RU2429343C1 - Oil deposit development method - Google Patents

Abstract

FIELD: oil and gas industry.

SUBSTANCE: according to the method, pumping of working medium through injection wells, extraction of oil through production wells, oil sampling, determination of optic properties of oil samples, analysis of results and preparation of recommendations regarding development of oil deposit is performed. Activities aimed at increasing the oil recovery of the deposit are carried out on the deposit. Oil samples are taken from products of production wells responding to carrying out of activities aimed at increase of oil recovery, at interval of 14-15 days. Oil is separated by means of centrifugation from water in oil samples. Photocolorimetric investigations and parametric correlation analyses are made between the change of oil light absorption factor and oil production volumes during determination of optic properties of oil samples. Correlation analysis during which values of linear Poisson correlation coefficient between the change of oil light absorption coefficient and oil production volumes are calculated for each well is made. Conclusion of involvement in development of oil deposits changed at positive value of correlation coefficient as a result of activities aimed at increasing the oil recovery and unchanged at negative value is made. Activities aimed at increasing the oil recovery in order to improve the involvement in development of oil deposits changed as a result of activities are changed.

EFFECT: increasing oil recovery of deposit.

3 ex, 6 tbl, 2 dwg

Description

The invention relates to the oil industry and may find application in the development of oil deposits.

A known method for the development of oil deposits, including the installation in terrestrial communication of a producing well of a device for automatically measuring the optical density of oil. The absolute value of the initial optical density of the oil is measured and the measurement is carried out at a wavelength of more than 800 nm. The current optical density of the oil is measured periodically over time. Judge the position and movement of the oil-water contact by changing the absolute value of the optical density of oil over time and by increasing the current optical density of oil relative to its initial optical density (publication number 93003302, publ. 1996.05.27).

The known method allows only to judge the movement of oil-water contact, while other characteristics of the development remain outside the scope of attention.

Closest to the proposed invention in technical essence is a method of developing a heterogeneous oil reservoir, which includes taking oil through production wells, injecting a working agent through injection wells, taking oil samples from various points of the formation at certain intervals, determining their optical properties at different wavelengths and making recommendations for developing an oil reservoir. When exposed to water flooding, the involvement in the development of low-permeability zones with predominantly undeveloped reserves is determined. For this, optical density, light transmission and absorption coefficients, refractive indices and dispersions are determined as the optical properties of oils. Oil samples are taken from all production wells located in low permeability and high permeability zones. After pumping a working agent into injection wells, the effect of exposure in reacting wells is expected, where oil sampling is also prescribed. The sampling of oil from production wells is repeated with the determination of the same optical properties of oil and, based on the appearance of traces of a working agent in oil, a conclusion is drawn on involvement in the development of low-permeability zones (RF patent No. 2304705, publ. 08.20.2007 - prototype).

The known method allows you to track the displacement of oil from low-permeability zones, but does not allow you to make a conclusion about the effectiveness of the impact on the reservoir, the impact of measures to increase oil recovery of the reservoir, and therefore, does not allow you to purposefully change the type and modes of exposure and increase oil recovery of the reservoir.

The proposed invention solves the problem of increasing oil recovery deposits.

The problem is solved in that in a method for developing an oil deposit, including pumping a working agent through injection wells, taking oil through production wells, taking oil samples, determining the optical properties of oil samples, analyzing the results and making recommendations for developing an oil reservoir, according to the invention, the deposits are carried out measures to increase oil recovery, oil sampling is carried out from the production of producing wells that respond to measures to increase oil recovery, with an interval of 14-15 days, and oil samples are separated by centrifugation of oil from water, when determining the optical properties of oil samples, photocolorimetric studies and parametric correlation analyzes between changes in the oil light absorption coefficient and oil production volumes are carried out, a correlation analysis is performed, during which the values of the Poisson linear correlation coefficient between the coefficient changes are calculated for each well light absorption of oil and oil production, with a positive value of the correlation coefficient do Turning on the involvement in the development of oil reserves, changed as a result of measures to increase oil recovery, with a negative - unaltered, change measures to increase oil recovery to increase involvement in the development of oil reserves, changed as a result of events.

SUMMARY OF THE INVENTION

When developing an oil deposit, it can be very difficult to assess the effectiveness of measures to increase oil recovery, to adjust and to increase their effectiveness. Existing technical solutions solve this problem only partially, which does not allow to achieve a significant increase in oil recovery. The proposed method solves the problem of increasing oil recovery deposits. The problem is solved as follows.

