A method, system and well group for synergistic development of a gas reservoir and a hydrate reservoir

Abstract

The present application relates to a kind of gas reservoir and hydrate reservoir collaborative development method and device, adopt well group to realize, well group includes center well and at least one communication well being arranged around center well;Method includes: the communication well is drilled to the first preset position of gas reservoir in hydrate reservoir and oil pipe, and respectively carries out perforation in hydrate reservoir and gas reservoir;Center well is drilled to the second preset position of hydrate reservoir, and carries out perforation in hydrate reservoir;Corresponding to the position of hydrate reservoir bottom in communication well installs packer, uses communication well and center well to carry out first round constant pressure mining;Change packer position, using center well carries out second round constant pressure mining, so that free gas in gas reservoir can be under the action of pressure difference between hydrate reservoir and gas reservoir and return to hydrate reservoir along communication well, while carrying heat energy to promote the decomposition of hydrate.The present application can realize gas reservoir and hydrate reservoir collaborative development, provides new technical thought for substantially improving the production capacity of natural gas hydrate reservoir.

Description

Technical Field

[0001] The present invention relates to a method, system and well group for collaborative development of gas reservoirs and hydrate reservoirs. Background Art

[0002] With rapid economic development, the global demand for oil and gas energy continues to increase, while conventional oil and gas resources are decreasing. Unconventional oil and gas resources are attracting widespread attention worldwide. Natural gas hydrates are ice-like solid crystals composed of natural gas and water molecules, distributed in seafloor sediments or terrestrial permafrost. Their combustion produces only carbon dioxide and water, without polluting the environment, making them a new type of green energy source. Methods for developing natural gas hydrate reservoirs mainly include depressurization, thermal shock, inhibitor injection, and CO2 displacement. Thermal shock, inhibitor injection, and CO2 displacement all require the injection of fluids (hot water, inhibitors, CO2), resulting in high costs. Depressurization, however, does not require fluid injection and is currently the most feasible development method. Summary of the Invention

[0003] The inventors of this invention have discovered that the results of two test productions conducted in existing sea areas indicate that the production capacity of natural gas hydrate reservoirs developed using a single pressure reduction method is low, making it difficult to achieve the minimum production capacity required for development. Improving development methods and significantly increasing the production capacity of natural gas hydrate reservoirs is a key issue that urgently needs to be addressed. In view of these issues, the present invention proposes a method, system, and well group for the coordinated development of gas and hydrate reservoirs to address or partially address these issues. The technical solutions proposed in this invention are as follows:

[0004] In a first aspect, the present invention provides a method for the coordinated development of a gas reservoir and a hydrate reservoir, which is implemented using a well group, wherein the well group includes a central well and at least one connecting well disposed around the central well; the method comprises:

[0005] An oil pipeline is run between the hydrate reservoir and the gas reservoir;

[0006] Drilling the connecting well through the hydrate reservoir and the oil pipe to a first preset position of the gas reservoir, and performing perforations in the hydrate reservoir and the gas reservoir respectively;

[0007] Drilling the central well to a second preset position of the hydrate reservoir and perforating the hydrate reservoir;

[0008] A packer is installed in the connecting well at a position corresponding to the bottom of the hydrate reservoir, and a first round of constant pressure production is carried out using the connecting well and the central well to decompose hydrates in the hydrate reservoir under the action of a pressure differential; wherein the bottom hole pressure during the first round of constant pressure production is less than the original pressure of the hydrate reservoir;

[0009] During the first round of constant pressure production, the gas production rates of the connecting well and the central well are monitored until the daily gas production of the central well and the connecting well decreases to a first preset gas production rate;

[0010] The packer is installed at a position in the connecting well corresponding to the top of the hydrate reservoir, and a second round of constant-pressure production is carried out using the central well, so that free gas in the gas reservoir can return to the hydrate reservoir along the connecting well under the action of the pressure difference between the hydrate reservoir and the gas reservoir, while carrying heat energy to promote the decomposition of the hydrate; wherein the bottom hole pressure during the second round of constant-pressure production is lower than the original pressure of the hydrate reservoir;

[0011] During the second round of constant pressure production, the gas production rate of the central well is monitored until the single-well daily gas production of the central well decreases to a second preset gas production, and then production is stopped.

