RU2023143C1 - Method for treatment of bottom-hole formation zone of producing well - Google Patents

Abstract

FIELD: oil producing industry. SUBSTANCE: method consists in injection of acid microemulsion into bottom-hole formation zone allowing the reagents in the well to undergo the reaction, additional successive injection water-solving solvent and 1.0-5.0 mas. % hydrocarbon solution of water-repellent cationic surfactant with volume ratio of acid microemulsion, water-solving solvent and hydrocarbon solution of water-repellent surfactant 1: (0.28-0.32):(0.95-1.0). EFFECT: higher oil recovery due to rise of period of recovery of final water permeability. 1 tbl

Description

 The invention relates to the oil industry and can be used in the treatment of bottom-hole zones of production wells for productive low- and medium-permeable formations.

 A known method of acid treatment of the bottom-hole zone of producing wells, including the injection into the bottom-hole zone of an acid solution. The disadvantage of this method is the increased rate of dissolution of the rock in an acid solution, a shallow depth of processing and the insolubility of asphalt-resin-paraffin deposits.

 Closest to the proposed invention in technical essence and the achieved result is a method of processing bottom-hole zones of producing wells, including the injection into the bottom-hole zone of an acidic microemulsion [1]. The disadvantage of the prototype method is the rapid flooding of well products due to the rapid restoration of water permeability and reduced oil production.

 The aim of the invention is to increase oil production by increasing the recovery period of the final water permeability.

 This goal is achieved by the fact that in the method for treating the bottom-hole zone of a producing well, which includes injecting an acid microemulsion into the bottom-hole zone and holding an acid microemulsion, after soaking the injected acid micro-emulsion into the bottom-hole zone, a water-solvent and a hydrophobic surfactant P with a volume ratio of acid microemulsion, a water-solvent solvent and a hydrophobic hydrocarbon solution insulating surfactant 1: (0.28 - 0.32):: (0.95-1.0).

The essential features are:
injection of acidic microemulsion into the bottomhole zone;
extract of acid microemulsion;
additional sequential injection into the bottomhole zone of a water-solvent;
injection of a hydrocarbon solution of hydrophobizing surfactant;
the volume ratio of acid microemulsion, a water-solvent solvent and a hydrocarbon solution of hydrophobic surfactant 1: (0.28-0.32): (0.95-1.0).

 The invention is as follows.

Acid microemulsion is pumped into the bottom-hole zone of a producing well with a permeability of up to 0.4 μm ² in known quantities and with a known composition, for example, 0.5-11 m ³ per 1 m of the processed thickness with an acid microemulsion composition, wt.%: Spent brand absorbent A - 54, neonol AF9-6 16, hydrochloric acid 16% 30). The injected acidic microemulsion is allowed to react for 8-12 hours. Then, any known water-soluble solvent (semi-polar liquid from the class of ketones, alcohols, glycols, aldehydes, for example acetone, methyl alcohol, formalin, ethylene glycol or mixtures thereof) is pumped into the bottomhole zone to be treated the volume related to the volume of the previously pumped acidic microemulsion, as (0.28-0.32) :( 0.95-1.0). Immediately after the water-soluble solvent, a hydrocarbon solution of a hydrophobizing surfactant of known composition is pumped into the bottomhole zone, for example, a Don-52 or ATM10-16 surfactant solution in kerosene, diesel fuel, oil, gasoline with a surfactant content of 0.1-5 wt. % in the volume of the solution, related to the volume of the previously pumped acid microemulsion, as (0.95-1): 1.

The injection of acidic microemulsions ensures the cleaning of the treated bottom-hole zone from asphalt-resin-paraffin deposits and the dissolution of part of the rock at a considerable distance from the wellbore, which leads to an increase in the permeability of the bottom-hole zone and an increase in well productivity by liquid. However, as will be shown below, treatment of the bottom-hole zone with an acid microemulsion does not slow down the water cut of the product after treatment and may be accompanied by an increase in water cut of the product above the level before treatment. Thus, the efficiency of treating the bottom-hole zone of an producing well with acid microemulsion due to an increase in the coefficient of productivity of a well by liquid decreases with time and can turn into deposition due to rapid flooding of well production due to increased water permeability. When processing according to the invention, the amount of acidic microemulsion is selected according to well-known recommendations from the calculation of 0.5-11 m ³ / m of the processed thickness in order to process the entire pore volume of the treated bottomhole zone with microemulsion.

