Water solubility test method for cavity construction of salt cavern storage cavern

Abstract

The invention discloses a salt cavern reservoir cavity construction water solubility test method, and belongs to the technical field of salt cavern reservoir cavity construction, and the salt cavern reservoir cavity construction water solubility test method comprises the following steps: executing a lateral dissolution test; the lateral dissolution test comprises the following steps: obtaining the net weight of a rock sample; the two end faces of the rock sample are subjected to gluing isolation treatment; obtaining the weight of the rock sample subjected to the gluing isolation treatment; the suspension device is placed in the first measuring container, and after the suspension device is immersed in water in the first measuring container, the suspension device is weighed; placing the rock sample in a suspension device, and integrally weighing the rock sample and the suspension device after the rock sample and the suspension device are both immersed into the water in the first measuring container; within the first set duration, recording the overall weight of the rock sample and the suspension device once every second set duration; and calculating the dissolution rate of the rock sample by adopting a dissolution rate calculation formula. The dissolution rate of the rock sample is accurately obtained through the weight change of the rock sample.

Description

Technical Field

[0001] The present invention relates to the technical field of salt cave reservoir cavity creation, in particular to a water-soluble test method for salt cave reservoir cavity creation. Background Art

[0002] Salt cavern reservoirs utilize thick underground salt layers or salt domes, artificially creating cavernous storage spaces through water dissolution within these layers to store oil and natural gas for peak load regulation and strategic reserves. The key technology in salt cavern construction is salt cavern creation, which is crucial to the success of the construction project. The size and shape of the cavity are primarily determined by geological conditions and construction techniques. Therefore, before constructing a salt cavern reservoir, it is necessary to fully understand the structure, composition, and water-soluble characteristics of the salt layer, and to research and design how to construct a safe and stable salt cavity in the underground salt layer. This requires indoor simulation tests to measure the water-soluble characteristic parameters of the salt rock (dissolution rate, dissolution angle, etc.) in order to predict and control the volume and morphology of the cavity.

[0003] As one of the main types of storage, salt cavern storage has the advantages of high injection and production efficiency, large short-term throughput, and recoverable bottom gas.

[0004] At present, the determination of salt cavern storage cavity parameters in China is mainly based on the "Laboratory Test Methods and Requirements for Water Solubility of Salt Ores" in the field of salt mining. The test method used is mainly a water solubility test, in which the sample is dissolved in water and the water solubility rate is obtained by the change in sample size. The accuracy is not high. Summary of the Invention

[0005] The object of the present invention is to provide a salt cavern reservoir water dissolution test method, which can accurately obtain the dissolution rate of a rock sample through the weight change of the rock sample.

[0006] As conceived above, the technical solution adopted by the present invention is:

[0007] The water-soluble test method for salt cavern reservoir cavity creation includes the following steps:

[0008] S1. Perform lateral dissolution test;

[0009] The lateral dissolution test comprises the following steps:

[0010] S11. Obtain the net weight, height and diameter of the rock sample;

[0011] S12, applying glue to the two end surfaces of the rock sample for isolation;

[0012] S13, obtaining the weight of the rock sample after the glue coating and isolation treatment;

[0013] S14, placing the suspension device in a first measuring container, and weighing the suspension device after the suspension device is immersed in water in the first measuring container;

[0014] S15, placing the rock sample in the suspension device, and after both the rock sample and the suspension device are immersed in water in the first measuring container, weighing the rock sample and the suspension device as a whole;

[0015] S16. Within the first set time period, every second set time period, record the total weight of the rock sample and the suspension device;

[0016] S17. Calculate the dissolution rate k of the rock sample (1) using a dissolution rate calculation formula, wherein the dissolution rate calculation formula is:

[0017]

[0018] Wherein, k is the dissolution rate of the rock sample (1), in cm / sec;

[0019] t is the second set duration, in seconds;

[0020] С n is the limit concentration of rock salt in water, in g / cm 3 ;

[0021] С0 is the concentration of the solution, in g / cm 3 ;

[0022] ΔM is the mass loss of the rock sample (1) during the second set time, in g;

[0023] Unit is mm 2 ;

[0024] in, Unit is mm 2 ;

[0025] h is the initial height of the rock sample (1), in mm;

[0026] M0 is the initial mass of the rock sample (1), in g;

[0027] ρ is the density of the rock sample (1), in g / mm 3 .

