KR101190386B1 - System and method of creating EGS Group - Google Patents

Abstract

FIELD OF THE INVENTION The present invention relates to a system and a method for forming a group of GS, and more particularly, a part of the outer boundary of certain Enhanced Geothermal Systems (EGS) contact each other, so that the EGS share some injection wells. The optimal number of EGSs determined according to the ground and ground conditions of the geothermal production complex, in the direction in which the desired crushing zones can be generated, based on the direction and shape of the crushing zone in the core rock layer. , In succession, relates to a system and method for forming an Enhanced Geothermal Systems Group (EGS Group).

The present invention makes it possible to significantly reduce the number of injection wells required per production well, compared to the case of single EGS, respectively, and to provide the effect of reducing the drilling cost burden. Through the above-mentioned effects, by creating more high-performance EGS in Korea, by expanding geothermal power generation, it is possible to produce electricity with pure domestic energy, thereby increasing the energy self-sufficiency rate of Korea and the energy import and greenhouse. Provides the effect of reducing gas emissions.

Hydraulic fracturing, drilling costs, deep drilling, production wells, AGS, ASG Group, injection wells, geothermal power generation, geothermal water, direct shredding, shredding

Description

System and method of creating EGS Group

FIELD OF THE INVENTION The present invention relates to a system and a method for forming a group of GS, and more particularly, a part of the outer boundary of certain Enhanced Geothermal Systems (EGS) contact each other, so that the EGS share some injection wells. The optimal number of EGSs determined according to the ground and ground conditions of the geothermal production complex, in the direction in which the desired crushing zones can be generated, based on the direction and shape of the crushing zone in the core rock layer. By forming the 'EGS Group (EGS Group)' in succession, the number of injection wells required per production well can be significantly reduced compared to the case of single EEG. The present invention relates to a composition system and a method for reducing the drilling cost burden.

Binary Geothermal Power Generation, which uses Geothermal Fluid to produce and produce EGS as a heat source, reduces greenhouse gas emissions in addition to rising oil prices and instability, as explained in Document 1. As pressure increases, it is emerging as a promising solution to the increasingly difficult energy situation.

Geothermal energy exists underground at any point in Korea's territory, and its size is almost infinite. However, the depth of geothermal energy at the same temperature is deeper than that of geothermal power generation projects around the world.

In many areas of Korea, it is possible to produce geothermal energy at a temperature that can achieve binary geothermal power generation if EGS is formed from 3km to 4km underground. Therefore, by securing and developing core technologies such as low-cost and high-efficiency deep drilling technology, it is possible to carry out geothermal power by drilling deeper and producing geothermal energy in parallel with rising energy prices.

Deep geothermal energy existing in our country has been left undeveloped because it was recognized as not worth developing with conventional geothermal power generation methods. Recently, however, beneficial geothermal energy production and binary geothermal power generation are disclosed in Documents 1 to 6. Means and methods have been disclosed to achieve this.

Korea's energy self-sufficiency rate is as low as 3%, and it is a very fragile structure that requires 97% of the energy required to be imported, and oil and gas prices are rising, making matters worse, according to the UN Convention on Climate Change. Due to the increasing pressure on greenhouse gas reduction due to the emission country, the energy situation is being condemned in an increasingly difficult direction. In addition to the systems and methods disclosed in Documents 1 to 6, EGS composition and geothermal energy production And the creation of means and methods to further improve the efficiency and economics of geothermal power generation.

Literature Information of the Prior Art

[Document 1] KR Patent Application No. 10-2008-0044966, "Method of binary geothermal power generation using deep seawater", filed: 2008.05.15.

[Document 2] KR Patent Application No. 10-2008-0105167, "System and method of binary geothermal power generation utilizing river zone", filed date: October 27, 2008.

[Patent 3] KR Patent Application No. 10-2008-0131009, "System and method of producing geothermal energy utilizing off-peak power", application date: December 22, 2008.

[Patent 4] KR Patent Application No. 10-2009-0003582, "System and method of creating EGS utilizing off-peak power", filed: 2009.01.16.

