RU2274740C1 - Method for oil production from bed - Google Patents

Abstract

FIELD: oil production, particularly oil displacement from bed with the use of displacement agents, namely alkaline solutions.

SUBSTANCE: method involves displacing oil from oil bed to production wells by cyclic injecting still waste liquid and sewage water plugs in still waste liquid/sewage water plug ratio of 0.1-10:1 in dependence of water content in product and of well intake capacity. Still waste liquid/sewage water plug ratio is 5-10:1 when well intake capacity is less than 50 m³/day and water content in treatment site less of than 60%. Still waste liquid/sewage water plug ratio is 3-4:1 when well intake capacity is more than 50 m³/day and water content in treatment site less than 60%. Still waste liquid/sewage water plug ratio is 0.1-1:1 when well intake capacity is less than 50 m³/day and water content in treatment site more than 60%. Still waste liquid/sewage water plug ratio is 1.5-2:1 when well intake capacity is more than 50 m³/day and water content in treatment site more than 60%.

EFFECT: increased efficiency of oil displacement, reduced water content in product and conformance.

1 ex, 3 tbl

Description

The invention relates to the oil industry, in particular to methods for producing oil from the reservoir using alkaline solutions as displacing agents.

A known method of oil production from the reservoir, providing for a cyclic injection into the reservoir of an alkaline distillation liquid (SCH) with a pH of 10 ... 12 in an amount of 0.05 ... 0.15 pore volume (bp), fresh water and waste water in an amount of 0.05 ... 0.30 pore volume (bp) (as USSR AS No. 1757263, class E 21 B 43/22, BI 25, 1996).

The disadvantage of this method is the need for a large-volume separating freshwater rims, as well as additional costs for the preparation of alkaline distillation fluid (SCH), which complicates and increases the cost of the process. The corrosive activity of SHDZh with a pH of 10 ÷ 12 in relation to the equipment of wells and pipelines with prolonged use as a displacing agent also reduces the effectiveness of this method to increase oil production.

The closest in technical essence and the achieved result to the claimed one is a method of oil production from the reservoir, providing for the cyclic injection of distillation fluid (J) with a pH of 5.5 ÷ 7 in the amount of 0.04 ÷ 0.09 bp, and waste water ( CB) - with a density of at least 1100 kg / m ³ in an amount of 0.017 ÷ 0.030 bp, and the ratio of J: CB in each cycle is from 2: 1 to 5: 1. (RF Patent No. 2158822 class E 21 V 43/22, BI 31, 2000)

The disadvantage of this method is not sufficiently high efficiency, due to the fact that when pumping the J and SV rims, the ratio of the rim volumes is chosen regardless of the water cut of the producing wells and the injectivity of the injection wells, which does not sufficiently reduce the water cut of the produced products, increase the coverage of the formation by water flooding and get an increase in oil production.

The objective of the invention is to increase oil production, reduce water cut in produced products and increase the coverage of the formation by water flooding as a result of the redistribution of filtration flows.

The problem is solved in that in the method of extracting oil from the reservoir by cyclic injection of distiller liquid and wastewater through an injection well, according to the proposed invention, the ratio of the volumes of injected rims J and CB is selected within 0.1 ÷ 10: 1 depending on the water cut of the production wells and injectivity of injection wells of the source of exposure in this way: the ratio of the volumes of the rims of the J: NE is 5 ÷ 10: 1 with the injection rate of the injection well less than 50 m ³ / day and the water cut at the source in impacts of less than 60%; the ratio of the volumes of the rims J: NE is 3 ÷ 4: 1 with an injection well injectivity of more than 50 m ³ / day and a water cut at the source of impact of less than 60%; the ratio of the volumes of the rims J: NE is 0.1 ÷ 1: 1 with an injection well injection of less than 50 m ³ / day and a water cut at the source of exposure of more than 60%; the ratio of the volumes of the rims J: NE is 1.5 ÷ 2: 1 with an injection well injectivity of more than 50 m ³ / day and water cut at the source of exposure more than 60%.

