CN113622885B - Layered injection-production method for improving recovery ratio through gas injection - Google Patents
Layered injection-production method for improving recovery ratio through gas injection Download PDFInfo
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- CN113622885B CN113622885B CN202010380489.5A CN202010380489A CN113622885B CN 113622885 B CN113622885 B CN 113622885B CN 202010380489 A CN202010380489 A CN 202010380489A CN 113622885 B CN113622885 B CN 113622885B
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- 238000004519 manufacturing process Methods 0.000 title claims abstract description 137
- 238000002347 injection Methods 0.000 title claims abstract description 37
- 239000007924 injection Substances 0.000 title claims abstract description 37
- 238000011084 recovery Methods 0.000 title claims abstract description 35
- 239000003921 oil Substances 0.000 claims abstract description 165
- 238000010793 Steam injection (oil industry) Methods 0.000 claims abstract description 79
- 230000005465 channeling Effects 0.000 claims abstract description 53
- 238000000034 method Methods 0.000 claims abstract description 23
- 239000000295 fuel oil Substances 0.000 claims abstract description 4
- 238000012544 monitoring process Methods 0.000 claims abstract description 4
- 239000010410 layer Substances 0.000 claims description 117
- 239000011229 interlayer Substances 0.000 claims description 30
- 238000005070 sampling Methods 0.000 claims description 10
- 238000009413 insulation Methods 0.000 claims description 7
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 claims description 4
- 238000010795 Steam Flooding Methods 0.000 abstract description 18
- 238000011161 development Methods 0.000 abstract description 16
- 230000008901 benefit Effects 0.000 abstract description 5
- 238000005065 mining Methods 0.000 abstract description 3
- 239000010779 crude oil Substances 0.000 description 17
- 230000005484 gravity Effects 0.000 description 10
- 230000035699 permeability Effects 0.000 description 9
- 230000008569 process Effects 0.000 description 9
- 230000000694 effects Effects 0.000 description 7
- 238000000605 extraction Methods 0.000 description 4
- 238000010586 diagram Methods 0.000 description 3
- 238000010796 Steam-assisted gravity drainage Methods 0.000 description 2
- 230000004888 barrier function Effects 0.000 description 2
- 238000004891 communication Methods 0.000 description 2
- 230000004069 differentiation Effects 0.000 description 2
- 238000005516 engineering process Methods 0.000 description 2
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- 230000007547 defect Effects 0.000 description 1
- 238000005553 drilling Methods 0.000 description 1
- 238000010438 heat treatment Methods 0.000 description 1
- 230000006872 improvement Effects 0.000 description 1
- 239000007788 liquid Substances 0.000 description 1
- 230000004048 modification Effects 0.000 description 1
- 238000012986 modification Methods 0.000 description 1
- 239000003129 oil well Substances 0.000 description 1
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- E—FIXED CONSTRUCTIONS
- E21—EARTH OR ROCK DRILLING; MINING
- E21B—EARTH OR ROCK DRILLING; OBTAINING OIL, GAS, WATER, SOLUBLE OR MELTABLE MATERIALS OR A SLURRY OF MINERALS FROM WELLS
- E21B43/00—Methods or apparatus for obtaining oil, gas, water, soluble or meltable materials or a slurry of minerals from wells
- E21B43/16—Enhanced recovery methods for obtaining hydrocarbons
- E21B43/24—Enhanced recovery methods for obtaining hydrocarbons using heat, e.g. steam injection
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- E—FIXED CONSTRUCTIONS
- E21—EARTH OR ROCK DRILLING; MINING
- E21B—EARTH OR ROCK DRILLING; OBTAINING OIL, GAS, WATER, SOLUBLE OR MELTABLE MATERIALS OR A SLURRY OF MINERALS FROM WELLS
- E21B43/00—Methods or apparatus for obtaining oil, gas, water, soluble or meltable materials or a slurry of minerals from wells
- E21B43/14—Obtaining from a multiple-zone well
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- E—FIXED CONSTRUCTIONS
- E21—EARTH OR ROCK DRILLING; MINING
- E21B—EARTH OR ROCK DRILLING; OBTAINING OIL, GAS, WATER, SOLUBLE OR MELTABLE MATERIALS OR A SLURRY OF MINERALS FROM WELLS
- E21B43/00—Methods or apparatus for obtaining oil, gas, water, soluble or meltable materials or a slurry of minerals from wells
- E21B43/30—Specific pattern of wells, e.g. optimising the spacing of wells
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Abstract
