JPS583119B2 - Hot oil extraction method - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to oil field development by oil extraction, and more particularly to a method of oil extraction using heat, that is, a thermal oil extraction method.

The invention is particularly useful in the development of oil fields containing highly viscous mobile crude bitumen, but can also be used in the development of oil beds that have been depleted of energy reserves.

At present, these oil fields cannot be developed efficiently using traditional methods of extracting oil from wells drilled from the surface, and the amount of oil recovered is very low.

Thermal extraction methods by applying steam and heat stimulation to an oil-bearing bed are described, for example, in V.M. Mishakov et al. “Experience gained with the application of thermal extraction methods in highly viscous oil fields” (Publication Neftyano Kojaistovo, No. 10, 1974, 3
1 to 35).

This method of thermal oil extraction consists in the creation of a set of underground works, including shafts, shaft works, drifts and drill rooms, above the oil-bearing bed by drilling.

From the drill room located in the drift, inclined injection wells and oil extraction wells and rising-shaped injection wells and oil extraction wells are formed.

Next, a heat carrier (steam) is supplied to the oil-bearing bed through the injection well, and the steam drives the oil from the injection well to the extraction well.
Next, the oil is transported from the bottom of the well to the drill room by air force.

The disadvantage of this oil extraction method is that water vapor flows into underground structures, reducing the thermal oil extraction efficiency.

According to another known method of oil extraction (US Pat. No. 1,634,235), a well is formed by drilling from an underground structure located above or below an oil-bearing bed.

The pore area at the bottom of the well is treated with steam, and the oil is recovered through a shallow well drilled either below or above the underground structure.

The bore area of the well bottom is heated by water vapor which is fed into the well bottom via pipes arranged in the well, and the oil is withdrawn through the same well.

The disadvantage of this method is the low oil production capacity of the oil-bearing bed.

According to yet another known oil extraction method (US Pat. No. 1,520,737), a shaft is formed through the oil-bearing bed by drilling, and a drill chamber is formed below the shaft.

A radially inclined hole is then drilled upward into the oil-bearing bed.

According to this oil extraction method, the thermal bodies are pumped through their inclined holes into the oil-containing bed, and the oil is withdrawn through the same inclined holes after the oil-bearing bed has been sufficiently heated.

According to this oil extraction method, a heat carrier (e.g. steam) is supplied via a pipe passing through an inclined borehole to remove oxidized oil and tar-like substances from the wellbore area and draw out the well product, and the oil is fed under the action of gravity. It is extracted by

The disadvantage of this oil extraction method, as with the known methods mentioned above, is that the oil cannot be efficiently expelled from the oil-bearing bed and the amount of oil recovered is low.

Yet another known oil extraction method (applicant's Soviet inventor's certificate 33)
No. 5370), a heating medium is periodically injected into the oil-bearing bed and cold water is injected during the cycle.

Alternating between heating medium injection and cold water injection reduces heat loss to the surrounding rock and reduces the amount of heat carrier required.

In the case of oil-bearing beds that are heterogeneous and have different permeability depending on the strata, alternating the supply of heat carrier and cold water in this way will reduce the thermal influence of one oil-bearing bed on other oil-bearing beds. This increases the overall amount of oil recovered from the bed.

A disadvantage of this oil extraction method is that in the case of an oil-bearing bed with foreign material or discontinuity in each zone, the oil extraction efficiency is substantially reduced compared to a monolithic, continuous oil-bearing bed.

The washout properties of water and condensate injected into highly viscous oil-bearing beds are also very poor.

Yet another known periodic oil extraction method (U.S. Pat. No. 34423
According to No. 3), the withdrawal of oil from an oil-bearing bed whose energy production capacity has been partially depleted is interrupted and the injection well is filled with water.

Once the pressure in the oil deposit has returned to its initial value, the injection of water through the injection well is immediately stopped and the withdrawal of oil through the extraction well is resumed.

Oil is withdrawn until the pressure in the oil-containing bed reaches a certain level, after which the oil extraction well is shut down and water is again pumped into the oil-containing bed via the injection well.

Alternate water pumping-oil withdrawal cycles are practiced until the oil resources in the oil-bearing bed are finally depleted.

The disadvantage of this oil extraction method is that the viscosity of the oil in the oil-bearing bed cannot be reduced, resulting in a decrease in oil extraction efficiency when developing oil-bearing beds containing highly viscous oil.

Also, in this oil extraction method, the pressure in the oil deposit is increased to the initial level, but when this oil extraction method is applied to oil fields with cracked or hollow-porous oil deposits, the initial pressure recovery is not always possible,
It won't have that many benefits.

Yet another known oil extraction method (applicant's Soviet inventor's certificate 46)
No. 8529), a set of underground structures and two working tunnels are excavated, an injection well is excavated from the upper working tunnel, and then an oil extraction well is excavated from the lower working tunnel.

A heat carrier is fed into the oil-bearing bed via an injection well in order to heat the oil-bearing bed to a temperature at which the oil is sufficiently fluid.

A heat carrier is then fed into the injection well to uniformly distribute the heat carrier throughout the oil-bearing bed and drive the oil into the production well, and then the oil is drawn from the production well into the working tunnel and from there further underground. Pull it out through the workpiece and onto the ground surface.

The disadvantage of this oil extraction method is that at least two working tunnels have to be installed, which makes the task of operating the working tunnels very large.

Also, the lack of proper correlation between the working conditions of the injection well and the extraction well results in high heat losses due to the flow of heat carriers through underground structures and cracks in the oil-bearing bed.

As a result, the amount of oil recovered from the final oil deposit is reduced.

The basic object of the present invention is to provide a thermal oil extraction process that increases the efficiency of heating the oil-bearing bed and the efficiency of oil recovery by controlling the process of heating the oil deposit and withdrawing the oil therefrom.