[0028] Optionally, the salt cavern reservoir water-soluble test method further comprises the following steps:

[0029] S2. Perform a complete dissolution test to determine the weight of the insoluble residue after the rock sample is completely dissolved.

[0030] Optionally, the complete dissolution test comprises the following steps:

[0031] S21. After the lateral dissolution test is completed, the rock sample and the insoluble residue in the first measuring container are taken out and placed into a second measuring container, and water is poured into the second measuring container;

[0032] S22, weighing the pallet;

[0033] S23, after the rock sample is completely dissolved, placing the insoluble residue in the second measuring container into the tray;

[0034] S24, drying the tray and the insoluble residue on the tray;

[0035] S25. Weigh the tray and the insoluble residue on the tray as a whole.

[0036] Optionally, the complete dissolution test further comprises the following steps:

[0037] S26. Obtaining the degree of separation of the insoluble residue through a sieve plate assembly:

[0038] The sieve plate assembly includes several sieve plates stacked in sequence from bottom to top, and the sieve holes of the sieve plates gradually increase from bottom to top; the insoluble residue is placed on the uppermost sieve plate, and the sieve plate assembly is shaken reciprocatingly until no more insoluble residue falls to the lowermost sieve plate, and the insoluble residue on each sieve plate is weighed and recorded.

[0039] Optionally, the sieve plate assembly includes seven sieve plates, and from bottom to top, the sieve hole diameters of the seven sieve plates are: 0.125mm, 0.15mm, 0.2mm, 0.45mm, 0.6mm, 2mm, and 4mm.

[0040] Optionally, the complete dissolution test further comprises the following steps:

[0041] S27. Determine the volume of all the insoluble residues.

[0042] Optionally, step S25 includes:

[0043] S271, placing all the insoluble residues in a third measuring container, wherein the third measuring container is provided with a scale;

[0044] S272, pouring a set volume of water into the third measuring container;

[0045] S273. Read the scale value of the liquid level in the third measuring container at this time. The difference between the scale value and the set volume is the volume of all the insoluble residues.

[0046] Optionally, the suspension device is suspended on a beam, the beam is spaced apart on the upper side of the first measuring container, a weighing piece is provided on the beam, and the suspension device is connected to the weighing piece via a pull rope.

[0047] Optionally, the weighing device is a dynamometer or a balance.

[0048] Optionally, the water is distilled water.

[0049] The beneficial effects of the present invention are:

[0050] The salt cavern reservoir water dissolution test method proposed in the present invention obtains the dissolution rate of the rock sample by changing the mass (ie weight) of the rock sample, and the test result has high accuracy.

[0051] Compared with the irregular size changes of rock samples after dissolving in water, the weight changes of rock samples are used to obtain the dissolution rate of rock samples. Since the weight of rock samples can be measured more accurately and conveniently, a more accurate rock sample dissolution rate can be obtained. BRIEF DESCRIPTION OF THE DRAWINGS

[0052] Figure 1 1 is a schematic flow chart of a lateral dissolution test provided in an embodiment of the present invention;

[0053] Figure 2 It is a schematic diagram of a rock sample and a suspension device provided by an embodiment of the present invention being immersed in water in a first measuring container.

[0054] In the picture:

[0055] 1. Rock sample; 2. Suspension device; 3. First measuring container; 4. Crossbeam; 5. Weight measuring piece. DETAILED DESCRIPTION

[0056] To make the technical problems solved by the present invention, the technical solutions adopted, and the technical effects achieved more clearly, the technical solutions of the present invention are further described below with reference to the accompanying drawings and through specific embodiments. It should be understood that the specific embodiments described herein are merely for the purpose of explaining the present invention and are not intended to limit the present invention. It should also be noted that, for ease of description, the drawings only show portions relevant to the present invention, not all of them.

