Deformation monitoring device and method for exploiting process of natural gas hydrate reservoir containing underlying gas

Abstract

The invention relates to a deformation monitoring device and method in the exploiting process of a natural gas hydrate reservoir containing underlying gas, the device comprises a natural gas exploiting system and a settlement deformation detecting system, the natural gas exploiting system is used for exploiting the natural gas hydrate reservoir containing underlying gas, and the settlement deformation detecting system is used for detecting settlement deformation of the natural gas hydrate reservoir containing underlying gas. An overlying layer is arranged on the underlying gas-containing natural gas hydrate reservoir; the settlement deformation detection system comprises settlement deformation monitoring sensors and a settlement data receiver, the settlement deformation monitoring sensors are arranged on the upper covering layer, and each settlement deformation monitoring sensor is wirelessly connected with the settlement data receiver; when the natural gas hydrate reservoir containing underlying gas settles in the mining process, the settlement deformation of the stratum is collected by the settlement deformation monitoring sensor in real time and transmitted to the settlement data receiver; according to the stratum settlement data of the settlement data receiver, the exploitation rate of the natural gas exploitation system is controlled, and therefore settlement deformation is monitored.

Description

Technical Field

[0001] The present invention relates to the technical field of natural gas mining, and in particular to a deformation monitoring device and method for a natural gas hydrate reservoir containing underlying gas during mining. Background Art

[0002] Gas hydrates are solid, crystalline substances composed of water and small hydrocarbon molecules, and are widely distributed in nature. Methane is the most abundant gas naturally present in gas hydrates. Due to their enormous resource potential (estimated at 30 trillion cubic meters) and exceptional energy storage capacity (their water-to-methane volume ratio is approximately 1:170), gas hydrates are considered a highly promising future energy source. Gas hydrates naturally maintain their stability under favorable conditions of low temperature and high pressure. Consequently, they are commonly found beneath permafrost and on the deep seafloor near continental shelves. Over the past decade, the safe and efficient extraction of methane from gas hydrate reservoirs has become a focus of research and industry. Various gas hydrate extraction methods have been proposed, including decompression, thermal stimulation, inhibitor injection, and carbon dioxide displacement. Previous field production tests in offshore areas have demonstrated the technical feasibility of decompression for gas hydrate production. However, achieving long-term, economically viable production still faces significant technical challenges. Geological exploration results indicate that reservoirs containing natural gas hydrates often contain underlying gas, including methane. The exploitation of these gas hydrate reservoirs exhibits the coexistence of multiple gas sources. For example, stratigraphic data from the second production test in the Shenhu Sea area revealed the vertical distribution of regional natural gas hydrate layers, three-phase methane hydrate reservoirs, and underlying gas reservoirs. The results indicate that the average saturations of hydrates and gas reach 13.2% and 11.7%, respectively. Furthermore, underlying gas reservoirs exceeding 80% in density have been discovered in the Qiongdongnan Basin, accompanied by overlying natural gas hydrate layers.

[0003] Depressurization combined with multi-gas production is one of the effective methods for commercializing hydrate development. However, depressurization of natural gas hydrates faces environmental and geological risks such as excessive water production, sand production, and reservoir subsidence, and the depressurization process still needs to be optimized. Reservoir subsidence not only exacerbates sand production but can also cause severe landslides and collapses, potentially damaging the wellbore and leading to production accidents, resulting in serious economic and environmental consequences.

[0004] However, currently, it is not possible to monitor the settlement deformation that occurs during the exploitation of a natural gas hydrate reservoir containing underlying gas. Summary of the Invention

[0005] In response to the above problems, the purpose of the present invention is to provide a deformation monitoring device and method for the exploitation process of a natural gas hydrate reservoir containing underlying gas, which is used to solve the problem that deformation monitoring cannot be performed on the subsidence that occurs during the exploitation process of a natural gas hydrate reservoir containing underlying gas.

