Method for predicting sediment accumulation angle of water-soluble salt rock storage cavity

Abstract

The application relates to the technical field of salt rock underground storage, in particular to a salt rock storage water-soluble cavity sediment accumulation angle prediction method. The method comprises the following steps: preparing at least four groups of sediment samples according to different particle sizes; obtaining average particle parameters and average accumulation angles of the sediment samples; obtaining an initial prediction formula of the accumulation angle, wherein the initial prediction formula of the accumulation angle comprises four prediction parameters; calculating the prediction parameters according to the average particle parameters and the average accumulation angles, and determining an accumulation angle prediction formula, so as to realize the prediction of the sediment accumulation angle. The application solves the problems that the sediment particle accumulation angle is not easy to measure and is not accurately measured, improves the transparency of the underground sediment particle accumulation, and can be used not only for analyzing the dynamic accumulation angle change process of the salt cavity bottom sediment particles in the water-soluble cavity forming process, but also for predicting the sediment accumulation situation at the bottom of the unexplored salt cave.

Description

Technical Field

[0001] This application relates to the field of underground salt rock storage technology, and more specifically, to a method for predicting the angle of accumulation of sediment in water-soluble cavity construction of salt rock storage. Background Technology

[0002] Currently, water-soluble cavity construction is a key technology for building salt rock reservoirs and has been widely applied in the field of salt cavern gas storage. However, my country's salt rock has many interlayers, and these interlayers contain a lot of insoluble impurities. After water-soluble cavity construction, the insoluble substances in the salt layer lose their support and slide off the salt wall. For insoluble substances in thin interlayers, they will be deposited as powder or particles at the bottom of the salt cavity during the process of being eroded by brine. For thicker interlayers, there is a possibility of overall collapse. The falling sediment will occupy the mining space, sometimes more than 60%, and the accumulation pattern of the sediment will restrict the volume of gas injection and brine discharge in the salt cavity.

[0003] Predicting the accumulation morphology of insoluble matter is crucial for the development of the entire brine cavity. Insoluble matter forms the bottom boundary of the cavity, and the height of its accumulation affects the overall height of the brine cavity. Simultaneously, the accumulation of insoluble matter can prevent the salt walls it covers from dissolving, thus reducing the volume of the brine cavity; in some cases, the height of the insoluble matter can even reach tens of meters, requiring control measures. Furthermore, the accumulation morphology of insoluble matter can also affect the water injection and brine drainage process of the cavity-forming tubing, and may even block the tubing.

[0004] In summary, controlling and predicting the accumulation morphology of insoluble matter at the bottom of salt caverns during water-soluble cavity formation is crucial, and the angle of repose is the most important factor affecting this morphology. Therefore, predicting the angle of repose is essential for analyzing sediment accumulation morphology. The angle of repose is related to many factors, including the coefficient of friction between particles, the coefficient of restitution, the shear modulus, Poisson's ratio, particle size, particle shape, and humidity. Due to the numerous influencing factors, an effective method for predicting the angle of repose has not yet been developed. Furthermore, due to the underground invisibility of salt cavern sediment particles, purely laboratory analysis ignores scale effects, which significantly impacts the accuracy of particle analysis. In addition, while the angle of repose is often considered constant in engineering, it actually changes significantly with changes in particle morphology.

[0005] In summary, the prediction of the angle of packing of sediment plays a significant role in analyzing the morphology of insoluble matter at the bottom of salt chambers and predicting the overall volume of the chamber during the water-soluble chamber-making process. However, under current standards, there is still no effective method for predicting the angle of packing of sediment particles.

[0006] Therefore, those skilled in the art urgently need a method for predicting the angle of accumulation of sediment in water-soluble cavity formation of salt rock reservoirs, so as to effectively predict the angle of accumulation of sediment at the bottom of the salt cavity. Summary of the Invention

[0007] The embodiments of this application provide a method for predicting the angle of accumulation of sediment in a salt reservoir with water-soluble cavity, which can at least to some extent effectively predict the angle of accumulation of sediment at the bottom of the salt cavity.

[0008] Other features and advantages of this application will become apparent from the following detailed description, or may be learned in part from practice of this application.

[0009] According to one aspect of the embodiments of this application, a method for predicting the angle of repose of sediment in a salt rock reservoir is provided. The method includes: preparing at least four groups of sediment samples according to different particle sizes; obtaining the average particle parameters and average angle of repose of each group of sediment samples; obtaining an initial prediction formula for the angle of repose, the initial prediction formula for the angle of repose including at least one prediction parameter; fitting each prediction parameter according to the average particle parameters and average angle of repose of each group to determine the angle of repose prediction formula, so as to achieve the prediction of the angle of repose of sediment.

