RU2791768C1 - Method of interwell tracer test with a low detection limit containing sodium or potassium salts of 2,4- or 3,5-dinitrobenzoic acids - Google Patents

Abstract

FIELD: oil industry.

SUBSTANCE: possibility of use in monitoring the development of an oil field. The claimed method of interwell tracer test with a low detection limit containing sodium or potassium salts of 2,4- or 3,5-dinitrobenzoic acids is carried out as follows. The sodium or potassium salt of 2,4- or 3,5-dinitrobenzoic acid is obtained by mixing 2,4- or 3,5-dinitrobenzoic acids with sodium or potassium hydroxide at a mass ratio of 1:1 and then dissolving in water to a concentration depending on the reservoir conditions. Water-soluble and distributable tracers are pumped into the injection well. A sample of produced water is taken from a production well at regular intervals. The concentrations of water-soluble and distributing tracers in the produced water sample are determined by high-performance liquid chromatography with UV detection. Build a cross-plot of concentrations of water-soluble and distributed tracers in the sample of produced water taken from the production well, from time. Then, based on the time values corresponding to the maximum concentrations of water-soluble and distributing tracers in the produced water sample, and the distribution factor of the distributing tracer, the residual oil saturation is calculated.

EFFECT: reduction of the harmful effects on the environment of the fluid injected into the reservoir containing the tracer, in accordance with toxicological requirements.

1 cl, 4 dwg

Description

The invention relates to the oil industry, in particular can be used to control the development of an oil field.

Cross-well tracer studies provide important information related to the characteristics of the oil reservoir, which is of key importance in determining the oil recovery strategy. With the help of interwell water-soluble tracers, an assessment of the hydrodynamic relationships of the reservoir in which filtration is carried out is carried out, and its residual oil saturation is also determined.

Tracers can be divided into two categories: water soluble and distributable [Larry W. Lake, Petroleum Engineering Handbook]. Water-soluble tracers strictly move with the water phase in the reservoir. The spreading tracers interact with other fluids in the system or with the rock surface. The degree of their distribution is determined in the laboratory and is characterized by the distribution coefficient K [Mario Silva. Development of new oil/water partitioning tracers for the determination of residual oil saturation in the inter-well region of water-flooded reservoirs]. Since the filtration of the oil phase is much less compared to the water phase, the water-soluble tracer is captured in the production well before it is distributed. The delay in the spreading tracer is proportional to the content of hydrocarbons present in the reservoir.

The water-soluble tracer should have high quantification accuracy at high dilution and be concentrated in the aqueous phase [Mario Silva. Development of new oil/water partitioning tracers for the determination of residual oil saturation in the inter-well region of water-flooded reservoirs].

From the prior art known information about the use of water-soluble tracers.

The most commonly used water-soluble tracers for cross-hole tracer testing are thiocyanic acid ester and fluorobenzoic acids. The thiocyanate ester has a low natural background in the reservoir and a detection limit in the range of 1 µg/l (1 ppb) which can be determined after separation on a high pressure liquid chromatograph [T. Bjornstad, O.B. Haugen, I.A. Hundere // Dynamic behavior of radio-labelled water tracer candidates for chalk reservoirs // Journal of Petroleum Science and Engineering, 10 (1994) // 223-238].

It is known to use as water-soluble tracers nitrate (NO ₃ ^- ), bromide (Br ^- ), iodide (I ^- ) and hydrogen borate (HBO ₃ ^- ) [T. Bjornstad, OB Haugen, IA Hundere // Dynamic behavior of radio-labelled water tracer candidates for chalk reservoirs // Journal of Petroleum Science and Engineering, 10 (1994) // 223-238; Janado, M., Yano, Y., Doi, Y., Sakamoto, H. // Peculiar effects of alkali thiocyanates on the activity coefficients of aromatic hydrocarbons in water // Journal of Solution Chemistry 12 (1983) // 741-754 ; Zemel, B // Developments in Petroleum Science, Elsevier Science // Tracers in the Oil Field, 43 (1983), Amsterdam, The Netherlands]. They can be examined using high pressure ion chromatography.

The disadvantages of known compounds is that their minimum detection limit is in the range from 25 to 1 µg/l for various compounds, which for many oil reservoirs is not enough for their intended use.