[0012] In an optional embodiment, during the first round of constant-pressure production, the bottom hole pressure is 0.3 to 0.7 times the original pressure of the hydrate reservoir.

[0013] In an optional embodiment, the daily gas production of the central well and the connecting well is gradually reduced to 500

[0014] 1000m 3 / d, the first round of constant pressure mining ends.

[0015] In an optional embodiment, the daily gas production in the central well is gradually reduced to 500-1000m 3 / d, the second round of constant pressure mining ends.

[0016] In an optional embodiment, during the second round of constant-pressure production, the bottom hole pressure is 0.3 to 0.7 times the original pressure of the hydrate reservoir.

[0017] In an optional embodiment, drilling the connecting well through the hydrate reservoir to a first preset position of the gas reservoir includes:

[0018] The connecting well penetrates the hydrate reservoir and is drilled to a distance from the top of the gas reservoir. Location.

[0019] In an optional embodiment, drilling the central well to a second preset position of the hydrate reservoir and performing perforation in the hydrate reservoir includes:

[0020] The central well is drilled to a distance from the top of the hydrate reservoir. location and perforated in the hydrate reservoir.

[0021] In an optional embodiment, both the connecting well and the central well are completed by perforation, and the perforation points are spaced 5 to 10 meters apart.

[0022] In an optional embodiment, the lowered oil pipe is made of heat-insulating material.

[0023] In an optional embodiment, the lowered oil pipe is made of glass fiber, and its thermal conductivity is less than 0.04 W / m·K.

[0024] In a second aspect, the present invention provides a system for collaborative development of gas reservoirs and hydrate reservoirs, which is implemented using a well group, wherein the well group includes a central well and at least one connecting well arranged around the central well;

[0025] The system includes: an oil pipe lowering device, a perforating device, a production device and a gas production monitoring device;

[0026] The oil pipe lowering device is used to lower the oil pipe between the hydrate reservoir and the gas reservoir;

[0027] The perforating device is used to drill the connecting well through the hydrate reservoir and the oil pipe to a first preset position of the gas reservoir, and perform perforations in the hydrate reservoir and the gas reservoir respectively; and to drill the central well to a second preset position of the hydrate reservoir, and perform perforations in the hydrate reservoir;

[0028] The mining device is used to install a packer at a position corresponding to the bottom of the hydrate reservoir in the connecting well, and use the connecting well and the central well to perform a first round of constant-pressure mining to decompose hydrates in the hydrate reservoir under the action of the pressure difference; wherein, during the first round of constant-pressure mining, the bottom hole pressure is less than the original pressure of the hydrate reservoir; and, install the packer at a position corresponding to the top of the hydrate reservoir in the connecting well, and use the central well to perform a second round of constant-pressure mining, so that free gas in the gas reservoir can return to the hydrate reservoir along the connecting well under the action of the pressure difference between the hydrate reservoir and the gas reservoir, while carrying heat energy to promote the decomposition of hydrates; wherein, during the second round of constant-pressure mining, the bottom hole pressure is less than the original pressure of the hydrate reservoir, and mining is stopped;

[0029] The gas production monitoring device is used to monitor the gas production rate of the connecting well and the central well during the first round of constant pressure production, until the daily gas production of the central well and the connecting well decreases to the first preset gas production; and, during the second round of constant pressure production, monitor the gas production rate of the central well until the daily gas production of the central well decreases to the second preset gas production.

[0030] In a third aspect, the present invention provides a well group for collaborative development of gas reservoirs and hydrate reservoirs, comprising: a central well and at least one connecting well arranged around the central well, the connecting well penetrating the hydrate reservoir and being drilled to a first preset position of the gas reservoir, and the central well being drilled to a second preset position of the hydrate reservoir.

[0031] In an optional embodiment, the connecting well penetrates the hydrate reservoir and is drilled to a distance from the top of the gas reservoir. Location.

[0032] In an optional embodiment, the central well is drilled to a depth of 100 m from the top of the hydrate reservoir. Location.