[0010] In some embodiments of this application, the step of preparing at least four groups of sediment samples according to different particle sizes includes: collecting sediment samples at least once and subjecting the sediment samples to constant temperature treatment; and screening and grouping the sediment samples according to different particle sizes to obtain at least four groups of sediment samples.

[0011] In some embodiments of this application, the average particle parameters include: average sphericity, average roundness, and average particle diameter.

[0012] In some embodiments of this application, based on the aforementioned scheme, obtaining the average particle parameters of each group of sediment samples includes: measuring the sphericity, roundness, and particle diameter of each group of sediment samples, and calculating the average sphericity, average roundness, and average particle diameter of each group of sediment samples.

[0013] In some embodiments of this application, obtaining the average angle of repose of each group of sediment samples includes: conducting at least three particle drop tests on each group of sediment samples to determine the average angle of repose of each group of sediment samples.

[0014] In some embodiments of this application, based on the foregoing scheme, obtaining the initial prediction formula for the angle of repose includes: determining the initial prediction formula for the angle of repose based on the average sphericity, the average roundness, and the correlation between the average particle diameter and the angle of repose.

[0015] In some embodiments of this application, based on the foregoing scheme, the initial prediction formula for the angle of accumulation is expressed by the following formula:

[0016]

[0017] Where AOR represents the predicted angle of repose of the sediment, k1, k2, k3, and k4 are prediction parameters, q is the mean sphericity, α is the mean roundness, and d is the mean particle diameter.

[0018] In some embodiments of this application, based on the foregoing scheme, the step of fitting each prediction parameter according to the average particle parameters of each group and the average angle of repose to determine the angle of repose prediction formula includes: substituting the average sphericity, average roundness, average particle diameter, and average angle of repose of each group into the initial angle of repose prediction formula; fitting the prediction parameters of each initial angle of repose prediction formula to calculate at least one prediction parameter; and determining the angle of repose prediction formula according to each prediction parameter.

[0019] Based on the above solution, this application has at least the following advantages or advancements:

[0020] In some embodiments of this application, the technical solutions involve obtaining the average particle parameters and average angle of repose of at least four sets of sediment samples. These parameters are then substituted into the initial prediction formula for the angle of repose to calculate the predicted parameters, thereby determining the prediction formula for the angle of repose and enabling the prediction of the sediment's angle of repose. This application solves the problem of uncertainty in the sediment accumulation morphology beneath salt caverns by fitting the predicted parameters, achieving transparency in the sediment's angle of repose. This is of great significance for the volume analysis of water-soluble salt caverns.

[0021] It should be understood that the above general description and the following detailed description are exemplary and explanatory only, and do not limit this application. Attached Figure Description

[0022] The accompanying drawings, which are incorporated in and form part of this specification, illustrate embodiments consistent with this application and, together with the description, serve to explain the principles of this application.

[0023] Obviously, the accompanying drawings described below are only some embodiments of this application. For those skilled in the art, other drawings can be obtained from these drawings without creative effort.

[0024] In the attached diagram:

[0025] Figure 1 A flowchart is shown below illustrating a method for predicting the angle of accumulation of sediment in a salt rock reservoir with water-soluble cavity construction, according to an embodiment of this application.

[0026] Figure 2 A schematic diagram illustrating sphericity and roundness according to one embodiment of this application is shown;

[0027] Figure 3A simplified schematic diagram illustrating the mathematical measurement of sphericity and roundness according to one embodiment of this application is shown.

[0028] Figure 4 A schematic diagram of an experimental setup for testing the angle of accumulation of sediment in a laboratory according to one embodiment of this application is shown;

[0029] Wherein, 1-sphericity, 2-roundness, 3-sludge particles, 4-circumscribed sphere, 5-circumscribed circle, 6-inscribed circle. Detailed Implementation

[0030] Exemplary embodiments will now be described more fully with reference to the accompanying drawings. However, these exemplary embodiments can be implemented in many forms and should not be construed as limited to the examples set forth herein; rather, these embodiments are provided to make this application more comprehensive and complete, and to fully convey the concept of the exemplary embodiments to those skilled in the art.