It is known to use a number of organic substances as water-soluble tracers: fluorescein, rhodamine B, methanol, ethanol and isopropanol [M.C. Adams, J. Davis, Kinetics of fluorescein decay and its application as a geothermal tracer, Geothermics 20 (1991) 53-66; US 2013/0084643A1; US 2011/0320128 A1; US 10061061 B2; Wood, K.N., Tang, J.S., and Luckasavitch, R.J // Interwell Residual Oil Saturation at Leduc Miscible Pilot. Presented at the SPE Annual Technical Conference and Exhibition // New Orleans, 23–26 September 1990. SPE-20543-MS].

The disadvantage of the known organic compounds is their low accuracy of quantitative determination, which leads to an increased consumption of the tracer.

It is known "The use of tracers based on biphenyl, terphenyl and fluorosulfonic acids for monitoring fluid flows" (patent WO2007148981, IPC G01N 33/18, G01N 33/22, G01N 33/26, publ. 27.12.2007). The essence of the invention is the use of biphenylmono- and polysulfonic acids and their salts, fluorenemono- and polysulfonic acids and their salts, and p-terphenylmono- and polysulfonic acids and their salts as tracers for monitoring the filtration of the aqueous phase. The use of tracers also suggests that one or more hydrogen atoms are attached to the ring system of biphenylamino and polysulfonic acids and their salts; fluorenmono- and polysulfonic acids and their salts; p-terphenylmono- and p-terphenylmono- and their salts; polysulfonic acids and salts substituted with one or more amino, hydroxyl and/or methyl groups.

Thus, in the known invention, the applicability of aromatic sulfonic acids as water-soluble tracers for monitoring the filtration of the aqueous phase in the reservoir was evaluated. Using 4,4-biphenyldisulfonic acid as an example, the ability to identify at a concentration of 100 ppt was demonstrated.

The disadvantage of the known technical solution is that the proposed compounds have a high detection limit.

"Alkoxyphenylcarboxylic acids as tracers" are known (patent WO2016124778, IPC C09K 8/58, E21B 47/10, publ. 11.08.2016).

The essence is the use of at least one aromatic acid compound or its salt as a water-soluble tracer. The aromatic acid compound is a compound of formula i wherein n is 0, 1 or 2, each of R1-R5 is independently H, alkyl or alkoxy, and where at least one of R1-R5 is an alkoxy.

A method for monitoring the filtration of an aqueous phase containing an injection line and a production line at least partially connected by a porous reservoir medium includes: a) introducing at least one tracer according to any one of claims 1 to 9 into said production line; and c) measuring the tracer concentration in said formation water sample taken from said production line over time. The method of claim 10, further comprising the steps of: d) plotting the concentration of said tracer in said formation water sample taken from the production line over time. The tracer concentration is measured either by high performance liquid chromatography or by gas chromatography with a mass spectrometer or tandem mass spectrometer. The method involves the use of the described water-soluble tracer with a second, distributable, tracer in order to determine the residual oil saturation.

Thus, the known invention describes the use of alkoxylated (R-O-, where R is an alkyl radical) aromatic acids in cross-well tests to monitor the filtration of the aqueous phase in an oil-saturated reservoir. The detection limit of tracers by gas chromatography–mass spectrometry (GC-MS) is 500 ppt.

The disadvantage of the known technical solution is that phenols have a high detection limit.

The technical result of the invention is the use of sodium or potassium salts of 2,4- or 3,5-dinitrobenzoic acids with a low detection limit of up to 5 and 1 ng/l for sodium and potassium salts, respectively, well soluble in water , meeting toxicological requirements, inexpensive and available on an industrial scale.

The technical result is achieved by a method of cross-well tracer test with a low detection limit containing sodium or potassium salts of 2,4- or 3,5-dinitrobenzoic acids, which consists in pumping a water-soluble and distributable tracer into an injection well, followed by sampling of formation water from a production well at intervals over time, determining the concentrations of water-soluble and distributing tracers in a formation water sample using high-performance liquid chromatography with UV detection, plotting the concentrations of water-soluble and distributing tracers in a formation water sample taken from a production well versus time, determining the residual oil saturation of the formation.

What is new is that sodium or potassium salts of 2,4- or 3,5-dinitrobenzoic acids obtained by mixing 2,4- or 3,5-dinitrobenzoic acids with sodium or potassium hydroxide at a mass ratio of 1:1 are used as a water-soluble tracer. and further dissolution in water to a concentration depending on reservoir conditions,

Based on the time values from the constructed dependence, corresponding to the maximum concentrations of water-soluble and distributing tracers in the formation water sample, and the distribution coefficient of the distributing tracer, the residual oil saturation of the formation is calculated:

WhereT _R,T _V are the retention time in the reservoir of a distributable and water-soluble tracer, respectively,

K is the distribution coefficient of the spreading tracer.