[Patent 5] KR Patent Application No. 10-2009-0078070, "System and method of constructing drilling derrick utilizing tower crane mast", filed: 2009.08.24

[Patent 6] KR Patent Application No. 10-2010-0046729, "System and method of creating EGS having zonal injection wells", filed: 2010.05.19

Document 7 US Patent Application 20100000736, "Enhanced Geothermal Systems and Reservoir Optimization", Bour et al. January 7, 2010

Production wells or injection wells drilled to create EGS are casing throughout the entire drilled hole except for the rock layers in the subterranean core where geothermal water is produced or injected. Will be inserted and cemented. The section in which the casing is inserted is called a casing hole section, and the section in which the casing is not inserted is called an open hole section. A slotted liner is generally inserted into the open hole section.

Hydraulic fracturing is performed in the open hole section of the injection well or production well, and as a result of the hydraulic fracturing, if EGS is formed in an optimal form, a plurality of fine shredding zones are dispersed and generated throughout the open hole section. When the injection well and the production well are connected with a plurality of fine crushing zones, the injection water injected into the injection well slowly passes through the crushing zone to sufficiently absorb the geothermal heat of the deep rock layer and reach the production well while heating the geothermal well at the required temperature and flow rate. Water can be produced continuously in production wells.

However, the difficulty is that, when performing hydraulic fracturing in a relatively long open hole section, due to the stress distribution characteristics of the deep rock layer, in some cases, fine fracture zones are not dispersed throughout the open hole section. The crushing zone may be generated only in some sections. The worst case scenario is the case where the crushing band is concentrated and generated only in the very small section of the top of the open hole section of the injection well and is connected with the production well to form a short-circuit or channel.

When the direct crushing zone is formed as described above, most of the injected water reaches the production well too quickly through the direct crushing zone, so that the geothermal water of the deep rock layer is not absorbed properly and the temperature of the produced geothermal water is lowered. Not only geothermal energy existing in the rock layer of the unproduced portion, but also geothermal energy existing in the rock layer of the portion where the fine crushing zone is properly generated cannot be produced. If the direct failure zone is too extended, EGS will eventually become useless.

As noted in '4.11 Remaining Needs' of Document 1 of Document 1 (MIT Report), the creation of means and methods to prevent and overcome the formation of the direct breaking zone is necessary for the successful creation and operation of EGS. It is urgent.

The industry related to EGS (EGS) has made a lot of efforts to solve the problems associated with the direct shredding zone. One example is the technique disclosed in Document 7.

According to the technique disclosed in Document 7, when the crushing stand is generated only in some sections as a result of the hydraulic crushing in the open hole section, the second crushing stand is closed after sealing the generated crushing stand with a temporary sealant. In addition, if additional sections are generated in another section, and the second hydraulic fracturing resulted in a considerable number of sections in which the fracturing zone is still not generated, the third-generation hydraulic fracturing may be performed after the second fracturing fracturing unit is sealed with a temporary sealing agent. It is to distribute and generate a plurality of crushing zones over the entire open hole section using a method such as to generate additional crushing zone in another section.

However, even if a large amount of hydraulic fracturing is carried out using a special method as described above at a considerable cost to distribute a large number of shredding bands throughout the open hole section, how long can it prevent the formation of a direct fracturing band? It is hard to be optimistic about it. This is because, as a result of the hydraulic fracturing, the fracture zone is generated only in some sections of the open hole section because the fracture initiation pressure of the partial rock layer is lower than that of the other sections. Therefore, if the injection is continued, the expansion rate of the crushing zone generated in the rock layer of the portion having the low crushing zone starting pressure gradually becomes faster than the other portions, and thus can be expanded into the direct crushing zone.

Even if there is a crushing part with a fast expansion speed, if it can be injected at a lower injection pressure than the other part, it can be prevented from extending into the direct crushing part. In a positive structure, it is very difficult to control the injection pressure cost effectively for a particular section.

