阅读说明：本技术 一种提高中深层砂岩地热回灌效率的回灌新方法 (Recharge novel method for improving geothermal recharge efficiency of medium-deep sandstone ) 是由 邓嵩 凌定坤 王磊 赵会军 杨硕 贺嘉蕾 马明宇 王浩 王财宝 于 2021-08-23 设计创作，主要内容包括：本发明公开了一种提高中深层砂岩地热回灌效率的回灌新方法,包括,分析中深层砂岩地热回灌地层参数条件,拟定合适参数；利用数值模拟软件建立多种井型的地热回灌模型进行数值模拟；分析不同回灌方案的数值模拟结果,得到以提高回灌效率为目的的回灌新方法。本发明方法对于提高砂岩地热井的回灌效率有着非常重大的意义,能够有效解决砂岩回灌困难且砂岩且回灌效率低下的问题,并为砂岩地热开采提供实质性的指导意义。(The invention discloses a recharge new method for improving the geothermal recharge efficiency of middle-deep sandstone, which comprises the steps of analyzing the parameter conditions of the geothermal recharge stratum of the middle-deep sandstone and drawing up appropriate parameters; establishing a geothermal recharging model of various well types by using numerical simulation software to carry out numerical simulation; and analyzing the numerical simulation results of different recharging schemes to obtain a novel recharging method aiming at improving the recharging efficiency. The method has great significance for improving the recharge efficiency of the sandstone geothermal well, can effectively solve the problems of difficult recharge of the sandstone and low recharge efficiency of the sandstone, and provides substantial guiding significance for sandstone geothermal exploitation.)

1. A recharge new method for improving geothermal recharge efficiency of middle-deep sandstone is characterized in that: comprises the steps of (a) preparing a mixture of a plurality of raw materials,

analyzing the parameter conditions of the geothermal recharge stratum of the sandstone in the middle and deep layers and drawing up appropriate parameters;

establishing a geothermal recharging model of various well types by using numerical simulation software to carry out numerical simulation;

and analyzing the numerical simulation results of different recharging schemes to obtain a novel recharging method aiming at improving the recharging efficiency.

2. The new recharge method for improving geothermal recharge efficiency of middle and deep sandstone according to claim 1, which is characterized in that: the novel recharging method comprises the following steps of,

the method is characterized in that a method of two-irrigation and one-mining different-layer horizontal well section with a long horizontal well section is selected, two-horizontal-irrigation and one-horizontal-well-mining are preferably selected for mining, the recharge layer is arranged at the lower part, the mining layer is arranged at the upper part, and the horizontal well section is 120m for sandstone geothermal mining.

3. The new recharge method for improving geothermal recharge efficiency of medium and deep sandstone according to claim 1 or 2, which is characterized in that: the sandstone geothermal recharge layer parameters comprise that,

reservoir depth, reservoir initial temperature, formation permeability, formation skin factor, formation initial pressure, and water-bearing layer thickness.

4. The new recharge method for improving geothermal recharge efficiency of middle and deep sandstone according to claim 3, which is characterized in that: the geothermal recharge models for the plurality of well types include,

a vertical well is reinjected into a vertical well for exploitation, a horizontal well is reinjected into a horizontal well for exploitation, and a horizontal well is reinjected into a vertical well for exploitation;

recharging two horizontal wells by recharging a vertical well, exploiting two horizontal wells by recharging a horizontal well, and exploiting two vertical wells by recharging a horizontal well;

two vertical wells are recharged with one horizontal well for exploitation, two horizontal wells are recharged with one horizontal well for exploitation, and two horizontal wells are recharged with one vertical well for recharging.

5. The new recharge method for improving geothermal recharge efficiency of middle and deep sandstone according to claim 4, wherein the new recharge method comprises the following steps: comprises the steps of (a) preparing a mixture of a plurality of raw materials,

the size of the geothermal recharge model is 200m multiplied by 150m, the depth of the top layer is 2000m, the initial temperature of the reservoir is 70 ℃, the grid number is 4500000, the boundary of the model is a non-permeable boundary, the reservoir is anisotropic, and a natural mining mode is adopted.

6. The new recharge method for improving geothermal recharge efficiency of middle and deep sandstone according to claim 5, wherein the new recharge method comprises the following steps: the different recharging schemes comprise one-irrigation one-mining, one-irrigation two-mining and two-irrigation one-mining.

