Estimation method of geothermal brine type lithium potential resource

Abstract

The invention relates to the field of mineral resource exploration, in particular to an estimation method of geothermal brine type lithium potential resources. The estimation method of the geothermal brine type lithium potential resource comprises the following steps: step 1, delineating a heat storage volume; 2, the heat storage void degree and the hot water density are determined; 3, estimating the amount of water in heat storage; 4, measuring the lithium content of the hot water; and 5, estimating potential lithium resources according to the water quantity in the heat storage and the lithium content in the hot water. According to the method, on the basis of geothermal exploration results, potential resources of lithium in geothermal system heat storage are estimated through the volumetric method, and support is provided for evaluation and development of geothermal brine type lithium resources.

Description

Technical Field

[0001] The invention relates to the field of mineral resource exploration, and in particular to a method for estimating potential geothermal brine-type lithium resources. Background Art

[0002] Lithium is a national strategic mineral and an important basic mineral resource for the development of the new energy industry. At present, domestic lithium resources are in urgent need of exploration and development. The high-temperature geothermal system on the Qinghai-Tibet Plateau in my country is generally rich in lithium. Compared with my country's salt lake-type lithium resources, it has the characteristics of low Mg / Li value and high Li / TDS value, and the lithium content is stable (Wang Chenguang et al., 2020), becoming a geothermal brine-type lithium resource. On the basis of high-temperature geothermal exploration and development, geothermal brine-type lithium resources have a very high comprehensive development value. Exploration and evaluation of them is an important supplement to my country's lithium resource security.

[0003] The estimation of potential resources of lithium in geothermal systems has become the key to the evaluation and development of geothermal brine-type lithium resources. Currently, there is no method for estimating the potential resources of geothermal brine-type lithium. Summary of the invention

[0004] The technical problem to be solved by the present invention is to provide a method for estimating the potential resources of geothermal brine-type lithium, including: delineating the volume of thermal reservoir, determining the porosity and density of hot water, measuring the lithium content in hot water, and estimating the potential resources of lithium. Through the above steps, the potential resources of lithium in the hot water of geothermal field thermal reservoir are estimated, providing support for the comprehensive development of geothermal resources.

[0005] The present invention provides a method for estimating potential geothermal brine lithium resources, comprising the following steps:

[0006] Step 1: Delineation of heat storage volume;

[0007] Step 2: Determine the heat storage porosity and hot water density;

[0008] Step 3: Estimate the amount of water in the thermal storage;

[0009] Step 4: Determine the lithium content of hot water;

[0010] Step 5: Estimate potential lithium resources based on the amount of water in the thermal reservoir and the lithium content of hot water.

[0011] Preferably, the step 1 specifically includes: classifying the heat reservoir types and defining the volumes of each type of heat reservoir according to the geothermal field exploration results.

[0012] Preferably, the step 2 specifically includes: measuring or determining the porosity and hot water density of each type of heat storage according to the heat storage type and heat storage temperature.

[0013] Preferably, the step three is specifically as follows: setting the gaps in the heat storage to be filled with hot water, ignoring the influence of pressure, gas and elastic water release,

[0014] According to the porosity of the heat storage and the density of hot water, the water volume in the heat storage is estimated using the following calculation formula:

[0015]

[0016] in:

[0017] S—hot water mass, kg;

[0018] A—heat storage area, m 2 ;

[0019] d—heat reservoir thickness, m;

[0020] φ—porosity of thermal reservoir rock, dimensionless;

[0021] ρ—density of hot fluid, kg / m 3 .

[0022] Preferably, the step 4 is specifically:

[0023] Hot water samples were collected from each thermal storage and the lithium content in the hot water was determined.

[0024] Preferably, the step five is specifically:

[0025] Estimate the potential resources of lithium in various types of thermal water storage;

[0026] The sum of the potential lithium resources in various types of thermal storage water is the potential lithium resource amount in the thermal storage water of the geothermal field.