[0057] In the description of the present invention, it should be noted that the terms "center," "up," "down," "left," "right," "vertical," "horizontal," "inside," and "outside" and the like, indicating orientations or positional relationships, are based on the orientations or positional relationships shown in the accompanying drawings and are intended only to facilitate the description of the present invention and simplify the description. They do not indicate or imply that the devices or components referred to must have a specific orientation, be constructed, or operate in a specific orientation. Therefore, they should not be construed as limitations on the present invention. Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance. The terms "first position" and "second position" refer to two different positions.

[0058] In the description of the present invention, it should be noted that, unless otherwise expressly specified or limited, the terms "mounted," "connected," and "connected" should be understood broadly. For example, they may refer to fixed or detachable connections; mechanical or electrical connections; direct or indirect connections through an intermediary; and internal communication between two components. Those skilled in the art will understand the specific meanings of the above terms in the present invention.

[0059] See also Figure 1 and Figure 2 This embodiment provides a water-soluble test method for creating a salt cavern reservoir.

[0060] The water dissolution test method for salt cavern reservoir cavity creation accurately obtains the dissolution rate of the rock sample 1 by changing the mass (i.e., weight) of the rock sample 1. The operation is simple and can quickly meet the needs of gas storage cavity creation simulation.

[0061] Specifically, the salt cavern reservoir water-soluble test method is characterized by comprising the following steps:

[0062] S1. Perform lateral dissolution test;

[0063] The lateral dissolution test includes the following steps:

[0064] S11, obtaining the net weight, height and diameter of the rock sample 1;

[0065] Specifically, the net weight of the rock sample 1 is obtained by weighing; after weighing, the net weight of the rock sample 1 is recorded; after weighing, the rock sample 1 is photographed, and the height and diameter of the rock sample 1 are measured and recorded;

[0066] S12, applying glue to the two end surfaces of the rock sample 1 for isolation;

[0067] Specifically, the glue-coating isolation treatment can prevent the end face of the rock sample 1 from being dissolved by water;

[0068] S13, obtaining the weight of the rock sample 1 after the glue coating and isolation treatment;

[0069] Specifically, in step S13, the weight of the rock sample 1 after the glue-coating and isolation treatment is obtained by weighing;

[0070] S14, placing the suspension device 2 in the first measuring container 3, and weighing the suspension device 2 after the suspension device 2 is immersed in the water in the first measuring container 3;

[0071] S15, placing the rock sample 1 in the suspension device 2, and after both the rock sample 1 and the suspension device 2 are immersed in the water in the first measuring container 3, weighing the rock sample 1 and the suspension device 2 as a whole;

[0072] S16. Within the first set time period, every second set time period, record the total weight of the rock sample 1 and the suspension device 2;

[0073] S17. Calculate the dissolution rate k of rock sample 1 using the dissolution rate calculation formula. The dissolution rate calculation formula is:

[0074]

[0075] Where, k is the dissolution rate of rock sample 1, in cm / sec;

[0076] t is the second set duration, in seconds;

[0077] С n is the limit concentration of rock salt in water, in g / cm 3 ;

[0078] С0 is the concentration of the solution, in g / cm 3 ;

[0079] ΔM is the mass loss of rock sample 1 within the second set time, in g;

[0080] Unit is mm 2 ;

[0081] in, Unit is mm 2 ;

[0082] h is the initial height of rock sample 1, in mm;

[0083] M0 is the initial mass of rock sample 1, in g;

[0084] ρ is the density of rock sample 1, in g / mm 3 .

[0085] The salt cavern reservoir water dissolution test method provided in this embodiment obtains the dissolution rate of the rock sample 1 by the change in the mass (ie, weight) of the rock sample 1, and the test result has high accuracy.

[0086] Specifically, in this embodiment, S cp is the average area of ​​the dissolved surface of rock sample 1.

[0087] Specifically, in this embodiment, С n 0.317g / cm 3 This value is the limit concentration of rock salt in water at a temperature of 20°C.

[0088] In this embodiment, water is distilled water, С0=1g / cm 3 .

[0089] Specifically, the shape of the rock sample 1 is cylindrical.