The used distiller liquid (DJ) is a waste of soda production, is produced according to TU 2152-035-00204872-02. Physico-chemical parameters of the liquid are shown in table 1.

Table No. 1 Name of indicator Norm 1. Appearance The solution is gray or greenish, transparent 2. Density, g / cm ³ 1.0-1.25 3. The concentration of hydrogen ions, pH units of pH 7.0-8.8 4. Mass concentration of calcium ions (Ca ²⁺ ), g / l, not more than 4.0 5. Mass concentration of chlorine ions (Cl ^- ), g / l, not more than 120 6. Mass concentration of sulfate ions (SO ₄ ^2- ) g / l, not more than 0.85 7. Mass concentration of suspended solids, g / l, no more 0.04

The distiller liquid contains calcium hydroxide (Ca (OH) ₂ ) and calcium salts (CaCO ₃ , CaCl ₂ , CaSO ₄ ).

Used wastewater with a specific gravity of 1.1-1.2 g / cm ³ with a pH of 4.5-7. The content of calcium ions is up to 30 g / l, the content of chlorine ions is 80-150 g / l, the content of sulfate ions is up to 0 , 7 g / l, the concentration of suspended particles in the form of solids not more than 0.05 g / l.

The essence of the proposed method is based on the following: when pumping in the rim of the waterlogging and mineral water in the washed channels of the formation, a fine precipitate is formed, which reduces the permeability of the washed channels and thereby contributes to the redistribution of filtration flows, and the amount of precipitated sediment and the size of its particles depend not only on the ratio of the volume of the J and NE, but also the operational parameters of the wells of the source of exposure. So, with low injectivity of wells (less than 50 m ³ / day) and low water cut of the source of impact (less than 60%), a large amount of sludge (for example, when pumping rims in the ratio of the volume of RJ: NE rims as 1.5: 1) can complicate the operation of the injection well as a result of salt deposition in the near-wellbore zone and a decrease in injectivity in a short period of time (more than 50%). Conversely, with an injection rate of more than 50 m ³ / day and a water cut of more than 60%, finely dispersed particles of a small amount of sediment formed during pumping of the rims in the ratio of the volumes of the RJ: NE rims of 5: 1 can be brought to the PPP of production wells. Thus, by varying the ratio of the rim volume depending on the injectivity of the injection well and the water cut of the producing wells in the focus of the impact, it is possible to significantly increase the coverage of the impact, increase the impact zone, thereby the depth and coverage of the formation by the impact.

Comparative analysis with the prototype allows us to conclude that the claimed method differs from the known introduction of new criteria for the applicability of the method, namely: the ratio of the volumes of injected rims of the DW and CB is selected depending on the injectivity of the injection well and the water cut of the reacting production wells of the test focus of exposure. Thus, the claimed invention meets the criterion of "novelty."

In field conditions, the method is as follows: injectivity of injection wells and water cut are measured in the impact area and, depending on the above-mentioned operational parameters, the ratio of the volumes of the RJ: SV rims is determined. After that, distillation liquid in the amount of 0.006 ÷ 0.1 pore volume and waste water in the amount of 0.005 ÷ 0.1 pore volume of the formation washed with water are sequentially pumped into the injection well in sequence. Through production wells carry out the selection of fluid.

The effectiveness of the proposed method was evaluated according to the results of laboratory and field experiments.