The invention relates to a layered injection-production method for improving the recovery ratio by gas injection, which comprises the following steps: s1, dividing an oil layer into a plurality of sub oil layers along the longitudinal direction according to the characteristics of a heavy oil reservoir; s2, arranging the production wells and the steam injection wells according to a well pattern structure; s3, a general steam injection pipe column is put into the steam injection well, and a layered production pipe column is put into the production well; s4, injecting steam into the general steam injection pipe column, monitoring the logging data of the production well in real time, and judging whether the production well has a steam channeling phenomenon according to the logging data; if the steam channeling phenomenon does not exist, the general mining is continued; otherwise, the position where the oil layer with the steam channeling phenomenon is located is determined, and the normally open sliding sleeve switch corresponding to the position where the oil layer with the steam channeling phenomenon is located is closed, so that layered injection and production are realized. The method can fully utilize steam heat energy, reduce the requirements of different interval wells, reduce the operation cost of the production well, improve the recovery ratio to the maximum extent, reduce the development cost of steam flooding and improve the overall economic benefit.
Description
Technical Field
The invention relates to the field of steam flooding development, in particular to a layered injection and production method for improving the recovery ratio by gas injection.
Background
In oil field development, natural energy depletion development is generally referred to as primary oil recovery, conventional waterflood development as secondary oil recovery, and oil recovery measures other than secondary oil recovery are all referred to as tertiary oil recovery, such as chemical flooding, fire flooding, and steam flooding. The steam flooding belongs to an important measure in tertiary oil recovery, and belongs to a powerful means for high-permeability, high-viscosity and medium-deep layer thick oil recovery.
In order to extract oil in an oil layer as much as possible in the prior art, the Steam Assisted Gravity Drainage (SAGD) technology is generally used for extracting the oil layer in a general mode, a perforation section of a production well is arranged on the lower portion of the oil layer, a bottom perforation section of a steam injection well is arranged on the upper portion of the oil layer, steam is injected into the steam injection well to heat the upper oil layer and move upwards continuously, a steam cavity is formed by utilizing the steam super-coverage characteristic, the crude oil is continuously expanded and further driven downwards along with the steam cavity, the oil layer is heated and softened from top to bottom, and the crude oil and condensate which are heated and viscosity reduced are downwards discharged to the perforation section of the production well under the action of gravity by utilizing the mode that the steam drives the crude oil downwards continuously.
However, if the steam cavity is used to gradually heat the oil reservoir from top to bottom to extract as much oil as possible, the oil reservoir needs to have the following conditions: (1) The inclination angle of the oil layer is relatively gentle and cannot have too large fluctuation change of the inclination angle; (2) The porosity and the permeability of each sub oil layer divided by the oil layer along the longitudinal direction are relatively homogeneous; (3) There is no shale interlayer between each oil layer, or the shale interlayer is less developed. If these three conditions are not satisfied, when the steam drives the development, drive the in-process downwards in the steam chamber, will inevitably appear serious steam channeling phenomenon, can't effectively realize steam assisted gravity draining.
However, the three conditions are ideal oil layers, such oil layers rarely exist in reality, in practice, most of sandstone oil layers develop certain shale interlayers, the shale interlayers play a role of barrier to separate the oil layers into sub oil layers, and the porosity and permeability of the sub oil layers are greatly different; and the inclination angle of the whole oil layer is not smooth, and the inclination angle of the stratum influenced by geological motion is also falling and fluctuating. Therefore, the actual reservoir tends to have strong heterogeneity with very poor permeability and is accompanied by discontinuous development of shale interbeddes. The shale interlayer directly influences the rising speed of steam, has obvious barrier effect on the development of a steam cavity, and the volume of the steam cavity is directly related to the steam flooding development effect. In addition, the uneven oil layer, the difference of permeability and porosity and the existence of a shale interlayer all cause the serious steam channeling phenomenon in the process of heating the oil layer by downward driving of steam, and the exploitation effect is influenced.
