using the proposed method as a result of injection of a composition of an aqueous solution of surfactant AF _9-12 , which additionally contains zinc oxide nanoparticles and a polymer.

In this case, the displacing ability of the composition increases and its washing ability increases due to the injection of a surfactant, the surface properties of which are enhanced by the introduction of zinc oxide nanoparticles, which leads to a decrease in the concentration of the surfactant and helps reduce material costs.

Claims (3)

A method for extracting oil from an oil reservoir using flooding with nanoparticles, including obtaining a composition for flooding containing nanoparticles and surfactant surfactants, and pumping it into the oil reservoir, characterized in that directly at the well, before injection into the reservoir, the mixing tank is dosed with pumps. fresh or mineralized water with a total mineralization of up to 300 g/l and a nonionic high-molecular surfactant alkylphenol with a carbon chain length of C9-12 - Neonol AF9-12 and at the same time water-insoluble zinc oxide nanoparticles of size 500 are dosed into the mixing container using a screw doser for bulk reagents nm of oval or round shape with continuous stirring for at least 30 minutes until they are evenly distributed, the resulting suspension is pumped into the loading unit of an installation for preparing solutions from liquid and bulk chemical reagents, then into the resulting suspension with a screw doser designed for dosing and supplying powdered reagents , with constant stirring, polyacrylamide is added to obtain a composition for flooding at the following ratio of components, wt.%: Neonol AF9-12 0.1-0.5 indicated zinc oxide nanoparticles 0.01-0.07 polyacrylamide 0.3-0.7 specified water rest, the flooding composition is stirred for 10-15 minutes, then pumped into the oil reservoir through an injection well, and oil is extracted from production wells.