As described in claim 1, the thermal oil extraction method according to the present invention includes forming a set of underground structures and at least one working tunnel by excavation, and forming an injection well and an oil extraction well from the working tunnel. forming the oil-bearing bed by drilling, supplying a heat carrier to the oil-bearing bed to heat the oil-bearing bed to a temperature sufficient for the oil in the oil-bearing bed to obtain the required fluidity, and injecting the heat carrier into the injection well. to uniformly distribute the heat carrier throughout the oil-bearing bed and expel the oil through the oil extraction well toward the working tunnel, from which the oil is delivered to the ground surface via the underground structure. t1 = cγτ・L2/d (where, C is the heat capacity J/deg. of the oil-bearing bed, l is the temperature conductivity m2/s of the oil-bearing bed, and γ is the specific gravity N of the oil-bearing bed. /m
3, L is the scale of the figure, τ is the time without dimension (o<
The heat carrier is fed into the injection well in a time interval t1 calculated from τ<1), and the time interval t1 of heat carrier feeding into the injection well is the time interval t3 of oil withdrawal from the oil extraction well 9. (where A is the distance m between the injection well and the oil extraction well, △
P is the pressure drop N/m2 that occurs in the oil-bearing bed between the injection well and the oil extraction well, μ is the oil viscosity N・S/m2, m is the porosity of the oil-bearing bed, and K is the permeability of the oil-bearing bed D, ρ1 -ρ2 is the cycle-to-cycle change in the heat transfer medium saturation of the oil-bearing bed, B is a dimensionless parameter (o<B<∞)), and the oil is withdrawn from the well in the time interval 13 represented by the multiplicity factor n. =t1/t3 is equal to or greater than 60 (n=t1/t2
>60).

Heating the oil-bearing bed and the oil that saturates it increases oil recovery by, among other things, reducing the viscosity of the oil and redirecting the filtration flow in the oil-bearing bed.

The heating efficiency of the oil-bearing bed is improved by increasing the periodicity of the introduction of heat carriers into the oil-bearing bed and the withdrawal of oil from the oil-bearing bed via the oil-bearing well.

Heating efficiency is also improved by reducing heat loss through the oil well.

Reducing the water content of the recovered oil is achieved by controlling the operation of the extraction and injection wells, taking into account the zone-to-zone heterogeneity and discontinuities of the oil bed structure.

Recovery of high viscosity oil from the well is increased by injecting steam into the well, forcing the well product into the working tunnel, and flowing the steam to the bottom of the well until the initial parameters of the steam are restored.

It is very advantageous to divide the injection wells of an oil-bearing bed with zone-wise heterogeneity into groups and to inject the heat carrier into alternating groups, thereby changing the direction of the filtrate flow in the oil-bearing bed and directing the oil storage points. The sweep amount and oil recovery amount can be increased.

When drilling wells in oil-bearing beds that exhibit band-wise heterogeneity and lithological heterogeneity are divided into groups, it is desirable to draw oil from each group alternately, thereby creating a directional flow in the oil-bearing bed. Certain oil flows can be created to flush more oil out of the stagnant zone and increase oil recovery from the containing bed.

Cracked oil-impregnated bed, crack - Porous oil-impregnated bed and crack -
In the case of oil-bearing beds of porous-porous heterogeneous oil-bearing beds,
It is in practice advantageous to withdraw oil from an oil well at such a rate that the time interval of the supply of heat exchanger to the injection well is divided by the average time interval of oil withdrawal from simultaneously operating oil wells.

This makes it possible to increase the amount of oil recovered by taking into consideration the structure of the oil-bearing bed when extracting oil from the oil-bearing bed and changing the direction of the overflow in the oil-bearing bed, and to prevent water vapor from entering the oil well. .

All these factors improve thermal extraction efficiency.

The heat carrier is supplied to the oil-bearing bed through a pipe which is arranged in the well and acts as the above-mentioned injection well and has two packers at the bottom of the well and approximately in the middle of the well, and which is arranged at the top of the well. Preferably, the oil is drawn off through holes formed in the string of the casing, which act as oil extraction wells, thereby heating the oil-bearing bed;
The oil expulsion adaptability of the oil-bearing bed is improved and the oil recovery efficiency is increased.

To expel oil from a crack-porous or crack-cavity-porous heterogeneous oil-bearing bed, water vapor is used as a heating medium, and after the water vapor traveling along the oil-bearing bed reaches the oil production well. , steam the oil through the production well until the point where the parameters of the steam (dryness, temperature and specific volume) are equalized in the production well and the injection well, i.e. until the initial parameters of the steam in the oil-bearing bed are restored. It is very advantageous to pull it out together.

In this case, water vapor is absorbed into relatively large cavities, pores, and cracks in the oil-bearing bed into which oil enters from the more solid rock mass by condensation in the porous media of the oil-bearing bed. It acts to first expel oil from the water.

Once the initial parameters of steam are restored in the oil-bearing bed after expelling the oil, the temperature of the oil-bearing bed is kept at a preset value, ensuring a high oil production capacity.

Simultaneously with the delivery of heat carriers to the injection wells and the withdrawal of oil from the extraction wells, continuous feeding into a group of injection wells with a solution of a substance that reduces the surface tension of the oil-water and oil-rock interfaces can be very Advantageously, the flushing power of the expulsion medium is improved and the oil recovery is increased.

Drawing oil from the well by pressurizing water vapor at the bottom of the well and forcing the oil from there into a working tunnel, then flowing steam through the well until the steam restores its initial parameters and becomes condensed. It is very advantageous to do so.

Flowing water vapor in this manner increases the dryness and specific volume of the water vapor.