To implement the method of interwell tracer test with a low detection limit containing sodium or potassium salts of 2,4- or 3,5-dinitrobenzoic acids, the following are used:

- sodium hydroxide produced in accordance with GOST 4328–77;

- potassium hydroxide produced in accordance with GOST 24363–80;

- 2,4-dinitrobenzoic acid (CAS 610-30-0);

- 3,5-dinitrobenzoic acid (CAS 99-34-3);

- fresh water (GOST 27065-86);

- 2-fluorobenzyl alcohol (CAS 446-51-5) or 3,5-difluorobenzyl alcohol (CAS 79538-20-8).

In FIG. Figure 1 shows a fragment of the HPLC chromatogram of the sodium salt of 2,4-dinitrobenzoic acid with a concentration of 5 ng/l (5 ppt) (injection volume 50 μl).

In FIG. Figure 2 shows a fragment of the HPLC chromatogram of sodium salt of 3,5-dinitrobenzoic acid with a concentration of 1 ng/l (1 ppt) (injection volume 50 μl).

In FIG. Figure 3 shows a fragment of the HPLC chromatogram of the potassium salt of 2,4-dinitrobenzoic acid with a concentration of 5 ng/l (5 ppt) (injection volume 50 μl).

In FIG. Figure 4 shows a fragment of the HPLC chromatogram of the potassium salt of 3,5-dinitrobenzoic acid with a concentration of 1 ng/l (1 ppt) (injection volume 50 μl).

The method of interwell tracer test with a low detection limit containing sodium or potassium salts of 2,4- or 3,5-dinitrobenzoic acids is carried out as follows.

The sodium or potassium salt of 2,4- or 3,5-dinitrobenzoic acid is obtained by mixing 2,4- or 3,5-dinitrobenzoic acids with sodium or potassium hydroxide at a mass ratio of 1:1 and then dissolving in water to a concentration depending on the reservoir conditions.

Water-soluble and distributable tracers are pumped into the injection well. A sample of formation water is taken from the production well at intervals of time, for example, once a day.

The concentrations of water-soluble and distributing tracers in the formation water sample are determined by high-performance liquid chromatography with UV detection. Build a graph of concentrations of water-soluble and distributed tracers in the sample of formation water taken from the production well, from time to time.

Then, based on the time values corresponding to the maximum concentrations of water-soluble and distributing tracers in the formation water sample, and the distribution coefficient of the distributing tracer, the residual oil saturation is calculated:

where T _r , T _in - the retention time in the reservoir of a distributable and water-soluble tracer, respectively,

K is the distribution coefficient of the spreading tracer.

Examples of specific implementation.

Example 1

To a suspension of 3.00 g (14.1 mmol) of 2,4-dinitrobenzoic acid in 20 ml of water was added 0.57 g (14.1 mmol) of sodium hydroxide with stirring. The resulting solution was stirred for 10 min at room temperature, after which it was dried in a vacuum. Yield 3.31 g (quantitative), brown crystalline solid.

Received: the melting point of the sodium salt of 2,4-dinitrobenzoic acid is 283–285 ° C (with decomposition).

¹ H NMR spectrum (DMSO-D ₆ +D ₂ O) δ, ppm: 7.69 (d, ³ J _HH = 8.3 Hz, 1H), 8.38 (dd, ³ J _HH = 8.3 Hz, ⁴ J _HH = 2.1 Hz, 1H). 8.52 (d, ^4J _HH = 2.1 Hz, 1H) .

^13C NMR spectrum (DMSO-D ₆ +D ₂ O) δ, ppm: 119.62 (CH), 128.43 (CH), 130.93 (CH), 143.52 ( C -C( O)ONa), 146.93 (C _- NO ₂ ), 147.28 (C _- NO ₂ ), 168.01 (C(O)).

These data confirmed the preparation of the sodium salt of 2,4-dinitrobenzoic acid.

A solution of a water-soluble tracer, the sodium salt of 2,4-dinitrobenzoic acid, was prepared. Why the resulting salt was dissolved in water with stirring to a concentration depending on reservoir conditions, for example, 500 ng/l for a well with an interval between wells of 213 m.