[0006] To achieve the above object, the present invention adopts the following technical solutions: In a first aspect, the present invention discloses a deformation monitoring device for a natural gas hydrate reservoir containing underlying gas during mining, comprising: A natural gas production system for producing a natural gas hydrate reservoir containing underlying gas; wherein the natural gas hydrate reservoir containing underlying gas is an overlying layer; A settlement deformation detection system, comprising at least one settlement deformation monitoring sensor and a settlement data receiver, wherein at least one of the settlement deformation monitoring sensors is disposed at least in an overlying layer above the natural gas hydrate reservoir containing underlying gas, and each settlement deformation monitoring sensor is wirelessly connected to the settlement data receiver; When the natural gas hydrate reservoir containing underlying gas sinks during the mining process, the settlement deformation of the formation is collected in real time by the settlement deformation monitoring sensor and transmitted to the settlement data receiver; based on the formation settlement data of the settlement data receiver, the mining rate of the natural gas mining system is controlled, thereby realizing the monitoring of settlement deformation.

[0007] Furthermore, the natural gas extraction system is arranged in a sea area of ​​a stratum containing a natural gas hydrate reservoir with underlying gas, and the stratum includes a natural gas hydrate reservoir with underlying gas, and the natural gas hydrate reservoir with underlying gas is a muddy silt sedimentary rock, above which is an overlying layer, and the seawater in the sea area is located above the overlying layer to form a seawater layer.

[0008] Furthermore, the natural gas hydrate reservoir containing underlying gas is a muddy silt sedimentary rock, which includes a natural gas hydrate layer, a three-phase layer and an underlying gas layer in order from top to bottom. wherein the natural gas hydrate layer is enriched with natural gas hydrate; The underlying gas layer is enriched with methane gas; The three-phase layer stores a mixture of natural gas hydrate and methane gas.

[0009] Furthermore, the natural gas production system includes a production well, a production string and an offshore drilling platform. The production well includes a vertical well, at least one natural gas hydrate layer horizontal well, at least one three-phase layer horizontal well, and at least one underlying gas layer horizontal well, wherein the vertical well sequentially passes through the seawater layer, the overburden layer, the natural gas hydrate layer, and the three-phase layer from top to bottom until it reaches the underlying gas layer, and the natural gas hydrate layer horizontal well, the three-phase layer horizontal well, and the underlying gas layer horizontal well are respectively horizontally arranged in the natural gas hydrate layer, the three-phase layer, and the underlying gas layer and are respectively connected to the vertical well; The production string includes a vertical production pipe, at least one underlying gas layer horizontal production pipe string, at least one three-phase layer horizontal production pipe string and at least one natural gas hydrate layer horizontal production pipe string, wherein the vertical production pipe is arranged in a vertical well, the underlying gas layer horizontal production pipe string, the three-phase layer horizontal production pipe string and the natural gas hydrate layer horizontal production pipe string are respectively arranged in the underlying gas layer horizontal well, the three-phase layer horizontal well and the natural gas hydrate layer horizontal well, and the underlying gas layer horizontal production pipe string, the three-phase layer horizontal production pipe string and the natural gas hydrate layer horizontal production pipe string are respectively connected to the vertical production pipe; The offshore drilling and production platform is arranged at the wellhead of the vertical well, and the top end of the vertical production pipe extends from the wellhead of the vertical well to the offshore drilling and production platform.

[0010] Furthermore, the settlement data receiver is installed on the offshore drilling and production platform, and is used to collect the settlement deformation data collected by the settlement deformation monitoring sensor.

[0011] Furthermore, the settlement deformation detection system includes a plurality of settlement deformation monitoring sensors, wherein a portion of the settlement deformation monitoring sensors are arranged at intervals in the overlying layer.

[0012] Furthermore, some of the plurality of settlement deformation monitoring sensors are arranged at intervals in the natural gas hydrate layer, and are staggered with the settlement deformation monitoring sensors arranged in the overlying layer in the vertical direction.