In addition to the above, with other forms of steam flooding general recovery, the problem of steam channeling of superheated steam in underground hyperosmotic channels is also becoming more pronounced as steam flooding is developed. Steam flooding with blow-by will face the following problems:
1. because the steam injection speed is too fast and the waste of steam is caused, steam carries a large amount of heat energy, if the heat energy can not be fully utilized underground, the crude oil in the stratum can not be fully heated, the mobility is deteriorated, and the effective thick oil yield which can enter a production well is continuously reduced due to the driving of the steam, so that the steam flooding development effect is directly influenced.
2. Due to the channeling of high-temperature steam, the production well directly carries high temperature and high pressure, the lifting effect of the production well is influenced, high risk is caused to the safety production of the well mouth, and the safety development of steam flooding is not facilitated.
The steam flooding layered exploitation is generally proposed at present aiming at the problem of steam channeling, however, the layered exploitation technology of the steam flooding is not mature at present, the layered steam injection of a steam injection well mainly utilizes a layered steam distribution valve or an eccentric double-pipe steam injection pipe column at present, one steam injection pipe column is used for specially injecting steam into an upper oil layer, the other steam injection pipe column is used for specially injecting steam into a lower oil layer, and the steam injection pipe column is matched with the lower oil layer and is used for specially extracting oil from the upper oil layer corresponding to one production well, and the other well is used for specially extracting oil from the lower oil layer. In the mode, more wells need to be arranged on the same oil layer level, so that the cost is higher; in addition, because the shale interlayers exist among the oil layers and are discontinuously developed, the oil layers cannot be strictly separated, and therefore layered mining in the true sense is not realized, and the oil layers are still mined in a general manner, so that the recovery ratio is influenced.
Therefore, the inventor provides a layered injection-production method for improving the recovery ratio by gas injection so as to overcome the defects of the prior art.
Disclosure of Invention
The invention aims to provide a layered injection-production method for improving the recovery ratio by gas injection, which can fully utilize steam heat energy, reduce the requirements of different layer wells, reduce the operation cost of a production well, improve the recovery ratio to the maximum extent, reduce the development cost of steam flooding and improve the overall economic benefit.
The invention aims to realize the method, and the method provides a well pattern structure when the method is adopted for layered injection and production, wherein the well pattern structure comprises at least one steam injection well and a plurality of production wells distributed around each steam injection well, and each production well is a straight well; the bottom end of each steam injection well is provided with a first perforation section, the lower part of each production well is provided with at least two second perforation sections, and the horizontal position of the first perforation section is lower than that of each second perforation section; a general steam injection pipe column can be inserted into each steam injection well, and a layered production pipe column can be inserted into each production well; each layered production pipe column comprises at least two interlayer packers which are sequentially connected from top to bottom, and a normally open sliding sleeve switch is connected between every two adjacent interlayer packers;
the layered injection-production method for improving the recovery ratio by gas injection comprises the following steps:
s1, dividing an oil layer into a plurality of sub oil layers along the longitudinal direction according to the characteristics of a heavy oil reservoir, wherein the number of interlayer packers and the number of second perforation segments are the same as that of the sub oil layers;
s2, arranging the production wells and the steam injection wells according to a well pattern structure;
s3, a general steam injection pipe column is put into the steam injection well, and a layered production pipe column is put into the production well;
s4, injecting steam into the general steam injection pipe column, monitoring the logging data of the production well in real time, and judging whether the production well has a steam channeling phenomenon according to the logging data; if the steam channeling phenomenon does not exist, the general exploitation is continued; if not, then,
putting an auxiliary sampling tool into the layered production string, and respectively sampling oil at the layer position of each sub-oil layer to obtain oil samples of each sub-oil layer; and then analyzing the oil sample, determining the layer position of the oil layer with the steam channeling phenomenon, and closing a normally open sliding sleeve switch corresponding to the layer position of the oil layer with the steam channeling phenomenon to realize layered injection and production.
In a preferred embodiment of the present invention, in step S4, the logging data at least includes wellhead temperature, oil production, water content and pressure disturbance frequency; the auxiliary sampling tool is a dryness sampler.
