Monitoring method and device for open-hole dissolution in the initial stage of ultra-deep salt cavern reservoir construction

Abstract

The present application relates to the technical field of water-soluble mining of salt mines, and discloses a method and device for monitoring the initial open-hole dissolution of ultra-deep salt cavern reservoirs. The monitoring method comprises: calculating the wellhead radius and the height of the salt layer in the open-hole section based on drilling data; injecting water into the well to discharge the brine in the well, and measuring the first mass percentage concentration of sodium chloride in the brine in the well; when the water injection into the well reaches a set time, measuring the second mass percentage concentration of sodium chloride in the brine in the well and the mass of the brine discharged within the set time; calculating the mass of salt in the brine based on the first mass percentage concentration, the second mass percentage concentration, and the discharged mass; and calculating the diameter of the salt layer in the open-hole section based on the salt mass, the wellhead radius, the height of the salt layer in the open-hole section, and the discharged mass. The salt layer in the open-hole section is expanded by injecting water into the drill bit, and the expanded size of the salt layer in the open-hole section and the amount of sediment formed are determined by measuring the concentration difference of sodium chloride and its change.

Description

Technical Field

[0001] The present application relates to the technical field of salt mine solution mining, and in particular, to a method and device for monitoring the naked-hole dissolution condition in the early stage of cavitation in ultra-deep salt cavern reservoirs. Background Art

[0002] Before water-dissolution cavitation in deep salt cavern reservoirs, the open-hole salt layer will shrink and deform under the influence of deep high-ground stress, and may even close. This will seriously affect the lowering of the drill bit and casing, and interfere with logging work and subsequent cavitation. The expansion of the open-hole salt layer is generally carried out by water dissolution. During the water dissolution process, interlayers may be encountered in the open-hole salt layer, affecting the subsequent water dissolution cavitation process. In addition, there is a lack of methods to detect the expansion of the open-hole salt layer during the well drilling process, making it impossible to control the expansion diameter of the open-hole salt layer. In summary, the creep closure of the open-hole salt layer in deep gas storage reservoirs will affect the water dissolution cavitation process, and there is a lack of reasonable and effective methods to monitor the diameter of the open-hole salt layer and the amount of sediment formed. Summary of the Invention

[0003] The purpose of this application is to provide a method and device for monitoring the open hole dissolution in the early stage of ultra-deep salt cavern reservoir formation. The salt layer in the open hole section is expanded by injecting water through the drill bit, and the expansion size of the salt layer in the open hole section and the amount of sediment formation are determined by measuring the concentration difference and change of sodium chloride.

[0004] Other features and advantages of the present application will become apparent from the following detailed description, or may be learned in part by practice of the present application.

[0005] According to one aspect of an embodiment of the present application, a method for monitoring open-hole dissolution in the initial stage of cavitation in an ultra-deep salt cavern reservoir is provided, the monitoring method comprising: calculating a wellhead radius and a salt layer height in an open-hole section based on drilling data; injecting water into the well to discharge brine in the well, and measuring a first mass percentage concentration of sodium chloride in the brine in the well; when water is injected into the well for a set time, measuring a second mass percentage concentration of sodium chloride in the brine in the well and the mass of the brine discharged within the set time; calculating the mass of salt in the brine based on the first mass percentage concentration, the second mass percentage concentration, and the discharged mass; and calculating the diameter of the salt layer in the open-hole section based on the salt mass, the wellhead radius, the salt layer height in the open-hole section, and the discharged mass.

[0006] In some embodiments, after the water injection into the well reaches a set time, the second mass percentage concentration of sodium chloride in the brine in the well and the mass of the brine discharged within the set time are measured and obtained, the monitoring method further includes: continuously injecting water into the well, obtaining a mass percentage concentration of sodium chloride at each set time interval, and continuously obtaining a preset number of mass percentage concentrations; and determining the amount of sediment formed based on the preset number of mass percentage concentrations.

[0007] In some embodiments, in determining the amount of sediment formed according to the preset number of mass percentage concentrations, the monitoring method includes: if two consecutive mass percentage concentrations differ by a preset concentration value, determining that an estimated amount of sediment is formed at the bottom of the well.

[0008] In some embodiments, in calculating the salt mass in the brine according to the first mass percentage concentration, the second mass percentage concentration, and the discharged mass, the salt mass is calculated using the following formula:

[0009] m salt =ΔcM 总 =(c2-c1)M 总 ;

[0010] Among them, m salt is the mass of salt, c1 is the first mass percentage concentration, c2 is the second mass percentage concentration, M 总 The discharge quality of brine.