[0013] Furthermore, the remaining portion of the plurality of settlement deformation monitoring sensors are arranged at intervals in the three-phase layer, and are staggered with the settlement deformation monitoring sensors arranged in the natural gas hydrate layer in the vertical direction.

[0014] In a second aspect, the present invention further discloses a method for monitoring deformation during the production process of a natural gas hydrate reservoir containing underlying gas, using the above-mentioned device, the method comprising the following steps: When the natural gas hydrate reservoir containing underlying gas subsides during the mining process, the subsidence deformation monitoring sensor collects the subsidence deformation of the formation in real time and transmits it to the subsidence data receiver; The offshore drilling and production platform controls the production rate of the natural gas production system according to the formation subsidence data of the subsidence data receiver, thereby realizing monitoring of subsidence deformation.

[0015] Compared with the prior art, the present invention has the following beneficial effects: (1) The present invention discloses a deformation monitoring device for the exploitation process of a natural gas hydrate reservoir containing underlying gas, comprising a natural gas exploitation system and a settlement deformation detection system. The natural gas exploitation system is used to exploit the natural gas hydrate reservoir containing underlying gas, wherein the natural gas hydrate reservoir containing underlying gas is above an overlying layer; the settlement deformation detection system comprises at least one settlement deformation monitoring sensor and a settlement data receiver, at least one of the settlement deformation monitoring sensors is arranged at least in the overlying layer, and each settlement deformation monitoring sensor is wirelessly connected to the settlement data receiver; when the natural gas hydrate reservoir containing underlying gas settles during the exploitation process, the settlement deformation of the formation is collected in real time by the settlement deformation monitoring sensor and transmitted to the settlement data receiver; the exploitation rate of the natural gas exploitation system is controlled according to the formation settlement data of the settlement data receiver, thereby realizing the monitoring of settlement deformation. The deformation monitoring device for the exploitation process of a natural gas hydrate reservoir containing underlying gas disclosed in the present invention solves the current problem that deformation monitoring cannot be performed for settlement occurring during the exploitation process of a natural gas hydrate reservoir containing underlying gas.

[0016] (II) The present invention discloses a method for monitoring deformation during the mining process of a natural gas hydrate reservoir containing underlying gas, comprising: step A: when the natural gas hydrate reservoir containing underlying gas settles during the mining process, the settlement deformation monitoring sensor (11) collects the settlement deformation of the formation in real time and transmits it to the settlement data receiver; step B: the offshore drilling and production platform controls the mining rate of the natural gas mining system based on the formation settlement data from the settlement data receiver, thereby realizing monitoring of the settlement deformation. The method for monitoring deformation during the mining process of a natural gas hydrate reservoir containing underlying gas disclosed by the present invention not only monitors and regulates the settlement during the mining process of the natural gas hydrate reservoir, but also provides guidance for increasing production and reservoir settlement in the actual multi-gas combined production process. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Figure 1 A schematic structural diagram of a deformation monitoring device for a natural gas hydrate reservoir containing underlying gas during production provided in Example 1 of the present invention.

[0018] Description of reference numerals: 11 - settlement deformation monitoring sensor, 12 - settlement data receiver; 2-vertical well; 30-vertical production string, 31-horizontal production string for the underlying gas layer, 32-horizontal production string for the three-phase layer, 33-horizontal production string for the natural gas hydrate layer; 4-Offshore drilling and production platforms. DETAILED DESCRIPTION

[0019] Exemplary embodiments of the present invention will be described in more detail below with reference to the accompanying drawings. Although exemplary embodiments of the present invention are shown in the accompanying drawings, it should be understood that the present invention can be implemented in various forms and should not be limited by the embodiments described herein. Rather, these embodiments are provided to enable a more thorough understanding of the present invention and to fully convey the scope of the present invention to those skilled in the art.

