A method and system for monitoring gas storage well bore annulus leaks

Abstract

The application discloses a method and system for monitoring annular leakage of a gas storage well shaft, comprising the following steps: analyzing geological conditions, geological profiles and seismic profile results of a current gas storage area, and determining ground monitoring points having a communication relationship with downhole leakage points; determining a corresponding annular monitoring point configuration scheme of the current gas storage well at each casing; and setting corresponding acquisition components at the ground monitoring points and the annular monitoring points, so as to form a sensor networking system. The application can provide monitoring guarantee for safety and environmental safety of gas storage.

Description

Technical Field

[0001] This invention relates to the field of gas storage well safety monitoring technology, and in particular to a method and system for monitoring annular leakage in gas storage wells. Background Technology

[0002] With advancements in energy technology and the environmental impact of modern industrial gases, gas storage wells have become an important technological means of storing energy and greenhouse gases, such as gas storage facilities, hydrogen storage wells, and CO2 gas storage in CCUS (Chemical Containment Systems). The most crucial aspect of gas storage technology is ensuring the safety of the stored gas; therefore, leak monitoring of stored gases has become a critical technology for safeguarding safety.

[0003] In the safety monitoring of gas storage wells, wellbore leakage risk is a significant concern, particularly the detection of the wellbore annulus, which presents a major technical challenge. During well construction, casings of varying sizes are fixed with cement, and the spaces between the casings and the formation are filled with cement, creating a sealed annulus. However, over time, factors such as cement quality, cementing techniques, prolonged underground chemical and physical reactions, and changes in the formation can damage the cement, leading to cracks, dissolution, corrosion, and fissures at the cement-formation interface. This disrupts the annulus seal, allowing trapped gas to leak through these gaps. If these gaps connect to the surface, to faults or fractures in the formation, or to existing or abandoned wells in the area, the annulus seal will completely fail, resulting in gas leakage to the surface and posing a serious threat to the ecological environment and biosafety.

[0004] Because the wellbore annulus is sealed with a cement ring, real-time long-term monitoring of its sealing performance presents significant challenges: 1. The wellbore annulus section is long and completely filled with cement, making it extremely difficult to place detection sensors within it; 2. Even if sensors are placed along the casing within the annulus, the steel casing, being completely sealed, presents technical difficulties such as the inability to supply power and transmit data, which are very difficult to resolve.

[0005] Existing methods for evaluating wellbore sealing are mostly conducted in laboratories. By understanding the characteristics of the cement sheath, these methods aim to avoid the risk of seal failure when preparing cement for well cementing. However, these methods cannot be used for on-site monitoring. Summary of the Invention

[0006] The purpose of this invention is to provide a wellbore annulus leakage monitoring scheme for gas storage wells, which can achieve long-term on-site monitoring of wellbore annulus leakage and ensure the safety of gas storage.

[0007] To address the aforementioned technical problems, this invention provides a method for monitoring annular leakage in a gas storage well, comprising: analyzing the geological conditions, geological profiles, and seismic profiles of the current gas storage area to determine ground monitoring points connected to the downhole leakage point; determining the configuration scheme of annular monitoring points at each casing layer of the current gas storage well; and setting corresponding acquisition components at the ground monitoring points and the annular monitoring points to form a sensor network system.

[0008] Preferably, the step of analyzing the geological conditions, geological profiles, and seismic profiles of the current gas storage area to determine the surface monitoring points connected to the downhole leakage point includes: clarifying the geological characteristics of the underground reservoir and caprock, as well as the groundwater hydrological characteristics, through the analysis of the geological conditions and geological profiles of the current gas storage area; based on the seismic profile results of the current gas storage area, combined with the geological characteristics of the underground reservoir and caprock, and the groundwater hydrological characteristics, clarifying the connection between the underground geological bodies that may become leakage channels and the surface, as well as the existing drilled wellbores within the gas storage area connected by the leakage channels; conducting geological analysis on the traversal of the actual drilling trajectory of the current gas storage well to clarify the underground geological bodies with leakage risk connected by the actual well trajectory and the existing wellbores; and determining the surface monitoring points based on the connectivity of the underground bodies that may become leakage channels, the existing drilled wellbores within the gas storage area connected by the leakage channels, and the underground geological bodies and existing wellbores when the actual drilling trajectory traverses the underground.