[0027] Preferably, the calculation formula for the sum of the potential lithium resources in the various types of thermal water storage is:

[0028] L=∑(S i ×C i ×10 -9 )

[0029] in:

[0030] L—potential resources of lithium metal, t;

[0031] S—mass of hot water in thermal storage No. i, kg;

[0032] C—Total lithium content in thermal storage water No. i, mg / kg.

[0033] i=1,2,…,n.

[0034] Compared with the prior art, the method for estimating the potential resources of geothermal brine-type lithium of the present invention adopts the volumetric method. On the basis of geothermal resource exploration results, by estimating the quality of various types of thermal storage hot water and determining the lithium content in various types of thermal storage hot water, the potential resources of lithium in thermal storage hot water can be estimated, the comprehensive utilization value of geothermal resources can be further improved, and support can be provided for the further development and utilization of geothermal brine-type lithium resources. BRIEF DESCRIPTION OF THE DRAWINGS

[0035] Figure 1 Flowchart showing the method for estimating geothermal brine-type lithium resource potential. DETAILED DESCRIPTION

[0036] In order to further understand the present invention, the embodiments of the present invention are described below in conjunction with examples, but it should be understood that these descriptions are only for further illustrating the features and advantages of the present invention, rather than limiting the present invention.

[0037] like Figure 1 As shown, an embodiment of the present invention discloses a method for estimating potential geothermal brine lithium resources, comprising the following steps:

[0038] Step S1: Delineation of heat storage volume:

[0039] Based on the results of geothermal field exploration, the heat reservoir types are divided and the volume of each type of heat reservoir is delineated.

[0040] Step S2: Determination of heat storage porosity and hot water density:

[0041] According to the lithology and temperature of the heat reservoir, the porosity and density of hot water of various heat reservoirs are measured or determined respectively. The porosity and density of hot water of various geological bodies in the Code for Geological Exploration of Geothermal Resources (GB / T 11615-2010) can be referred to.

[0042] Step S3: Estimation of water volume in thermal storage:

[0043] By default, the voids in the heat reservoir are filled with hot water, and the effects of pressure, gas, etc., and the elastic water release are not considered. According to steps S1 and S2, the void volume in the heat reservoir, that is, the volume of hot water in the heat reservoir, can be estimated. According to the temperature of the heat reservoir, the hot water density at the corresponding temperature in the "Specifications for Geological Exploration of Geothermal Resources" (GB / T 11615-2010) is referred to, and the hot water volume is converted into the hot water mass S.

[0044] S=A×d×φ×ρ

[0045] in:

[0046] S—hot water mass, kg;

[0047] A—heat storage area, m 2 ;

[0048] d—heat reservoir thickness, m;

[0049] φ—porosity of thermal reservoir rock, dimensionless;

[0050] ρ—density of hot fluid, kg / m 3 .

[0051] Step S4: Determination of hot water lithium content:

[0052] Collect hot water samples from various thermal reservoirs, such as representative warm spring water samples on the surface, or borehole water samples that expose thermal reservoirs, and send them to the testing laboratory to determine the lithium content in the hot water. Usually the data unit is volume fraction. According to the room temperature conditions of the test, refer to the "Geothermal Resources Geological Exploration Code" (GB / T 11615-2010), the data is converted into mass fraction C.

[0053] Step S5: Potential lithium resource estimation:

[0054] According to steps S3 and S4, the potential resources L of lithium in various types of thermal hot water storage are estimated respectively. The sum of the potential resources of lithium in various types of thermal hot water storage is the potential resources of lithium in the geothermal system. The overall estimation formula is as follows:

[0055] L=∑(S i ×C i ×10 -9 )

[0056] in:

[0057] L—potential resources of lithium metal, t;

[0058] S—mass of hot water in thermal storage No. i, kg;

[0059] C—Lithium content of thermal storage water No. i, mg / kg;

[0060] i=1,2,…,n.