7. The new recharge method for improving geothermal recharge efficiency of middle and deep sandstone according to claim 6, wherein the new recharge method comprises the following steps: also comprises the following steps of (1) preparing,

and carrying out numerical simulation on the geothermal recharging models of the multiple well types by using the different recharging schemes to obtain the influences of the recharging amount and the exploitation amount, the length of the horizontal well, the position of the recharging layer and the recharging efficiency, and analyzing.

8. The new recharge method for improving geothermal recharge efficiency of middle and deep sandstone according to claim 7, wherein the new recharge method comprises the following steps: the new recharging method is obtained according to the change chart of the recharging efficiency, and comprises the following steps of,

and drawing a recharge quantity and production quantity change diagram, a recharge efficiency change curve diagram, a recharge efficiency change diagram under different horizontal well section lengths and a recharge efficiency change diagram under different recharging layer positions of the 9 recharging geothermal models according to a numerical simulation result.

Technical Field

The invention relates to the technical field of geothermal resource development and utilization, in particular to a novel recharge method for improving geothermal recharge efficiency of middle-deep sandstone.

Background

The existing novel environment-friendly energy source, namely terrestrial heat, draws wide attention of people, the exploitation of geothermal wells is more and more intense, the exploitation of geothermal wells to utilize geothermal energy for power generation, heating and the like is a relatively normal means at present, geothermal fluid has the characteristics of deep burial, slow supply and the like, belongs to relatively non-renewable resources, and along with the large-scale development and utilization of geothermal resources, the geothermal fluid is unbalanced in complementary exploitation, so that a series of geological environment problems such as reduction of pressure of a heat storage layer, water chemical pollution, thermal pollution and the like are caused. Geothermal recharge is the most effective way to solve the problems and ensure the sustainable development and utilization of geothermal resources, and research finds that the recharge efficiency of the sandstone geothermal recharge is lower at present.

Therefore, in order to improve the recharge efficiency of the geothermal recharge of the sandstone in the middle and deep layers, the invention provides a new recharge method with high recharge efficiency of the sandstone in the middle and deep layers.

Disclosure of Invention

This section is for the purpose of summarizing some aspects of embodiments of the invention and to briefly introduce some preferred embodiments. In this section, as well as in the abstract and the title of the invention of this application, simplifications or omissions may be made to avoid obscuring the purpose of the section, the abstract and the title, and such simplifications or omissions are not intended to limit the scope of the invention.

The present invention has been made in view of the above-mentioned conventional problems.

Therefore, the technical problem solved by the invention is as follows: how to improve the recharge efficiency of the geothermal recharge of the sandstone in the middle and deep layers.

In order to solve the technical problems, the invention provides the following technical scheme: analyzing the parameter conditions of the geothermal recharge stratum of the sandstone in the middle and deep layers and drawing up proper parameters; establishing a geothermal recharging model of various well types by using numerical simulation software to carry out numerical simulation; and analyzing the numerical simulation results of different recharging schemes to obtain a novel recharging method aiming at improving the recharging efficiency.

The preferable scheme of the novel recharge method for improving the geothermal recharge efficiency of the sandstone in the middle and deep layers is as follows: the new recharging method comprises the steps of selecting a method with two recharging and one exploiting and recharging different layers and a longer horizontal well section, preferentially selecting two horizontal recharging and one horizontal well for exploiting, wherein the recharging layer is arranged below the exploiting layer, the exploiting layer is arranged above the horizontal well section, and the sandstone geothermal heat exploitation is carried out by adopting a scheme with the horizontal well section being 120 m.

The preferable scheme of the novel recharge method for improving the geothermal recharge efficiency of the sandstone in the middle and deep layers is as follows: the sandstone geothermal recharge stratum parameters comprise the depth of a reservoir, the initial temperature of the reservoir, the permeability of the stratum, the skin coefficient of the stratum, the initial pressure of the stratum and the thickness of a water-containing layer.

The preferable scheme of the novel recharge method for improving the geothermal recharge efficiency of the sandstone in the middle and deep layers is as follows: the geothermal recharging model of the multiple well types comprises a vertical well recharging and vertical well mining mode, a horizontal well recharging and horizontal well mining mode and a horizontal well recharging and vertical well mining mode; recharging two horizontal wells by recharging a vertical well, exploiting two horizontal wells by recharging a horizontal well, and exploiting two vertical wells by recharging a horizontal well; two vertical wells are recharged with one horizontal well for exploitation, two horizontal wells are recharged with one horizontal well for exploitation, and two horizontal wells are recharged with one vertical well for recharging.