[0009] Preferably, the step of determining the configuration scheme of annular monitoring points at each casing layer of the current gas storage well includes: analyzing the annular cementing situation of each casing layer during the drilling and construction of the gas storage well, clarifying the return height and cementing quality of the annular cement at each casing layer, and determining the configuration scheme of annular monitoring points for each casing layer based on this. Specifically, a first type of annular monitoring point configuration scheme is configured in the annulus of adjacent casing layers. This first type of annular monitoring point is used to monitor whether stored gas leaks to the surface through failed annular cement. The first type of annular monitoring point configuration scheme involves setting multiple first-type sensor groups evenly distributed circumferentially at the current casing annulus layer near the surface. A second type of annular monitoring point configuration scheme is configured around the casing layer. This second type of annular monitoring point is used to monitor whether the underground gas sealed in the gas storage well leaks to the surface along the outer wall of the casing. The second type of annular monitoring point configuration scheme involves setting multiple second-type sensor groups evenly distributed circumferentially at the outermost casing layer near the surface.

[0010] Preferably, the first type of sensor group includes, but is not limited to, gas sensors, temperature sensors, pressure sensors, and flow sensors.

[0011] Preferably, the second type of sensor group includes, but is not limited to, a gas sensor for measuring the near-surface concentration of gas stored in a gas well, a flux sensor for measuring soil gas concentration, a sensor for measuring groundwater pH, and an ion sensor.

[0012] Preferably, the method further includes: transmitting the information collected in real time by each set of acquisition components to the annular leakage online monitoring system, so that the annular leakage online monitoring system can analyze the downhole leakage situation and leakage location through the leakage channel represented by the monitoring point.

[0013] Preferably, the method further includes: drilling holes in each cement sheath layer using a small drill bit after cementing and before well completion, and simultaneously drilling holes between the outermost cement sheath and the formation cementing surface, to construct a space for accommodating the acquisition components at different monitoring point locations.

[0014] Preferably, if the cement sheath in the casing annulus rises to the surface, a rubber sealing layer is installed in each casing annulus space. The rubber sealing layer contains corresponding pre-drilled channels. A small drill bit is used to drill holes in each cement sheath layer within these pre-drilled channels, ensuring that leaked gas can only return to the wellhead through the corresponding channels. If the cement sheath in the casing annulus does not rise to the surface, a rubber sealing layer is directly installed in each casing annulus space. The rubber sealing layer contains pre-drilled channels, ensuring that leaked gas can only return to the wellhead of each casing through the corresponding channels. The drilling depth between the outermost cement sheath and the formation bonding surface is below the surface water table.

[0015] Preferably, a wellhead integration device is constructed for sealing, fixing, and installing the various acquisition components at the annular monitoring point; a multi-channel first-type data acquisition system is constructed for communicating with the various acquisition components at the annular monitoring point and completing signal acquisition, so as to obtain annular monitoring sensor data in real time; a multi-channel second-type data acquisition system is constructed for communicating with the ground sensor group at the ground monitoring point and completing signal acquisition, so as to obtain ground monitoring sensor data in real time; a data transmission system is constructed for communicating with the first-type data acquisition system and the second-type data acquisition system, so as to transmit the annular monitoring sensor data and the ground monitoring sensor data to the annular leakage online monitoring system through the data transmission system.

[0016] On the other hand, a system for monitoring annular leakage in a gas storage well is provided, the system being constructed using the method described above.

[0017] Compared with the prior art, one or more embodiments of the above solutions may have the following advantages or beneficial effects:

[0018] This invention proposes a method and system for monitoring annular leakage in gas storage wells. This method and system can effectively monitor whether gas storage wells, such as hydrogen storage, gas storage, and CCUS wells, have experienced gas leakage. By analyzing the source of the leakage, the leak location can be quickly pinpointed, providing monitoring assurance for gas storage safety and environmental safety. Specific effects are as follows:

[0019] 1. A method for monitoring the risk of annular leakage in gas storage wells was established, solving the technical difficulties of monitoring the annulus in the wellbore;

[0020] 2. It has good deployment and implementation capabilities, good maintainability of the sensors, is easy to install and use, and has controllable costs;

[0021] 3. The use of wired and / or wireless networking of monitoring points facilitates the connection of sensors at each monitoring point, which is beneficial to the monitoring work.