The flow of steam significantly reduces the specific volume of the working medium during condensation of the steam, thereby ensuring that a significant amount of oil enters the well bottom during each cycle.

This increases the output of the well and the oil recovery of the oil-bearing bed.

Next, a practical example of the present invention will be explained in detail with reference to the drawings.

The oil extraction method according to the invention consists of two drill holes, namely a lift drill hole 1 (see Figures 1 and 2), a degassing bore hole 2, and a storage area 3 (see Figure 2) at an electric locomotive stop. A combination of underground structures consisting of structures near the well for receiving the receiving well, pumping plant, containment, etc. (not shown), drift 4 (see Figures 1 and 2) and inclined holes 5, 6. This is done by digging up the area.

The drift 4 is located above the roof of the oil-bearing floor 7 at a height of 1 with respect to the horizontal plane.
Form to form an angle of ~3°.

All oil drilling operations in oil fields are carried out in the same multiple classifications.

These divisions may be regular polygons (hexagons) as shown in FIG. 1, squares as shown in FIG. 3, or any other shape.

The inclined holes 5, 6 are drilled from the drift (see FIGS. 1 and 2) into the oil-bearing bed 7 (see FIG. 2) to form at least one working tunnel 8 (see FIGS. 1 and 2).

The working tunnel 8 may be circular (see Figure 1), square, rectangular, oval, linear (see Figure 3), curved, or any other shape suitable for the classification of the oil field.

Next, from the working tunnel 8 (see Figures 1 and 2) to the oil extraction well 9.
and an injection well 10 are dug.

If the working tunnel 8 is circular (see Figure 1), the well 9
, 10 are drilled uniformly and parallel to each other over the cross-sectional area.

The heat carrier (for example, steam) is supplied from the boiler device 11 (see FIG. 2) to a pipeline on the ground surface, a steam supply well 13, and an underground pipe (not shown) installed in the drift 4.
to the top of the injection well 10.

The oil-bearing bed 7 is heated by a system of injection wells 10 to a temperature that brings the oil to the required fluidity.

This temperature can vary within a fairly wide range from about 80 to 250° depending on the nature of the oil.

Because the pattern of injection wells 10 extends over a considerable length through the oil-bearing bed 7, the oil-bearing bed 7 is heated uniformly and rapidly over its entire volume.

This means that the injection well 1 passes through the oil-bearing bed 7 over several tens to hundreds of meters in a horizontal and upwardly inclined direction.
0 has been developed and various heterogeneous regions of the oil-bearing bed 7,
This is achieved by interconnecting channels, cavities, etc., thereby increasing the possibility of developing the oil-containing bed 7.

Due to the presence of mostly vertical cracks, highly permeable regions and cavities in the oil-bearing bed 7, the oil-bearing bed 7 heats up rapidly.

As the temperature of the oil-bearing bed 7 increases, the viscosity of the oil decreases and its fluidity increases.

If the heating of the oil-bearing bed 7 requires a long time with only the supply of heat carrier through the injection well 10, the oil-bearing bed 7 can be heated by both the injection well 10 and the extraction well 9 using one of the methods commonly used for thermal oil extraction. The above-mentioned process can also be accelerated by heating the bed 7.

The distance between the oil extraction well 9 and the injection well 10 is selected based on specific geological conditions, and may be the same or different.

Oil produced from the well 9 and fed into the working tunnel 8 is directed into a groove formed in the drift 4.

The oil supplied with the water into the gills is fed by gravity due to the 1 to 3 inclination of the underground structure with respect to the horizontal plane and flows into a facility, not shown, where it is separated from the water.

Oil and water can also be pumped from the working tunnel 8 via the inclined holes 5, 6, the drifts 4 and the pipes to the installation for water separation described above.

The oil is pumped from the equipment to an underground collection point (not shown), and after primary separation and heating, it is passed through pipes,
It is fed through a special well 14 or shaft to a surface tank at the oil storage site.

There is no problem even if the drift 4 is arranged below the oil-bearing bed 7.
On the contrary, the conditions for supplying oil from the working tunnel 8 to the drift 4 are thereby improved.

In this case the oil is conveyed by gravity.

The working tunnel 8 may be a pair of underground works (FIG. 3) or a single circular work (FIG. 1), and may be linear or curved.

The length of the working tunnel 8 is selected with particular emphasis on accurate degassing.

The ventilation system shall be designed to ensure adequate standards of worker safety and work protection.

After heating, the oil-bearing bed 7 (FIG. 2) is supplied with a heat carrier by means of an injection well 10 at time intervals calculated according to the formula t1=cγτL2/l.

However, in the above formula, I = temperature conductivity of oil-bearing bed 7 m2/s, γ = specific gravity of oil-bearing bed 7 N/m3, L = scale of drawing m, τ = thickness of oil-bearing bed 7, bottom of injection well 10 is a dimensionless time (0<τ<1) that depends on the temperature of and the number and arrangement of injection wells 10.

The value of time τ is determined from a formula including all of the above parameters.

If the injection well 10 is located in the upper and bottom portions of the oil-bearing bed 7, the formula for determining the time τ is as follows.

X=y1F1(h,τ)+y2F2(h,τ)θ1,θ
2 = Temperature at the bottom of the injection well 10 in the upper part and the bottom part of the oil-bearing bed 7 θ0 = Initial temperature of the oil-bearing bed 7 in °C, θ = Temperature scale °C, X = Average temperature of the oil-bearing bed 7 ν.

= Jacobitator function, a=h/L, h=thickness of the oil-impregnated bed 7.

Oil is withdrawn from the oil extraction well 9 at a time interval t3 such that when the time interval 11 for supplying the heat carrier to the injection well 10 is divided by the time interval t3 for withdrawing oil from the oil extraction well, the multiplicity coefficient n is . be done.