The resulting solution of a water-soluble tracer and a distributing tracer, for example, 2-fluorobenzyl alcohol, were pumped into an injection well and formation water samples were taken from the production well at a certain frequency, for example, 1 time per day.

The concentration of a water-soluble and distributing tracer in a formation water sample was determined by high-performance liquid chromatography with UV detection. The concentration of sodium salt of 2,4-dinitrobenzoic acid was found to be 5 ng/l, which corresponds to the lower limit of detection (Fig. 1).

We built a graph of the dependence of the concentrations of water-soluble and distributing tracers on time, and determined the retention time of tracers. Based on tracer retention times of 138 days for a spreadable tracer and 52 days for a water soluble tracer, and a spreading tracer distribution ratio of 6.2, the residual oil saturation was calculated according to the formula.

Received the value of residual oil saturation, equal to 21.2%.

Example 2

To a suspension of 3.00 g (14.1 mmol) of 3,5-dinitrobenzoic acid in 20 ml of water was added 0.57 g (14.1 mmol) of sodium hydroxide with stirring. The resulting solution was stirred for 10 min at room temperature, after which it was dried in a vacuum. Yield 3.31 g (quantitative), brown crystalline solid.

Received: the melting point of the sodium salt of 3,5-dinitrobenzoic acid is 322–327 ° C (with decomposition).

¹ H NMR spectrum (DMSO-D ₆ +D ₂ O) δ, ppm: 8.77 (br. s, 2H), 8.93 (br. s, 1H).

¹³ C NMR spectrum (DMSO-D ₆ +D ₂ O) δ, ppm: 122.23 (CH), 130.54 (CH), 141.96 ( C -C(O)ONa), 149, 69 (C _- NO ₂ ), 171.14 (C(O)).

These data confirmed the preparation of the sodium salt of 3,5-dinitrobenzoic acid.

A solution of a water-soluble tracer, the sodium salt of 3,5-dinitrobenzoic acid, was prepared. Why the salt was dissolved in water with stirring to a concentration depending on reservoir conditions, for example, 100 ng/l, for a well with an interval of 105 m.

The resulting solution of a water-soluble tracer and a distributing tracer, for example, 2-fluorobenzyl alcohol, were pumped into an injection well and then samples of formation water were taken from the production well at a certain frequency, for example, once a day.

The concentrations of the water-soluble and distributing tracer in the formation water sample were determined by high-performance liquid chromatography with UV detection. The concentration of sodium salt of 3,5-dinitrobenzoic acid was found to be 1 ng/l, which corresponds to the lower limit of detection (Fig. 2).

We built a graph of the dependence of the concentrations of water-soluble and distributing tracers on time, and determined the retention time of tracers. Based on tracer retention times of 154 days for a spreadable tracer and 33 days for a water soluble one, and a spreading tracer distribution coefficient of 6.6 according to the formula, the residual oil saturation was calculated.

Received the value of residual oil saturation, equal to 35.6%.

Example 3

To a suspension of 3.00 g (14.1 mmol) of 2,4-dinitrobenzoic acid in 20 ml of water was added 0.79 g (14.1 mmol) of potassium hydroxide with stirring. The resulting solution was stirred for 10 min at room temperature, after which it was dried in a vacuum. Yield 3.54 g (quantitative), beige crystalline solid.

Received: the melting point of the potassium salt of 2,4-dinitrobenzoic acid -> 200 ° C (with decomposition).

¹ H NMR spectrum (DMSO-D ₆ ) δ, ppm: 7.82 (d, ³ J _HH = 8.4 Hz, 1H), 8.38 (dd, ³ J _HH = 8.4 Hz, ⁴ J _HH = 2.2 Hz, 1H), 8.50 (d, ⁴ J _HH = 2.3 Hz, 1H).

¹³ C NMR spectrum (DMSO-D ₆ ) δ, ppm: 118.34 (CH), 126.64 (CH), 130.73 (CH), 142.58 ( C -C(O)OK) , 146.09 (C _- NO ₂ ), 147.74 (C _- NO ₂ ), 164.64 (C(O)).

These data confirmed the preparation of the potassium salt of 2,4-dinitrobenzoic acid.

A solution of a water-soluble tracer was prepared - the potassium salt of 2,4-dinitrobenzoic acid, for which the salt was dissolved in water with stirring to a concentration depending on reservoir conditions, for example, 500 ng/l for a well with an interval of 189 m.