[0022] Other features and advantages of the invention will be set forth in the description which follows, and will be apparent in part from the description, or may be learned by practicing the invention. The objects and other advantages of the invention may be realized and obtained by means of the structures particularly pointed out in the description, claims, and drawings. Attached Figure Description

[0023] The accompanying drawings are provided to further illustrate the invention and form part of the specification. They are used in conjunction with the embodiments of the invention to explain the invention and do not constitute a limitation thereof. In the drawings:

[0024] Figure 1 This is a schematic diagram illustrating the steps of a method for monitoring annular leakage in a gas storage well according to an embodiment of this application.

[0025] Figure 2 This is a schematic diagram illustrating the specific process of a method for monitoring annular leakage in a gas storage well according to an embodiment of this application.

[0026] Figure 3 This is a top view example of the configuration scheme of annular monitoring points at each casing layer in the method for monitoring annular leakage in a gas storage well according to an embodiment of this application.

[0027] Figure 4 This is a side view example of the configuration scheme of annular monitoring points at each casing layer in the method for monitoring annular leakage in a gas storage well according to an embodiment of this application.

[0028] Figure 5 This is a schematic diagram of the system for monitoring annular leakage in a gas storage well, according to an embodiment of this application. Detailed Implementation

[0029] The embodiments of the present invention will be described in detail below with reference to the accompanying drawings and examples, so that the process of how the present invention uses technical means to solve technical problems and achieve technical effects can be fully understood and implemented accordingly. It should be noted that, as long as there is no conflict, the various embodiments and features in the various embodiments of the present invention can be combined with each other, and the resulting technical solutions are all within the protection scope of the present invention.

[0030] Furthermore, the steps illustrated in the flowcharts of the accompanying drawings can be executed in a computer system such as a set of computer-executable instructions. Also, although a logical order is shown in the flowcharts, in some cases the steps shown or described may be performed in a different order than that shown here.

[0031] The terminology used herein is for the purpose of describing particular embodiments only and is not intended to limit the exemplary embodiments. Unless the context clearly indicates otherwise, the singular forms “a” and “an” as used herein are also intended to include the plural. It should also be understood that the terms “comprising” and / or “including” as used herein specify the presence of the stated features, integers, steps, operations, units, and / or components, without excluding the presence or addition of one or more other features, integers, steps, operations, units, components, and / or combinations thereof.

[0032] With advancements in energy technology and the environmental impact of modern industrial gases, gas storage wells have become an important technological means of storing energy and greenhouse gases, such as gas storage facilities, hydrogen storage wells, and CO2 gas storage in CCUS (Chemical Containment Systems). The most crucial aspect of gas storage technology is ensuring the safety of the stored gas; therefore, leak monitoring of stored gases has become a critical technology for safeguarding safety.

[0033] In the safety monitoring of gas storage wells, wellbore leakage risk is a significant concern, particularly the detection of the wellbore annulus, which presents a major technical challenge. During well construction, casings of varying sizes are fixed with cement, and the spaces between the casings and the formation are filled with cement, creating a sealed annulus. However, over time, factors such as cement quality, cementing techniques, prolonged underground chemical and physical reactions, and changes in the formation can damage the cement, leading to cracks, dissolution, corrosion, and fissures at the cement-formation interface. This disrupts the annulus seal, allowing trapped gas to leak through these gaps. If these gaps connect to the surface, to faults or fractures in the formation, or to existing or abandoned wells in the area, the annulus seal will completely fail, resulting in gas leakage to the surface and posing a serious threat to the ecological environment and biosafety.

[0034] Because the wellbore annulus is sealed with a cement ring, real-time long-term monitoring of its sealing performance presents significant challenges: 1. The wellbore annulus section is long and completely filled with cement, making it extremely difficult to place detection sensors within it; 2. Even if sensors are placed along the casing within the annulus, the steel casing, being completely sealed, presents technical difficulties such as the inability to supply power and transmit data, which are very difficult to resolve.

[0035] Existing methods for evaluating wellbore sealing are mostly conducted in laboratories. By understanding the characteristics of the cement sheath, these methods aim to avoid the risk of seal failure when preparing cement for well cementing. However, these methods cannot be used for on-site monitoring.