Injection of a hydrocarbon solution of a hydrophobizing surfactant, for example, a 2% solution of Don-52 surfactant in kerosene. The amount of injected hydrocarbon solution hydrophobic surfactant is also selected from the condition of filling the pore volume of the treated bottom-hole zone after the injection of a water-solvent solvent at a saturation (0.95-1 ^about ). Therefore, the volume ratio of the injected acidic microemulsion and the hydrocarbon solution of the hydrophobic surfactant is 1: (0.95-1.0). The purpose of the hydrocarbon solution of hydrophobizing surfactant is well known - this is hydrophobization of the surface of an oil-saturated porous medium in order to increase oil permeability. However, special preliminary studies have established that the quality of hydrophobization of the surface of a porous oil-saturated medium when a hydrophobizing surfactant is treated with a hydrocarbon solution, as well as the effectiveness of reducing water permeability or increasing the recovery period, depends on the quality of the hydrophobizing surface, the absolute permeability of the rock, and the ratio of the volumetric flow rates of oil and water filtered through treated hydrophobized porous medium. It was found that the hydrophobizing effect is significantly reduced in the presence of water in a porous medium, as well as in porous media with permeabilities of 0.8 μm ² and higher. Additional studies revealed that exposure to acid microemulsion provides an increase in absolute permeability of the treated porous medium up to two times. With this in mind, the field of effective application of the invention is limited by the permeability of the treated bottom-hole zone to 0.4 μm ² .

 Thus, pretreatment of the bottom-hole zone with acid microemulsion is necessary to enhance the hydrophobic effect (removal of asphalt-resin-paraffin deposits) and to increase oil permeability while reducing water permeability and increasing the period of its recovery. The operations of injecting an acidic microemulsion and a hydrocarbon solution of a hydrophobizing surfactant in the indicated injection sequence provide simultaneous enhancement of the effects of microemulsion treatment due to additional hydrophobizing effect and hydrophobizing effect due to preliminary removal of asphalt-resin-paraffin substances.

 The treatment of the bottom-hole zone with an acid microemulsion before the injection of a hydrocarbon solution of a hydrophobic surfactant nevertheless cannot provide the greatest hydrophobic effect due to the leaving of the aqueous phase on the surface of the porous medium.

 The studies conducted by the authors also found that when a hydrocarbon solution of a hydrophobizing surfactant comes in contact with a neutralized acidic microemulsion, a surfactant precipitates out of the hydrocarbon solution, which significantly reduces the effectiveness of the hydrophobizing effect of the surfactant hydrocarbon solution on the treated porous medium.

 Based on these considerations, the authors found that water-soluble solvents (such semi-polar liquids as alcohols, aldehydes, ketones, glycols, or mixtures thereof) simultaneously possess the properties of desiccants and stabilizers of hydrocarbon solutions of hydrophobic surfactants when they come into contact with neutralized acidic microemulsions.

 Thus, the invention provides for the injection of a water-soluble solvent into the bottomhole zone of a producing well after an acidic microemulsion with an external hydrocarbon phase and before a hydrocarbon solution of a hydrophobizing surfactant.

 The estimated amount of injected water-solvent solvent or a mixture of them is determined by its expenditure on removing the aqueous phase from the bottomhole zone previously treated with microemulsion and on stabilizing the hydrocarbon solution of hydrophobizing surfactant upon its contact with neutralized acidic microemulsion.

 From numerous studies it is known that the complete removal of liquid from a porous medium is ensured by injection of a solvent in an amount of 0.15 of the pore volume of the medium occupied by the displaced liquid. Used known acidic microemulsions in their composition have 0.4-0.6 by volume of the aqueous phase. The range of application of these microemulsions for water saturation of the treated bottom-hole zones is 0.1-0.9. When filling the treated bottom-hole zone, the total amount of the aqueous phase in fractions of the pore volume will be in this case 0.5-0.8, which will require removal, respectively, 0.15x0.5 = 0.75 and 0.15 x 0.8 = 0 , 12 pore volumes of a water-solvent. So, the removal of the aqueous phase from the treated bottom-hole zone requires 0.08-0.12 pore volumes of a water-solvent. The studies carried out by the authors found that when a neutralized acidic microemulsion and a hydrocarbon solution of a hydrophobic surfactant are contacted in equal volumes, stabilization of the latter is ensured by introducing into the system a water-soluble solvent in an amount of 0.2 from each of the contacting volumes.

 The total amount of water-soluble solvent or their mixture, thus, is (0.2 + 0.08 = 0.28) - (0.2 + 0.12 = = 0.32) of the pore volume of the treated bottom-hole zone.

 Thus, the volume ratio of the quantities of acidic microemulsion injected into the bottomhole zone of the producing well, a water-solvent solvent or a mixture of them and a hydrocarbon solution of hydrophobizing surfactant is 1: (0.28-0.32) :( 0.95-1.0).

