阅读说明：本技术 一种异型羽状地热井开发系统 (Development system for special-shaped pinnate geothermal well ) 是由 汪健生 谢经轩 刘雪玲 于 2020-12-22 设计创作，主要内容包括：本发明提供一种异型羽状地热井开发系统,包括注入井、生产井和干热岩储层,位于所述注入井和所述生产井之间岩体被压裂,形成连通所述注入井和所述生产井的裂隙网络。其特征在于：所述注入井包括注入井垂直段、注入井造斜段和注入井主井段；所述注入井主井段向下倾斜延伸；沿所述注入井主井段向下延伸方向,在不同的平面上设置N层分支井；所述生产井位于注入井的上方H处,所述生产井的结构与所述注入井的注入井垂直段、注入井造斜段和注入井主井段平行；所述注入井和所述生产井在所述干热岩储层的体对角方向上布置。(The invention provides a special-shaped pinnate geothermal well development system which comprises an injection well, a production well and a dry hot rock reservoir, wherein a rock body positioned between the injection well and the production well is fractured to form a fracture network for communicating the injection well and the production well. The method is characterized in that: the injection well comprises an injection well vertical section, an injection well deflecting section and an injection well main well section; the main well section of the injection well extends downwards; arranging N layers of branch wells on different planes along the downward extending direction of the main well section of the injection well; the production well is positioned above an injection well at the position H, and the structure of the production well is parallel to the vertical section of the injection well, the deflecting section of the injection well and the main well section of the injection well; the injection well and the production well are arranged in a body diagonal direction of the dry heat rock reservoir.)

1. A profile-feathered geothermal well development system comprises an injection well, a production well and a reservoir of hot dry rock between which a rock mass is fractured forming a fracture network communicating the injection well and the production well. The method is characterized in that:

the injection well comprises an injection well vertical section, an injection well deflecting section and an injection well main well section; the main well section of the injection well extends downwards;

arranging N layers of branch wells on different planes along the downward extending direction of the main well section of the injection well;

the production well is positioned above an injection well at the position H, and the structure of the production well is parallel to the vertical section of the injection well, the deflecting section of the injection well and the main well section of the injection well;

the injection well and the production well are arranged in a body diagonal direction of the dry heat rock reservoir.

2. The contoured-feather geothermal well development system of claim 1, in which the injector main section intersects lateral wells of the same layer on the side of the injector main section on the same horizontal plane.

3. The profile-feathered geothermal well development system of claim 2, wherein there are two laterals in each layer and the angle between the laterals on either side of the main section of the injection well is α, the α being [60 °, 150 ° ].

4. The profile-feathered geothermal well development system of claim 3, in which α is 120 °.

5. The contoured feather geothermal well development system of any one of claims 1 to 4, wherein the branch wells of each layer are staggered.

6. The contoured-feather geothermal well development system of claim 1, in which the lateral wells of each layer are drilled down at an inclination β.

Technical Field

The invention belongs to the field of development and utilization of deep dry-hot rock geothermal energy, and particularly relates to a development system of a special-shaped pinnate geothermal well.

Background

The dry-hot rock geothermal resource has the advantages of large reserve, high temperature, no carbon emission in the utilization process and the like, and has great application potential in the field of development of future renewable energy sources. However, the high-temperature hot dry rock geothermal resources are often buried deeply and have poor permeability, so that the utilization efficiency of high-quality geothermal energy is low. The enhanced geothermal system has attracted much attention in recent years as an effective technical means for the development of geothermal energy of deep dry-hot rock. The complete enhanced geothermal system consists of a circulating working medium, an injection and production well, an effective fracture network and a specific target thermal reservoir. Therefore, reasonable well arrangement scheme design and application are the key points for efficient development of deep dry hot rock geothermal resources.

Patent CN 202020566317.2, a hot dry rock horizontal well multi-branch intercommunication heat transfer system, adopts the multi-runner intercommunication method to change the flow direction of working medium, strengthens the heat transfer of working medium and rock mass.

Patent CN 201820398305.6, a hot dry rock double-deck horizontal multi-branch heat exchange well system, adopts the method that multiunit horizontal well and multiunit branch well are linked together, improves the area of overflowing of working medium.

Patent CN 201711127849.5, a process method for developing geothermal energy of hot dry rock by adopting a horizontal well, and a method for combining a horizontal well arrangement scheme of 'two-injection one-extraction' and staged fracturing, so that the development efficiency of geothermal energy is improved.

Patent CN201710263932.9, a method for developing hot dry rock by using bi-level circulating supercritical carbon dioxide, which adopts supercritical carbon dioxide as a fracturing and circulating medium to realize carbon sequestration, thereby avoiding the water-rock effect and improving the economic development of hot dry rock geothermal resources.

