RU2242592C1 - Method for extracting low-penetrable oil, gas or gas-condensate-oil deposits - Google Patents

Abstract

FIELD: oil and gas extractive industry.

SUBSTANCE: method includes driving of horizontal-slanted wells in sub-gas area of deposit with their perforation with placement of their upper perforation range above oil-gas contact at distance from 0 to 20 meters. Lower perforation range is placed in sub-gas or oil area. Extraction of deposit is performed with support of pressure by pumping in of working agent or in mode of gas repression. During deposit extraction in gas repression mode periodical measurement of gas-liquid factor is performed, in case of exceeding of which more than 600-700 m³/ton, upper interval of perforation of horizontal-slanting wells is lowered until reaching given value of gas-liquid factor. Lower perforation interval for horizontal-slanting wells is placed in area of gas-oil contact.

EFFECT: higher oil yield.

3 cl, 3 ex, 2 tbl, 8 dwg

Description

The invention relates to the oil and gas industry and may find application in the development of low permeability oil and gas or gas condensate-oil deposits.

A known method of oil production from the sub-gas zone of an oil and gas reservoir by a system of producing horizontal and / or vertical wells, while the connection of the producing well is carried out in sections of the oil rim with a relatively high filtration resistance between the filter and the gas-oil and / or oil-water contacts [1].

A known method of oil production, if it is carried out in low permeability reservoirs, leads to a decrease in oil production. The oil production rate and oil well productivity are reduced.

Closest to the technical nature of the present invention is a method of developing low-permeability oil and gas or gas condensate-oil fields, including wiring into the wells with their perforation and oil selection [2].

The disadvantage of this method is the low productivity of wells for oil.

The invention solves the problem of increasing the productivity of oil wells.

The problem is solved in that in the known method of developing low-permeability oil and gas or gas condensate-oil deposits, including wiring wells with their perforation and oil selection, according to the invention, horizontally inclined wells are carried out in the sub-gas zone of the reservoir with their upper perforation interval located above the gas-oil contact on a distance from 0 to 20 m, and the lower perforation interval in the sub-gas zone or oil zone, while the development of the deposits is carried out while maintaining pressure by pumping a working agent or in the regime of gas repression, as well as the fact that when developing a deposit in the regime of gas repression, a periodic measurement of the gas-liquid factor is carried out, when exceeding a value of more than 600-700 m ³ / t, the upper perforation interval of horizontally-deviated wells is lowered to achieve this value of the gas-liquid factor . The lower perforation interval of horizontally inclined wells is located in the gas-oil contact area.

The essential features of the invention are.

1. Posting in the deposits of horizontal-deviated wells.

2. Posting in wells with their perforation.

3. The selection of oil.

4. Carrying out horizontal-deviated wells in the sub-gas zone of the reservoir.

5. The location of the upper perforation interval above the gas-oil contact at a distance from 0 to 20 m

6. The location of the lower interval of perforation in the sub-gas zone or oil zone.

7. The development of deposits is carried out in the mode of maintaining pressure by pumping a working agent or in the regime of gas repression.

8. When developing deposits in the regime of gas repression, periodically measure the gas-liquid factor.

9. If the value of the gas-liquid factor is exceeded more than 600-700 m ³ / t, the upper perforation interval of horizontally-deviated wells is lowered until this value of the gas-liquid factor is reached.

10. The lower perforation interval is located in the gas-oil contact area.

Signs 1-3 are common with the prototype, the essential features, signs 4-7 are the essential distinguishing features of the invention, and signs 7-10 are additional significant features.

SUMMARY OF THE INVENTION

In known technical solutions in the development of low-permeability oil and gas and gas condensate-oil deposits by wells with perforation, the upper perforation interval is placed at an indefinite distance from the gas-oil contact, which reduces their oil productivity. Therefore, in the proposed technical solution, horizontal-deviated wells are drilled in the sub-gas zone of the reservoir with the location of their upper perforation interval above the GOC at a distance of 0 to 20 m, and their lower perforation interval is located in the sub-gas or oil (above which there is no gas cap, there is no GOC ) zones. It is to these limits of placement of the upper interval of well perforation that the maximum value of oil production rates corresponds. At the same time, gas entering in small quantities from a low-permeability formation into the upper interval of well perforation plays the role of an internal gas lift and contributes to the rise of oil.

In the case of the location of the lower interval of perforation of horizontally-deviated wells in the sub-gas zone, it can be withdrawn (placed) in the GOC area.

Then the gas from the gas cap will enter the well through the upper and lower perforation intervals, partially dissolving in the oil, increasing its volume and thereby increasing the pressure (it is known that when oil is extracted from low-permeability reservoirs, the reservoir pressure in the producing well decreases rapidly). Thus, a double gas lift is provided and the oil productivity of the well is increased.