In a preferred embodiment of the invention, each steam injection well is a vertical well.
In a preferred embodiment of the invention, the lower portion of each production well has two second perforated sections and each of the zonal production strings includes two zonal packers.
In a preferred embodiment of the present invention, each of the layered production strings further comprises a tubing connected to a lower end of the lower interlayer packer, and an inner plug can be sleeved on the lower end of the tubing.
In a preferred embodiment of the invention, each of the zonal production strings further comprises a first telescoping tube positioned above the zonal packer of the top zone.
In a preferred embodiment of the present invention, each of the conventional steam injection strings comprises an upper heat insulation pipe, a heat-sensitive packer and a lower heat insulation pipe which are connected in this order from top to bottom.
In a preferred embodiment of the invention, each general steam injection string further comprises a second telescoping tube located above the heat sensitive packer.
In a preferred embodiment of the invention, four production wells are arranged around each steam injection well, and the steam injection wells and the surrounding production wells are arranged in a five-point pattern.
In a preferred embodiment of the invention, the horizontal distance between the steam injection well and the production well is less than or equal to 150m.
According to the invention, the plurality of divided oil layers can be separated by utilizing the interlayer packer, the horizontal position of the first perforation section of the steam injection well is controlled to be lower than the second perforation section of the production well, when steam is injected, the steam is normally pushed to preferentially displace the lower oil layer, meanwhile, the steam moves upwards, and finally, the steam is displaced upwards to a certain degree, so that steam channeling can occur from the upper oil layer. If steam channeling occurs, closing the corresponding steam channeling layer position to fully utilize steam heat energy; and then a steam cavity is formed in an upper oil layer with steam channeling due to the steam overtopping characteristic, the original crude oil space is occupied, crude oil is driven downwards by utilizing the steam gravity drainage characteristic, the crude oil in the oil layer can be extracted to the maximum extent, and the recovery ratio is improved to the maximum extent.
The whole exploitation process does not need to consider how many shale interlayers exist in each sub oil layer, the gentle degree and the permeability difference of each sub oil layer can not influence the whole exploitation process, the steam channeling layer position is closed by means of a layering mode for preventing steam channeling, the steam gravity oil drainage characteristic is used, the two modes are combined together, oil layer resources can be fully utilized, all crude oil is exploited as far as possible, the steam injection of a steam injection well is realized by utilizing the steam overtaking and gravity differentiation characteristics, the well drilling of a production well is reduced, oil recovery is increased, and the operation is reduced. In addition, as the whole exploitation process does not need layered steam injection, but directly carries out general steam injection, and each normally-open sliding sleeve switch of the production well is opened, and the steam channeling layer is closed when steam channeling occurs subsequently, the requirements of different layer position wells can be reduced, the operation cost of the production well is reduced, the development cost of steam flooding is reduced, and the overall economic benefit is improved.
Drawings
The drawings are only for purposes of illustrating and explaining the present invention and are not to be construed as limiting the scope of the present invention.
Wherein:
FIG. 1: the invention provides a schematic structural diagram of a well pattern structure.
FIG. 2: is a front view of the well pattern structure provided by the present invention.
FIG. 3: a top view of a well pattern structure is provided for the present invention.
FIG. 4 is a schematic view of: the invention provides a schematic structural diagram of a steam injection well and a general steam injection pipe column.
FIG. 5: the invention provides a schematic structural diagram of a production well and a layered production string.
The reference numbers illustrate:
1. a steam injection well; 11. first perforation section
2. A production well; 21. a second perforation segment;
3. a steam injection pipe column is integrated; 31. an upper insulating tube; 32. a second telescopic tube; 33. a heat sensitive packer; 34. a lower insulating tube;
4. producing the tubular column by layers; 41. a first telescopic tube; 42. an interlayer packer; 43. a normally open sliding sleeve switch;
5. and (3) an oil layer.
Detailed Description
In order to more clearly understand the technical features, objects, and effects of the present invention, embodiments of the present invention will now be described with reference to the accompanying drawings.