[0090] ΔM is the mass loss of the rock sample 1 within the second set time period, and the mass loss of the rock sample 1 within the second set time period may be the average mass loss of the rock sample 1 within multiple second set time periods. For example, in step S16, four values ​​are recorded, and the four values ​​are: M n 、M n+1 、M n+2 and M n+3 , get the three differences in order: M n -M n+1 、M n+1 -M n+2 and M n+2 -M n+3 , and obtain the average value of the three differences, which is ΔM.

[0091] Specifically, the suspension device 2 is suspended on the crossbeam 4 , which is spaced apart on the upper side of the first measuring container 3 . A weighing piece 5 is provided on the crossbeam 4 , and the suspension device 2 is connected to the weighing piece 5 via a pull rope.

[0092] In step S14 , after the suspension device 2 is immersed in the water in the first measuring container 3 , the measurement result of the weighing member 5 is read to obtain the weight of the suspension device 2 in the water.

[0093] Specifically, in step S15 , after the rock sample 1 and the suspension device 2 are immersed in the water in the first measuring container 3 , the overall weight of the rock sample 1 and the suspension device 2 in the water can be obtained.

[0094] Specifically, the suspension device 2 serves to support the rock sample 1 . The suspension device 2 includes a suspension plate. Both ends of the suspension plate are provided with pull ropes. The upper ends of the pull ropes are connected to the weighing piece 5 .

[0095] Furthermore, the crossbeam 4 is a crossbeam 4 of a gantry.

[0096] Specifically, the weighing element 5 is a dynamometer or a balance.

[0097] Preferably, in step S16, the first set time length is 1 hour; the second set time length is 2 minutes.

[0098] That is, within 1 hour, the total weight of the rock sample 1 and the suspension device 2 in water is recorded every 2 minutes. After 1 hour, the lateral dissolution test is completed.

[0099] After the lateral dissolution test is completed, the total weight of the rock sample 1 and the suspension device 2 in the water after the lateral dissolution test is subtracted from the total weight of the rock sample 1 and the suspension device 2 in the water recorded in step S15 to obtain the amount of rock sample 1 dissolved, thereby obtaining the dissolution rate of the rock sample 1.

[0100] Furthermore, the salt cavern reservoir water-soluble test method further includes the following steps:

[0101] S2. Perform a complete dissolution test to determine the weight of the insoluble residue after the rock sample 1 is completely dissolved.

[0102] For rock samples that need to be completely dissolved, step S2 is performed.

[0103] Specifically, the complete dissolution test includes the following steps:

[0104] S21. After the lateral dissolution test is completed, the rock sample 1 and the insoluble residue in the first measuring container 3 are taken out and placed into a second measuring container, and water is poured into the second measuring container;

[0105] S22, weighing the pallet;

[0106] S23. After the rock sample 1 is completely dissolved, the insoluble residue in the second measuring container is placed in a tray;

[0107] S24, drying the tray and the insoluble residue on the tray;

[0108] S25. Weigh the tray and the insoluble residue on the tray as a whole.

[0109] After step S25 is performed, the weight of the insoluble residue after the rock sample 1 is completely dissolved can be obtained.

[0110] Specifically, in step S24, the tray and the insoluble residue on the tray are placed in a drying cabinet and dried for at least 5 hours at a drying temperature not lower than 105°C.

[0111] Specifically, when the rock sample 1 and the insoluble residue are dissolved in the second measuring container, the water in the second measuring container can be replaced as needed to increase the dissolution rate; it should be noted that the insoluble residue cannot be lost during the water replacement process.

[0112] Furthermore, the complete dissolution test further comprises the following steps:

[0113] S26. Obtaining the degree of separation of insoluble residues through the sieve plate assembly:

[0114] The sieve plate assembly includes several sieve plates stacked in sequence from bottom to top, and the sieve holes of the sieve plates gradually increase from bottom to top; the insoluble residue is placed on the uppermost sieve plate, and the sieve plate assembly is shaken back and forth until no more insoluble residue falls to the lowermost sieve plate, and the insoluble residue on each sieve plate is weighed and recorded.

[0115] During the reciprocating shaking of the screen plate assembly, the insoluble residue will fall through the screen holes on the screen plate.