The developed method allows to determine the mechanism by which additional oil production is ensured: by improving the oil displacement or by increasing the coverage of oil reserves not previously included in the development. The change in the composition and physico-chemical properties of the produced oil can be significant, and this is due both to changes in the course of the interaction of oil with injected agents, and due to the involvement of unreached reserves in the process of developing the field development system. In the first case, the produced oil will be characterized by an increase in chromophore compounds, since for the zones of the formation previously covered by the action of injected agents, the remaining hydrocarbon reserves are characterized by a higher density, viscosity, an increased content of resins, asphaltenes and other changes, the light absorption coefficient (K _cn ) of the produced oil will be relatively large. In the second case, among the main changes, it will be important to increase the content of light fractions of hydrocarbons in the produced oil due to the involvement of oil reserves that are little changed during the development of the field; the light absorption coefficient of the produced oil will be relatively smaller.

To implement the method, regular sampling of oil from wells located in areas where the methods of increasing oil recovery (EOR) were carried out. The change in K _{c of the} extracted oil is determined during the development process as a result of the application of EOR. The main research method is photocolorimetry using spectrophotometers or photoelectrocolorimeters. By increasing the value of K _sp it can be stated that the oil reserves changed during the development process were additionally extracted from the water-filled zone of the reservoir. And by decreasing the value of K _c, it can be stated that oil reserves not affected by water flooding, which had not previously been in contact with the agents injected into the reservoir, were additionally recovered.

This method includes the selection of representative samples of production of producing wells that respond to activities by methods of increasing oil recovery, with an interval of 14-15 days (selection of products from wellhead samplers into vessels with a volume of at least 1,500 ml, then sampling with a syringe from the oil part of the sample vessel with a volume of 15 ml), separating oil from water in an OPn-3m centrifuge for 5 minutes at a frequency of 2500 rpm, conducting photocolorimetric studies on a KFK-3 photocolorimeter and performing parametric correlations ion analyzes between changes in the oil absorption coefficient and oil production.

The OPN-3m centrifuge is made in a climatic modification UHL4.2 according to GOST 15150-69, it provides the test tube holder speed from 500 to 2700 rpm with a resolution of 100 rpm, the permissible reduced deviation of the rotation frequency from the maximum working speed in the range from 2000 up to 2700 rpm - not more than 5%, the maximum separation factor is 1670, the maximum volume of the centrifuge is 150 ml, the centrifuge provides the setting of the centrifugation time in the range from 0 to 99 min with a resolution of 1 min, deviations of the drive time of the price drive rifuges from a predetermined value of ± 2%, the maximum continuous operation time of a centrifuge is at least 120 minutes, powered by an alternating current network of 220 V (+22, -11 V) frequency of 50 ± 0.5 Hz, the power consumed by an alternating current network, no more than 200 watts.

The KFK-3 photometric photometer is intended for measuring transmittance and optical density of transparent liquid solutions, as well as for measuring the rate of change of the optical density of a substance and determining the concentration of a substance in solutions after preliminary calibration of the photometer by a user. The spectral range of the photometer is from 315 to 990 nm. Measurement limits: transmittance 0.1-100%, optical density 0-3. The limit of the permissible value of the basic absolute error of the photometer when measuring the transmittance of 0.5% abs. The limit of permissible basic absolute error of setting the wavelength is 3 nm. The limit of the standard deviation of the random component of the main absolute error of 0.15% abs. Power supply from an alternating current main of voltage 220 ± 4.4 V, frequency 50-60 Hz, power no more than 60 W. In the experiments, a quartz cuvette with an optical path length of 1.060 mm was used.

To measure the optical density of the samples, 0.08 ml of dehydrated oil is taken, which dissolves in 10 ml of toluene. The measurements are carried out on a KFK-3 device in the wavelength range from 310 nm to 990 nm.

All quantitative measurements in spectroscopy are based on the Bouguer-Lambert-Baer law (abbreviated BLB law), which relates the ability of a substance to absorb light with the concentration of a given substance.

The dependence characterizing the attenuation of light by matter can be represented as:

where I and I ₀ - the intensity of the transmitted and incident light on the sample; C is the concentration of oil in toluene; l is the optical path length; To _sp - the coefficient of proportionality, called the molar absorption coefficient or extinction coefficient of the substance. After transformations, the formula for calculating the light absorption coefficient takes the form:

Since in spectroscopy the length of the cell l is measured in cm, the concentration of the substance is in fractions of units or in percent, and the optical density is a dimensionless quantity, the unit of measurement of the extinction coefficient (K _sp ) is cm ^-1 .

The light absorption coefficient (K _sp ) depends on the wavelength of transmitted light, the temperature of the solution, the nature of the dissolved substance and does not depend on the thickness of the absorbing layer and the concentration of the dissolved substance. The light absorption coefficient reflects the individual properties of colored compounds and is their defining characteristic.