[0036] To address the aforementioned technical problems, this application proposes a method and system for monitoring annular leakage in gas storage wells. Specifically, firstly, a geological survey and analysis are conducted on the entire gas storage area, including the strike of underground strata, geological outcrops, and regional geological profiles, to understand the geological characteristics and hydrological conditions of the reservoir caprock. Combined with seismic profile results, the potential leakage faults and water layers are further identified. Geological analysis is performed on the well trajectory to understand the strata, faults, and water layers traversed by the well trajectory underground. Possible leakage channels are determined, along with existing / abandoned wells connected to these channels, and surface monitoring points are identified. During the drilling and construction of the gas storage well, necessary monitoring channels are set up within the casing annulus and at the cement sheath-surface bonding surface. Various detection sensors are installed within these channels, and the monitoring data from each sensor is integrated to achieve data monitoring and early warning. This effectively monitors the annular leakage status of the gas storage well and analyzes the leakage point, ensuring the safety of the gas storage well and the environment. This invention can effectively monitor whether annular leakage has occurred in a gas storage well, thereby ensuring the safety of the gas storage well and the storage area.

[0037] Figure 1 This is a schematic diagram illustrating the steps of a method for monitoring annular leakage in a gas storage well according to an embodiment of this application. Figure 1 As shown in the embodiment of the present invention, the method for monitoring annular leakage in a gas storage well (also referred to as the "wellbore annular leakage method") includes the following steps: Step S110 analyzes the geological conditions, geological profiles, and seismic profiles of the current gas storage area to determine surface monitoring points connected to the downhole leakage point; Step S120 determines the configuration scheme of annular monitoring points at each casing layer of the current gas storage well; Step S130 sets up corresponding acquisition components at each surface monitoring point and each annular monitoring point to form a sensor network system. Thus, the embodiment of the present invention can utilize the formed sensor network system to complete long-term monitoring of annular leakage near the wellhead and directly pinpoint the downhole leakage location through the connectivity between the monitoring points and the downhole leakage point.

[0038] Figure 2 This is a schematic flowchart illustrating a method for monitoring annular leakage in a gas storage well according to an embodiment of this application. The following is in conjunction with... Figure 2 The process of the wellbore annulus leakage method described in the embodiments of the present invention will be specifically explained.

[0039] like Figure 2As shown, step 1001 first clarifies the geological characteristics of the underground reservoir and caprock, as well as the groundwater characteristics, by analyzing the geological conditions and geological profiles of the current gas storage area. In step 1001, the geological conditions of the entire gas storage area are investigated and analyzed. Combined with the geological profiles, the fault strike, underground stratum strike, and geological outcrop conditions within the current gas storage area are determined, thereby clarifying the geological characteristics of the underground reservoir and caprock, and the groundwater conditions.

[0040] Step 1002: Based on the seismic profile results of the current gas storage area, and combined with the geological characteristics of the underground reservoir and caprock, as well as the groundwater hydrological characteristics obtained in Step 1001, determine the connectivity between underground geological bodies that may become leakage channels and the surface, and identify the existing drilled wells within the gas storage area connected by the leakage channels. Specifically, first analyze the seismic profile results of the current gas storage area, and combine them with the geological characteristics of the underground reservoir and caprock, as well as the groundwater hydrological characteristics obtained in Step 1001, to determine the connectivity between underground geological bodies such as fractures, faults, and water layers that may become leakage channels and the surface, and identify the existing drilled wells within the gas storage area connected by the leakage channels.

[0041] In step 1003, a geological analysis is performed on the actual drilling trajectory of the current gas storage well to identify the underground geological bodies with leakage risks connected by the actual well trajectory and existing wellbores. Specifically, the well trajectory formed during the actual drilling process of the current gas storage well is obtained, and a geological analysis is performed on the geological passage of the well trajectory during drilling to determine the underground geological bodies connected by the well trajectory, such as strata, faults, and water layers, as well as the existing and abandoned wells connected by these leakage channels.

[0042] Step 1004, based on the connectivity of potential underground leakage channels and the drilled wellbore, as well as the connectivity of the underground body during the actual wellbore's underground passage as obtained in Step 1003, and the existing wellbore, identifies multiple surface monitoring points connected to the underground leakage point. Specifically, through the analysis results of Steps 1001 to 1003, the possible underground leakage channels (i.e., the locations of underground fractures connected to the surface) faced by the current gas storage wellbore are determined, thereby determining the monitoring point layout on the surface.