Example 1. To determine the amount of sludge released, laboratory experiments were conducted to mix in the free volume of distiller liquid and commercial waste water. In the experiments we used G with a pH of 7 and a specific gravity of 1.119 g / cm ³ and incidentally produced waste water with a pH of 5.5 and a specific gravity of 1.153 g / cm ³ . As a result of mixing the liquid fuel with wastewater at various ratios, precipitates are formed that contain mainly poorly soluble salts CaSO ₄ , Fe (OH) ₂ , CaCO ₃ . The particle size of the precipitate was determined using an electron microscope. Under thermostating conditions (25 degrees), the sedimentation time of the particles precipitated was determined, which for some time, depending on the ratio of the volume of the liquid and the mixture in the mixture, are in suspension. Information about the precipitate formed is given in table 2.

table 2 Experience No. The ratio of the volumes of J: CB The amount of precipitate, g / l Particle size, mm Particle settling time, days one 0.1: 1 0.017 0.05-0.15 5 2 0.5: 1 0.05 0.12-0.2 3 3 1: 1 0,065 0.18-0.25 2 four 1.5: 1 0.147 0.2-0.3 one 5 2: 1 0,062 0.16-0.24 2 6 3: 1 0,053 0.17-0.23 2,5 7 4: 1 0,039 0.18-0.21 3 8 5 0,023 0.19-0.20 four 9 6 0,021 0.16-0.18 5 10 8 0.02 0.15-0.17 5 eleven 10 0.018 0.14-0.16 6

According to table 2, it can be seen that the amount of precipitate formed and the size of the sediment particles and the place of precipitation during the mixing of the liquid and solid can be adjusted by choosing the ratio of the mixed volumes. It also follows from the table that, with an increase in sediment volume, the particle size of the formed salts also increases (up to 0.3 mm), and the particle settling rate increases, which, when applied in commercial conditions, especially at low water cut at the source of impact (less than 60%) and injectivity ( less than 50 m ³ / day) leads to the preferential deposition of salts in the bottom-hole zone of the injection well formation and thereby reduces the efficiency of the method.

Thus, in the implementation of the proposed method, so that the precipitation does not occur in the bottomhole zone of the injection and production wells, but in highly permeable washed interlayers, the ratio of the volumes of injected water into the reservoir and waste water must be selected depending on the main geological and field parameters for the impact site : injectivity of the injection well and water cut of the product at the source of exposure, which will significantly increase the efficiency of the known method of oil production due to ereraspredeleniya filtration flows and increase the coverage of the reservoir flooding.

To determine the dependence of the ratio of the volumes of injected water and wastewater on the injectivity of injection wells and water cut at the source of exposure, examples of the implementation of the proposed method in the field are considered. 9 foci of influence according to the claimed method and 3 foci — of the prototype at the Buzovyazovsky field, terrigenous Devonian reservoir D1 with permeability of 0.100-0.55 μm ² and porosity of 20-22%, geological and reservoir parameters of the formation: injectivity, average water cut at the source of exposure, are considered are given in table 3.

The proposed method was carried out as follows. Pre-measured in the prescribed manner the throttle response and watering of the extracted products for each outbreak and, depending on the size of the operational parameters, determined the ratio of the volumes of the rims of the J and SV rims. Then, through the injection wells through the pumping station, the rims of water and sewage are pumped sequentially, the volumes of which are shown in table 3. After the first cycle, the decrease in water cut and the increase in oil production were determined according to field studies. The cycles are repeated and in each cycle the ratio of volumes is determined similarly to the first. The results of the fishing experiment are shown in table 3.

Table 3 No. center Pickup
m ³ / day Water cut
by
hearth
% Ratio
volumes
rim
J: NE Volume J
in bp SV volume
in bp Average
decline
water cut
by
hearth,% Production increase
oil on the outbreak
impact, t Increase
To _OHV layer
water flooding
according to
flow meters,% Pickup
after the first
cycle, m ³ / day one 56 45,2 5: 1 0.05 0.01 4,5 1244 7.1 56 2 fifty 40.1 6: 1 0.06 0.01 5,0 1100 6.1 48 3 45 39.6 10: 1 0.05 0.005 4.1 678 5.7 fifty four 43 83.0 3: 1 0,03 0.01 14.3 1400 8.9 28 5 75 42.7 1: 1 0.05 0.05 11.3 1278 4,5 65 6 78 37,4 0.5: 1 0,045 0.09 7.5 1345 8.3 70 7 89 43.1 0.1: 1 0.006 0.06 8.8 1100 10.1 80 8 130 91 1.5: 1 0.1 0,066 7.2 987 25.9 115 9 98 84 2: 1 0.09 0,045 6.3 896 15.7 90 Prototype 38
36
40 35
fifty
40 2: 1
3: 1
5: 1 0.05
0.01
0,025 0,025
0.003 0.005 3,1
2,5
1,6 310
290
256 1.3
2,5
1.9 12
16
17