Next, a correlation analysis is performed. For each well, the Poisson’s linear correlation coefficient between the change in oil light absorption coefficient and oil production volumes are calculated. If the value of the correlation coefficient is positive, then this means that the method of increasing oil recovery involved the development of changed oil reserves, but if the value of the correlation coefficient is negative, then the oil reserves that are little changed during the development process. The oil recovery enhancement mechanism can be accepted as mixed if, as a result of statistical calculations, insignificant correlation coefficients are obtained when additional production is fixed from the application of the oil recovery increase method for the dynamics of production of well products. Changes are being made to increase oil recovery to increase involvement in the development of oil reserves that have been changed as a result of measures. As EOR, injection of crosslinkable polymer systems, water-dispersed polymer systems, injection of solutions of surface-active systems and their compositions, injection of carbon dioxide, etc. are used.

Example 1

Investigations of field oil samples taken from 3 sections of the Severo-Almetyevskaya area of the Romashkinskoye field, at which EOR was carried out, were carried out. Taking into account the need to exclude the influence of any factors other than EOR, sections of injection wells were selected where no measures were taken for 3 years that could affect the change in the light absorption coefficient of the produced oil.

In the injection well section No. 21317, which has three reacting wells: No. 5710, No. 14776, No. 14777, in late January - early February 2009, GER technology was implemented.

GER is a multicomponent system containing a hydrocarbon phase, an emulsifier Neftenol H3, calcium chloride and water. In-situ reaction leads to the formation of an emulsion, resistant to erosion, with a high hydrophobic ability. The resulting water-insulating mass increases the filtration resistance of the flooded intervals of the formation, thereby increasing the coverage of the formation in thickness.

Information about the analyzed area is presented in table 1.

Table 1 Information on the working formations of the well section No. 21317 Options Well numbers 21317 5710 14776 14777 Roof depth, m 1743.6 1745.2 1748 1757 1598,2 1702.2 1718 1610, 8 Depth of the sole, m 1744.6 1747.4 1750.8 1758 1603.8 1705 1719.2 1614 Naim. layer D0 D0 D0 TOP. KNOWN. D0 D0 D0 + D1A D0 Collector zaglin. sandstone sandstone sandstone non-collector sandstone siltstone siltstone sandstone Eff. thickness., m one 2.2 2,8 0 5,6 2,8 1,2 3.2 Nave. thickness., m one 2.2 2,8 0 5,6 2,8 1,2 3.2 Water-boat. thickness., m 0 0 0 0 0 0 0 0 The pierce. phases., μm ² 97.5 176.7 196.5 0 150 - - 230 The pierce. abs., microns ² 331.9 597.4 663.6 0 - - - 807 Porosity,% 18.2 21 21.5 0 twenty - - 22.2 Neftena
sat.,% 76,4 85.6 79.6 0 77 - - 86.2 Clay 0.6 0.6 0.8 0 - - - - Saturation pattern - - - - oil. layer oil. layer oil. layer oil. layer

As a result of statistical analysis, an inverse linear correlation was established between the optical density of oil samples from well No. 5710 and oil production. It should be noted that the reservoir, discovered by this well, has an oil-saturated thickness (5.6 m), which is almost 2 times the oil-saturated thickness of the reservoir, discovered by the remaining wells of this section. The presence of a direct relationship between the change in optical properties and the change in oil production volumes is due to the fact that the injection of GER led to additional washing out of the residual oil to a greater extent than the involvement of new reservoir zones not previously covered by water flooding.

A comparison of the dynamics of changes in the optical density of oil samples taken from well No. 14776 of the considered section and the volumes of oil production from this well showed the presence of a direct relationship between them (see table 2, figure 1).

Analysis of changes in the performance of well No. 14777 of this section shows that the well responded to the use of GER by additional oil production.

table 2 The results of the calculation of correlation coefficients based on laboratory studies of oil samples Analyzed Date Well No. 5710 Well No. 14776 Well No. 14777 K _sp , cm ^-1 Oil production, t K _sp , cm ^-1 Oil production, t K _sp , cm ^-1 Oil production, t February 2009 2867,464 59 - 80 - one hundred March 2009 - 164 3117,443 147 3140,241 105 April 2009 - 81 3465,955 151 3358,299 90 May 2009 2772,581 76 4603,439 155 3045,322 99 June 2009 3591,857 75 2851,954 134 2717,841 97 September 2009 4043,462 105 2772,581 137 2706,454 71 October 2009 - - 2543,217 147 2693,208 99 Coeff. linear
correlations with
K values _cn - -0.816 - 0.707 - 0.270 ΔK _sp / ΔQn, cm ^-1 / t - 43,823 - 257,527 - -73,899

It was decided to continue the use of GER in this development area.

Oil recovery at the development site increased by 1.2%.