[0061] In order to further understand the present invention, the estimation method of geothermal brine-type lithium potential resources provided by the present invention is described in detail below in conjunction with the examples, and the protection scope of the present invention is not limited by the following examples.

[0062] Example 1

[0063] Estimation of potential lithium resources in the Gulu geothermal field in Tibet

[0064] The Tibet Gulu geothermal field is a hydrothermal high-temperature geothermal field. The pre-feasibility survey has been completed and the thermal reserve range has been delineated. On this basis, the specific steps for estimating the potential lithium resources of the geothermal field are as follows:

[0065] Step S1: Delineation of heat storage volume

[0066] According to the exploration results of the Gulu geothermal field, the heat reservoir of the Gulu geothermal field is composed of Quaternary pore-type heat reservoir and bedrock fissure-type heat reservoir. The area of ​​the Quaternary pore-type heat reservoir is about 3.89 km 2 , with a thickness of 100m; the bedrock fissure-type heat storage is 1500m wide, 2200m long, and 2400m vertically thick.

[0067] Step S2: Determination of heat storage porosity and hot water density

[0068] According to the "Geothermal Resources Geological Exploration Code" (GB / T 11615-2010), the Quaternary thermal reservoir of Gulu is an uncemented sandstone aquifer. The porosity (φ) of the Quaternary porous thermal reservoir rock is 20%, and the porosity (φ) of the bedrock fracture thermal reservoir granite rock is 6%. According to the thermal reservoir temperature, the hot water volume is converted into hot water mass. The Quaternary thermal reservoir temperature is 120℃, and the hot water density is 942.80kg / m 3 ; The bedrock fissure heat storage temperature is 210℃, and the hot water density is 897.74kg / m 3 ; The density of the hot fluid at room temperature 20°C is 998.30 kg / m 3 .

[0069] Step S3: Estimation of water volume in thermal storage

[0070] By default, the voids in the heat reservoir are filled with hot water, and the effects of pressure, gas, and elastic water release are not considered. Based on steps S1 and S2, the void volume in the heat reservoir can be estimated, and combined with the hot water density, the hot water mass in the heat reservoir can be obtained. After calculation, the hot water mass S1 of the Quaternary porous heat reservoir is 7.33×10 10 kg, and the hot water mass S2 of bedrock fracture heat storage is 4.27×10 11 kg. The estimation formula is as follows:

[0071]

[0072]

[0073]

[0074] in:

[0075] S—hot water mass, kg;

[0076] A—Calculation area, m 2 ;

[0077] d—heat reservoir thickness, m;

[0078] —Porosity of reservoir rock, dimensionless;

[0079] ρ—density of hot fluid, kg / m 3 ;

[0080] S1—the quality of hot water in the Quaternary porous heat reservoir;

[0081] S2—Quality of hot water in bedrock fissure-type heat storage.

[0082] Step S4: Determination of hot water lithium content

[0083] The samples of geothermal water from the surface hot springs and geothermal wells of the Gulu geothermal field were sent to the laboratory for testing. The average lithium content of the surface hot spring water represented the pore-type thermal lithium content of the Quaternary system, and the hot water revealed by the drilling represented the bedrock fissure-type thermal lithium content. After calculation, the pore-type thermal lithium content of the Quaternary system was 20.94 mg / L, and the bedrock fissure-type thermal lithium content was 25.93 mg / L. According to the "Geological Exploration Specifications for Geothermal Resources" (GB / T 11615-2010), the density of the hot fluid at room temperature of 20°C is 998.30 kg / m 3 After conversion, the mass fraction of the Quaternary pore-type thermal lithium storage is 20.98 mg / kg, and the main mass fraction of the bedrock fissure-type thermal lithium storage is 25.97 mg / kg.