[0020] Example 1: A deformation monitoring device for the production process of a natural gas hydrate reservoir containing underlying gas Embodiment 1 of the present invention provides a deformation monitoring device for the exploitation process of a natural gas hydrate reservoir containing underlying gas, which is used to be set in a sea area on a stratum containing a natural gas hydrate reservoir containing underlying gas, wherein the stratum includes a natural gas hydrate reservoir containing underlying gas, and the natural gas hydrate reservoir containing underlying gas includes, from top to bottom, a natural gas hydrate layer, a three-phase layer, and an underlying gas layer, and the upper surface of the natural gas hydrate reservoir containing underlying gas is an overlying layer. The structure thereof is described in detail below with reference to the accompanying drawings.

[0021] refer to Figure 1 The deformation monitoring device for the exploitation process of the natural gas hydrate reservoir containing underlying gas includes a natural gas exploitation system and a settlement deformation detection system.

[0022] The natural gas production system is used for producing a natural gas hydrate reservoir containing underlying gas, wherein the upper surface of the natural gas hydrate reservoir containing underlying gas is an overlying layer.

[0023] The settlement deformation detection system includes at least one settlement deformation monitoring sensor 11 and a settlement data receiver 12. At least one of the settlement deformation monitoring sensors 11 is at least arranged in the overlying layer above the natural gas hydrate reservoir containing underlying gas. Each settlement deformation monitoring sensor 11 is wirelessly connected to the settlement data receiver 12.

[0024] When the natural gas hydrate reservoir containing underlying gas sinks during the mining process, the settlement deformation of the formation is collected in real time by the settlement deformation monitoring sensor 11 and transmitted to the settlement data receiver 12; based on the formation settlement data of the settlement data receiver 12, the mining rate of the natural gas mining system is controlled, thereby realizing the monitoring of settlement deformation.

[0025] Specifically, the natural gas extraction system is arranged in a sea area on a stratum containing a natural gas hydrate reservoir containing underlying gas, the stratum including the natural gas hydrate reservoir containing underlying gas, the natural gas hydrate reservoir containing underlying gas is above an overlying layer, and the seawater on the sea area is located above the overlying layer to form a seawater layer.

[0026] Preferably, the underlying gas layer is further divided into a shallow gas layer and a deep gas layer. In view of the fact that this part is prior art, it will not be described in detail.

[0027] More specifically, the natural gas hydrate reservoir containing underlying gas is a muddy silt sedimentary rock, and the muddy silt sedimentary rock includes a natural gas hydrate layer, a three-phase layer and an underlying gas layer from top to bottom.

[0028] wherein the natural gas hydrate layer is enriched with natural gas hydrate; The underlying gas layer is enriched with methane gas; The three-phase layer stores a mixture of natural gas hydrate and methane gas.

[0029] As a specific implementation, the natural gas production system includes a production well, a production string and an offshore drilling platform 4.

[0030] The production well includes a vertical well 2, at least one natural gas hydrate layer horizontal well, at least one three-phase layer horizontal well, and at least one underlying gas layer horizontal well, wherein the vertical well 2 sequentially passes through the seawater layer, the overburden layer, the natural gas hydrate layer, and the three-phase layer from top to bottom until it reaches the underlying gas layer, and the natural gas hydrate layer horizontal well, the three-phase layer horizontal well, and the underlying gas layer horizontal well are respectively arranged horizontally in the natural gas hydrate layer, the three-phase layer, and the underlying gas layer and are respectively connected to the vertical well; The production string includes a vertical production pipe 30, at least one underlying gas layer horizontal production pipe string 31, at least one three-phase layer horizontal production pipe string 32, and at least one natural gas hydrate layer horizontal production pipe string 33, wherein the vertical production pipe 30 is arranged in the vertical well 2, the underlying gas layer horizontal production pipe string 31, the three-phase layer horizontal production pipe string 32, and the natural gas hydrate layer horizontal production pipe string 33 are respectively arranged in the underlying gas layer horizontal well, the three-phase layer horizontal well, and the natural gas hydrate layer horizontal well, and the underlying gas layer horizontal production pipe string 31, the three-phase layer horizontal production pipe string 32, and the natural gas hydrate layer horizontal production pipe string 33 are respectively connected to the vertical production pipe 30; The offshore drilling platform 4 is disposed at the wellhead of the vertical well 2 , and the top end of the vertical production pipe 30 extends from the wellhead of the vertical well 2 to the offshore drilling platform 4 .