[0043] The ground monitoring point distribution scheme involves configuring a set of ground sensor groups for each ground monitoring point. Furthermore, each ground monitoring point is equipped with a corresponding ground monitoring channel, and each ground monitoring channel is equipped with a set of ground sensor groups, including but not limited to water environment (ion, pH, etc.) detection sensors placed below the groundwater level (through ground boreholes to below the groundwater level), gas (storage gas type) flux sensors placed in near-surface soil, and gas (storage gas type) detection sensors placed in near-surface air (1m to 3m above the ground surface, mounted on a support), etc., to form a sensor group for detecting whether stored gas is leaking on the ground.

[0044] Furthermore, this embodiment of the invention not only needs to determine the distribution scheme of surface monitoring points near the gas storage well, but also the distribution scheme of annular monitoring points. Specifically, the annular cementing situation of each casing layer during the drilling and construction of the gas storage well is analyzed to clarify the return height and cementing quality of the annular cement of each casing layer. Based on this, the configuration scheme of annular monitoring points for each casing layer is determined.

[0045] like Figure 2 As shown in step 1005, during the drilling and well construction process of the current gas storage well, the annular cementing situation of each casing layer is analyzed starting from the surface casing to understand key parameters such as the return height and cementing quality of the annular cement in each casing layer. Then, in step 1006, based on the key parameters of the annular cement in each casing layer, a corresponding annular monitoring point configuration scheme is designed at the location near the wellhead in each casing annulus to monitor the upward leakage of downhole stored gas along the casing annulus.

[0046] Furthermore, a first-type annular monitoring point configuration scheme is implemented in the annulus of adjacent casing layers. These first-type annular monitoring points are used to monitor whether stored gas leaks to the ground through failed annular cement. The first-type annular monitoring point configuration scheme involves setting up multiple first-type sensor groups evenly distributed circumferentially in the current casing annulus layer, near the ground.

[0047] Furthermore, a second type of annular monitoring point configuration is installed around the casing layer. These second-type annular monitoring points are used to monitor whether the underground gas sealed in the gas storage well leaks to the surface along the outer wall of the casing. The second-type annular monitoring point configuration consists of multiple groups of second-type sensors evenly distributed circumferentially around the outermost casing layer, near the surface.

[0048] Figure 3 This is a top view example of the configuration scheme of annular monitoring points at each casing layer in the method for monitoring annular leakage in a gas storage well according to an embodiment of this application. Figure 4 This is a side view example of the annulus monitoring point configuration scheme at each casing layer in the method for monitoring annulus leakage in a gas storage well according to an embodiment of this application. Figure 3 and Figure 4 As shown, the current gas storage well has a first layer of casing 201, a second layer of casing 202, ..., an nth layer of casing 203. These n layers of casing form a set of concentric circular casings for cementing (since the gas storage well casing program is designed according to the needs of the gas storage well, the number of casing layers is determined according to the actual situation, that is, the nth layer of casing is designed according to the needs of the gas storage well).

[0049] At the near-surface, there is an annular cement ring 205 between the first casing 201 and the formation. The second casing and the first casing, as well as the nth casing and the (n-1)th casing, are all cement-bonded. A corresponding annular monitoring point configuration scheme was designed for each casing annular layer, and a corresponding first-type annular monitoring channel 204 was configured at each monitoring point. Each first-type annular monitoring channel 204 contains a set of first-type sensors. For example... Figure 3 and Figure 4 As shown, in one specific embodiment, each annular layer has 8 Class I monitoring channels 204.

[0050] It should be noted that the number of the first type of sensor groups included in the configuration scheme of the first type of annular monitoring points in this embodiment of the invention is not specifically limited, and can be determined according to the actual situation of the gas storage well, that is, it is not necessarily required to set 8 monitoring channels 204 (it may be more or less). Furthermore, the first type of sensor group includes, but is not limited to: gas sensors, temperature sensors, pressure sensors and flow sensors, used to monitor whether there is any leakage of stored gas to the ground when the annular cement seal fails, and to measure parameters such as temperature, pressure and flow rate at the current monitoring point in real time.