[0084] Step S5 Potential lithium resource estimation

[0085] According to steps S3 and S4, the potential resource metal amount L of lithium in the thermal reservoir of the Gulu geothermal field is estimated to be 12627.02t. The estimation formula is:

[0086] L=∑(S i ×C i ×10 -9 )

[0087] L1=S1×C1×10 -9 =7.33×10 10 kg×20.98mg / kg×10 -9 =1537.83t

[0088] L2=S2×C2×10 -9 =4.27×10 11 kg×25.97mg / kg×10 -9 =11089.19t

[0089] L=L1+L2=1537.83t+11089.19t=12627.02t

[0090] in:

[0091] L—potential resources of lithium metal, t;

[0092] L1—Quaternary pore-type thermal lithium metal potential resources, t;

[0093] L2—Potential resources for thermal storage of lithium metal in bedrock fractures

[0094] S1—mass of hot water in quaternary porous thermal storage, kg;

[0095] S2—mass of hot water stored in bedrock fissures, kg;

[0096] C1—Lithium content of Quaternary porous thermal storage water, mg / kg;

[0097] C2—Lithium content of bedrock fissure-type thermal water storage water, mg / kg.

[0098] The above embodiments are only used to help understand the method and core idea of ​​the present invention. It should be noted that, for those skilled in the art, several improvements and modifications can be made to the present invention without departing from the principles of the present invention, and these improvements and modifications also fall within the scope of protection of the claims of the present invention.

[0099] The above description of the disclosed embodiments enables one skilled in the art to implement or use the present invention. Various modifications to these embodiments will be apparent to one skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the present invention. Therefore, the present invention will not be limited to the embodiments shown herein, but rather to the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A method for estimating potential geothermal brine lithium resources, characterized in that: The following steps are involved: Step 1: Delineation of heat storage volume; Step 2: Determine the heat storage porosity and hot water density; Step 3: Estimate the amount of water in the thermal storage; Step 4: Determine the lithium content of hot water; Step 5: Estimate potential lithium resources based on the amount of water in the thermal reservoir and the lithium content of hot water.

2. The method for estimating potential geothermal brine lithium resources according to claim 1, characterized in that: The step 1 specifically includes: classifying the heat reservoir types and defining the volumes of each type of heat reservoir according to the geothermal field exploration results.

3. The method for estimating potential geothermal brine lithium resources according to claim 2, characterized in that: The step 2 specifically includes: measuring or determining the porosity and hot water density of each type of heat storage according to the heat storage type and heat storage temperature.

4. The method for estimating potential geothermal brine lithium resources according to claim 3, characterized in that: The step three is as follows: assuming that all the spaces in the heat storage are filled with hot water, without considering the influence of pressure, gas and elastic water release. According to the porosity of the heat storage and the density of hot water, the water volume in the heat storage is estimated using the following calculation formula: S=A×d×φ×ρ in: S—hot water mass, kg; A—heat storage area, m 2 ; d—heat reservoir thickness, m; φ—porosity of thermal reservoir rock, dimensionless; ρ—density of hot fluid, kg / m 3 .

5. The method for estimating potential geothermal brine lithium resources according to claim 4, characterized in that: The step 4 is specifically as follows: Hot water samples were collected from each thermal storage and the lithium content in the hot water was determined.

6. The method for estimating potential geothermal brine lithium resources according to claim 5, characterized in that: The step five is specifically as follows: Estimate the potential resources of lithium in various types of thermal water storage; The sum of the potential lithium resources in various types of thermal storage water is the potential lithium resource amount in the thermal storage water of the geothermal field.

7. The method for estimating potential geothermal brine lithium resources according to claim 6, characterized in that: The calculation formula for the sum of the potential lithium resources in the various types of thermal water storage is: L=∑(S i ×C i ×10 -9 ) in: L—potential resources of lithium metal, t; Si—mass of hot water stored in No. i thermal storage, kg; Ci—total lithium content in thermal storage water No. i, mg / kg; i=1,2,…,n.

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