[0033] In a fourth aspect, the present invention provides an application of the coordinated development well group of gas reservoirs and hydrate reservoirs as described in the third aspect in the coordinated development of gas reservoirs and hydrate reservoirs.

[0034] Based on the above technical solution, the present invention has the following beneficial effects compared with the prior art:

[0035] The method for collaborative development of gas reservoirs and hydrate reservoirs provided by the present invention comprises the following steps: installing a packer at a position corresponding to the bottom of the hydrate reservoir in the connecting well, performing a first round of constant pressure production on the hydrate reservoir using a well group, namely the connecting well and the central well, and controlling the bottom hole pressure during the first round of production to be lower than the original pressure of the hydrate reservoir, so that the hydrate in the hydrate reservoir decomposes under the action of the pressure difference, and the natural gas generated by the decomposition enters the wellbore through the perforated holes and is produced by the well group, and the pressure of the hydrate reservoir continuously decreases; after the first round of production is completed, the position of the packer in the connecting well is changed, and the packer is installed in the connecting well. The center well corresponds to the top of the hydrate reservoir, and the second round of constant pressure production is carried out using the central well. The bottom hole pressure during the second round of constant pressure production is controlled to be lower than the original pressure of the hydrate reservoir. After the first round of pressure reduction production, due to the reduction of the hydrate reservoir pressure, the free gas in the gas reservoir can return to the hydrate reservoir along the connecting well under the action of the pressure difference between the hydrate reservoir and the gas reservoir, and at the same time carry heat energy to promote the decomposition of hydrates, which can greatly increase the gas production rate and hydrate decomposition rate of the gas reservoir, realize the coordinated development of gas and hydrate reservoirs, and provide a new technical idea for significantly improving the production capacity of natural gas hydrate reservoirs.

[0036] Other features and advantages of the present invention will be described in the following description, and in part will become apparent from the description, or understood by practicing the present invention. The purposes and other advantages of the present invention are realized and obtained by the structures particularly pointed out in the description, claims and drawings.

[0037] In order to make the above-mentioned objects, features and advantages of the present invention more obvious and easy to understand, preferred embodiments are given below and described in detail with reference to the accompanying drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0038] In order to more clearly illustrate the specific embodiments of the present invention or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the specific embodiments or the description of the prior art. Obviously, the drawings described below are some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0039] Figure 1 1 is a flow chart of a method for collaborative development of gas reservoirs and hydrate reservoirs provided by an embodiment of the present invention;

[0040] Figure 2 Schematic diagram of a well group for depressurizing and developing a hydrate reservoir according to an embodiment of the present invention;

[0041] Figure 3 Schematic diagram of a well group for jointly developing a hydrate reservoir and a gas reservoir by utilizing thermal energy of a gas reservoir according to an embodiment of the present invention;

[0042] In the figure: 1, sea level; 2, connecting well; 3, central well; 4, gas reservoir; 5, natural gas flow direction; 6, cap rock; 7, hydrate reservoir; 8, packer; 9, oil pipe; 10, perforation point. DETAILED DESCRIPTION

[0043] Exemplary embodiments of the present disclosure will be described in more detail below with reference to the accompanying drawings. Although exemplary embodiments of the present disclosure are shown in the accompanying drawings, it should be understood that the present disclosure can be implemented in various forms and should not be limited by the embodiments set forth herein. Rather, these embodiments are provided to enable a more thorough understanding of the present disclosure and to fully convey the scope of the present disclosure to those skilled in the art.

[0044] Exemplary embodiments will be described in detail herein, examples of which are illustrated in the accompanying drawings. In the following description, when referring to the drawings, like numbers in different figures represent like or similar elements unless otherwise indicated. The embodiments described in the following exemplary embodiments are not intended to represent all possible embodiments consistent with the present invention. Rather, they are merely examples of apparatus and methods consistent with certain aspects of the present invention, as detailed in the appended claims.