[0031] Specifically, the settlement data receiver 12 is installed on the offshore drilling and production platform 4 and is used to collect the settlement deformation data collected by the settlement deformation monitoring sensor 11 .

[0032] In order to monitor the settlement of the overlying layer, the settlement deformation detection system includes a plurality of settlement deformation monitoring sensors 11, wherein a portion of the settlement deformation monitoring sensors 11 are arranged at intervals in the overlying layer.

[0033] In order to monitor the formation settlement of the natural gas hydrate layer, some of the settlement deformation monitoring sensors 11 are arranged at intervals in the natural gas hydrate layer and are staggered with the settlement deformation monitoring sensors 11 arranged in the overlying layer in the vertical direction.

[0034] In order to monitor the settlement of the three-phase layer, the remaining ones of the plurality of settlement deformation monitoring sensors 11 are arranged at intervals in the three-phase layer and are staggered with the settlement deformation monitoring sensors 11 arranged in the natural gas hydrate layer in the vertical direction.

[0035] Example 2: A method for monitoring deformation during the production of a natural gas hydrate reservoir containing underlying gas Example 2 of the present invention provides a method for monitoring deformation during the production process of a natural gas hydrate reservoir containing underlying gas, using the deformation monitoring device of Example 1. The method includes the following steps: Step A: When the natural gas hydrate reservoir containing underlying gas subsides during the mining process, the subsidence deformation monitoring sensor 11 collects the subsidence deformation of the formation in real time and transmits it to the subsidence data receiver 12; Step B: The offshore drilling and production platform 4 controls the production rate of the natural gas production system according to the formation subsidence data from the subsidence data receiver 12, thereby monitoring the subsidence deformation.

[0036] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or make equivalent replacements for some of the technical features therein. However, these modifications or replacements do not deviate the essence of the corresponding technical solutions from the spirit and scope of the technical solutions of the various embodiments of the present invention.

Claims

1. A deformation monitoring device for a natural gas hydrate reservoir containing underlying gas during mining, characterized in that: include A natural gas production system for producing a natural gas hydrate reservoir containing underlying gas; wherein the natural gas hydrate reservoir containing underlying gas is an overlying layer; A settlement deformation detection system comprises at least one settlement deformation monitoring sensor (11) and a settlement data receiver (12), wherein at least one of the settlement deformation monitoring sensors (11) is arranged at least in an overlying layer above the natural gas hydrate reservoir containing underlying gas, and each settlement deformation monitoring sensor (11) is wirelessly connected to the settlement data receiver (12); When the natural gas hydrate reservoir containing underlying gas settles during the mining process, the settlement deformation of the formation is collected in real time by the settlement deformation monitoring sensor (11) and transmitted to the settlement data receiver (12); based on the formation settlement data of the settlement data receiver (12), the mining rate of the natural gas mining system is controlled, thereby realizing the monitoring of the settlement deformation.

2. The deformation monitoring device for the natural gas hydrate reservoir containing underlying gas during the mining process according to claim 1, characterized in that: The natural gas production system is set up in the sea area of ​​the stratum containing the natural gas hydrate reservoir containing the underlying gas, and the stratum includes the natural gas hydrate reservoir containing the underlying gas. The natural gas hydrate reservoir containing the underlying gas is muddy silt sedimentary rock, and the overlying layer is above it. The seawater in the sea area is located above the overlying layer to form a seawater layer.