Example 2

The impact assessment of the application of SNPCH-9030 technology, the effect of which is based on the combined effects of hydrochloric and hydrofluoric acids, an organic solvent, and oil-soluble surfactant, was carried out on the basis of sampling at the injection well section No. 21347 of three reactive producing wells: No. 11321 , 11322, 21345. Information about the analyzed area is presented in table.3.

A significant change in the optical properties of oil was recorded at the injection well site as a result of the introduction of SNPCH-9030 technology. In samples taken from well No. 11321, the content of optically denser components decreased, and in samples taken from well No. 21345, the optical density of oil increased significantly (see Table 4). The dependence of K _cn on oil production in well No. 11321 has an inversely proportional relationship (see table 4, figure 2). This is due to the complexity of the effect of displacement processes on the optical density of oil, heterogeneity in wettability, local changes in the structure of the pore space, and various molecular weights of sorbed asphaltenes. The distance between wells No. 21477 and No. 11321 is many times greater than the distance between wells No. 21477 and No. 21355, that is, the pore space between wells No. 21477 and No. 11231 is even greater than the volume of pore space between wells No. 21347 and No. 21345. In addition, the life of well No. 21345 is longer than the life of well No. 1121, if well No. 11321 was launched in June 2007, then well No. 21345 was put into operation in June 2005. Inter-well distances, operating periods allow us to judge the greater variability of the residual oil reserves of the pore space in the zone between wells No. 21347 and No. 21345, which also clearly follows from an analysis of the dynamics of the optical properties of oil.

Table 4 The results of calculating the coefficients of linear and rank correlation based on laboratory studies of oil samples Analyzed Date Well No. 11321 Well No. 21345 K _sp , cm ^-1 Oil production, t K _sp , cm ^-1 Oil production, t March 2009 3,712,345 124 - - April 2009 2690,471 779 2805,425 145 May 2009 2753,422 816 2742,470 74 June 2009 2563,425 802 2685,104 299 September 2009 2667,125 643 3405,498 229 October 2009 2789,003 837 4132,871 224 Coeff. linear correlation with K _sp - -0.937 - 0.259 ΔK _sp / ΔQn, cm ^-1 / t - -1.694 - -19,304

Changes are being made to increase oil recovery to increase involvement in the development of oil reserves that have been changed as a result of measures. To do this, the GER composition is pumped through the injection well.

As a result of ERT has changed in a positive direction K _sp, and oil recovery development area increased by 0.4%.

Example 3

At well No. 10008, the technology of composite systems based on low-concentrated solutions of polymers and surfactants (NKPS) was used. The use to increase oil recovery of aqueous solutions of polymers in concentrations that do not lead to the formation of low-mobility high-strength gels is aimed at leveling the waterflooding front, involving in the development previously not covered by the influence of the formation zones. The injection of surfactant solutions contributes to the destruction of the oil-water emulsion and increases the wettability of the rock.

Information about the analyzed area is presented in table 5.

Despite the fact that the change in the optical density of the oil sample of reacting producing well No. 5613 is ambiguous, one can observe an increase in the light absorption coefficient of oil with an increase in the monthly oil production (see Table 6).

Continue the use of NKPS in this area. As a result, oil recovery at the development site increased by 1.8%.

The application of the proposed method will increase the recovery of deposits.

Table 6 The results of the calculation of the correlation coefficients based on laboratory studies of oil samples of well No. 5613 Analyzed Date K _sp , cm ^-1 Oil production in the well. No. 5613, t April 2009 3931,245 602 May 2009 3257,943 554 June 2009 3246,995 538 September 2009 3971,812 608 October 2009 3098,284 595 Coeff. linear correlation with K _sp - 0.644 ΔK _sp / ΔQn, cm ^-1 / t - 10,355

Claims (1)

A method of developing an oil deposit, including pumping a working agent through injection wells, taking oil through production wells, taking oil samples, determining the optical properties of oil samples, analyzing the results and making recommendations for developing an oil reservoir, characterized in that measures are taken to increase oil recovery in the deposits deposits, oil sampling is carried out from the production of producing wells that are responsive to measures to increase oil recovery, with an interval of 14-15 days, from centrifuged oil samples the oil is separated by water, when determining the optical properties of oil samples, photocolorimetric studies and parametric correlation analyzes between changes in the oil light absorption coefficient and oil production volumes are carried out, a correlation analysis is carried out, during which the values of the Poisson linear correlation coefficient between the changes in oil light absorption coefficient are calculated and volumes of oil production, with a positive value of the correlation coefficient make a conclusion about involvement in rabotku oil reserves, changed as a result of measures to increase oil recovery, with a negative - unaltered, change measures to increase oil recovery to increase involvement in the development of oil reserves, changed as a result of events.

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