However, in this case (placement of the lower interval of perforation in the GOC area) during development in the gas repression mode due to the expansion of the gas cap, the level of GOC decreases, which naturally leads to an excess of the lower interval of perforation of wells over the level of GOC. In this regard, carry out the movement of the lower interval of perforation to the level of GOC (for example, by isolating the lower, above the GOC, the interval of perforation of the well). Thus, the lower interval of perforation will always be in the region of GNA.

A deposit is developed while maintaining pressure (reservoir) by pumping a working agent (water or gas) or by gas repression, i.e. to exhaustion. In the latter case, there is a decrease in the level of GOC with the expansion of the gas cap, which leads to an increase in gas-liquid factors and a decrease in oil production over time. Therefore, when developing deposits in the regime of gas repression, periodic measurements of the gas-liquid factor are performed. If its value exceeds 600-700 m ³ / t, then the upper perforation interval is omitted until the gas-liquid factor reaches 600-700 m ³ / t. This value corresponds to the maximum values of oil production.

The invention is illustrated in the drawing, where:

in FIG. 1 - shows a section of an oil and gas deposit developed under gas repression mode, with a horizontally-inclined well with its upper perforation interval above the GOC and the lower in the sub-gas zone;

figure 2 - shows a section of an oil and gas reservoir, developed with the maintenance of reservoir pressure, with a horizontally-inclined well with the location of the upper perforation interval above the GOC, and the bottom in the oil zone and the injection well;

figure 3 - shows a section of the oil and gas deposits, developed under the regime of gas repression, with a horizontally inclined well and the location of the upper perforation interval above the GOC, the lower perforation interval in the sub-gas zone, in the GOC;

figure 4 - shows a graph of changes in the flow rates of two horizontal wells with the location of the upper interval of perforation of one of the wells above the GOC, and the other below the GOC, according to the years of development;

figure 5 is a graph of the dependence of the flow rate of oil from the distance of the upper interval of perforation to GNK;

figure 6 is a graph of changes in the flow rate of oil and gas-liquid factor by years of development;

Fig.7 is a graph of the change in gas-liquid factor depending on the distance above the GNA;

on Fig is a graph of changes in oil production from gas-liquid factor for gushing horizontally-deviated wells of the East block of the Orenburg field with the upper interval of perforation in the field of GOC.

The method is as follows.

The development of low-permeability oil and gas or gas condensate-oil deposits includes wiring horizontally deviated wells in the sub-gas zone. Moreover, their upper perforation interval is located above the SOC at a distance of 0 to 20 m, and their lower perforation interval is in the sub-gas or oil zones. The development of the deposits is carried out with the maintenance of pressure (reservoir) by pumping a working agent (water or gas) through an injection well (figure 2) or in the mode of gas repression (figure 1).

In this case, oil under the influence of reservoir pressure enters a horizontally-inclined well, and the gas entering through the upper perforation interval from the gas cap plays the role of an internal gas lift and contributes to the rise of oil. When developing a deposit under the regime of gas repression, the distance from the upper perforation interval to the GOC changes (a decrease in the level of GOC with the expansion of the gas cap). As a result, the gas-liquid factor changes (increases). Periodically measure its value. In this case, the well is stopped and when the gas-liquid factor exceeds 600-700 m ³ / t, the upper perforation interval is lowered and, including the well, the gas-liquid factor is again measured. The procedure is repeated until the gas-liquid factor reaches a value of 600-700 m ³ / t, at which the well production will be maximum.

When the location of the lower interval of perforation in the region of GNA (Fig. 3) as a result of the above measures and a decrease in the level of GNA, a protrusion of the lower interval of perforation above the GNA occurs. In order to maintain the indicated perforation interval in the GOC region, it is moved to this region, for example, by isolating the lower well perforation interval above the GOC.

The following is information confirming the essence of the method.

So, figure 4 shows the change in flow rates in time for two horizontal wells 29.1 and 29.2, located on the same section of the East block of the Orenburg field. The upper perforation interval of the well 29.1 is located below the GOC at a distance of 14.8 m, and the well 29.2 above the GOC is 2.4 m. From figure 1 it follows that the flow rate of the well 29.2 is higher than the well 29.1, and is more stable during development. This is explained by the fact that in the well 29.2, the gas coming from the low-permeability formation to the upper interval of the perforation of the well plays the role of an internal gas lift and contributes to the rise of oil.

The results of the process of oil production from the East block of the Orenburg field by a system of horizontally deviated wells showed that the volume of oil production from a group of horizontally deviated wells with an upper perforation interval above the GOC (wells 3.1, 3.2, 13.3, 20.1, 29.2) compared with the volume of oil production groups of horizontally-deviated wells with an upper perforation interval below the GOC by 6 or more m (wells 29.1, 12.1, 13.2, 4.1, 4.3) for the same period of operation turned out to be 1.7 times higher (Table 1).

From the dependence shown in Fig. 5, it can be seen that the distance of the upper maximum oil flow rate lies in the range of distances from 0 to 20 m.