Here ■ represents an operation that takes all parts of the relationship between two values.

Here, A = distance m between injection well 10 and oil extraction well 9, △P = pressure drop N/m2 occurring in oil-bearing bed 7 between injection well 10 and oil extraction well 9, μ = viscosity of oil, N, s /m2 K = permeability of the oil-bearing bed 7, D m = porosity of the oil-bearing bed 7 ρ1 - ρ2 = cycle-to-cycle change in heat carrier saturation of the oil-bearing bed 7, B = nature of the phase permeability of oil and heat carrier is a dimensionless parameter that depends on .

Parameter B is determined by the following equation.

K1, K2 = permeability D of the oil-bearing bed 7 with respect to oil and heat carrier, μ1, μ2 = viscosity of oil and heat carrier, N. s/m2.

Further, -f1 (ξ) and f2 (ξ) = phase permeability regarding oil and heat carrier, ξ = degree of impregnation of heat carrier in oil-impregnated bed 7, ξ0: degree of saturation of oil-impregnated bed 7 in the driving range.

The selection of the ratio of the time interval division between the pumping cycle of the heat carrier (steam) and the oil withdrawal cycle is determined by the fact that the geographical symmetry and regularity of the division of the oil field are such that in this case the pumping of the heat carrier This is because it is compensated for by time symmetry in the sense of the degree of overlap of the respective time intervals with the extraction of oil.

Under the conditions of the above-mentioned division of the time intervals of the pumping of the heat carrier and the withdrawal of the oil, the influence exerted on the filtration process becomes of a periodic or approximately periodic nature.

Such influence on the filtration process is advantageous in increasing oil recovery.

The minimum overlap factor 60 between the time interval 1 for supplying the heat carrier to the injection well 10 and the time interval t3 for withdrawing oil from the extraction well 9 is obtained by thermo-hydraulic calculation of the thermal equilibrium of the oil-bearing bed 7. It is something that was given.

In this case, the heat losses through the upper and bottom parts of the oil-bearing bed 7 and the heat losses that occur along with the recovery of oil during each oil extraction cycle from the oil-bearing bed 7 through the oil-bearing well 9 are related to the heating of the oil-bearing bed 7. It is taken into consideration.

All injection wells 10 of the working section 16, which are separated from each other by arbitrary boundaries 17, are supplied with heat carrier within a certain time 11 (see FIG. 5).

Thereafter, the injection well 10 (see Figures 1 and 2) is closed,
It is in an open and closed state for a time interval of 12 (see FIG. 5).

In a special case, the time interval t1 (FIG. 5) during which the heat carrier is supplied from the injection well 10& is equal to the above-mentioned time interval t2 (rest time).

The entire working cycle T (5th
(Fig. 5) is equal to the sum of the time intervals t1 and t2 (Fig. 5).

Oil is withdrawn through the entire extraction well 9 (FIGS. 1 and 2) both during the supply of heat carrier to the injection well 10 and during its downtime.

Oil withdrawal time interval t3 from oil extraction well 9 (Figs. 1 and 2)
(FIG. 5) alternates with its pause time t4 (FIG. 5).

In a special case, the time interval t3 is equal to the time interval t4.

The oil recovery cycle T' from the oil extraction well 9 is performed at the time interval t3.
Equal to the sum of t4.

The above-described process is illustrated in FIG. 5, which represents the operating time diagram of the injection well 10 and the oil extraction well 9.

FIG. 5a shows the action of the injection well 10 (FIGS. 1 and 2), the shaded area indicating the supply time of the heat carrier through the injection well 10. In FIG.

FIG. 5b shows the operation of the oil extraction well 9 (FIGS. 1 and 2), and the portion represented by the vertical line represents the oil recovery time from the oil extraction well 9.

During the supply of heat carrier to the oil-bearing bed (FIG. 2) and the recovery of oil from the oil-bearing well 9, oil is driven out of the oil-bearing bed 7 hydraulically.

When heat treatment is injected into the oil-bearing bed 7 and oil recovery from the oil extraction well 9 is completed, the pressure and temperature of the oil-bearing bed 7 begin to rise.

Because of this phenomenon, the oil will be removed from the injection well 10 during the next recovery cycle.
He is expelled from the oil extraction well 9.

During the outage of the injection well 10 and the oil extraction well 9, capillary suction occurs in the low-permeability sections of the heterogeneous oil-bearing bed 7 and in the cracked rock blocks, and a concomitant pressure redistribution takes place.

When oil is being withdrawn from the well 9 in this manner, the filter flow changes its direction, thus increasing oil recovery.

In a variant implementation of the process according to the invention, all the injection wells 1 of the different oil-bearing beds 7, which are heterogeneous as zones, are divided into groups and the groups are filled alternately with heat carrier according to the technical conditions.

FIG. 6 shows an oil-bearing bed 7 (
4) is shown.

The injection wells 10 are divided into two groups N1 and N2 every other injection well.

FIGS. 6a and 6b show the effects of those two groups N1 and N2 within the same division.

FIG. 7 shows an operating time diagram of the injection well 9 and the oil extraction well 10.

where t1 = first group N1 of injection wells 10 (see Figure 6)
(indicated by diagonal lines), t2 = time during which heat carriers are supplied to the oil-containing bed 7 via the second group N2 of injection wells 10 (indicated by diagonal lines in the opposite direction) It is.

The rest time of the first group N1 of the injection wells 10 is t' (see FIG. 7), and the rest time of the second group N2 (see FIG. 6) is t'1.

This means that while heat carriers are supplied via the injection wells 10 of the first group N1, the injection wells 10 of the second group N2 are at rest, and vice versa, while heat carriers are supplied via the second group N2. 1st
Group N1 means resting.