[0011] In some embodiments, in calculating the diameter of the open hole salt layer according to the salt mass, the wellhead radius, the height of the open hole salt layer, and the discharge mass, the open hole salt layer diameter 2R is calculated using the following formula:

[0012]

[0013] Where R is the radius of the salt layer in the open hole, c1 is the first mass percent concentration, c2 is the second mass percent concentration, M 总 is the discharge mass of brine, ρ is the solid salt density, h is the height of the salt layer in the open hole section, and r is the wellhead radius.

[0014] In some embodiments, the set duration is set to 15 minutes.

[0015] According to one aspect of an embodiment of the present application, a monitoring device for the initial open hole dissolution of an ultra-deep salt cavern reservoir is provided, the monitoring device adopts the monitoring method as described above, and the monitoring device includes: a technical casing, the technical casing being arranged on the inner wall of a well; a brine drainage pipe, the brine drainage pipe being connected to the technical casing at one end of the wellhead; a drill rod, the interior of which can transport liquid, one end of the drill rod being arranged outside the well and connected to a water injection pipe, the other end of the drill rod being connected to a drill bit, and extending through the brine drainage pipe through the inner side of the technical casing to below the salt layer in the open hole section, the drill bit being provided with a plurality of water outlets; and a water injection valve, the water injection valve being arranged on the water injection pipe to control the switch of the water injection pipe.

[0016] In some embodiments, the monitoring device further includes a concentration detector, which is disposed on the brine discharge pipe to detect the mass percentage concentration of sodium chloride in the brine.

[0017] In some embodiments, the monitoring device further includes a drain valve, which is disposed on the brine drainage pipe to control the switch of the brine drainage pipe.

[0018] In some embodiments, the monitoring device further includes a first flow meter and a second flow meter, wherein the first flow meter is disposed on the water injection pipe, and the second flow meter is disposed on the brine discharge pipe.

[0019] The technical solution of the present application has the following significant beneficial effects compared with the prior art: the two ends of the drill rod of the present application are respectively connected to the water injection pipe and the drill bit, and when the drill bit enters below the salt layer of the open hole section, the salt layer of the open hole section is expanded by injecting water through the drill bit; the salt mass in the brine is calculated by measuring the first mass percentage concentration, the second mass percentage concentration and the discharged mass of the brine, and the diameter of the salt layer of the open hole section is calculated according to the salt mass, the wellhead radius, the height of the salt layer of the open hole section and the discharged mass, thereby knowing the expanded size of the salt layer of the open hole section; the amount of sediment formed is determined according to the preset mass percentage concentration; the drill bit is positioned below the salt layer of the open hole section, thereby ensuring that fresh water can fully dissolve the salt layer of the open hole section.

[0020] It should be understood that the foregoing general description and the following detailed description are exemplary and explanatory only and are not restrictive of the present application. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] The above and other features and advantages of the present application will become more apparent by describing in detail exemplary embodiments thereof with reference to the attached drawings.

[0022] Figure 1 A flow chart of a monitoring method according to an embodiment of the present application is shown;

[0023] Figure 2 A schematic diagram of the structure before water injection according to one embodiment of the present application is shown;

[0024] Figure 3 A schematic structural diagram of drill pipe water injection according to one embodiment of the present application is shown;

[0025] Figure 4 A schematic structural diagram of salt layer expansion in an open hole section after continuous water injection according to an embodiment of the present application is shown.

[0026] The accompanying numerals are explained as follows: 1. technical casing; 2. brine drainage pipe; 3. wellhead; 4. drill pipe; 5. water injection pipe; 6. drill bit; 7. water injection valve; 8. concentration detector; 9. drainage valve; 10. first flow meter; 11. second flow meter; 12. salt layer in the open hole section; 13. interlayer; 14. salt layer in the cavity section. DETAILED DESCRIPTION

[0027] Example embodiments will now be described more fully with reference to the accompanying drawings. However, example 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 so that this application will be thorough and complete and will fully convey the concepts of the example embodiments to those skilled in the art.

[0028] In addition, described feature, structure or characteristic can be combined in one or more embodiments in any suitable manner.In the following description, many specific details are provided so as to provide a full understanding of the embodiments of the present application. However, it will be appreciated by those skilled in the art that the technical scheme of the present application can be put into practice without one or more of the specific details, or other methods, components, devices, steps etc. can be adopted. In other cases, known methods, devices, implementations or operations are not shown or described in detail to avoid blurring the various aspects of the application.

[0029] The block diagrams shown in the accompanying drawings are merely functional entities and do not necessarily correspond to physically separate entities. That is, these functional entities may be implemented in software, in one or more hardware modules or integrated circuits, or in different networks and / or processor devices and / or microcontroller devices.