Patent CN201710182823.4, single well hot dry rock heat energy extraction system adopts the mode of placing the heat exchanger in the pit, realizes the extraction of heat energy.

In the development mode of the geothermal resources of the hot dry rock, a horizontal well arrangement scheme is mostly adopted to improve the flow area of the working medium so as to improve the development efficiency of the enhanced geothermal system. According to the report, the injection rate of the development of the hot dry rock is internationally specified to be 80kg/s, and the heat storage volume is more than 1000m³. However, the three-dimensional development of the thermal reservoir is difficult to realize in such a mode, the local rock mass cooling can also cause uneven distribution of the ground stress field in the reservoir, the compressive stress is obviously reduced near an injection well, and the compressive stress has a rising trend near a production well, so that the thermal energy is reduced, the injection pressure is increased, and the thermal breakthrough time is advanced.

In conclusion, with the maturity of the reservoir transformation technology, the development mode of the hot dry rock resource with high heat recovery rate and low development cost is provided according to the existing problems, and the development mode has important significance.

Disclosure of Invention

The purpose of the invention is as follows: in order to improve the utilization efficiency of deep hot dry rock geothermal resources and realize the three-dimensional development of large reservoir geothermal energy, the special-shaped pinnate geothermal well development system is particularly provided. In order to achieve the purpose, the invention adopts the technical scheme that:

a development system for a profile-feathered geothermal well comprises an injection well, a production well and a reservoir of hot dry rock, located between the injection well and the production well

The interbody is fractured, forming a fracture network connecting the injection well and the production well. The method is characterized in that:

the injection well comprises an injection well vertical section, an injection well deflecting section and an injection well main well section; the main well section of the injection well extends downwards;

arranging N layers of branch wells on different planes along the downward extending direction of the main well section of the injection well;

the production well is positioned above an injection well at the position H, and the structure of the production well is parallel to the vertical section of the injection well, the deflecting section of the injection well and the main well section of the injection well;

the injection well and the production well are arranged in a body diagonal direction of the dry heat rock reservoir.

Further, the contoured-feather geothermal well development system of claim 1, in which the injector main section intersects lateral wells of the same layer on the side of the injector main section on the same horizontal plane. The branch wells of each layer are two, the included angle between the branch wells at the two sides of the main well section of the injection well is alpha, and the alpha takes the values of [60 degrees ], 150 degrees ].

The branch wells of each layer may also be staggered.

The lateral wells of each layer may also be drilled all down at a dip angle β.

The invention has the beneficial effects that: 1. the well body has simple structure; 2. the injection well has a large heat exchange control area and rich hydraulic fracture network structure, and the injection pressure is reduced; 3. the layered arrangement of the branch wells and the extension of the main well can realize the three-dimensional development of the reservoir and improve the heat exchange efficiency; 4. the length, the included angle and the number of layers of the branch wells and the length of the main well section in the injection well can be changed according to the volume of the thermal reservoir; 5. the system may be applicable to a variety of complex formations.

Drawings

FIG. 1 is a schematic diagram of the present invention.

Fig. 2 is an isometric view of fig. 1 of the present invention.

Figure 3 is a left side view of the wellbore configuration of the present invention.

Fig. 4 is an isometric view of fig. 3 of the present invention.

Figure 5 is a schematic diagram of a well offset of the present invention.

Figure 6 is a schematic diagram of a branch downhole dip of an injection well of the present invention.

FIG. 7 is a graph of the production temperature variation for the lateral wells of the present invention at different included angles α.

In the figure: 1. an injection well; 11. an injection well vertical section; 12. injecting a well into the deflecting section; 13. an injection well main wellbore section; 14. a first horizontal branch well; 15. a second horizontal branch well; 16. a third horizontal branch well; 17. a fourth layer of horizontal branch wells; 2. a production well; 3. a hot dry rock reservoir.

Detailed Description

The present invention is not limited to the following embodiments, and the specific embodiments may be determined according to the technical solution and the practical situation of the present invention. The present invention will be described below with reference to fig. 1, 2, 3, 4, 5, and 6. The positional relationship of up, down, left, right, etc. is determined in accordance with the layout direction of fig. 1 in the specification.

As shown in fig. 1, 2, 3, 4, 5, 6 and 7.