[0051] Continue to refer to Figure 3 and Figure 4 Between the cement sheath 205 of the first casing and the formation, a corresponding second-type annular monitoring point configuration scheme was designed, and a corresponding second-type annular monitoring channel 206 was configured at each monitoring point. The monitoring channel 206 extends through a ground borehole to below the ground water table, and each second-type annular monitoring channel 206 is equipped with a set of second-type sensors. Figure 3 and Figure 4 As shown, in one specific embodiment, there are four second-type monitoring channels 206 around the outermost casing. It should be noted that the number of second-type sensor groups included in the configuration scheme of the second-type annular monitoring points in this embodiment of the invention is not specifically limited, and can be determined according to the geological conditions of the gas storage area, the cementing situation, and the monitoring technology requirements. Furthermore, the second-type sensor groups include, but are not limited to: gas sensors, flux sensors for measuring soil gas concentration, sensors for measuring groundwater pH, and ion sensors, used to detect near-surface gas content, soil gas flux, water quality, etc., thereby evaluating whether there is reservoir gas leakage to the surface.

[0052] After completing the design of the ground monitoring point distribution scheme and the annular monitoring point configuration scheme, proceed to step 1007. In step 1007, at each ground monitoring point and annular monitoring point 204 and 206, corresponding acquisition components (ground sensor group, first type sensor group and second type sensor group) will be constructed to form a sensor network system for monitoring leakage at different locations.

[0053] Furthermore, before well completion after cementing, holes are drilled in each layer of cement sheath using a small drill bit, and simultaneously, holes are drilled between the outermost cement sheath and the formation cementing surface to construct space for accommodating the acquisition components at different monitoring points. Specifically, before well completion after cementing, if the casing annulus cement returns to the surface, a rubber sealing layer is installed in each layer of casing annulus space, with reserved channels (monitoring channels) in the sealing layer. Holes are drilled in each layer of cement sheath using a small drill bit through the reserved channels, ensuring that leaked gas can only return to the casing wellhead device through the corresponding channels of the drilled holes. If the casing annulus cement sheath does not return to the surface, a rubber sealing layer is directly installed in each layer of casing annulus space, with reserved channels (monitoring channels) in the sealing layer, ensuring that leaked gas can only return to the casing wellhead device through the corresponding channels. Acquisition components (Type I sensor group) are then installed in the annulus. In addition, a hole is drilled between the outermost cement ring and the cemented surface of the stratum to set up a reserved channel (monitoring channel) for the rubber sealing layer, and a data acquisition component (second type of sensor group) is installed in the channel. The drilling depth is below the groundwater level.

[0054] Step 1007: Set up corresponding acquisition components at each monitoring point designed in steps 1004 and 1006 to form a network of all monitoring sensors, so as to realize the data acquisition of all sensors by constructing a sensor networking system.

[0055] Next, in step 1008, the information collected in real time by the acquisition components corresponding to each monitoring channel (also a monitoring point) will be transmitted to the annular leakage online monitoring system, so that the annular leakage online monitoring system can analyze and locate the downhole leakage situation and leakage location through the leakage channel represented by the monitoring point.

[0056] Furthermore, this embodiment of the invention accomplishes the task of transmitting real-time data collected by multiple acquisition components to the annular leakage online monitoring system in the following manner. Specifically, firstly, a wellhead integration device is constructed for sealing, fixing, and installing each acquisition component at the annular monitoring point; then, a multi-channel first-type data acquisition system is constructed for communicating with each acquisition component at the annular monitoring point and completing signal acquisition, so as to obtain annular monitoring sensor data in real time; next, a multi-channel second-type data acquisition system is constructed for communicating with the ground sensor group at the ground monitoring point and completing signal acquisition, so as to obtain ground monitoring sensor data in real time; finally, a data transmission system is constructed for communicating with the first-type and second-type data acquisition systems (the data transmission system can achieve wired or wireless transmission with the two types of data acquisition systems, and can also achieve wired or wireless transmission with the annular monitoring sensors), so as to transmit the annular monitoring sensor data and the ground monitoring sensor data to the annular leakage online monitoring system through the data transmission system.

[0057] Thus, by setting up acquisition components, wellhead integration devices, a first type of data acquisition system, a second type of data acquisition system, and a data transmission system at different monitoring points, the embodiments of the present invention upload data from all sensors to the monitoring system, which performs long-term continuous monitoring to promptly detect whether there is gas leakage in the annulus of the monitoring well. By analyzing the possible location of the leak point downhole through the leakage channel represented by the monitoring point, the leak point can be accurately located and quickly dealt with, thereby ensuring the safety of the gas storage well and the environment.