As shown in fig. 1 to 3 and 5, the present embodiment provides a gas injection enhanced recovery layered injection-production method, which provides a well pattern structure during layered injection-production. The well pattern structure comprises at least one steam injection well 1 and a plurality of production wells 2 distributed around each steam injection well 1, wherein each production well 2 is a vertical well. The bottom end of each steam injection well 1 is provided with a first perforation section 11, the lower part of each production well 2 is provided with at least two second perforation sections 21, and the horizontal position of the first perforation section 11 is lower than that of each second perforation section 21. A general steam injection pipe column 3 can be inserted into each steam injection well 1, and a layered production pipe column 4 can be inserted into each production well 2. Each layered production string 4 comprises at least two interlayer packers 42 which are sequentially connected from top to bottom, and a normally open sliding sleeve switch 43 is connected between every two adjacent interlayer packers 42.
Wherein, the normally open sliding sleeve switch 43 is in an open state at an initial state, so that the corresponding sub-oil layer is in a communication state with the layered production string 4; when the appointed oil layer needs to be closed and the communication between the appointed oil layer and the layered production string 4 is cut off, the normally-open sliding sleeve switch 43 can be closed by putting an impact tool; then another impact tool can be put in to open the normally open sliding sleeve switch 43 as required. The specific structure of the normally open sliding sleeve switch 43 and the impact tool for opening and closing the switch are the prior art, and the invention is not limited thereto as long as the repeated opening and closing of the switch can be realized by the impact tool. In addition, when a plurality of normally-open sliding sleeve switches 43 are provided, the specific structure of each normally-open sliding sleeve switch 43 is different, so that repeated opening and closing can be conveniently realized, and the specific structure is also the prior art.
The layered injection-production method for improving the recovery ratio by gas injection comprises the following steps:
s1, dividing an oil layer 5 into a plurality of sub oil layers along the longitudinal direction according to the characteristics of the heavy oil reservoir, wherein the number of the interlayer packers 42 and the number of the second perforation segments 21 are the same as that of the sub oil layers.
When the oil layer 5 is divided, one oil layer may simultaneously include a plurality of shale interlayers, and the specific division is determined according to actual needs, which is not limited in the present invention.
And S2, arranging the production well 2 and the steam injection well 1 according to the well pattern structure.
S3, a general steam injection pipe column 3 is put into the steam injection well 1, and a layered production pipe column 4 is put into the production well 2.
Generally, in order to improve the economic benefit, the production wells 2 are not simultaneously produced, but one production well 2 is first produced or a plurality of production wells 2 are simultaneously produced according to the overall plan of the oil reservoir 5.
S4, injecting steam into the general steam injection pipe column 3, monitoring the logging data of the production well 2 in real time, and judging whether the steam channeling phenomenon exists in the production well 2 according to the logging data; if the steam channeling phenomenon does not exist, the general exploitation is continued; if not, then the mobile terminal can be switched to the normal mode,
an auxiliary sampling tool is put into the layered production pipe column 4, and oil at the layer position of each sub-oil layer is sampled respectively to obtain oil samples of each sub-oil layer; and then analyzing the oil sample, determining the position of the oil layer with the steam channeling phenomenon, and closing the normally open sliding sleeve switch 43 corresponding to the position of the oil layer with the steam channeling phenomenon to realize layered injection and production.
In detail, in step S4, if there is no steam channeling, when general exploitation is performed, as long as the production well 2 can produce naturally, the production can be performed by direct flowing, and continuous oil recovery is realized. If the self-injection production cannot be realized, the oil production string with the oil well pump can be put into the oil extraction pipe for manual lifting oil extraction, and the oil production string can be pulled out when an auxiliary sampling tool needs to be put into the oil extraction pipe in the subsequent steam channeling phenomenon. And if the steam channeling phenomenon exists in the production well 2 in the mining process according to the logging data, determining a steam channeling horizon by using an oil liquid sample collected by an auxiliary sampling tool, and then closing the steam channeling horizon.