That is, while the heat carrier is injected into the second group N2, the first group N1
is on hiatus.

The total operating cycle T of one group of injection wells 10 is T=t
1+t2.

t3 = oil recovery time from the oil extraction well 9 (see the portion indicated by the vertical line in FIG. 6), t4 = downtime of the oil extraction well 9.

The downtime of the oil production well 9 depends on the physical properties of the containing bed 7 and the oil saturating it.

In some cases, the oil recovery time from the well 9 is equal to its downtime.

The total operating cycle T' of the oil extraction well 9 is T'=t3+t4 (see FIG. 7b).

The heat carrier is periodically transferred to the oil-bearing bed 7 via different groups of injection wells 7.
Pumping into the wells 9 and withdrawing oil periodically through all oil wells 9 changes the direction of the filter flow in the oil-bearing bed 7, flushing oil out of stagnant zones and bed sections of low permeability. The productivity of the oil-impregnated bed 7 is improved.

In another variant embodiment of the invention, the oil wells 9 of the zoned and lithologically heterogeneous oil-bearing beds 9 are also divided into groups, and the oil is withdrawn from each group alternately according to the technical conditions.

In FIG. 8, time t1 is the time for injecting the heat carrier into the first group of injection wells 10, and time t'2 is the time for injecting the heat carrier into the second group of injection wells 10.
The time 13 and t4 for injecting the heat carrier into the oil wells 9 and t4 respectively represent the time for recovering oil from the oil extraction wells 9 of the first group and the second group.

t3=time to draw oil from the oil extraction wells 9 of the first group (indicated by diagonal lines), 14=time to draw oil from the oil extraction wells 9 of the second group (indicated by horizontal lines).

The downtime of the first group of oil wells 9 (see Figures 1 and 2) is t.
4. The pause time of the second group is t3, which means that while oil is being drawn from the first group of the oil extraction well 9, the second group is paused, and oil is being drawn from the second group. Time means that the first group is at rest.

When steam is periodically injected into the first group N1 and second group N2 of the injection well 10 and oil is periodically removed, the expulsion of oil from the oil-bearing bed 7 is caused by zonal and lithological heterogeneity. adaptation, resulting in increased oil recovery.

According to a further variant of the process according to the invention, oil is extracted from a well 9 (FIGS. 1 and 2) of a heterogeneous cracked, cracked-porous and cracked-voided-porous oil-bearing bed 1. , the injection time of the heat carrier into the injection well 10 is drawn in a temporal relationship such that it is divisible by the average time of oil recovery from the oil extraction wells 9 in simultaneous operation.

FIG. 9 shows two groups of injection wells 10 and a second group of oil extraction wells 9.
An operating time diagram is shown, in which t3 and t4 are the average oil recovery times from oil extraction wells 9 of different groups.

The withdrawal of oil from each group of wells 9 takes place within different time intervals, which essentially depends on the ingress of water vapor or water into the wells 9 .

As a result, a flow is created in the oil-impregnated bed 7, and the oil in the oil-impregnated bed (see FIG. 2) is expelled to the maximum extent, so that the amount of oil recovered increases and the water content in the recovered oil decreases.

Since the oil is recovered from the oil extraction well 9 at different time intervals, water vapor can be prevented from penetrating into the underground structure through the oil extraction well 9, and the heat carrier is saved.

FIG. 10 shows that the time intervals t1, t2 required for injecting the heat carrier into the injection wells 10 of different groups are different, and the average time intervals t3, t of oil recovery from the oil extraction wells 9 of different groups are different.
The operating time diagrams for 4 different cases are shown.

Well 1 included in each group of injection well 10 and oil extraction well 9
The numbers 0 and 9 may be the same or different.

Heat carrier injection cycle time t into different groups of injection wells 10
1, t2 depends on the geological and physical characteristics of the oil-bearing bed 7 and is between 10 and 30 days or more than 30 days.

The injection pressure may be set at a level of 20 kgf/cm2.

Oil withdrawal cycle time t3 from different groups of oil wells 9
, t4 may be 1 to several hours.

According to a preferred embodiment of carrying out the method of the invention, the heat carrier is injected into the oil-bearing bed 7 via a pipe 19 inserted into a well 18 (see FIG. 11, serving as injection well 10).

The pipe 19 is located at the lip of the well and approximately in the center. With two packers, oil is recovered via through holes (acting as oil extraction wells 9) formed in the string of casing 22 near the top of the well 18.

The injection time of the heat carrier into the pipe 18 is therefore a value that can be divided by the recovery time of the oil through the through holes formed in the string of the casing 22 at the top of the well 18.

In the process according to the invention, the injection of the heat carrier into the oil-bearing bed 1 and the recovery of oil from the oil-bearing layer 7 through the same well are carried out simultaneously or separately according to the technical procedure adopted.

In order to prevent the heat carrier supplied to the oil-bearing layer 1 from flowing into the working tunnel 8, a packer 20.21 is arranged at the bottom and approximately in the center of the well 18.

The well 18 is excavated from the working tunnel 18 (see FIGS. 1 and 2).

This embodiment may be configured according to any of the embodiments described above.

In this case as well, the operating time diagrams of the injection well and oil extraction well shown in FIG. 5 and FIGS. 1 to 9 hold true.

In this case, the "injection well" refers to the first packer 20 from the bottom.
The part of well 18 (see Figure 11) that extends to
Furthermore, the term "oil extraction well" refers to the portion of the well 18 from the top to the second tanker 21.

As an example, consider the case in which the injection of the heat carrier and the withdrawal of the oil take place with the aid of mutually parallel horizontal wells divided into every other group.