[0030] The flowcharts shown in the accompanying drawings are for illustrative purposes only and do not necessarily include all contents and operations / steps, nor must they be executed in the order described. For example, some operations / steps may be decomposed, while others may be combined or partially combined. Therefore, the actual execution order may vary depending on the actual situation.

[0031] The following is a brief description of the method for monitoring the initial open-hole dissolution of the ultra-deep salt cavern reservoir in the embodiment of the present application:

[0032] According to some embodiments, Figure 1 As shown, the present application provides a method for monitoring the open-hole dissolution in the early stage of ultra-deep salt cavern reservoir formation, the monitoring method comprising:

[0033] Step 101, calculating and obtaining the radius of the wellhead 3 and the height of the salt layer 12 in the open hole section based on the drilling data;

[0034] Step 102: injecting water into the well to discharge the brine in the well, and measuring and obtaining a first mass percentage concentration of sodium chloride in the brine in the well;

[0035] Step 103, when the water injection into the well reaches a set time, the second mass percentage concentration of sodium chloride in the brine in the well and the mass of the brine discharged within the set time are measured;

[0036] Step 104, calculating the mass of salt in the brine based on the first mass percentage concentration, the second mass percentage concentration, and the discharged mass;

[0037] Step 105 : Calculate the diameter of the open hole section salt layer 12 according to the salt mass, the radius of the wellhead 3 , the height of the open hole section salt layer 12 , and the discharge mass.

[0038] Based on the above embodiment, in step 101, the radius of the wellhead 3 and the height of the salt layer 12 in the open hole section are calculated and obtained according to the drilling data.

[0039] like Figures 2 to 4 As shown, the well contains, from top to bottom, an openhole salt layer 12, an interlayer 13, and a cavity-forming salt layer 14. A technical casing 1 is attached to the wellbore inner wall, one end of which is connected to a brine drainage pipe 2 through a wellhead 3. A drill pipe 4 is connected to an injection pipe 5 at one end and a drill bit 6 at the other. The drill bit 6 and drill pipe 4 penetrate the sidewall of the brine drainage pipe 2 and extend through the interior of the technical casing 1 to below the openhole salt layer 12.

[0040] After preparation is completed, enter step 102, control the water injection pipe 5 to open, the water injection pipe 5 inputs fresh water into the drill pipe 4, the drill pipe 4 outputs fresh water through the drill bit 6, the fresh water and the solute in the well form brine, and fresh water is continuously injected into the well to discharge the brine in the well through the brine discharge pipe 2, and the first mass percentage concentration of sodium chloride in the brine is measured.

[0041] In step 103, when water injection into the well reaches a set time, the second mass percentage concentration of sodium chloride in the brine in the well and the mass of the brine discharged during the set time are measured. The set time can be set according to actual needs. In some embodiments, the set time is set to 15 minutes. The mass of the brine discharged is the total mass of the brine discharged during the set time period.

[0042] In step 104, the mass of salt in the brine is calculated based on the first mass percentage concentration, the second mass percentage concentration, and the discharge mass.

[0043] In step 105 , the diameter of the open hole section salt layer 12 is calculated based on the salt mass, the radius of the wellhead 3 , the height of the open hole section salt layer 12 , and the discharge mass.

[0044] In the present application, both ends of the drill rod 4 are connected to the water injection pipe 5 and the drill bit 6 respectively. When the drill bit 6 enters below the open hole salt layer 12, the open hole salt layer 12 is expanded by injecting water through the drill bit 6; the salt mass in the brine is calculated by measuring the first mass percentage concentration, the second mass percentage concentration and the discharged mass of the brine, and the diameter of the open hole salt layer 12 is calculated according to the salt mass, the radius of the wellhead 3, the height of the open hole salt layer 12 and the discharged mass, thereby knowing the expanded size of the open hole salt layer 12; the position of the drill bit 6 extends below the open hole salt layer 12, thereby ensuring that the fresh water can fully dissolve the open hole salt layer 12.

[0045] In order to make those skilled in the art better understand this application, Figure 1 The details of this application are described in detail.

[0046] According to some embodiments, in step 104, after the water injection into the well reaches a set time, the second mass percentage concentration of sodium chloride in the brine in the well and the mass of the brine discharged within the set time are measured and obtained, the monitoring method further includes:

[0047] Step 1041: continuously inject water into the well, obtain a mass percentage concentration of sodium chloride at each set time interval, and continuously obtain a preset number of mass percentage concentrations;

[0048] Step 1042: Determine the amount of sediment formed according to the preset mass percentage concentration.