[0058] On the other hand, based on the above-described wellbore annulus leakage method, this embodiment of the invention also provides a system for monitoring wellbore annulus leakage in gas storage wells (hereinafter referred to as the "wellbore annulus leakage system"). This wellbore annulus leakage system is constructed using the above-described wellbore annulus leakage method.

[0059] Figure 5 This is a schematic diagram of a system for monitoring annular leakage in a gas storage well, according to an embodiment of this application. Figure 5As shown, the sensor group 301 of each first or second annular monitoring channel needs to be centrally fixed and installed at the wellhead via the sensor wellhead integration device 302. The sensor signal lines, power lines, etc. are integrated and safely passed through the completed annular wellhead device, and the leads are connected to the multi-channel first data acquisition system 303 for data acquisition and processing, forming annular monitoring sensor data 304 (including data collected by all first-type sensor groups and all second-type sensor groups). The data collected by the sensor group 305 of each ground monitoring channel is collected and processed by the multi-channel second data acquisition system 306 to form ground monitoring sensor data 307 (including data collected by all ground sensor groups). The data collected from each monitoring point is transmitted to the annular leakage online monitoring system 309 through the wired or wireless data transmission system 308 for various monitoring and processing.

[0060] This invention discloses a method and system for monitoring annular leakage in gas storage wells. This method and system can effectively monitor whether gas storage wells, such as hydrogen storage, gas storage, and CCUS wells, have experienced gas leakage. By rapidly locating the leakage point, it provides monitoring assurance for gas storage safety and environmental safety. Specific effects are as follows:

[0061] 1. A method for monitoring the risk of annular leakage in gas storage wells was established, solving the technical difficulties of monitoring the annulus in the wellbore;

[0062] 2. It has good deployment and implementation capabilities, good maintainability of the sensors, is easy to install and use, and has controllable costs;

[0063] 3. The use of wired and / or wireless networking of monitoring points facilitates the connection of sensors at each monitoring point, which is beneficial to the monitoring work.

[0064] The above description is merely a preferred embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any variations or substitutions that can be easily conceived by those skilled in the art within the technical scope disclosed in the present invention should be included within the scope of protection of the present invention. Therefore, the scope of protection of the present invention should be determined by the scope of the claims.

[0065] In the description of this invention, unless otherwise stated, "a plurality of" means two or more; the terms "upper," "lower," "left," "right," "inner," "outer," "front end," "rear end," "head," "tail," etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings, and are only for the convenience of describing the invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of the invention. Furthermore, the terms "first," "second," "third," etc., are used for descriptive purposes only and should not be construed as indicating or implying relative importance.

[0066] In the description of this invention, it should be noted that, unless otherwise explicitly specified and limited, the terms "connected" and "linked" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium. Those skilled in the art can understand the specific meaning of the above terms in this invention based on the specific circumstances.

[0067] It should be understood that the embodiments disclosed herein are not limited to the specific structures, processing steps, or materials disclosed herein, but should be extended to equivalent substitutions of these features as understood by those skilled in the art. It should also be understood that the terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting.

[0068] The phrase "an embodiment" or "an embodiment" used in this specification means that a particular feature, structure, or characteristic described in connection with the embodiment is included in at least one embodiment of the invention. Therefore, the phrase "an embodiment" or "an embodiment" appearing in various places throughout the specification does not necessarily refer to the same embodiment.

[0069] While the embodiments disclosed in this invention are as described above, the content is merely for the purpose of facilitating understanding of the invention and is not intended to limit the invention. Any person skilled in the art to which this invention pertains may make any modifications and changes in form and detail of the implementation without departing from the spirit and scope disclosed herein; however, the scope of patent protection of this invention shall still be determined by the scope defined in the appended claims.