Techniques for forming an EGS (EGS) capable of adjusting the injection pressure for a particular section may be a technique disclosed in Document 6. Using the above technique, the injection section corresponding to the entire open hole section of the production well is divided into an optimal number of sections based on the direction and shape of the fracture zone in the core rock layer and the geothermal production characteristics, and each section is completed as an open hole. By constructing the injection wells in each section, EEG can be formed to distribute and generate the crushing zone in the whole section, and by adjusting the injection pressure in the wellhead of each section, Formation can be prevented, significantly increasing the amount of geothermal energy that can be produced in the deep rock layers.

However, in order to drill a plurality of injection wells per section as described above, the drilling cost (Drilling Cost) is so much, the drilling cost burden is increased.

Drilling costs in accordance with existing drilling techniques are still very high, so in the case of geothermal power generation projects with EGS, drilling costs account for more than 80% of the total project cost. This can be done.

Therefore, in order to develop geothermal power generation by constructing a large number of EGSs with excellent performance in Korea, as described above, a large number of injection wells are needed to disperse and generate crushing zones throughout the entire zone and prevent the formation of direct crushing zones. Drilling is required to create means and methods to solve the increasing drilling cost burden.

The present invention was created according to the above needs, and an object of the present invention is to disperse and generate a crushing band in the whole section and to prevent the formation of a short-circuit to form and operate an EGS of excellent performance. It is to provide a system and method that can create EGS (EGS) while reducing the burden of drilling costs that are increased by drilling a plurality of injection wells.

In order to achieve the above object, the present inventors have been conducting in-depth investigation and research on the characteristics, development conditions and technologies of geothermal energy resources existing in various forms in our land for a long time, Similar to forming honeycomb clusters by sharing walls to maximize efficiency, some parts of the edges of certain EGSs are in contact with each other, so that the EGSs share some injection wells. The number of EGSs in succession is pasted in a direction in which a desired crushing band can be generated, thereby forming an 'EGS Group', thereby significantly reducing the number of injection wells required per production well. As a result, the burden of drilling costs can be reduced, and the present invention has been reached with the conclusion that the above-described object can be achieved.

Accordingly, in the present invention for achieving the above object, each EGS is composed of one production well and one or more injection wells, the production wells Completion of the entire section to produce geothermal fluid from the rock layer into an open hole section, and the injection wells complete all of the injection sections corresponding to the open hole section of the production well into an open hole section. Alternatively, only a portion of the injection section is completed as an open hole section, and hydraulic injection is performed to connect the injection hole between the open hole sections of the injection wells and the open hole section of the production well, and to inject the injection water into the injection wells. While passing through the crushing zone to absorb geothermal heat of the deep rock layer is characterized in that the composition to flow out to the production wells.

In addition, the open hole sections of the injection wells are distributed at an optimal position spaced at least 200m horizontally from the position of the open hole section of the production wells, 50m or more horizontally from the positions of the open hole section of all other injection wells When the number of injection wells is two or more, the open-hole sections of the injection wells are arranged in such a way as to surround the production hole with the open-hole sections as the center.

The composition system and method of the present invention comprises the EGSs having the above characteristics, i.e., the optimal number of EGSs determined according to various conditions of the ground and the ground of the geothermal production complex. A part of the outer boundary of the (EGS) is in contact with each other, so that the EEGs share some injection wells in a direction in which a desired fracture zone can be generated based on the direction and the shape of the fracture zone in the core rock layer. In order to create an 'EGS Group (EGS Group)', the number of injection wells required per production well can be significantly reduced compared to a single EEG. To reduce the drilling cost burden.

The composition system and method of the present invention injects an optimal number of specific EGSs determined in accordance with various underground and ground conditions of the geothermal production complex, and partially injects some of the boundary boundaries of the EGSs. When the number of injection wells per production well is formed into a single EGS, by forming an EGS Group, in which the desired crushing zones are formed in succession to share the wells, Compared to this, it is possible to significantly reduce the number of injection wells needed to disperse and generate the crushing zone over the entire section and to prevent the formation of short-circuit, thereby forming and operating a high performance EGS. It provides the effect of drastically reducing the burden of drilling costs, which increases with drilling.