3. The deformation monitoring device for the exploitation process of a natural gas hydrate reservoir containing underlying gas according to claim 2, characterized in that: The natural gas hydrate reservoir containing underlying gas is a muddy silt sedimentary rock, which includes a natural gas hydrate layer, a three-phase layer and an underlying gas layer in order from top to bottom. wherein the natural gas hydrate layer is enriched with natural gas hydrate; The underlying gas layer is enriched with methane gas; The three-phase layer stores a mixture of natural gas hydrate and methane gas.

4. The deformation monitoring device for the exploitation process of a natural gas hydrate reservoir containing underlying gas according to claim 3, characterized in that: The natural gas production system comprises: A production well, comprising a vertical well (2), at least one natural gas hydrate layer horizontal well, at least one three-phase layer horizontal well and at least one underlying gas layer horizontal well, wherein the vertical well (2) sequentially passes through the seawater layer, the overlying layer, the natural gas hydrate layer and the three-phase layer from top to bottom until it reaches the underlying gas layer, and the natural gas hydrate layer horizontal well, the three-phase layer horizontal well and the underlying gas layer horizontal well are respectively arranged horizontally in the natural gas hydrate layer, the three-phase layer and the underlying gas layer and are respectively connected to the vertical well; A production string, comprising a vertical production pipe (30), at least one underlying gas layer horizontal production pipe string (31), at least one three-phase layer horizontal production pipe string (32), and at least one natural gas hydrate layer horizontal production pipe string (33), wherein the vertical production pipe (30) is arranged in a vertical well (2), the underlying gas layer horizontal production pipe string (31), the three-phase layer horizontal production pipe string (32), and the natural gas hydrate layer horizontal production pipe string (33) are respectively arranged in the underlying gas layer horizontal well, the three-phase layer horizontal well, and the natural gas hydrate layer horizontal well, and the underlying gas layer horizontal production pipe string (31), the three-phase layer horizontal production pipe string (32), and the natural gas hydrate layer horizontal production pipe string (33) are respectively connected to the vertical production pipe (30); An offshore drilling and production platform (4) is arranged at the wellhead of the vertical well (2), and the top end of the vertical production pipe (30) extends from the wellhead of the vertical well (2) to the offshore drilling and production platform (4).

5. The deformation monitoring device for the exploitation process of a natural gas hydrate reservoir containing underlying gas according to claim 1, characterized in that: The settlement data receiver (12) is installed on the offshore drilling and production platform (4) and is used to collect the settlement deformation data collected by the settlement deformation monitoring sensor (11).

6. The deformation monitoring device for the exploitation process of a natural gas hydrate reservoir containing underlying gas according to claim 1, characterized in that: The settlement deformation detection system comprises a plurality of settlement deformation monitoring sensors (11), wherein a portion of the settlement deformation monitoring sensors (11) are arranged at intervals within the overlying layer.

7. The deformation monitoring device for the exploitation process of a natural gas hydrate reservoir containing underlying gas according to claim 6, characterized in that: A portion of the plurality of subsidence deformation monitoring sensors (11) are arranged at intervals in the natural gas hydrate layer and are staggered with the subsidence deformation monitoring sensors (11) arranged in the overlying layer in the vertical direction.

8. The deformation monitoring device for the exploitation process of a natural gas hydrate reservoir containing underlying gas according to claim 7, characterized in that: The remaining portion of the plurality of subsidence deformation monitoring sensors (11) is arranged at intervals in the three-phase layer and is staggered in the vertical direction from the subsidence deformation monitoring sensors (11) arranged in the natural gas hydrate layer.

9. A method for monitoring deformation during the production process of a natural gas hydrate reservoir containing underlying gas, using the apparatus according to any one of claims 1 to 8, comprising: When the natural gas hydrate reservoir containing underlying gas subsides during the mining process, the subsidence deformation monitoring sensor (11) collects the subsidence deformation of the formation in real time and transmits it to the subsidence data receiver (12); The offshore drilling and production platform (4) controls the production rate of the natural gas production system according to the formation settlement data of the settlement data receiver (12), thereby realizing monitoring of settlement deformation.

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