Figure 11a shows the effects of the first and second groups of oil extraction wells, Figure 11b shows the effects of the first group of injection wells and the first group of oil extraction wells, and Figure C shows the effects of the second group of injection wells. Figure d shows the effects of the second group of injection wells and the first group of oil extraction wells.

In FIG. 11, the arrows indicate the flow of the expelling medium and the expelled oil, and as can be seen from FIG. 11, a filtration flow occurs along with the changing oil flow direction.

Because a heat carrier is injected into the pipe 19, the temperature in the bottom region of the well 18 is kept at a preset level and thus a high degree of fluidity is maintained.

All these factors accelerate the heating process of the oil-bearing bed 7 and improve the oil release of the oil-bearing bed 7 and its degree of development.

If the cohesion of the rocks in the oil-bearing bed 7 is weak, the annular distance between the walls of the well 18 and the pipes 19 in its interior between the packers 20.21 can be reduced with a fast-drying composition impermeable to heat carriers, e.g. cement mortar. Fill it with water.

In this case it is not necessary to arrange the string of case sigs 22 over the entire length in the well 18 and also to arrange the two packers 20, 21.

In particular, it is sufficient to provide only one packer in the center of the well 18 and to run the string of casings 20 down to the place where the packer is attached.

Effective sealing of the annular space prevents water vapor from entering the working tunnel 8, further improving the thermal extraction efficiency.

According to yet another embodiment of the invention applied to heterogeneous crack-porous and crack-void-porous oil-containing beds 7, the oil reaches the extraction well 9 from the injection well 10 by a heat mixer. It will be pulled out later.

The oil begins to be drawn through the extraction well 9 with the heat carrier until the point where the parameters of the steam (dryness, specific volume and temperature) are equalized in the extraction well 9 and the feed well 10.

The thermal mixer injected into the oil-bearing bed 7 (FIG. 2) via the injection well 10 causes a certain flow in the oil-bearing bed 7.

The properties of the pumped steam (dryness, deepness and specific volume) are selected based on the physical properties of the oil and the oil-bearing bed 1.

The characteristics of the water vapor flowing into the oil extraction well 9 are different from the characteristics of the water vapor injected into the injection well 10.

This occurs due to heat loss through the upper and bottom parts of the oil-bearing bed 7 and the oil being extracted.

If the oil well 9 is closed at the point of inflow of the first part of the steam in the section of the oil-bearing bed 7 adjacent to the oil-bearing well 9, the expulsion process of oil in the oil-bearing bed 7 is accompanied by extensive heat exchange; The properties of that water vapor will be lower than those of the injected water vapor.

When the oil is withdrawn after the water vapor has entered the oil extraction well 9, the water vapor parameters (dryness, temperature and specific volume) rise to values very close to those present at the top of the injection well 10.

In the next step, during the condensation of the water vapor in the oil-bearing bed 7,
Heat and mass exchange occurs, increasing in intensity as the water vapor parameters approach their initial values. The oil-bearing bed 7 is heated more forcefully and the oil flows by capillary suction from the less permeable sections towards the larger pores and cracks. When water vapor condenses in large pores and cracks,
The additional local pressure difference ensures better conditions for the inflow of oil from the smaller pores and low permeability sections of the oil-bearing bed 7.

This oil flows into the working tunnel 8 during the next oil withdrawal cycle from the well 9.

Equalization of the steam parameters in the extraction well 9 and the injection well 10 improves the efficiency of heating and oil extraction from the oil-bearing bed 7.

According to a further embodiment of the method according to the invention, injection well 10
is divided into groups, one of which is constantly supplied with a solution that reduces the surface tension of the oil-water and oil-rock interfaces.

The uniformity of the flow of this solution (for example alkaline NaOH) is controlled by the operation of the oil extraction well 9.

When the oil-containing bed 7 is filled with an alkaline aqueous solution, an oil-in-water emulsion is generated, and the rock changes from hydrophobic to hydrophilic.
Transition to wettability.

The emulsification of the oil in the hydrophilic oil-containing bed 7 caused by the injection of the alkaline aqueous solution increases the fluidity of the oil and decreases the fluidity of the water.

Changes in the wettability of rocks and significant reductions in the surface tension of oil-water systems are achieved only by certain well-defined relationships of salt and alkali in solution.

Surface-active substances are produced by the interaction of the oil's organic acids and alkalis.

The alkaline aqueous solution is preferably formed using water that does not contain polyvalent ions (eg, calcium).

The presence of sodium chloride in water reduces surface tension.

In order to emulsify oil, the concentration of alkaline aqueous solution is 0.0.
01-0.1% by weight, in order to change the wettability properties of the rock in the oil-bearing bed 7, the concentration should be 05-3.0% by weight; The amount is generally 0.1 to 0.3 times the pore volume.

The surface tension of the oil-water boundary ranges from 25 to 30 dynes/cm to 0.
．． A reduction from 0.01 to 0.001 dynes/cm produces a finely divided emulsion of oil-in-water type that can migrate through the solid, low-permeability rock of the oil-bearing bed 7.

This phenomenon increases the injectability of the injection well 10.

Since the aqueous alkaline solution is injected into the already heated extraction bed 7, the flushability of the expulsion medium is improved and the efficiency of the expulsion process is increased.

Increasing the efficiency of the thermal oil extraction process and the productivity of the oil-bearing bed will
The generated surfactant adheres to the rock-oil boundary and facilitates the separation of oil droplets from the rock surface, and also adheres to the oil-water boundary to form the above-mentioned finely divided system. promoted.

The hydrophilization of the rock by the action of the aqueous alkaline solution, thereby increasing its wettability and emulsifying the oil in the expulsion region, results in a greater concentration of oil from the oil-bearing bed 7 than with water and steam alone. It contributes to strong expulsion and improves the most important factor in oil field development, that is, the oil extractability of the oil-bearing bed 7.