Accordingly, the present invention, through the above effect, to make geothermal power generation by developing more excellent EGS (EGS) in our country, by increasing the amount of power produced by pure domestic energy only, It increases the energy self-sufficiency rate and reduces the energy import and greenhouse gas emissions.

In the AEG group composition system and method of the present invention, each AEG is composed of one production well and one or more injection wells, and the production wells are geothermal in the deep rock layers. Completion of the entire section to produce the geothermal fluid into an open hole section, the injection wells complete all of the injection section corresponding to the open hole section of the production well to the open hole section or Only a portion of the injection section is completed in the open hole section, and the hydraulic fracturing is performed to connect the open hole sections of the injection wells with the open hole sections of the production well to the crushing zone, and the injection water injected into the injection wells passes through the crushing stand. While absorbing the geothermal heat of the deep rock layer is formulated to flow into the production well while heating.

The open hole sections of the injection wells are distributed at optimal positions 200 m or more horizontally away from the position of the open hole section of the production well and 50 m or more horizontally from the positions of the open hole sections of all other wells. If the number of the injection wells is two or more, the open hole sections of the injection wells are arranged in the form of surrounding the open hole sections of the production well as possible.

The reason for arranging the open hole sections of the injection wells at a position 200 m or more horizontally from the position of the open hole section of the production well is that the injection water reaches the production well while absorbing geothermal heat while passing through the crushing zone of that distance. To do that. Based on geothermal production characteristics, particularly geothermal heat absorption characteristics, since the 200m is the lower limit, a distance of 500m or more may be necessary depending on the temperature of the rock layer and the characteristics of the crushing zone. The optimum distance can be calculated by observing the performance of at least one injection well and production well for a long time in the EEG.

Further, the reason why the open hole sections of the injection wells are disposed at a position 50 m or more horizontally away from the positions of the open hole sections of all other injection wells is that in order to produce geothermal water at a required temperature for 20 years, This is because, based on the thermal conductivity, at least 50 m of dark layer is required between the open hole sections of the injection wells.

Even when the open hole sections of the injection wells are vertically separated by more than a few hundred meters, when the injection well is operated for more than 10 years, the injection may occur in a section in which casing or cementing is weakened and blocked. . Considering such a situation, the distance between the open hole sections of all the injection wells is disposed at a distance of 50m or more horizontally.

In the arrangement as described above, the distance between the open hole intervals of the injection wells and the open hole intervals of the production wells is 200m or more, and the open hole intervals of the injection wells are surrounded by the open hole intervals of the production wells as possible. Considering the arrangement in form, there is no difficulty in arranging the distance between the open hole sections of the injection wells more than 50m apart. Since 50m is a lower limit, it is preferable to arrange | position further away as conditions permit.

The crushing zone generated by the hydraulic fracturing has a unique three-dimensional orientation and shape according to the stress distribution characteristics of the core rock layer. That is, it has a characteristic of being created and expanded in three directions in a specific direction and in a specific form.

Therefore, in the composition system and method of the present invention, in the direction in which a desired crushing zone can be generated based on the generation direction and shape of the crushing zone described above, it is optimal to be determined according to various conditions of the ground and ground of the geothermal production complex. Some of the above-described features (EGS), as in the example shown in Figure 1, the parts of the outer boundary of the (EGS) is in contact with each other, so that the EGS, that is the production wells By sharing, the injection water injected into the shared injection wells flows into the shared production wells in order, thereby forming an 'EGS Group (Enhanced Geothermal Systems Group)'.

Using the above-described composition system and method of the present invention, an EGS Group is formed in the geothermal production complex according to the following procedure.

(1) EGS 1 is formed to have the above characteristics. Drill and complete the first injection well and perform hydraulic fracturing to determine the direction and shape of the fracture zone through microseismic monitoring and logging.

In a complex where the basic data on the direction and shape of the crushing zone is poor, it is necessary to complete the open hole section of the first injection well into the whole section to produce the geothermal water to determine the direction and form of the crushing zone by the hydraulic fracturing. desirable.