[0049] Based on the above embodiment, the set duration can be set according to actual needs. In some embodiments, the set duration is set to 15 minutes. Water is continuously injected, and a mass percentage concentration of sodium chloride is obtained every 15 minutes, and a preset number of mass percentage concentrations are continuously obtained. The preset number can be set according to actual needs.

[0050] Furthermore, in step 1042, in determining the amount of sediment formed according to the preset mass percentage concentration, the monitoring method includes:

[0051] If two consecutive mass percentage concentrations differ by a preset concentration value, it is determined that an estimated amount of sediment has formed at the bottom of the well.

[0052] Based on the above example, if the mass percentage concentration of sodium chloride varies slightly every 15 minutes, it indicates that the sediment content in the openhole salt layer 12 is high. At this point, no new sodium chloride dissolves within the well, and the sediment from the openhole salt layer 12 accumulates mostly at the bottom of the wellhead 3. The preset concentration value can be set based on actual needs and is close to 0. The estimated value varies based on the preset concentration value. The estimated value is used to assess the amount of sediment at the bottom of the wellhead 3.

[0053] According to some embodiments, in step 105, the mass of salt in the brine is calculated based on the first mass percentage concentration, the second mass percentage concentration, and the discharged mass, and the salt mass is calculated using the following formula:

[0054] m salt =ΔcM 总 =(c2-c1)M 总 ;

[0055] Among them, m salt is the mass of salt, c1 is the first mass percentage concentration, c2 is the second mass percentage concentration, M 总 The discharge quality of brine.

[0056] Further, in step 106, the diameter of the open hole section salt layer 12 is calculated based on the salt mass, the radius of the wellhead 3, the height of the open hole section salt layer 12 and the discharge mass, wherein m salt =ρ salt ×π(R 2 -r 2 )h, after substituting the two formulas, the following formula is obtained to calculate the diameter 2R of the salt layer 12 in the open hole section:

[0057]

[0058] Where R is the radius of the salt layer 12 in the open hole section, c1 is the first mass percent concentration, c2 is the second mass percent concentration, and M 总 is the discharge mass of brine, ρ is the solid salt density, h is the height of the open hole salt layer 12, r is the radius of the wellhead 3, and Δc is the concentration difference. If Δc changes little in the later period and is within the preset concentration value, it means that the sediment content in the open hole salt layer 12 is high. At this time, no new sodium chloride will be dissolved in the well, and most of the sediment in the open hole salt layer 12 will accumulate at the bottom of the wellhead 3.

[0059] The following is a brief description of the monitoring device for the initial open-hole dissolution of the ultra-deep salt cavern reservoir in the embodiment of the present application:

[0060] According to some embodiments, Figures 2 to 4 As shown, the present application provides a monitoring device for the early stage of open-hole dissolution in ultra-deep salt cavern reservoirs. The monitoring device adopts the monitoring method described above, and the monitoring device includes:

[0061] A technical casing 1, wherein the technical casing 1 is arranged on the inner wall of the well;

[0062] A brine discharge pipe 2, the brine discharge pipe 2 being connected to a technical casing 1 at one end of a wellhead 3;

[0063] A drill pipe 4, wherein liquid can be transported inside the drill pipe 4. One end of the drill pipe 4 is disposed outside the well and is connected to a water injection pipe 5. The other end of the drill pipe 4 is connected to a drill bit 6, which passes through the brine drainage pipe 2 and extends through the inside of the technical casing 1 to below the salt layer 12 in the open hole section. The drill bit 6 has multiple water outlets.

[0064] The water injection valve 7 is provided on the water injection pipe 5 to control the switch of the water injection pipe 5 .

[0065] Based on the above embodiment, the other end of the drill pipe 4 is connected to a drill bit 6. The drill pipe 4 and drill bit 6 pass through the brine drainage pipe 2 and then extend through the inside of the technical casing 1 to below the open hole salt layer 12. The water injection valve 7 is opened, and the water injection pipe 5 inputs fresh water into the drill pipe 4. The drill pipe 4 outputs fresh water through the drill bit 6. The fresh water and the solutes in the well form brine. The drill bit 6 is located below the open hole salt layer 12 to ensure that the fresh water can fully dissolve the open hole salt layer 12. Fresh water is continuously injected into the well, and the brine rises to the technical casing 1. After further fresh water injection, the brine is discharged through the brine drainage pipe 2.

[0066] In order to make those skilled in the art better understand this application, Figures 2 to 4 The details of this application are described in detail.

[0067] According to some embodiments, Figure 3 As shown, the monitoring device further includes a concentration detector 8, which is arranged on the brine discharge pipe 2 to detect the mass percentage concentration of sodium chloride in the brine.