The invention includes the following operations.

1. The oil-bearing bed is heated by any known method to a temperature at which the oil obtains the required fluidity.

2. Divide the injection wells into multiple groups.

A heat carrier (eg, water vapor) is injected into at least one group of injection wells.

The other group of injection wells is filled with alkaline solution.

The number of injection wells for injecting the heating medium into the oil-bearing bed shall be sufficient to maintain the above-mentioned temperature in the oil-bearing bed.

The number of injection wells for injecting the aqueous alkaline solution into the oil-bearing bed shall be sufficient to act on the oil-bearing bed horizontally and vertically.

That is, the well pattern is uniform throughout the volume of the oil-bearing bed.

In the area of the wells used for applying the alkaline aqueous solution to the oil-bearing bed, respective wells are provided for the injection of steam.

3. The oil-bearing bed is always filled with aqueous alkaline solution in wells selected for that purpose.

The amount of the alkaline aqueous solution is 0.1 to 0.0% of the pore volume of the oil-containing bed.
Triple it.

4. Another group of injection wells is filled with water vapor according to any of the embodiments described above.

5. Oil is withdrawn from a production well in accordance with any of the embodiments described above such that the time for injection of heat transfer medium into the injection well can be divided by the time for oil recovery from the production well.

Controlling the injection of heat transfer medium through the injection well into the oil-bearing bed and the withdrawal of oil through the oil-bearing well makes it possible to change the direction of the aqueous alkaline flow to obtain the maximum amount of oil from the oil-bearing bed. Become.

Consider the action of each well 9, 10 in the floor section in which the injection well 10 and the extraction well 9 are excavated from the working tunnel 8.

In FIG. 12, the black dots are the oil extraction wells 9, the circled points are the steam injection wells 10, and the circled crosses are the alkaline aqueous solution injection wells.

The injection well was divided into two groups, and the first group was filled with alkaline aqueous solution.
The second groups are each filled with water vapor.

The injection well 23 (see FIG. 12) filled with aqueous alkaline solution is operated continuously.

The injection wells 24, 26, 28, and 30 filled with water vapor are operated intermittently in the following order.

First Embodiment During the first half cycle, wells 24 and 26 (see FIG. 13) are activated and wells 28 and 30 are inactive.

Meanwhile, the alkaline aqueous solution zone is well 2B, 29, 30.
move towards.

Second half cycle.

Wells 24 and 26 (see Figure 14) will be shut down, and well 2B will be closed.
, 30 are activated.

The zone of aqueous alkaline solution begins to move toward wells 24, 25, and 26.

The zones marked with diagonal lines in different directions in FIGS. 13 and 14 are expulsion adaptation zones for aqueous alkaline solutions in different half-cycles, and the black dots indicate areas with heat carriers.

Second embodiment First half cycle.

Wells 24 and 28 (see Figure 15) are in operation, wells 26 and 3
0 is at rest.

The oil expulsion zone using alkaline aqueous solution is well 25, 26,
27 and wells 29, 30, and 31.

Second half cycle.

Wells 26 and 30 are in operation, and wells 24 and 28 are inactive.

The oil expulsion zone is wells 31, 24, 25 and well 27,
Move towards 28 and 29.

Similar to Figures 13 and 14, the zones represented by diagonal lines in different directions in Figures 15 and 16 represent zones compatible with oil expulsion due to the action of the aqueous alkaline solution injected during different half-cycles, marked with black dots. The zone represents the floor section over which the heat carrier sweeps.

The type of steam injection method is selected according to the oilfield equipment system and the geological structure of the oil-bearing bed.

The oil extraction wells 25, 27, 29, and 31 (see Figures 13 to 16) also operate periodically in the above order.

It serves as an auxiliary element that controls the entire process.

According to a further embodiment of the method of the invention, the oil is removed by injecting steam into the bottom of the oil well through the annular space between the string of casing and the pipe for expelling the oil towards the working tunnel. It is drawn from inclined and vertical wells.

Steam is then allowed to flow through the oil production well until it recovers its initial parameters and condenses by stopping the steam supply.

This method is actually implemented by performing the following operations.

(a) Steam is injected into the bottom of the oil well through the wall of the oil well or the annular space between the string of casing and the string of pipes in order to drive the oil from there into the working tunnel.

(b) Flowing steam into the oil production well until the steam is at or near its initial parameters, i.e., the parameters at the time of injection.

This process increases the dryness and specific volume of the water vapor.

(c) Close the oil extraction well and set conditions for condensation of water vapor inside the well.

The steam flow process sharply reduces the specific volume of the condensing steam, thereby allowing oil from the oil-bearing bed to flow into the well.

Oil is injected from the well into the working tunnel during the next steam injection cycle.

The additional pressure drop improves the extractability of the oil-bearing bed, not only in inclined and vertical wells, but also in horizontal and stand-up wells.

Wells that are regularly filled with steam are freed from the products (oil, water and sand) that enter the well from the oil-bearing bed, the walls of the well are cleaned by flowing steam, and then the water vapor condenses. New oil is more likely to flow into the well from the oil-bearing bed.

The method of the invention can also be used for the production of fluid (ie free-flowing) bitumen.