The preferable scheme of the novel recharge method for improving the geothermal recharge efficiency of the sandstone in the middle and deep layers is as follows: the size of the geothermal recharge model is 200m multiplied by 150m, the depth of a top layer is 2000m, the initial temperature of a reservoir is 70 ℃, the grid number is 4500000, the boundary of the model is a non-permeable boundary, the reservoir is anisotropic, and a natural mining mode is adopted.

The preferable scheme of the novel recharge method for improving the geothermal recharge efficiency of the sandstone in the middle and deep layers is as follows: the different recharging schemes comprise one-irrigation one-mining, one-irrigation two-mining and two-irrigation one-mining.

The preferable scheme of the novel recharge method for improving the geothermal recharge efficiency of the sandstone in the middle and deep layers is as follows: and carrying out numerical simulation on the geothermal recharging models of the multiple well types by using the different recharging schemes to obtain the influences of the recharging amount and the exploitation amount, the length of the horizontal well, the position of the recharging layer and the recharging efficiency, and analyzing the influences.

The preferable scheme of the novel recharge method for improving the geothermal recharge efficiency of the sandstone in the middle and deep layers is as follows: the new recharging method is obtained according to the recharging efficiency change diagram and comprises the steps of drawing 9 recharging amount and production amount change diagrams, recharging efficiency change curve graphs, recharging efficiency change diagrams under different horizontal well section lengths and recharging efficiency change diagrams under different mining and recharging layer positions of the recharging geothermal model according to a numerical simulation result.

The invention has the beneficial effects that: the method has great significance for improving the recharge efficiency of the sandstone geothermal well, can effectively solve the problems of difficult recharge of the sandstone and low recharge efficiency of the sandstone, and provides substantial guiding significance for sandstone geothermal exploitation.

Drawings

In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings needed to be used in the description of the embodiments will be briefly introduced below, and it is obvious that the drawings in the following description are only some embodiments of the present invention, and it is obvious for those skilled in the art to obtain other drawings based on these drawings without inventive exercise. Wherein:

FIG. 1 is a schematic diagram of the recharge efficiency of nine different scenarios of geothermal recharge numerical simulation according to one embodiment of the present invention;

FIG. 2 is a schematic diagram of fluid accumulation for nine different scenarios of geothermal recharge value simulation in accordance with an embodiment of the present invention;

FIG. 3 is a schematic diagram of geothermal recharge efficiency for different horizontal well sections according to one embodiment of the present invention;

FIG. 4 is a schematic view of fluid accumulation for different horizontal well sections for a numerical simulation of geothermal recharge in accordance with an embodiment of the present invention;

FIG. 5 is a schematic diagram of the recharge efficiency at different mining and recharging horizons of the geothermal recharge numerical simulation according to an embodiment of the present invention;

fig. 6 is a schematic diagram of fluid accumulation at different mining and recharging horizons of the geothermal recharging numerical simulation according to an embodiment of the present invention.

Detailed Description

In order to make the aforementioned objects, features and advantages of the present invention comprehensible, specific embodiments accompanied with figures are described in detail below, and it is apparent that the described embodiments are a part of the embodiments of the present invention, not all of the embodiments. All other embodiments, which can be obtained by a person skilled in the art without making creative efforts based on the embodiments of the present invention, shall fall within the protection scope of the present invention.

In the following description, numerous specific details are set forth in order to provide a thorough understanding of the present invention, but the present invention may be practiced in other ways than those specifically described and will be readily apparent to those of ordinary skill in the art without departing from the spirit of the present invention, and therefore the present invention is not limited to the specific embodiments disclosed below.

Furthermore, reference herein to "one embodiment" or "an embodiment" means that a particular feature, structure, or characteristic described in connection with the embodiment is included in at least one implementation of the invention. The appearances of the phrase "in one embodiment" in various places in the specification are not necessarily all referring to the same embodiment, nor are separate or alternative embodiments mutually exclusive of other embodiments.

The present invention will be described in detail with reference to the drawings, wherein the cross-sectional views illustrating the structure of the device are not enlarged partially in general scale for convenience of illustration, and the drawings are only exemplary and should not be construed as limiting the scope of the present invention. In addition, the three-dimensional dimensions of length, width and depth should be included in the actual fabrication.