Claims

1. A method for monitoring annular leakage in a gas storage well, characterized in that, include: Step S1: Analyze the geological conditions, geological profiles and seismic profiles of the current gas storage area to determine the ground monitoring points that are connected to the downhole leakage point; Step S2: Determine the configuration scheme of annulus monitoring points at each casing layer of the current gas storage well; Step S3: Corresponding data acquisition components are installed at the ground monitoring points and the surrounding air monitoring points to form a sensor network system. Step S1 includes: By analyzing the current geological conditions and geological profiles of the gas storage area, the geological characteristics of the underground reservoir and caprock, as well as the groundwater hydrological characteristics, can be clarified. Based on the current seismic profile results of the gas storage area, combined with the geological characteristics of the underground reservoir and caprock, as well as the groundwater hydrological characteristics, the connection between the underground geological bodies that may become leakage channels and the surface, and the existing drilled wells in the gas storage area connected by the leakage channels are identified. A geological analysis was conducted on the actual drilling trajectory of the current gas storage well to identify the underground geological bodies with leakage risks and existing wellbores connected by the actual well trajectory. The ground monitoring points are determined based on the connectivity of potential underground leakage channels, the existing drilled wells within the gas storage area connected to the leakage channels, and the underground geological structure and existing wells along the path of the drilled well. Step S2 includes: The annular cementing situation of each casing layer during the drilling and construction of gas storage wells was analyzed to clarify the return height and cementing quality of the annular cement for each casing layer. Based on this, the configuration scheme of annular monitoring points for each casing layer was determined. A first-type annular monitoring point configuration scheme is implemented in the annulus of adjacent casing layers. These first-type annular monitoring points are used to monitor whether stored gas leaks to the ground through failed annular cement. The configuration scheme involves placing multiple groups of first-type sensors evenly distributed circumferentially in the current casing annulus layer, near the ground. A second type of annular monitoring point configuration scheme is configured around the casing layer. The second type of annular monitoring point is used to monitor whether the underground gas sealed in the gas storage well leaks to the ground along the outer wall of the casing. The second type of annular monitoring point configuration scheme is to set multiple second type sensor groups evenly distributed in the circumferential direction around the outermost casing and near the ground.

2. The method according to claim 1, characterized in that, The first type of sensor group includes, but is not limited to, gas sensors, temperature sensors, pressure sensors, and flow sensors.

3. The method according to claim 1 or 2, characterized in that, The second type of sensor group includes, but is not limited to, gas sensors for measuring the near-surface concentration of gas stored in gas wells, flux sensors for measuring soil gas concentration, sensors for measuring groundwater pH, and ion sensors.

4. The method according to claim 1 or 2, characterized in that, The method further includes: transmitting the information collected in real time by each set of acquisition components to the annular leakage online monitoring system, so that the annular leakage online monitoring system can analyze the downhole leakage situation and leakage location through the leakage channel represented by the monitoring point.

5. The method according to claim 4, characterized in that, The method further includes: Before well completion after cementing, holes are drilled in each cement sheath layer using a small drill bit, and simultaneously, holes are drilled between the outermost cement sheath and the formation cementing surface to construct a space for accommodating the acquisition components at different monitoring point locations.

6. The method according to claim 5, characterized in that, If the cement sheath in the casing annulus rises to the ground, a rubber sealing layer is installed in each layer of casing annulus space. The rubber sealing layer has a corresponding reserved channel. In the reserved channel, a small drill bit is used to drill holes in each layer of cement sheath so that the leaked gas can only return to the wellhead through the channel corresponding to the cement sheath hole. If the cement ring in the casing annulus does not return to the surface, a rubber sealing layer is directly installed in each casing annulus space. The rubber sealing layer has a reserved channel so that the leaked gas can only return to the wellhead of each casing through the corresponding channel. The borehole between the outermost cement ring and the cemented surface of the formation is drilled to a depth below the groundwater level.

7. The method according to claim 5, characterized in that, Construct a wellhead integrated device for sealing, fixing and installing the various acquisition components at the annular monitoring point; A multi-channel Class I data acquisition system is constructed to communicate with each acquisition component at the annular monitoring point and complete signal acquisition, so as to obtain annular monitoring sensor data in real time. A multi-channel second-class data acquisition system is constructed to communicate with the ground sensor group at the ground monitoring point and complete signal acquisition, so as to obtain ground monitoring sensor data in real time. A data transmission system is constructed to communicate with the first type of data acquisition system and the second type of data acquisition system, so as to transmit the annular monitoring sensor data and the ground monitoring sensor data to the annular leakage online monitoring system through the data transmission system.

8. A system for monitoring annular leakage in a gas storage well, characterized in that, The system is constructed using the method described in any one of claims 1 to 7.

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