Because the connectivity of a certain sub-oil layer corresponding to the steam injection well 1 and the production well 2 is good, the connectivity with other sub-oil layers is possibly poor, and steam flows more easily in the oil layer 5 than thick oil, so that the sub-oil layer with poor permeability and the sub-oil layer with strong heterogeneity can hardly absorb the heat of the steam sufficiently and can not be used effectively, and the steam channeling phenomenon is easy to occur at the moment. Because the characteristic of steam itself just upwards moves easily, utilize steam upward movement to form the steam chamber above the upper oil reservoir among the prior art, occupy original crude oil space to the mode of drive crude oil downwards extrudees crude oil gradually downwards and is mined out, and serious steam channeling phenomenon and unable improvement can't be avoided appearing in this kind of mode, and whether current this kind of mode can effectively realize still having very big relation with the mud shale intermediate layer, the degree of smoothness and the permeability and the porosity difference of oil reservoir simultaneously.
In the embodiment, because the horizontal position of the first perforation section 11 of the steam injection well 1 is lower than the second perforation section 21 of the production well 2, the first perforation section 11 of the steam injection well 1 is arranged corresponding to the middle lower part of the oil layer 5, and the second perforation section 21 of the production well 2 is arranged above. During steam injection, the lower oil layer is heated by the steam, and then the oil layer 5 is gradually driven and softened from bottom to top by utilizing the gravity differentiation characteristic and adopting a steam driving mode, so that the lower oil layer is exploited as far as possible. After the oil production is continued for a period of time, the crude oil in the lower oil layer can be basically produced, the upper oil layer possibly still has part of crude oil which is not used, when steam is upwards displaced to a certain degree, steam channeling inevitably occurs, and after the steam channeling occurs, the steam can upwards jump to the upper part of the upper oil layer which is not used; but in this embodiment can find out the position of taking place steam scurring and close the normally open sliding sleeve switch 43 that layering production string 4 corresponds after appearing steam scurring, reserve steam in the underground as far as possible, effectively prevent steam scurring, make full use of steam heat energy.
Like this, because steam self characteristic will continue constantly upward movement, if form the hypertonic passageway in upper oil reservoir when the steam scurries, later steam also can continue upwards to deposit through this hypertonic passageway, and then utilize the steam to surpass the characteristic and will form the steam chamber in the oil reservoir top that upper portion did not use completely, later the steam chamber begins from the top down redriven oil reservoir 5, forces steam to the horizon flow of hyposmosis, utilizes the characteristic of steam gravity draining to make the oil reservoir that does not use be exploited as far as possible exploited.
Thus, in the present embodiment, the divided sub-oil layers can be separated by using the interlayer packer 42, and the horizontal position of the first perforation section 11 of the steam injection well 1 is controlled to be lower than the horizontal position of the second perforation section 21 of the production well 2, so that when steam is injected, the lower oil layer is preferentially displaced by the normal propulsion of the steam, and meanwhile, the steam also moves upwards, and finally, the steam is displaced upwards to a certain extent, so that steam channeling from the upper oil layer can occur. If steam channeling occurs, closing the corresponding steam channeling layer position to fully utilize steam heat energy; and then, a steam cavity is formed in an upper oil layer with steam channeling due to the steam overtopping characteristic, the original crude oil space is occupied, crude oil is driven downwards by utilizing the steam gravity oil drainage characteristic, the crude oil in the oil layer 5 can be extracted to the maximum extent, and the recovery ratio is improved to the maximum extent.
The whole exploitation process does not need to consider how many shale interlayers exist in each sub-oil layer, the gentle degree and the permeability difference of each sub-oil layer do not influence the whole exploitation process, the steam channeling layer is closed by means of a layering mode for preventing steam channeling, and the steam gravity oil drainage characteristic is also used, the two modes are combined together, resources of the oil layer 5 can be fully utilized, crude oil is completely exploited as far as possible, the steam injection well 1 can inject less steam by means of steam overlap and gravity diversity characteristics, the production well 2 can drill less wells, and the purposes of more oil extraction and less operation are achieved. In addition, as the whole exploitation process does not need layered steam injection, but directly carries out general steam injection, and each normally-open sliding sleeve switch 43 of the production well 2 is opened, and the steam channeling layer is closed when steam channeling occurs subsequently, the requirements of different layer position wells can be reduced, the operation cost of the production well 2 is reduced, the development cost of steam flooding is reduced, and the overall economic benefit is improved.
In a specific implementation manner, in step S4, the logging data at least includes wellhead temperature, oil production, water content, and pressure disturbance frequency, and the auxiliary sampling tool is a dryness sampler.