 The present invention may provide for the exposure of injected fluids in the bottomhole zone after the introduction of a solution of hydrophobic surfactant for 8-12 hours to complete the adsorption-hydrophobizing processes.

Experiments were conducted in which the time to restore the water permeability of a water-saturated porous medium with an absolute permeability of 0.280 μm ^{2 was} determined.

 In experiment 1, the porous medium is successively saturated with water, water is replaced by oil, and oil is again water. In this case, the initial water permeability, water permeability in the presence of residual oil and the time of restoration of water permeability (from the moment the oil is displaced by water to the moment the stable value of water permeability in the presence of residual oil is restored) are determined.

 The experimental data are given in the table.

 In experiment 1 (prototype), an acid microemulsion is additionally sequentially injected (spent absorbent - 54%, neonol AF9-6 - 16%, 16% hydrochloric acid - 30%) in the amount of one pore volume, and is kept in a porous medium for 12 h, after which water is pumped into the porous medium. The values of water permeability and the time of its recovery are determined (from the moment the acid microemulsion is displaced to the establishment of a stable value).

 In experiment 3, water, oil, water, 0.3 pore volume of acetone and again water are pumped through a sample of a model porous medium. The value of the final water permeability after the displacement of acetone and the time of its recovery are determined.

 In experiment 4, all operations of experiment 2, including the injection and aging of the acid microemulsion according to example 2, complement the sequential injection of acetone in an amount of 0.3 pore volume and water. At the same time, the value of water permeability and the time of its recovery are determined (from the moment water is started to be injected after acetone until the stable value is established).

 In experiment 5, all operations in experiment 1 are repeated and supplemented with a preliminary injection of acetone in front of a hydrocarbon solution of hydrophobizing surfactant in an amount of 0.3 pore volume. In this case, the values of water permeability and the time of its recovery are determined, as in experiment 5. The results of the experiment are shown in the table (line at position 6). The composition of the surfactant solution in experiment 5.

 In experiment 7 (according to the proposed method), all operations of experiment 1 are repeated and supplemented with the following: 1) injection of one pore volume of an acidic microemulsion of the composition according to experiment 2, followed by exposure in a porous medium for 12 hours; 2) injection of 0.28 pore volume of acetone; 3) injection of one pore volume of a hydrocarbon solution of hydrophobic surfactant (2% solution of Don-52 in light oil), followed by injection of water. At the same time, the values of water permeability and the time of its recovery are determined (from the moment of the start of water injection after holding the system to the establishment of a stable value of water permeability). The experimental results are shown in the table (line at position 7). The composition of the surfactant solution according to experience 5. The composition of the acid microemulsion according to example 2 with the difference that instead of the spent absorbent used light pyrolysis resin.

 In experiment 8 (according to the invention), all operations of experiment 7 are repeated with the injection of acetone in an amount of 0.3 pore volume. The experimental results are shown in the table (line at position 8). Surfactants were dissolved in a mixture of oil and kerosene at a volume ratio of 1: 1.

 In experiment 9 (according to the invention), all operations of experiments 7 and 8 are repeated with the injection of acetone in an amount of 0.32 pore volume. The results are shown in the table by line 9. In the microemulsion, nefras was used as a hydrocarbon.

 In experiment 10 (according to the invention), all operations of experiment 8 are repeated when isopropyl alcohol and benzene are used as a water-soluble solvent as a solvent in a hydrocarbon solution of hydrophobizing surfactant. The results in the table in a row at position 10.

 In experiment 11 (according to the invention), all operations of experiment 8 are repeated using formalin as a water-soluble solvent and gasoline as a solvent in a hydrocarbon solution of hydrophobizing surfactant, where ATM10-16 (alkyltrimethylammonium chloride) is used as surfactant. The results in the table in a row at position 11.

 Surfactant Don-52 is produced according to TU 38.507-63-062-89.

 The cationic surfactant ATM10-16 is produced according to TU 38.507-63-016-89.

 From the data of the table it follows that the present invention (positions 7-10) provides a recovery period of water permeability of 263-285 minutes, significantly exceeding that noted for the prototype in 32 minutes, as well as the sum of the periods according to the methods pos. 2 + 3 - 56 minutes, 2 + 3 + 4 - 181 min. and 2 + 3 + 6 - 188 minutes, which will justify the claimed mechanism for achieving the objective of the invention. That is, the invention provides a synergistic effect regarding the recovery period of water permeability, achieved separately in examples 2-6.

So, the invention provides about six times longer recovery period of the final relative water permeability compared to the prototype method to lower values (on average 0.33 versus 0.40 for the prototype), which leads to a significant reduction in the average integral permeability to water permeability recovery period K _c .