The production wells and necessary injection wells are drilled and completed so as to produce the desired crushing zones based on the identified direction and shape of the crushing zones.

The reason for drilling and finalizing the production well after performing hydraulic fracturing in the injection well as described above is to grasp the direction and shape of the fracture zone in the injection well and to more accurately arrange the open hole section of the production well based on the injection well. However, if necessary, the well can be drilled and completed first, and the direction and form of the crushing band can be identified.

Analyzing the hydraulic fracturing results obtained from the production wells and injection wells of the EGSs successively constructed, the direction and shape of the fracture zones are analyzed in more detail.

(2) EEG 2 is formed to have the above characteristics. As shown in the example shown in Figure 1, some of the injection tablets (EGS) 1 or some of the injection tablets are shared (EGS 2) so that it also functions as the injection tablets of the (EGS) 2, that is, (EGS) 2 in contact with a portion of the outer boundary of the EEG 1 in a direction in which a desired fracture zone can be generated based on the identified direction and the direction of formation of the fracture zone so that 2 shares one or more injection wells. (EGS) 2 is formed.

(3) EEG 3 is formed to have the above characteristics. As shown in FIG. 1, some of the injection wells of the EGS 1 and the EEG 2 are shared so as to function as the injection wells of the EEG 3. Based on this, the EEG 3 is formed in contact with a part of the outer boundary of the EGS 1 and the EEG 2 in the direction in which the desired crushing zone can be generated.

(4) EEG 4 is formed to have the above characteristics. As shown in FIG. 1, some of the injection tablets of EGS 1, EGS 2 and EGS 3 are shared to function as injection tablets of EGS 4. Based on the direction and shape of the crushing zone, the EGS 4 is contacted with a part of the outer boundary of the EGS 1, the EGS 2 and the EGS 3 in the direction in which the desired crushing band can be generated. To create.

(5) EGS 5 is formed to have the above characteristics. As shown in FIG. 1, some of the infusion tablets of EGS 1, EGS 2, EGS 3, and EGS 4 are shared to be an EGS 5 injection tablet. Also, the outside of the EGS 1, the EEG 2, the EEG 3 and the EEG 4 in the direction in which the desired crushing zone can be generated based on the identified direction and the generation direction of the crushing stand. In contact with a part of the boundary, EGS 5 is formed.

(6) As described above, the EEG 2 is formed in contact with a part of the outer boundary of the EGS 1, and then the part is in contact with the part of the outer boundary of the EEG 1 and the EEG 2. (EGS) 3, followed by a portion of the boundary of AEG 1, AEG 2 and EEG 3 to form AEG 4, and then AEG. ) 1, AEGs 2, AEGs 3 and AEGs 4 according to the method of forming the AEGs 5 in contact with a part of the outer boundary of the AEGs (EGS) 1, AEGs (EGS) 2 EEG 6 is formed in contact with a part of the outer boundaries of EEG 3, EEG 4 and EEG 5, and then EEG 1, EEG 2, EEG (EGS) 3, EGS 4, EGS 5, and EGS 6 in contact with a part of the outer boundary to create a (EGS) 7, etc. An EGS Group is formed by successively forming an optimal number of EGSs determined in accordance with various conditions of underground and ground of the geothermal complex.

In the present invention, each of the AEGs constituting the AGS group is composed of one production well and one or more injection wells as described above. Therefore, the number of injection wells and the arrangement of open hole sections of each EGS group forming the EGS Group is optimized according to the various conditions of the underground and the ground of each EGS, and is irregularly unique. It will have the number and arrangement of.

For example, in the case of a group of five EEGs, including the shared injection wells, EEG 1 is two injection wells, and EEG 2 is three injection wells. EGS 3 can be composed of five injection wells, EGS 4 can be composed of four injection wells, and EGS 5 can be composed of three injection wells. The arrangement of sections also has irregular shapes.