If development is underway on a gas repression regime, i.e. depletion, then in the process of exploitation of the reservoir and the selection of oil there is a decrease in the level of GOC. This phenomenon will lead to an increase in gas-liquid factors, and this, in turn, will lead to a decrease in oil production over time. Figure 6 shows the change in oil production and gas-liquid factor (for well 3.1) by years of development. Since 1998-1999 the gas-liquid factor began to grow, and the oil flow rate to fall. Calculations showed that during this period in the area of well 3.1, the level of GOC decreased by 9 m. The distance of the upper interval of perforation above the GOC changed. The change in the gas-liquid factor depending on the distance from the GNA (for well 3.1) is shown in Fig.7. Fig. 8 shows a graph of the dependence of oil production on the gas-liquid factor for gushing horizontally-deviated wells of the East block of the Orenburg field (wells 3.1, 3.2, 13.3, 14.1, 20.1, 20.2, 30.1, 30.2) with upper perforation intervals in the GOC area. The results showed that the optimal value of oil flow rates lies within the gas-liquid factor of 600-700 m ³ / t. In this regard, a periodic measurement of the gas-liquid factor is carried out, the transfer of the upper perforation interval is repeated, etc.

Examples of specific performance.

Example 1

As an example, data on oil production from the East block of the Orenburg field are given.

Average depth

occurrence, m 1800-1950

Average gas saturated thickness 25 m

Average oil saturated thickness 105 m

Porosity, C.E. 0.08-0.12

The average oil saturation, d.ed. 0.75-0.85

Permeability, 10 ^-3 μm ² 0.005-0.015

The reservoir temperature, ° C 37

Reservoir pressure, MPa 21.4

The viscosity of oil in reservoir conditions, MPa · s 0.44

The density of oil under standard conditions, kg / m ³ 836

Saturation pressure of oil with gas, MPa 15.4

The gas content of oil, m ³ / t 150

Table 1 shows the data on oil production from two groups of horizontal wells, one of which had a perforation interval above the GOC, and the other below the GOC. From this table it follows that the average production rate of the first group is 40% higher than the average production rate of the second group, and the productivity of the first group is 44% higher than the productivity of the wells of the second group.

Example 2

As an example, data on oil production from the oil and gas reservoir Yu-1 of the Luchenets field are given.

Average depth, m 1807

Average gas saturated thickness 6.9 m

Average oil saturated thickness, 5.6 m

Porosity 0.16

Average oil saturation, d.ed. 0.63

Permeability, 10 ^-3 μm ² 0.0132

Formation temperature, ° С 98

Reservoir pressure, MPa 31.8

Oil viscosity in reservoir conditions, MPa · s 0.53

Density of oil under standard conditions, kg / m 813

Saturation pressure of oil with gas, MPa 30.0

The gas content of oil, m ³ / t 250

Table 2 shows the data on the production and production of oil, liquid, gas-liquid factor of horizontal wells at their various distances under the GOC. From table 2 it follows that the maximum oil production rate corresponds to the values of the gas-liquid factor in the range of 600-700 m ³ / t.

Example 3

The horizontally-deviated well 19.1, drilled in the East block of the Orenburg field, has an upper perforation interval at a mark 0.5 m above the GOC, and the lower perforation interval is located in the GOC area. This well in 2002 had a flow rate of 46 tons / day, which was 16 tons / day higher than the average production rate of other horizontally-deviated wells, in which the upper perforation interval was located above the GOC in the region from 0 to 20 m, and the lower below GNK.

As a result, the oil production rate of horizontal-deviated wells increases by 40%, and their productivity - by 1.3-1.5 times.

Sources of information

1. Baturin Yu.E., Bogdanov V.L., Degtyanikov E.A., Medvedev N.Ya., Sargsyants B.R., Yuriev A.N. A method for developing a complex oil reservoir with a thin oil rim. RF patent 95116013/03.

2. RF patent No. 2112868, 06/10/1998 (prototype).

Claims (3)

1. The method of developing low-permeability oil and gas or gas condensate-oil deposits, including wiring wells with their perforation and oil selection, characterized in that they carry out horizontal-deviated wells in the subgas zone of the reservoir with the location of their upper perforation interval above the gas-oil contact at a distance from 0 up to 20 m, and their lower interval of perforation - in the sub-gas or oil zone, while the development of the deposits is carried out with the maintenance of pressure by pumping a working agent or in gas repression mode. 2. The method according to claim 1, characterized in that when developing a deposit in the gas repression mode, the gas-liquid factor is periodically measured, above which more than 600-700 m ³ / t, the upper perforation interval of horizontally-deviated wells is lowered until this gas-liquid value is reached factor a. 3. The method according to claim 1 or 2, characterized in that the lower interval of perforation of horizontally-deviated wells is located in the gas-oil contact area.

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