[Brief explanation of drawings]

Figure 1 is a plan view of one section of an underground structure in which injection wells and extraction wells are arranged in the horizontal and vertical directions in the radial direction. Figure 2 is a sectional view taken along the line Figure 3 is
A plan view of one section of an underground structure in which an injection well and an oil extraction well in the rising direction are arranged parallel to each other. Figure 4 is a sectional view taken along the line ■-■ in Figure 3. Figure 5 is a diagram showing the injection well and Fig. 6 is a normal working time diagram of an oil extraction well, where a shows the characteristics of the injection well, and b shows the characteristics of the oil extraction well.
It is an explanatory diagram showing one section of the oil-bearing bed along with a system of injection wells and oil extraction wells drilled in parallel, with a showing the action of the first group of injection wells and b showing the action of the second group of injection wells. Fig. 1 is a normal operating time diagram of injection wells and oil extraction wells, showing injection wells divided into two groups;
Figure 8 is a normal working time diagram for injection wells and oil extraction wells, where the injection wells and oil extraction wells are divided into two groups, respectively, and Figure 9 is a diagram showing the case where the average oil withdrawal times from oil extraction wells in different groups are different. The normal operating time diagram of injection wells and oil extraction wells in FIG. A normal operating time diagram of an injection well and an oil extraction well, FIG. 11 is an explanatory diagram of the operation of a group of wells when a heat carrier is injected into the same well and oil is withdrawn from it, and FIG. An arrangement diagram of an injection well and an oil extraction well, FIG. 13 is an explanatory diagram of the operation of an injection well and an oil extraction well, FIG. 14 is an explanatory diagram of an operation of an injection well and an oil extraction well in another embodiment, and FIG. FIG. 16 is an explanatory diagram of the operation of an injection well and an oil extraction well in yet another embodiment,
It is an explanatory diagram of the operation of an injection well and an oil extraction well in another embodiment. 7...Oil-bearing bed, 8...Working tunnel, 9...Oil extraction well,
10...Injection well, 18...Well, 19...Pipe, 2
0, 21...Patzker, 22...Casing string.

Claims (1)

[Claims] Eleven sets of underground structures and at least one working tunnel 8 are formed by drilling, and from the working tunnel 8 an injection well 10 and an oil extraction well are formed by drilling, and an oil-bearing bed 7 is formed by drilling.
heating the oil-bearing bed 1 to a temperature sufficient for the oil in the oil-bearing bed 7 to obtain the required fluidity by supplying a heat carrier to the oil-bearing bed 7, and feeding the heat-absorbing body into the injection well 10 to cool the heat-bearing body. uniformly distributed throughout the oil-bearing bed 1 and expelling the oil through the extraction well 9 towards the working tunnel 8, from which the oil is fed to the ground surface via the underground structure. In the oil extraction method, the formula t1 = cγτ・I2/l (where C is the heat capacity of the oil-impregnated bed J/deg., l is the temperature conductivity of the oil-impregnated bed m2/s, and γ is the specific gravity of the oil-impregnated bed N/m3
, L is the scale of the figure, τ is the dimensionless time (o<τ
<1)) The heat carrier is fed into the injection well 10 at a time interval t1 calculated from The formula is such that it is divided by the interval t3 (where A is the distance m between the injection well and the oil extraction well, ΔP is the pressure drop N/m2 that occurs in the oil-bearing bed between the injection well and the oil extraction well, μ is the oil viscosity N・S
/m2, m is the porosity of the oil-containing bed, K is the permeability D of the oil-containing bed,
ρ1-ρ2 is the cycle-by-cycle change in thermal carrier saturation of the oil-bearing bed, B is a dimensionless parameter (0<B<∞
))) The well 9 extracts oil in the time interval t3 represented by 9
, such that the multiplicity factor n=t1/t3 is equal to or greater than 60 (n=t1/t
3>60). 2. The thermal oil extraction method according to claim 1, wherein the two injection wells 10 are divided into a plurality of groups, and the heat carrier is alternately supplied to each group. 3. The thermal oil extraction method according to claim 1 or 2, characterized in that the three oil extraction wells 9 are divided into a plurality of groups, and oil is drawn out from each group alternately. 4. Oil is drawn out from the oil extraction well 9 so that the time interval of supplying the heat medium to the injection well 10 becomes a value that can be divided by the average time interval of oil extraction from the oil extraction well 9 in simultaneous operation. The oil extraction method according to any one of items 1 to 3. 5 disposed in well 18 and acts as injection well 10;
Packer 20 is placed at the bottom of the well and especially in the center of the well 18.
, 21, a heat carrier is injected into the oil-bearing bed 1, and the oil is drawn out through a through-hole arranged at the top of the well 18 offshore of the string of the casing 22 and which acts as an oil extraction well. A thermal oil extraction method according to any one of claims 1 to 4. 6 The annular space between the wall of the well 18 and the packers 20 and 21 of the pipe 19 disposed inside the well 18 is filled with a quick-drying composition that is impermeable to the heat carrier. The thermal oil extraction method according to claim 5. 7 The heat carrier is water vapor, and after the water vapor moves from the injection well 10 and reaches the oil extraction well 9, the water vapor parameters (dryness, temperature and specific volume) are equalized in the oil extraction well 9 and the injection well 10. The thermal oil extraction method according to any of the preceding clauses, characterized in that oil and steam are simultaneously withdrawn from the oil extraction well 9 up to a point in time. 8. At the same time as feeding the heating medium to the injection wells 10 and withdrawing oil from the extraction well 9, a solution of a substance that reduces the surface tension of the oil-water and oil-rock interfaces is introduced into the injection wells 10 of a group.
The hot oil extraction method according to any one of claims 2 to 7, characterized in that the oil is constantly supplied. 9. The wells supplying the surface tension-reducing substance are arranged in every other row, alternating in each row, i.e. in every other injection well. Oil extraction method. 10 To draw oil from the well 9, steam is forced into the bottom of the well 9, from where it is driven into the working tunnel 8, until the steam recovers its initial parameters and undergoes condensation again. A thermal oil extraction method according to any one of claims 1 to 4, 1 and 8, characterized in that steam is caused to flow through the oil extraction well 9.