The resulting solution of a water-soluble tracer and a distributing tracer, for example, 3,5-difluorobenzyl alcohol, were pumped into an injection well and then samples of formation water were taken from the production well at intervals, for example, 1 time per day.

The concentration of a water-soluble and distributing tracer in a formation water sample was determined by high-performance liquid chromatography with UV detection. The concentration of the potassium salt of 2,4-dinitrobenzoic acid was found to be 5 ng/l, which corresponds to the lower limit of detection (Fig. 3) .

We built a graph of the dependence of the concentrations of water-soluble and distributing tracers on time, and determined the retention time of tracers. Based on tracer retention times of 143 days for a spreadable tracer and 52 days for a water soluble tracer, and a spreading tracer distribution ratio of 5.7 according to the formula, the residual oil saturation was calculated.

Received the value of residual oil saturation, equal to 23.7%.

Example 4

To a suspension of 3.00 g (14.1 mmol) of 3,5-dinitrobenzoic acid in 20 ml of water was added 0.79 g (14.1 mmol) of potassium hydroxide with stirring. The resulting solution was stirred for 10 min at room temperature, after which it was dried in a vacuum. Yield 3.54 g (quantitative), beige crystalline solid.

Obtained: the melting point of the potassium salt of 3,5-dinitrobenzoic acid is 220–225 °C (with decomposition).

¹ H NMR spectrum (DMSO-D ₆ ) δ, ppm: 8.81–8.82 (m, 1H), 8.84–8.86 (m, 2H).

¹³ C NMR spectrum (DMSO-D ₆ ) δ, ppm: 120.27 (CH), 129.38 (CH), 142.85 ( C -C(O)OK), 148.61 ( _C- NO ₂ ), 166.29 (C(O)).

These data confirmed the preparation of the potassium salt of 3,5-dinitrobenzoic acid.

A solution of a water-soluble tracer was prepared - the potassium salt of 3,5-dinitrobenzoic acid, for which the salt was dissolved in water with stirring to a calculated concentration depending on reservoir conditions, for example, 100 ng/l for a well with an interval of 98 m.

The resulting solution of a water-soluble tracer and a distributing tracer, for example, 3,5-difluorobenzyl alcohol, were pumped into an injection well and subsequent sampling of formation water from a production well at a certain frequency, for example, 1 time per day.

The concentration of a water-soluble and distributing tracer in a formation water sample was determined by high-performance liquid chromatography with UV detection. The concentration of potassium salt of 3,5-dinitrobenzoic acid was equal to 1 ng/l, which corresponds to the lower limit of detection (figure 4) .

We built a graph of the dependence of the concentrations of water-soluble and distributing tracers on time, and determined the retention time of tracers. Based on tracer retention times of 141 days for a spreadable tracer and 46 days for a water soluble tracer, and a spreading tracer distribution coefficient of 5.8 according to the formula, the residual oil saturation was calculated.

Received the value of residual oil saturation, equal to 26.1%.

Thus, shows the use of sodium or potassium salts of 2,4- or 3,5-dinitrobenzoic acids as a water-soluble tracer in the cross-well tracer test with a low detection limit of up to 5 and 1 ng/l for sodium and potassium salts, respectively, well soluble in water, satisfying toxicological requirements, inexpensive and commercially available.

Claims (4)

A method for cross-well tracer testing using a water-soluble tracer with a low detection limit, which consists in pumping water-soluble and distributable tracers into an injection well, then taking formation water samples from the production well at regular intervals, determining the concentrations of water-soluble and distributable tracers in the formation water sample using the method high-performance liquid chromatography with UV detection, build the dependence of the concentrations of water-soluble and distributing tracers in a sample of formation water taken from a production well over time, determine the residual oil saturation of the formation, characterized in that sodium or potassium salts of 2,4- or 3,5-dinitrobenzoic acids obtained by mixing 2,4- or 3,5-dinitrobenzoic acids with sodium or potassium hydroxide at a mass ratio of 1:1 and further dissolving in water to a concentration depending on the formation the initial conditions, based on the time values from the constructed dependence corresponding to the maximum concentrations of water-soluble and distributing tracers in the formation water sample, and the distribution coefficient of the distributing tracer, the residual oil saturation of the formation is calculated:

where T _r , T _in - the retention time in the reservoir of a distributable and water-soluble tracer, respectively, K is the distribution coefficient of the spreading tracer.

Images