[0116] Specifically, when weighing the insoluble residue on each sieve plate, the residue on each layer of sieve plates is placed on a balance for weighing.

[0117] Optionally, in this embodiment, the sieve plate assembly includes seven sieve plates, and the sieve hole diameters of the seven sieve plates are, from bottom to top, 0.125 mm, 0.15 mm, 0.2 mm, 0.45 mm, 0.6 mm, 2 mm, and 4 mm, respectively.

[0118] Further preferably, a solid plate is placed below the lowermost sieve plate.

[0119] Furthermore, the complete dissolution test further comprises the following steps:

[0120] S27. Determine the volume of all insoluble residues.

[0121] Specifically, step S27 includes:

[0122] S271. Place all insoluble residues in a third measuring container, where the third measuring container is provided with a scale;

[0123] Specifically, in step S271, if there are large pieces in the insoluble residue that are difficult to directly place into the third measuring container, the large pieces can be carefully separated with a tool so that they can be smoothly placed into the third measuring container;

[0124] S272, pouring a set volume of water into the third measuring container;

[0125] It is understood that the set volume of water is sufficient to cover all insoluble residues;

[0126] Optionally, the volume of water is set to 1000 ml;

[0127] S273. Read the scale value of the liquid level in the third measuring container at this time. The difference between the scale value and the set volume is the volume of all insoluble residues.

[0128] Preferably, the specification of the third measuring container is 2000±20 ml.

[0129] Optionally, in this embodiment, the weight measurement accuracy can be 0.1g or 0.01g; the volume measurement accuracy is ±20ml.

[0130] In the existing technology, the "Laboratory Test Methods and Requirements for Water Solubility of Salt Ores" requires that the diameter of the test sample must not be less than 90 mm, and the length after cutting the top and bottom surfaces flat must be 20 cm. The test sample specifications are required to be single.

[0131] However, by using the water-soluble test method for salt cavern reservoirs provided in this embodiment, the test can be performed even if the diameter of the rock sample 1 is less than 90 mm and the height is less than 20 cm.

[0132] In the existing technology, the "Laboratory Test Methods and Requirements for Water-Solubility of Salt Ores" requires that the side-dissolving sample "be further cut off a side with a width of 7 cm" and "the processed sample be coated with a boiling mixture of paraffin and asphalt in a ratio of about 1:1, and a 7cm×15cm exposed surface is left on the cut side as the dissolution test surface. That is, the upper 3cm, lower 2cm, cylindrical surface, top and bottom surfaces of the cut side of the sample are all sealed with paraffin and asphalt liquid." This results in a cumbersome processing and preparation process for the test samples.

[0133] However, using the water-soluble test method for salt cavern reservoirs provided in this embodiment, it is only necessary to coat the top and bottom of the rock sample 1, i.e., the side-soluble sample, with glue for isolation.

[0134] In the existing technology, the "Laboratory Test Methods and Requirements for Water Solubility of Salt Ores" requires "observation every 15 minutes, half an hour or every hour." Under normal circumstances, most top dissolution experiments require more than 20 hours to complete, and side dissolution also requires more than 10 hours. Experimental personnel need to work in two shifts to ensure the continuity of the experiment and its smooth completion.

[0135] By using the water-soluble test method for salt cavern gas storage cavity creation provided in this embodiment, the water-soluble part only needs two hours to obtain the required experimental data for salt cavern gas storage cavity creation simulation.

[0136] The above embodiments merely illustrate the basic principles and features of the present invention. The present invention is not limited to the above embodiments. Various changes and modifications may be made to the present invention without departing from the spirit and scope of the present invention. Such changes and modifications are intended to fall within the scope of the present invention. The scope of protection claimed in the present invention is defined by the appended claims and their equivalents.