, (1) где t - время; q_в(t) - дебит скважины по воде;
q_н(t) - дебит скважины по нефти. Но

=

, (2) где К_в(t) и K_н(t) - соответственно водо- и нефтепроницаемость,
μ_в - вязкость воды;
μ_н - вязкость нефти.At the same time, the average integral value of water cut of the PV product over this period is proportionally reduced, since:
n _in (t) =

, (1) where t is time; q _in (t) - well flow rate in water;
q _n (t) - oil flow rate. But

=

, (2) where K _in (t) and K _n (t) are water and oil permeability, respectively
μ _in - viscosity of water;
μ _n - oil viscosity.

It is experimentally shown that the equality is approximately satisfied:
_K (t) μ _n + K _n (t) μ _a = const. (3)
Then
n _in (t) = ZK _in (t), (4) where Z is the coefficient of proportionality.

] Δt_в (5) где q_ж - дебит скважины по жидкости, в случае механизированной добычи это постоянная величина;

- среднеинтегральное значение обводненности продукции за период.It is known that oil production Q _n for the period Δ t _in will be
Q _n = q _w (t) [1-

] Δt _in (5) where q _w is the liquid flow rate of the well, in the case of mechanized production it is a constant value;

- the average integral value of the water cut of the product for the period.

]Δt $\genfrac{}{}{0ex}{}{\text{п}}{\text{в}}$ . (6)
Для предлагаемого способа запишется
Q_н ^н=q_ж [1 - n_В ⁿ]Δt_В ⁿ (7)

≈

(8)
Δ t_в ^н≈6Δt_в ⁿ (9)
Тогда

≈

≈ 6 (10)
То есть изобретение обеспечивает существенное (в 6 раз) увеличение добычи нефти за период Δ t_В.For a known method will be written
Q $\genfrac{}{}{0ex}{}{\text{P}}{\text{n}}$ = q _x [1-

] Δt $\genfrac{}{}{0ex}{}{\text{P}}{\text{at}}$ . (6)
For the proposed method is written
Q _n ⁿ = q _w [1 - n _V ⁿ ] Δt _V ⁿ (7)

≈

(8)
Δ t _in ⁿ ≈6Δt _in ⁿ (9)
Then

≈

≈ 6 (10)
That is, the invention provides a significant (6 times) increase in oil production for the period Δ t _In .

PRI me R 1. Process the bottom-hole zone of a producing well with a pore volume of 10 m ³ . 10 m ^{3 of} acidic microemulsion of the composition, wt. %: light pyrolysis resin - 54%, neonol AF _9-6 - 16%, 16% hydrochloric acid - the rest. The injected acidic microemulsion is allowed to react for 12 hours. Then, acetone is pumped into the bottomhole zone in an amount of 0.3 x 10 = 3 m ³ and followed by a 2% solution of Don-52 surfactant in kerosene and in an amount of 9 , 8 m ³ , after which the well is put into operation. The volume ratio of the microemulsion, acetone and hydrocarbon surfactant solution is 1: 0.3: 0.98, respectively. After processing within 24 days, an additional 470 tons of oil were obtained.

PRI me R 2. Process the bottom-hole zone of a producing well with a pore volume of 25 m ³ . An acidic microemulsion is pumped into the bottomhole zone in an amount of 25 m ^{3 of the} following composition, wt.%: Lean absorbent - 54%, neonol A _F9 - 6% - 16%, 16% hydrochloric acid - the rest. The injected acidic microemulsion is allowed to react for 9 hours. Then, isopropyl alcohol in the amount of 0.32 x 25 = 8 m ^{3 is} pumped into the bottomhole zone and a 1% solution of ATM 10-16 surfactant in gasoline is pumped in the amount of 25 m ³ , after which they launch the well into operation. The ratio of the volumes of microemulsions, isopropyl alcohol and hydrocarbon surfactant solution is 1: 0.32: 1, respectively. After processing within 30 days after processing, 1645 tons of oil were additionally extracted.

 The use of the invention provides an increase in oil production by an average of 11 tons / day at an oil production rate of 100 tons / day.

Claims (1)

 METHOD FOR PROCESSING THE BOTH ZONE OF THE PRODUCING WELL, which includes injecting an acid microemulsion into the bottomhole zone and holding an acid microemulsion, characterized in that after soaking the acid microemulsion, a water-soluble solvent and 0.1 to 5 wt. surfactant in a volume ratio of acid microemulsion, a water-solvent solvent and a hydrophobic hydrocarbon solution cationic surfactant 1: (0.28 - 0.32): (0.95 - 1.0).

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