Wherein, the logging data can be observed on the computer of the well head. Under normal condition without steam channeling, the temperature of injected steam is generally 350 ℃, and the wellhead temperature of the production well 2 is 50-70 ℃. After steam injection, if various data such as rapid temperature rise of a wellhead, water content rise, oil production quantity reduction, unstable pressure disturbance frequency and the like are detected to be out of a normal range, the fact that the steam channeling phenomenon occurs in the production well 2 is indicated.
When the steam channeling phenomenon occurs, the dryness sampler is put into the layered production pipe column 4, oil samples of all oil layers can be collected, the oil samples are cooled to room temperature on the ground, the oil samples are analyzed to obtain the gasoline ratio of the oil samples, then the gasoline ratio of all the oil samples is compared and analyzed, and the oil layer position with the steam channeling phenomenon can be judged. The dryness sampler and the gasoline-oil ratio process for analyzing the oil sample are all the prior art, and are not described herein again.
In practical application, each steam injection well 1 is a vertical well in order to facilitate construction and reduce cost.
To improve economics and to facilitate the production operation, each production well 2 has two second perforated sections 21 in its lower part, as shown in fig. 5, and each of said separate production strings 4 comprises two interlayer packers 42. Of course, according to actual needs, three or more second perforation sections 21 may be disposed at the lower part of the production well 2 to meet the development requirements.
In the specific implementation, each layered production string 4 further comprises an oil pipe connected to the lower end of the bottom layer interlayer packer 42, and an inner plug can be sleeved on the lower end of the oil pipe.
Specifically, most of the common gas channeling phenomenon exists in the upper oil layer, and the lower oil layer is relatively easy to be extracted, so that the gas channeling phenomenon is less, and therefore, a normally open sliding sleeve switch 43 is basically arranged between two adjacent interlayer packers 42, and the opening and closing of the corresponding sub oil layer are convenient to control. In a few cases, when the steam channeling layer is determined to be the sub-oil layer of the lowest layer, an inner blanking plug can be put into the layered production string 4, so that the bottom end of the layered production string 4 can be plugged, and the purpose of closing the sub-oil layer of the lowest layer is achieved. The structure of the inner plug is prior art and will not be described in detail herein.
Further, in order to compensate for absorbing deformations of the layered production string 4 in the vertical direction, each of said layered production strings 4 further comprises a first telescopic tube 41 above a top layer of inter-layer packers 42, as shown in fig. 5.
Further, as shown in fig. 4, each conventional steam injection string 3 includes an upper heat insulation pipe 31, a heat sensitive packer 33, and a lower heat insulation pipe 34, which are connected in this order from top to bottom.
Wherein the heat sensitive packer 33 is set a distance above the first perforated section 11 in use. Vacuum heat insulating pipes are preferably used for the upper heat insulating pipe 31 and the lower heat insulating pipe 34. The specific structure of the thermal packer 33 and the vacuum insulation pipe are the prior art and will not be described in detail herein. In addition, in order to compensate and absorb the deformation of the conventional steam injection columns 3 in the vertical direction, as shown in fig. 4, each of the conventional steam injection columns 3 further includes a second telescopic pipe 32 located above the heat-sensitive packer 33.
In practical application, in order to facilitate production, four production wells 2 are arranged around each steam injection well 1, and the steam injection wells 1 and the surrounding production wells 2 are arranged in a five-point method, as shown in fig. 1 and 3.
Of course, the steam injection wells 1 and the production wells 2 may be arranged in other arrangements according to actual needs, and this embodiment is only for illustration.
Further, in order to be more beneficial to the production effect of steam flooding, the horizontal distance between the steam injection well 1 and the production well 2 is less than or equal to 150m.
In actual well placement, the horizontal spacing between each production well 2 and the steam injection well 1 generally varies according to factors such as permeability and porosity of the oil layer 5, and the production wells 2 which are relatively close to the steam injection wells 1 (for example, the horizontal spacing is between 50 and 75 m) are generally called first-line wells, and the production wells 2 which are relatively far from the steam injection wells 1 (for example, the horizontal spacing is between 100 and 150 m) are generally called second-line wells. The specific value of the horizontal distance is determined according to the actual condition of the on-site oil layer 5 so as to ensure a reasonable development range.