[0031] Furthermore, the described features, structures, or characteristics can be combined in any suitable manner in one or more embodiments. Numerous specific details are provided in the following description to give a thorough understanding of embodiments of this application. However, those skilled in the art will recognize that the technical solutions of this application can be practiced without one or more of the specific details, or other methods, components, apparatuses, steps, etc., can be employed. In other instances, well-known methods, apparatuses, implementations, or operations are not shown or described in detail to avoid obscuring various aspects of this application.

[0032] The flowcharts shown in the accompanying drawings are merely illustrative and do not necessarily include all content and operations / steps, nor do they necessarily have to be performed in the described order. For example, some operations / steps can be broken down, while others can be combined or partially combined; therefore, the actual execution order may change depending on the specific circumstances.

[0033] It should be noted that "multiple" in this article refers to two or more. "And / or" describes the relationship between related objects, indicating that three relationships can exist. For example, A and / or B can represent: A alone, A and B simultaneously, or B alone. The character " / " generally indicates that the preceding and following related objects have an "or" relationship.

[0034] The implementation details of the technical solutions in the embodiments of this application are described in detail below:

[0035] Please see Figure 1 .

[0036] Figure 1 A flowchart illustrating a method for predicting the angle of accumulation of sediment in a salt rock reservoir with water-soluble cavity construction according to an embodiment of this application is shown, as follows: Figure 1As shown, the method may include steps S101-S104:

[0037] Step S101: Prepare at least four groups of sediment samples according to different particle sizes.

[0038] Step S102: Obtain the average particle parameters and average angle of repose for each group of sediment samples.

[0039] Step S103: Obtain the initial prediction formula for the angle of accumulation, which includes four prediction parameters;

[0040] Step S104: Based on the average particle parameters and average angle of repose of each group, fit each prediction parameter to determine the angle of repose prediction formula, so as to realize the prediction of the angle of repose of the sediment.

[0041] In this application, the method for preparing at least four groups of sediment samples according to different particle sizes may include steps S201-S202:

[0042] Step S201: Collect at least one sediment sample and perform constant temperature treatment on the sediment sample;

[0043] Step S202: According to different particle sizes, the sediment samples are screened and grouped through a multi-stage sieve to obtain at least four groups of sediment samples.

[0044] In this application, sediment samples can be obtained directly from the bottom of the salt cavity through a wellbore, which is suitable for predicting the sediment deposition angle of salt cavities that have already been water-dissolved. Alternatively, salt rock samples from the salt cavity can be obtained by core drilling, and then dissolved in fresh water to obtain sediment samples, which is suitable for measuring the sediment deposition angle of undeveloped salt cavities.

[0045] In this application, in order to ensure that the obtained sediment samples can represent the state under real conditions, the sediment samples can be repeated three or more times, and then these obtained sediment samples can be mixed multiple times to eliminate the error problem caused by uneven sediment sampling, thereby obtaining a sufficient number of sediment particle samples with good uniformity.

[0046] In this application, after collecting the sediment sample, the sediment sample can be dried for 48 hours to obtain salt rock sediment particles, and then screened using a three-layer multi-stage sieve (so that the sediment particles can pass through sieves with different pore sizes) to obtain four groups of sediment samples with different particle size ranges.

[0047] In this application, the average particle parameters may include: average sphericity, average roundness, and average particle diameter.

[0048] Please refer to the following. Figure 2 , Figure 2A schematic diagram illustrating sphericity and roundness according to one embodiment of this application is shown, as follows: Figure 2 As shown, sphericity 1 is a mathematical measure of the degree of deviation between the sediment particles 3 and the outer sphere 4. The greater the sphericity, the smoother the sediment particles 3 are, the closer the contact between the sediment particles 3, and the smaller the gaps.

[0049] Roundness 2 refers to the mathematical measure of the angularity of the sediment particles, that is, the relative protrusion of the sediment particles 3 and the outer sphere. It is an important factor that determines the natural angle of repose of the sediment particles and an important factor that affects the friction performance of the sediment particles. A large angularity indicates that the right-angle interlocking effect of the sediment particles is strong and the number of contact points varies greatly. Therefore, it exhibits stronger shear strength and internal friction angle, which in turn increases the natural angle of repose of the sediment particles.

[0050] Please see Figure 3 , Figure 3 A schematic diagram illustrating mathematical measurements of sphericity and roundness according to one embodiment of this application is shown.