Claims

1. A water-soluble test method for salt cavern reservoirs, characterized in that: The following steps are involved: S1. Perform lateral dissolution test; The lateral dissolution test comprises the following steps: S11, obtaining the net weight, height and diameter of the rock sample (1); S12, applying glue to the two end faces of the rock sample (1) for isolation; S13, obtaining the weight of the rock sample (1) after the glue-coating isolation treatment; S14, placing the suspension device (2) in a first measuring container (3), and after the suspension device (2) is immersed in water in the first measuring container (3), weighing the suspension device (2); S15, placing the rock sample (1) in the suspension device (2), and after both the rock sample (1) and the suspension device (2) are immersed in the water in the first measuring container (3), weighing the rock sample (1) and the suspension device (2) as a whole; S16. Within the first set time period, every second set time period, record the total weight of the rock sample (1) and the suspension device (2); S17. Calculate the dissolution rate k of the rock sample (1) using a dissolution rate calculation formula, wherein the dissolution rate calculation formula is: Wherein, k is the dissolution rate of the rock sample (1), in cm / sec; t is the second set duration, in seconds; С n is the limit concentration of rock salt in water, in g / cm 3 ; С0 is the concentration of the solution, in g / cm 3 ; ΔM is the mass loss of the rock sample (1) during the second set time, in g; Unit is mm 2 ; in, Unit is mm 2 ; h is the initial height of the rock sample (1), in mm; M0 is the initial mass of the rock sample (1), in g; ρ is the density of the rock sample (1), in g / mm 3 .

2. The water-soluble test method for salt cavern reservoir construction according to claim 1, characterized in that: The salt cavern reservoir water-soluble test method further comprises the following steps: S2. Perform a complete dissolution test to determine the weight of the insoluble residue after the rock sample (1) is completely dissolved.

3. The water-soluble test method for salt cavern reservoir construction according to claim 2, characterized in that: The complete dissolution test comprises the following steps: S21. After the lateral dissolution test is completed, the rock sample (1) and the insoluble residue in the first measuring container (3) are taken out and placed in a second measuring container, and water is poured into the second measuring container; S22, weighing the pallet; S23, after the rock sample (1) is completely dissolved, the insoluble residue in the second measuring container is placed into the tray; S24, drying the tray and the insoluble residue on the tray; S25. Weigh the tray and the insoluble residue on the tray as a whole.

4. The water-soluble test method for salt cavern reservoir cavity creation according to claim 3, characterized in that: The complete dissolution test further comprises the following steps: S26. Obtaining the degree of separation of the insoluble residue through a sieve plate assembly: The sieve plate assembly includes several sieve plates stacked in sequence from bottom to top, and the sieve holes of the sieve plates gradually increase from bottom to top; the insoluble residue is placed on the uppermost sieve plate, and the sieve plate assembly is shaken reciprocatingly until no more insoluble residue falls to the lowermost sieve plate, and the insoluble residue on each sieve plate is weighed and recorded.

5. The water-soluble test method for salt cavern reservoir construction according to claim 4, characterized in that: The sieve plate assembly includes seven sieve plates. From bottom to top, the sieve hole diameters of the seven sieve plates are: 0.125mm, 0.15mm, 0.2mm, 0.45mm, 0.6mm, 2mm, and 4mm.

6. The water-soluble test method for salt cavern reservoir construction according to claim 4, characterized in that: The complete dissolution test further comprises the following steps: S27. Determine the volume of all the insoluble residues.

7. The water-soluble test method for salt cavern reservoir construction according to claim 6, characterized in that: The step S25 includes: S271, placing all the insoluble residues in a third measuring container, wherein the third measuring container is provided with a scale; S272, pouring a set volume of water into the third measuring container; S273. Read the scale value of the liquid level in the third measuring container at this time. The difference between the scale value and the set volume is the volume of all the insoluble residues.

8. The water-soluble test method for salt cavern reservoir construction according to claim 1, characterized in that: The suspension device (2) is suspended on a crossbeam (4), the crossbeam (4) is spaced apart on the upper side of the first measuring container (3), a weighing piece (5) is provided on the crossbeam (4), and the suspension device (2) is connected to the weighing piece (5) via a pull rope.

9. The water-soluble test method for salt cavern reservoir construction according to claim 8, characterized in that: The weighing piece (5) is a dynamometer or a balance.

10. The water-soluble test method for salt cavern reservoir construction according to any one of claims 1 to 9, characterized in that: The water is distilled water.

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