Meanwhile, in the description of the present invention, it should be noted that the terms "upper, lower, inner and outer" and the like indicate orientations or positional relationships based on the orientations or positional relationships shown in the drawings, and are only for convenience of describing the present invention and simplifying the description, but do not indicate or imply that the referred device or element must have a specific orientation, be constructed in a specific orientation and operate, and thus, cannot be construed as limiting the present invention. Furthermore, the terms first, second, or third are used for descriptive purposes only and are not to be construed as indicating or implying relative importance.

The terms "mounted, connected and connected" in the present invention are to be understood broadly, unless otherwise explicitly specified or limited, for example: can be fixedly connected, detachably connected or integrally connected; they may be mechanically, electrically, or directly connected, or indirectly connected through intervening media, or may be interconnected between two elements. The specific meanings of the above terms in the present invention can be understood in specific cases to those skilled in the art.

Example 1

The embodiment provides a new recharge method for providing geothermal recharge efficiency of middle-deep sandstone, which specifically comprises the following steps:

s1: and analyzing the parameter conditions of the geothermal recharge stratum of the sandstone in the middle and deep layers and drawing up appropriate parameters. Wherein, the sandstone geothermal recharge stratum parameters comprise:

reservoir depth, reservoir initial temperature, formation permeability, formation skin factor, formation initial pressure, and water-bearing layer thickness.

S2: and establishing various well-type geothermal recharging models by using numerical simulation software to perform numerical simulation. It should be noted in this step that the geothermal recharging models of various well types include:

a vertical well is reinjected into a vertical well for exploitation, a horizontal well is reinjected into a horizontal well for exploitation, and a horizontal well is reinjected into a vertical well for exploitation;

recharging two horizontal wells by recharging a vertical well, exploiting two horizontal wells by recharging a horizontal well, and exploiting two vertical wells by recharging a horizontal well;

two vertical wells are recharged with one horizontal well for exploitation, two horizontal wells are recharged with one horizontal well for exploitation, and two horizontal wells are recharged with one vertical well for recharging.

Specifically, still include:

the size of the geothermal recharge model is 200m multiplied by 150m, the depth of the top layer is 2000m, the initial temperature of the reservoir is 70 ℃, the grid number is 4500000, the boundary of the model is a non-permeable boundary, the reservoir is anisotropic, and a natural mining mode is adopted.

S3: and analyzing the numerical simulation results of different recharging schemes to obtain a novel recharging method aiming at improving the recharging efficiency. It is also noted that the different recharging schemes include one-irrigation-one-mining, one-irrigation-two-mining, two-irrigation-one-mining;

and carrying out numerical simulation on the geothermal recharging models of various well types by using different recharging schemes to obtain the influences of the recharging amount and the exploitation amount, the length of the horizontal well, the position of the recharging layer and the recharging efficiency, and analyzing.

Further, the novel recharging method comprises the following steps:

the method is characterized in that a method of two-irrigation and one-mining different-layer horizontal well section with a long horizontal well section is selected, two-horizontal-irrigation and one-horizontal-well-mining are preferably selected for mining, the recharge layer is arranged at the lower part, the mining layer is arranged at the upper part, and the horizontal well section is 120m for sandstone geothermal mining.

Table 1: nine recharge simulation scheme statistics tables.

The novel recharging method is obtained according to a change diagram of recharging efficiency and comprises the following steps:

and drawing a recharge quantity and production quantity change diagram, a recharge efficiency change curve diagram, a recharge efficiency change diagram under different horizontal well section lengths and a recharge efficiency change diagram under different recharging layer positions of the 9 recharging geothermal models according to the numerical simulation result.

Table 2: and (5) a parameter setting table.

Referring to table 2, the size of the geothermal recharge numerical model was set to 200m × 150m × 150m, and the sandstone heat capacity was 2.392 × 10⁷J/(m³The initial fluid temperature is 70 ℃, the initial formation pressure is 2Mpa, the length of the vertical well section is 150m, the depth of the reservoir is 2000m, the recharging temperature is 35 ℃, and the well diameter of the production and recharging well is 9 DEG C^1/2in, the single-day recharge quantity is 800m³The permeability is 500mD, the thickness of the recharging layer is 80m, the thickness of the mining layer is 40m, the surface coefficient of the well section is 0, the bottom pressure of the production well is 1Mpa, and the running time is 30 years.

Preferably, the method has very important significance for improving the recharge efficiency of the sandstone geothermal well, can effectively solve the problems of difficult recharge of the sandstone and low recharge efficiency of the sandstone, and provides substantial guiding significance for sandstone geothermal exploitation.