[0051] Among them, such as Figure 3 As shown, the formula for calculating sphericity can be:

[0052]

[0053] Where, r max The radius r represents the radius of the largest inscribed circle 6 of the sediment particles. min The radius of the largest circumcircle of the sediment particles is 5. See details. Figure 3 If the q value is close to 1, it indicates that the sphericity is good, the sludge particles are smooth, and the voids are small, which can be used as an important measure of the shape of the sludge particles.

[0054] Among them, such as Figure 3 As shown, the formula for calculating roundness is:

[0055]

[0056] Where P is the outer perimeter of the projected sediment particle 3, and A is the maximum projected area of ​​the sediment particle. The closer the value is to 1, the smoother its shape is; the larger the value is, the rougher it is.

[0057] In this application, the method for obtaining the average particle parameters of each group of sediment samples may include: measuring at least one sphericity, roundness, and particle diameter of each group of sediment samples, and calculating the average sphericity, average roundness, and average particle diameter of each group of sediment samples.

[0058] In this application, the sphericity, roundness, and particle diameter of the extracted sediment samples can be measured. The sphericity, roundness, and particle diameter of each group of sediment particles 3 are measured three times, and then the average value is taken.

[0059] In this application, after calculating the average sphericity, average roundness, and average particle diameter of each group of sediment samples, the size of the sediment's angle of repose can be preliminarily analyzed based on the average sphericity and average roundness of the sediment samples. If the average sphericity and average roundness of the sediment samples are close to 1, it indicates that the sphericity and roundness of the sediment samples are very good, and the corresponding angle of repose can be determined as the angle of repose under ideal conditions. At this time, the sediment morphology is approximately a near-horizontal sediment accumulation morphology. The so-called near-horizontal sediment accumulation morphology refers to the sediment surface morphology of the salt cave sediment accumulation body exhibiting a relatively horizontal state. Because the sphericity and roundness of the particles are relatively large, the frictional ability between sediment particles is less than the sliding force between particles, so the final morphology of the particles is a near-horizontal state.

[0060] In this application, if the average sphericity and average roundness of the sediment sample are both less than 1, the angle of repose can be reasonably predicted by constructing an angle of repose prediction formula.

[0061] In this application, the method for obtaining the average angle of repose of each group of sediment samples may include: conducting at least three particle drop experiments on each group of sediment samples, determining the angle of repose of each particle drop experiment, and thus determining the average angle of repose of each group of sediment samples.

[0062] Please see Figure 4 , Figure 4 This diagram illustrates a laboratory setup for testing the angle of repose of sediment according to one embodiment of this application. Four groups of sediment particles, sieved through a three-layer multi-stage sieve, are then subjected to... Figure 4 The small-hole leakage stacking apparatus shown in the diagram performs three free-fall tests on sediment particles, and then takes the average of these three tests to obtain the stacking angle of this set of sediment samples. This yields a set of data on the stacking angle in relation to sphericity, roundness, and particle diameter. The same operation is then performed on other sets of sediment samples to obtain three other sets of data on the stacking angle in relation to sphericity, roundness, and particle diameter.

[0063] In this application, the method for obtaining the initial prediction formula for the angle of repose may include: determining the initial prediction formula for the angle of repose based on the average sphericity, the average roundness, and the correlation between the average particle diameter and the angle of repose.

[0064] In this application, the physical meaning of the angle of repose and various parameters has been considered and verified. The larger the sphericity and roundness, the smaller the angle of repose; the larger the particle diameter, the larger the angle of repose. Therefore, the initial prediction formula for the angle of repose is obtained as follows:

[0065]

[0066] Where AOR represents the predicted angle of repose of the sediment, k1, k2, k3, and k4 are prediction parameters, q is the mean sphericity, α is the mean roundness, and d is the mean particle diameter.

[0067] In this application, the method for determining the repose angle prediction formula by fitting each prediction parameter based on the average particle parameters and average repose angle of each group may include steps S601-S603:

[0068] Step S601: Substitute the average sphericity, average roundness, and average particle diameter of each group into the initial prediction formula for the angle of repose.

[0069] Step S602: Calculate the prediction parameters for each initial prediction formula of the accumulation angle, and calculate at least one prediction parameter.

[0070] Step S603: Determine the formula for predicting the angle of accumulation based on each prediction parameter.