Example 1

(1) Determining the position and volume parameters of the hot dry rock reservoir 3 according to geological survey data;

(2) establishing a three-dimensional model of a dry hot rock reservoir 3, and determining the positions of an injection well 1 and a production well 2 and relevant parameters of a well body structure;

(3) planning the branch well length L on both sides of the injection well 1 according to the volume of the dry heat rock reservoir 3₁、L₂、L₃、L₄Determining the number of layers and the layer spacing h of the branch well;

(4) drilling an injection well vertical section 11, an injection well deflecting section 12, an injection well main well section 13 and a well body structure corresponding to the production well 2 in the dry hot rock reservoir 3, and completing the well cementation of the geothermal well;

(5) determining an included angle alpha of the branch wells, drilling a first layer of horizontal branch well 14, a second layer of horizontal branch well 15, a third layer of horizontal branch well 16 and a fourth layer of horizontal branch well 17 at corresponding positions on two sides of the injection well 1 by using a casing windowing technology, and completing the cementing of a geothermal well;

(6) performing staged fracturing in an injection well main well section 13, a first layer horizontal branch well 14, a second layer horizontal branch well 15, a third layer horizontal branch well 16, a fourth layer horizontal branch well 17 and a production well 2 of an injection well 1 by applying a staged fracturing technology to construct a fracture network of a dry hot rock reservoir 3;

(7) injecting heat-carrying cycle working media into the hot dry rock reservoir 3 through an injection well 1, wherein the cycle working media sequentially pass through an injection well vertical section 11, an injection well deflecting section 12 and an injection well main well section 13 and flow into horizontal branch wells of each layer; under the pressure of a wellhead, low-temperature working media enter a fracture network for heat exchange, and the low-temperature working media are gradually changed into high-temperature working media in the migration process and then are converged into the production well 2; the high-temperature fluid is discharged to the ground through the production well 2, high-quality heat is applied, and then the high-temperature fluid is injected into the hot dry rock reservoir 3 through the injection well 1.

According to the scheme of the invention, a three-dimensional dry-hot rock reservoir development model is established, and the simulation operation time limit is 40 years. The heat reservoir is located at a burial depth of 3800-4350 meters, and the volume of the heat reservoir is 550 meters multiplied by 550 meters. The injection well is positioned at the lower part of the reservoir, the production well is positioned at the upper part of the reservoir, the horizontal branch wells are 100 meters in length, and the horizontal branch well of the first layer is positioned at the position of 4180 meters of buried depth. When H is 51.96 meters, H is 300 meters and supercritical carbon dioxide is used as a circulating working medium, under the conditions that the injection rate is 50kg/s, the injection temperature is 60 ℃ and the leakage of the working medium is not considered, comparing the difference between the scheme of the invention and the traditional twin-well development mode, the heat extraction performance under different included angles alpha of the branch wells is respectively analyzed, and the values of the selected parameters alpha are 150 degrees, 120 degrees, 90 degrees and 60 degrees. The comparative differences in production temperature and the results of the production temperature as a function of α are shown in FIG. 7. The result shows that when the included angle is 60 degrees, the heat extraction performance of the scheme of the invention has no obvious difference with the heat extraction performance of the traditional double-well development system; when the included angle is larger than 60 degrees and smaller than 120 degrees, the production temperature level is increased along with the increase of the included angle; when the included angle is larger than 120 degrees, the heat extraction performance is not enhanced along with the increase of the included angle in the first 30 years of the operation of the system, and the heat extraction performance has a slight rising trend in the last 10 years. Therefore, when H is 51.96 m and H is 300 m, the optimum value of the included angle α is 120 °.

Example 2

On the basis of the embodiment 1, the method further comprises the following steps:

and arranging the branch wells in the first layer of horizontal branch well 14, the second layer of horizontal branch well 15, the third layer of horizontal branch well 16 and the fourth layer of horizontal branch well 17 in a staggered manner, so as to further improve the heat exchange volume of the dry hot rock reservoir 3, as shown in fig. 5.

Embodiment 3

On the basis of the embodiment 1, the method further comprises the following steps:

drilling one of the first horizontal multilateral well 14, the second horizontal multilateral well 15, the third horizontal multilateral well 16 and the fourth horizontal multilateral well 17 at a certain inclination angle beta to further increase the heat exchange volume of the hot dry rock reservoir 3, as shown in fig. 6.

The principle of the invention is as follows:

in the whole geothermal exploitation system, the injection well 1 and the production well 2 are arranged up and down in the dry hot rock reservoir 3 and are arranged along the diagonal line of the dry hot rock reservoir 3, and the first-layer horizontal branch well 14, the second-layer horizontal branch well 15, the third-layer horizontal branch well 16 and the fourth-layer horizontal branch well 17 are combined with each other, so that the utilization rate of rock mass in the dry hot rock reservoir 3 is improved, and three-dimensional exploitation is realized.