[0068] Based on the above embodiment, when the brine is discharged through the brine discharge pipe 2, the concentration detector 8 on the brine discharge pipe 2 detects the mass percentage concentration of sodium chloride in the brine.

[0069] According to some embodiments, Figure 3 As shown, the monitoring device further includes a drain valve 9 , which is provided on the brine discharge pipe 2 to control the switch of the brine discharge pipe 2 .

[0070] According to some embodiments, Figure 3 As shown, the monitoring device further includes a first flow meter 10 and a second flow meter 11 . The first flow meter 10 is arranged on the water injection pipe 5 , and the second flow meter 11 is arranged on the brine discharge pipe 2 .

[0071] Based on the above embodiment, the amount of fresh water injected is recorded by the first flow meter 10, and the mass of brine discharged every 15 minutes is recorded by the second flow meter 11.

[0072] Those skilled in the art will readily conceive of other embodiments of the present application after considering the specification and practicing the embodiments disclosed herein. This application is intended to cover any variations, uses, or adaptations of the present application that follow the general principles of this application and include common knowledge or customary techniques in the art that are not disclosed herein.

[0073] It should be understood that the present application is not limited to the exact structures described above and shown in the drawings, and that various modifications and changes may be made without departing from the scope thereof. The scope of the present application is limited only by the appended claims.

Claims

1. A method for monitoring the initial open-hole dissolution of ultra-deep salt cavern reservoirs, characterized in that: The monitoring method comprises: Calculate the wellhead radius and salt layer height in the open hole section based on drilling data; injecting water into the well to discharge the brine in the well, and measuring and obtaining a first mass percentage concentration of sodium chloride in the brine in the well; When water is injected into the well for a set time, the second mass percentage concentration of sodium chloride in the brine in the well and the mass of the brine discharged within the set time are measured; Calculating the mass of salt in the brine according to the first mass percentage concentration, the second mass percentage concentration and the discharged mass; Calculating the diameter of the salt layer in the open hole section according to the salt mass, the wellhead radius, the height of the salt layer in the open hole section, and the discharge mass; Continuously inject water into the well, obtain a mass percentage concentration of sodium chloride at each set time interval, and continuously obtain a preset number of mass percentage concentrations; If two consecutive mass percentage concentrations in the preset number of mass percentage concentrations differ by a preset concentration value, it is determined that a predetermined amount of sediment is formed at the bottom of the well.

2. The monitoring method according to claim 1, characterized in that: In calculating the salt mass in the brine according to the first mass percentage concentration, the second mass percentage concentration and the discharged mass, the salt mass is calculated using the following formula: ； in, is the mass of salt, is the first mass percent concentration, is the second mass percent concentration, The discharge quality of brine.

3. The monitoring method according to claim 2, characterized in that: In the calculation of the diameter of the open hole salt layer according to the salt mass, wellhead radius, open hole salt layer height and discharge mass, the following formula is used to calculate the diameter of the open hole salt layer: : in, is the radius of the salt layer in the open hole section, is the first mass percent concentration, is the second mass percent concentration, is the discharge quality of brine, is the density of solid salt, is the height of the salt layer in the open hole section, is the wellhead radius.

4. The monitoring method according to claim 1, characterized in that: The set duration is set to 15 minutes.

5. A monitoring device for the initial open-hole dissolution of ultra-deep salt cavern reservoirs, the monitoring device adopting the monitoring method according to any one of claims 1 to 4, characterized in that: The monitoring device comprises: A technical casing, which is arranged on the inner wall of the well; a brine drainage pipe, the brine drainage pipe being connected to a technical casing at one end of the wellhead; A drill pipe, wherein the interior of the drill pipe can transport liquid. One end of the drill pipe is arranged outside the well and is connected to a water injection pipe. The other end of the drill pipe is connected to a drill bit, which passes through the brine drainage pipe and extends to below the salt layer in the open hole section through the inside of the technical casing. The drill bit is provided with multiple water outlets. A water injection valve is provided on the water injection pipe to control the switch of the water injection pipe.

6. The monitoring device according to claim 5, characterized in that The monitoring device also includes a concentration detector, which is arranged on the brine discharge pipe to detect the mass percentage concentration of sodium chloride in the brine.

7. The monitoring device according to claim 6, characterized in that The monitoring device also includes a drain valve, which is arranged on the brine discharge pipe to control the switch of the brine discharge pipe.

8. The monitoring device according to claim 7, characterized in that The monitoring device further includes a first flow meter and a second flow meter, wherein the first flow meter is arranged on the water injection pipe, and the second flow meter is arranged on the brine discharge pipe.

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