[0071] In this application, each set of sediment samples corresponds to a set of data on average sphericity, average roundness, average particle diameter, and average angle of repose. By substituting the parameters into the above formula, at least one equation about k1, k2, k3, and k4 can be obtained. By combining the corresponding equations of each set, a set of equations can be constructed. Based on the set of equations, k1, k2, k3, and k4 are obtained, and the set of k1, k2, k3, and k4 with the highest degree of fit is obtained, thereby determining the formula for predicting the angle of repose.

[0072] For example, given the aforementioned four sets of sediment samples, and having measured the average sphericity, average roundness, average particle diameter, and average angle of repose respectively, it is not difficult to obtain the following set of equations:

[0073]

[0074] Then, based on the system of equations, k1, k2, k3, and k4 are calculated to obtain their values, thereby determining the formula for predicting the angle of accumulation.

[0075] In this application, the more groups of sediment samples collected, the higher the accuracy of the formula fitting.

[0076] In this application, by obtaining the average particle parameters and average angle of repose of at least four sets of sediment samples, the average particle parameters and average angle of repose of each set are substituted into the initial prediction formula for the angle of repose, and the prediction parameters are fitted to obtain the prediction formula for the angle of repose, thereby determining the prediction formula for the sediment angle of repose. This application solves the problem of uncertainty in the sediment accumulation morphology underground in salt caverns by calculating the prediction parameters, and realizes the transparency of the sediment angle of repose, which is of great significance for the volume analysis of salt caverns in water-soluble cavity construction.

[0077] In this application, the prediction formula can also predict the sediment accumulation situation in areas where water-soluble cavity creation has not yet been carried out, and can also measure salt rock samples at a specific stratum to analyze the changes in their sediment accumulation angle.

[0078] In this application, dynamic testing and prediction of the angle of accumulation of sediment can be achieved. Compared with the traditional engineering practice experience that the angle of accumulation does not change, dynamic prediction of the angle of accumulation is more in line with actual needs.

[0079] Other embodiments of this application will readily occur to those skilled in the art upon consideration of the specification and practice of the embodiments disclosed herein. This application is intended to cover any variations, uses, or adaptations of this application that follow the general principles of this application and include common knowledge or customary techniques in the art not disclosed herein.

[0080] It should be understood that this application is not limited to the precise structure described above and shown in the accompanying drawings, and various modifications and changes can be made without departing from its scope. The scope of this application is limited only by the appended claims.

Claims

1. A method for predicting the sediment accumulation angle of a salt rock repository aqueous cavity, characterized in that, The method comprises: preparing at least four groups of sediment samples according to different particle sizes; obtaining average particle parameters and average packing angles of the groups of sediment samples; obtaining an initial prediction formula of the packing angle, which comprises four prediction parameters; calculating the prediction parameters according to the average particle parameters and the average packing angles of each group to determine a prediction formula of the packing angle, so as to realize prediction of the packing angle of the sediment; the average particle parameters comprise average sphericity, average roundness, and average particle diameter; the obtaining of the initial prediction formula of the packing angle comprises: determining the initial prediction formula of the packing angle according to the correlation between the average sphericity, the average roundness, the average particle diameter, and the packing angle; the initial prediction formula of the packing angle is represented by the following formula: wherein AOR represents the predicted packing angle of the sediment, k1, k2, k3, and k4 are prediction parameters, q is the average sphericity, a is the average roundness, and d is the average particle diameter; the calculation of the prediction parameters according to the average particle parameters and the average packing angles of each group to determine the prediction formula of the packing angle comprises: substituting the average sphericity, the average roundness, the average particle diameter, and the average packing angle of each group into the initial prediction formula of the packing angle; performing prediction parameter fitting on each initial prediction formula of the packing angle to calculate at least one prediction parameter; determining the prediction formula of the packing angle according to each prediction parameter.

2. The method of claim 1, wherein, the preparation of at least four groups of sediment samples according to different particle sizes comprises: collecting at least one sediment sample and performing constant-temperature treatment on the sediment sample; performing screening and grouping treatment on the sediment sample by a multi-stage screen according to different particle sizes to obtain at least four groups of sediment samples.

3. The method of claim 1, wherein, the obtaining of the average particle parameters of each group of sediment samples comprises: respectively measuring the sphericity, the roundness, and the particle diameter of each group of sediment samples to calculate the average sphericity, the average roundness, and the average particle diameter of each group of sediment samples.

4. The method of claim 1, wherein, the obtaining of the average packing angle of each group of sediment samples comprises: performing at least three particle falling experiments on each group of sediment samples to determine the packing angle of each group of particle falling experiments and to determine the average packing angle of each group of sediment samples.

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