The EGS Group shown in FIG. 1 was composed of 11 EGS. Here, including the shared injection wells, Easy 1 is 1 injection well, Easy 2 is 2 injection wells, Easy 3 is 3 injection wells, Easy 4 is 4 injection wells 5 is 3 injection tablets, 6 is 2 injection tablets, 7 is 1 injection tablet, 8 is 3 injection tablets, 8 is 1 injection tablet, and 10 is easy Three injection wells, and GS11, consisted of one injection well.

If the 11 EEGs are separated and formed into single EEGs, a total of 24 injection wells should be drilled. In that case, the average number of injection wells per production well is 2.2 (= 24/11).

However, since 10 injection wells were drilled in the EGS Group shown in FIG. 1, the average number of injection wells per production well is significantly reduced to 0.9 (= 10/11).

As described above, by forming an EGS Group by using the composition system and method of the present invention, the number of injection wells per production well can be significantly reduced compared to the case where each is composed of a single EGS. Increasing drilling costs due to drilling and dispensing of multiple injection wells needed to disperse and generate shreds throughout the entire section and prevent the formation of short-circuit to create and operate high performance EGS. Can be significantly reduced.

1 is a plan explanatory diagram showing an example of an EGS group.

Description of the Related Art

1: Location of the open hole section of the production well of EGS 1

2: Position of the open hole section of the production well of ASG 2

3: Location of the open hole section of the production boat of EGS 3

4: Location of the open hole section of the production boat of EGS 4

5: Location of the open hole section of the production boat of EGS 5

6: Position of the open hole section of the production boat of AEGS 6

7: Location of the open hole section of the production boat of EGS 7

8: Location of the open hole section of the production boat of EGS 8

9: Position of the open hole section of the production well of EGS 9

10: Location of the open hole section of the production well of AGS 10

11: Location of the open hole section of the production boat of EGS 11

20: Position of the open hole section of the injection well

Claims (1)

In the method of forming an 'EGS Group' composed of a plurality of Enhanced Geothermal Systems (EGS), It is composed of one production well and one or more injection wells, and the production well completes the entire section for producing geothermal fluid to an open hole section. The tablets may complete all of the injection section corresponding to the open hole section of the production well into an open hole section, or may complete only part of the injection section as an open hole section, and between the open hole section of the production well and the open hole sections of the injection wells. Distributing and arranging the open hole sections of the injection wells so that the horizontal distance is 200 m or more and the horizontal distance between the open hole sections of the injection wells is 50 m or more, and performing hydraulic fracturing to open the open hole sections of the injection wells. EEG (EGS) is formed by connecting between the opening of the production hole and the crushing zone; EGS (EGS) 1 is configured to have the same characteristics as the EGS (EGS); In contact with the part of the outer boundary of the EGS 1 so that some of the injection tablets of the EGS 1 or some of the injection tablets are shared to function as the injection tablet of the following EGS 2. EGS 2 which is formulated to have such characteristics as EGS; Some of the injection wells of the EGS 1 and the EEG 2 are shared so that they also function as the injection wells of the following EEG 3, the outer boundary of the EGS 1 and the EEG 2 In contact with a portion of the AEG (EGS) 3 is configured to have a feature such as (EGS); Some of the injection tablets of EGS 1, EGS 2 and EGS 3 are shared so that they also function as injection tablets of EEG 4 below. EGS (EGS) 4 which is constructed to have a characteristic such as EGS (EGS) in contact with a part of an outer boundary of EGS) 2 and EGS 3; And As described above, the EEG 2 is formed in contact with a part of the outer boundary of the EEG 1, and then the EEG is in contact with the part of the outer boundary of the EEG 1 and the EEG 2. 3, and then, according to the method of forming the EGS 4 in contact with a part of the outer boundary of the EGS 1, the EEG 2, and the EEG 3, and according to the method of forming the EEG 1, EGS 5 is formed in contact with a part of the outer boundaries of EGS 2, EGS 3, and EGS 4, and then EGS 1, EGS 2, EGS (EGS). EGS Groups (EGS) 3, EGS 4 and EGS 5 in contact with a part of the outer boundary, such as (EGS) 6, such as to form a number of AEGs in succession, such as EGS Group (EGS Group) ) A method for forming an easy group, characterized in that for forming.

Images