In a possible implementation, the vertical distance between the first perforation segment 11 and the second perforation segment 21 of the bottom layer is less than or equal to 20m. Of course, the vertical distance may also be adjusted according to actual needs, and this embodiment is only for illustration.
The above description is only an exemplary embodiment of the present invention, and is not intended to limit the scope of the present invention. Any equivalent changes and modifications of the invention without departing from the spirit and principles of the invention should be considered within the scope of the invention.
Claims (10)
1. A gas injection layered injection and production method for improving the recovery ratio is characterized in that a well pattern structure is provided when the method is used for layered injection and production, the well pattern structure comprises at least one gas injection well and a plurality of production wells distributed around each gas injection well, and each production well is a straight well;
the bottom end of each steam injection well is provided with a first perforation section, the lower part of each production well is provided with at least two second perforation sections, and the horizontal position of the first perforation section is lower than that of each second perforation section; a general steam injection pipe column can be inserted into each steam injection well, and a layered production pipe column can be inserted into each production well; each layered production pipe column comprises at least two interlayer packers which are sequentially connected from top to bottom, and a normally-open sliding sleeve switch is connected between every two adjacent interlayer packers;
the layered injection-production method for improving the recovery ratio by gas injection comprises the following steps:
s1, dividing an oil layer into a plurality of sub oil layers along the longitudinal direction according to the characteristics of a heavy oil reservoir, wherein the number of the interlayer packers and the number of the second perforation segments are the same as that of the sub oil layers;
s2, arranging the production wells and the steam injection wells according to the well pattern structure;
s3, lowering the general steam injection pipe column into the steam injection well, and lowering the layered production pipe column into the production well;
s4, injecting steam into the general steam injection pipe column, monitoring the logging data of the production well in real time, and judging whether the production well has a steam channeling phenomenon according to the logging data; if the steam channeling phenomenon does not exist, the general exploitation is continued; if not, then,
putting an auxiliary sampling tool into the layered production string, and respectively sampling oil at the layer position of each sub-oil layer to obtain an oil sample of each sub-oil layer; and then analyzing the oil sample, determining the position of the oil layer with the steam channeling phenomenon, and closing a normally open sliding sleeve switch corresponding to the position of the oil layer with the steam channeling phenomenon to realize layered injection and production.
2. The gas injected enhanced oil recovery (AER) layered injection production method of claim 1,
in step S4, the logging data at least comprise wellhead temperature, oil production, water content and pressure disturbance frequency; the auxiliary sampling tool is a dryness sampler.
3. The gas injection enhanced oil recovery (AER) stratified injection method of claim 1,
and each steam injection well is a vertical well.
4. The gas injection enhanced oil recovery (AER) stratified injection method of claim 1,
the lower portion of each of said production wells has two of said second perforated sections, and each of said layered production strings includes two of said interlayer packers.
5. The gas injection enhanced oil recovery (AER) stratified injection method of claim 1 or 4,
each layered production pipe column further comprises an oil pipe connected to the lower end of the interlayer packer at the bottom layer, and an inner plug can be sleeved at the lower end of the oil pipe.
6. The gas injected enhanced oil recovery (AER) layered injection production method of claim 1,
each of the layered production strings further comprises a first telescoping tube positioned above the inter-layer packer at the top layer.
7. The gas injection enhanced oil recovery (AER) stratified injection method of claim 1,
each of the general steam injection pipe columns comprises an upper heat insulation pipe, a heat-sensitive packer and a lower heat insulation pipe which are sequentially connected from top to bottom.
8. The gas injection enhanced oil recovery (AER) stratified injection method of claim 7,
each general steam injection pipe column further comprises a second telescopic pipe located above the heat-sensitive packer.
9. The gas injected enhanced oil recovery (AER) layered injection production method of claim 1,
four production wells are arranged around each steam injection well, and the steam injection wells and the surrounding production wells are arranged according to a five-point method.
10. The gas injection enhanced oil recovery (AER) stratified injection method of claim 1,
the horizontal distance between the steam injection well and the production well is less than or equal to 150m.
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