The technological efficiency from the cyclical effects of water and wastewater according to the proposed method was evaluated according to RD 39-0147035-209-87 "Methodological guidance on determining the technological efficiency of hydrodynamic methods to enhance oil recovery". M., VNII, 1987.

The results of the pilot industrial works, shown in table 3, indicate that when selecting the ratios of the rims J and NE according to the claimed method, taking into account the data of laboratory studies and operational parameters of the wells of the injection sites, the efficiency of oil production increases. If according to the proposed method, the technological efficiency is 678-1400 tons of additional oil per 1 hotbed and the average decrease in water cut for the hotbed is 4.5-14.3%, while the prototype for each hot spot additionally produced 256-310 tons with a decrease in water cut 1.6-3.1%, that is, 5 times less efficiency, which indicates the high efficiency of the method to increase oil production. In addition, according to flow measurement data before and after the cycle, it was found that the increase in the coefficient of coverage by water flooding (K _OKHV ) within the perforation interval in the proposed method is 5.7-25.9% for a number of injection wells, and for focal injection wells, where the rims were injected according to the known method, the growth of K _{OKHV was} only 1.3-2.5%, that is, 8 times less, which also indicates the high efficiency of the method for increasing the coverage of the formation by water flooding. The injectivity of injection wells after the injection cycle of the RJ and SV rims according to the claimed method slightly decreased for a number of wells - from 5 to 20%, and for well No. 3 the injectivity even increased from 45 m ³ / day to 47 m ³ / day, whereas after the impact of the prototype injectivity of injection wells for 1 cycle decreased by 54-65.7%.

The sludge-forming technology developed on the basis of the proposed method is carried out through a cluster pump station (SPS) and allows you to cover the inter-well zone, that is, a zone in a large radius between focal injection wells. The method is economical and affordable, since it uses a free production waste, the resources of which are unlimited, in addition, the method is implemented using the existing waterflooding system. The qualified use of petrochemical production wastes allows to reduce the cost of waterproofing work in heterogeneous reservoirs and contributes to environmental protection.

Thus, the application of the proposed method in the oil industry contributes to more efficient regulation of the permeability of a heterogeneous formation, increasing the coverage of the formation by water flooding.

Claims (1)

A method of oil production from the reservoir, including the displacement of oil from the reservoir to production wells by cyclic injection of distiller fluid (DF) and wastewater (CB) into focal injection wells, characterized in that the ratio of the volumes of the rims of injected DF and CB is selected within 0.1. ..10: 1 depending on the water cut of the production of the producing wells and the injectivity of the injection wells in this way: the ratio of the volumes of the rims of the DW: CB is 5 ÷ 10: 1 with the injectivity of the injection well less than 50 m ³ / day and the water cut over the source of water less than 60%; the ratio of the volumes of the rims J: NE is 3 ÷ 4: 1 with an injection well injectivity of more than 50 m ³ / day and a water cut at the source of impact of less than 60%; the ratio of the volumes of the RJ: SV rims is 0.1 ÷ 1: 1 with an injection well injectivity of less than 50 m ³ / day and a water cut at the source of exposure of more than 60%; the ratio of the volumes of the rims J: NE is 1.5 ÷ 2: 1 with an injection well injectivity of more than 50 m ³ / day and water cut at the source of exposure more than 60%.