Example 2

Referring to fig. 1 to 6, a second embodiment of the present invention, which is different from the first embodiment, provides a test verification of a new recharge method for providing geothermal recharge efficiency of middle and deep sandstone, specifically including:

the flowing heat transfer of the underground fluid is a complex flowing process of multi-component three-phase combination, comprising water, solid and gas, in order to solve the problem of a low-temperature hydrothermal geothermal system of the intermediate-depth geothermal sandstone, most components in a geothermal reservoir are geothermal water, so that the condition that the water phase flows underground is only considered, and the mathematical model is simplified as much as possible.

In order to ensure the accuracy of the model calculation, the following simulation conditions are proposed:

firstly, the flows in the calculated model region all obey Darcy's law and all obey the basic theory of seepage;

neglecting the time for the fluid in the model area to reach thermal equilibrium, and neglecting the influence of thermal radiation;

the liquid is non-volatile and has only one liquid phase, and the whole process only relates to one substance (geothermal water);

the fluid does not react with the stratum material chemically or biologically;

the simulated working condition pressure P is less than 25MPa, and the temperature T is less than 400K and less than 0K.

Referring to fig. 1, a schematic diagram of geothermal recharging efficiency under nine schemes is shown, the recharging efficiency of the scheme eight is 98.88% at most, the recharging efficiency of the scheme five is 49.85% at least, the recharging efficiency of the scheme four, the scheme five and the scheme six adopting one-irrigation and two-mining is lower than that of the scheme one, the scheme two and the scheme three adopting one-mining and one-irrigation and the scheme seven, the scheme eight and the scheme nine adopting two-irrigation and one-mining, wherein the recharging efficiency adopting two-irrigation and one-mining is the highest and reaches more than 95%.

Referring to fig. 2, a schematic diagram of fluid accumulation under nine schemes, the recharging amount of the nine schemes is basically the same, and the throughput of one-irrigation and two-mining is the largest, so in order to ensure high recharging efficiency of geothermal heat, the mode of two-irrigation and one-mining is preferably selected, and the scheme eight is preferably adopted.

Referring to fig. 3, a schematic diagram of geothermal recharging efficiency at different horizontal well section lengths is shown, the recharging efficiency is increased along with the increase of the horizontal well section, and when the horizontal well section reaches 120m, the geothermal recharging efficiency reaches 96.99% of the maximum.

Referring to fig. 4, a schematic diagram of fluid cumulant at different horizontal well section lengths is shown, the recharge amount increases with the increase of the horizontal well section, and the influence of the change of the horizontal well section length on the production rate is small, so that in order to ensure high recharge efficiency of geothermal heat, a scheme with a long horizontal well section should be preferably selected.

Referring to fig. 5, a schematic diagram of geothermal recharging efficiency at different mining and recharging layers is shown, in which the recharging efficiency of the recharging layer at the lower layer is 84.78% at the maximum when the mining layer is at the upper layer, the recharging efficiency of the recharging layer at the upper layer is 26.59% at the minimum when the mining layer is at the lower layer, and the recharging efficiency of the recharging layer at the same mining and recharging layer is 62.67%.

Referring to fig. 6, a schematic diagram of fluid accumulation under different production zones, the production capacity under different production zones is the same, but the recharge quantity is maximum up to 7432126m when the recharge zone is at the lower layer and the production zone is at the upper layer³The minimum recharge quantity of the irrigation layer at the upper layer and the recovery layer at the lower layer is 2331731.75m³. Therefore, in order toThe high recharge efficiency of the geothermal energy is ensured, different-layer mining and recharging are preferably selected, and the scheme that the recharge layer is arranged below and the mining layer is arranged above is preferably adopted.

In summary, it can be seen from the simulation results that, in order to ensure high recharge efficiency of the sandstone geothermal heat in the middle and deep layers, a method of recharging and recharging different layers and a method of longer horizontal well section should be selected, and a scheme of preferably recharging and recharging two horizontal wells and one horizontal well for mining, wherein the recharge layer is on the lower mining layer and the recharge layer is on the upper mining layer, and the horizontal well section is 120m, is used for mining the sandstone geothermal heat.

It should be noted that the above-mentioned embodiments are only for illustrating the technical solutions of the present invention and not for limiting, and although the present invention has been described in detail with reference to the preferred embodiments, it should be understood by those skilled in the art that modifications or equivalent substitutions may be made on the technical solutions of the present invention without departing from the spirit and scope of the technical solutions of the present invention, which should be covered by the claims of the present invention.