[0045] In the description of the present invention, it should be noted that the terms "center," "upper," "lower," "left," "right," "vertical," "horizontal," "inner," and "outer," etc., indicating orientations or positional relationships, are based on the orientations or positional relationships shown in the accompanying drawings and are intended solely to facilitate and simplify the description of the present invention. They are not intended to indicate or imply that the devices or components referred to must have, be constructed, or operate in a specific orientation, and therefore should not be construed as limitations on the present invention. Furthermore, the terms "first," "second," and "third" are used for descriptive purposes only and should not be construed as indicating or implying relative importance.

[0046] In the description of the present invention, it should be noted that, unless otherwise expressly specified or limited, the terms "mounted," "connected," and "connected" should be understood in a broad sense. For example, they may refer to fixed, detachable, or integral connections; mechanical or electrical connections; direct or indirect connections through an intermediate medium; and internal communication between two components. Those skilled in the art will understand the specific meanings of the above terms in the present invention based on the specific circumstances.

[0047] Example 1

[0048] The embodiment of the present invention provides a method for collaborative development of gas reservoirs and hydrate reservoirs, referring to Figure 2 As shown, a well group is used for implementation, wherein the well group includes a central well 3 and at least one connecting well 2 arranged around the central well 3; the connecting well 2 and the central well 3 penetrate the hydrate reservoir 7, the cap rock 6 and the sea level 1;

[0049] Reference Figure 1 As shown, the method includes:

[0050] S101, running the oil pipe 9 between the hydrate reservoir 7 and the gas reservoir 4;

[0051] In this embodiment, a block with a natural gas hydrate reservoir 7 and an underlying gas reservoir 4 was selected as the intervention area based on the block's geological structure. The thickness of the hydrate reservoir 7 was no less than 15 meters. After the intervention area was selected, an insulated oil pipeline 9 was run between the selected hydrate reservoir 7 and the gas reservoir 4.

[0052] S102, drilling the connecting well 2 through the hydrate reservoir 7 and the oil pipe 9 to a first preset position of the gas reservoir 4, and performing perforations in the hydrate reservoir 7 and the gas reservoir 4 respectively;

[0053] S103, drilling the central well 3 to a second preset position of the hydrate reservoir 7, and performing perforation in the hydrate reservoir 7;

[0054] S104. Reference Figure 2 As shown, a packer 8 is installed in the connecting well 2 at a position corresponding to the bottom of the hydrate reservoir 7, and the connecting well 2 and the central well 3 are used to carry out a first round of constant pressure production to decompose the hydrates in the hydrate reservoir 7 under the action of the pressure difference; wherein, the bottom hole pressure during the first round of constant pressure production is lower than the original pressure of the hydrate reservoir;

[0055] The well group, i.e. the connecting well 2 and the central well 3, adopts constant pressure production. The bottom hole pressure is lower than the original pressure of the hydrate reservoir. Under the action of the pressure difference, the hydrate decomposes and the decomposed natural gas enters the wellbore through the perforations and is produced by the well group (see Figure 2 The direction of natural gas flow in 5).

[0056] S105, during the first round of constant pressure production, monitoring the gas production rates of the connecting well 2 and the central well 3 until the daily gas production of the central well 3 and the connecting well 2 decreases to a first preset gas production rate;

[0057] S106, reference Figure 3 As shown, the packer 8 is installed at a position corresponding to the top of the hydrate reservoir 7 in the connecting well 2, and the central well 3 is used to perform a second round of constant-pressure production, so that the free gas in the gas reservoir 4 can return to the hydrate reservoir 7 along the connecting well 2 under the action of the pressure difference between the hydrate reservoir 7 and the gas reservoir 4, while carrying heat energy to promote the decomposition of the hydrate; wherein, the bottom hole pressure during the second round of constant-pressure production is lower than the original pressure of the hydrate reservoir;

[0058] The packer 8 installed at the bottom of hydrate reservoir 7 is used to separate hydrate reservoir 7 from gas reservoir 4 in the wellbore. The packer 8 installed at the top of hydrate reservoir 7 is used to separate hydrate reservoir 7 from the area above it in the wellbore. After the first round of depressurization development, the reservoir pressure, that is, the pressure of hydrate reservoir 7, decreases. By changing the position of packer 8, a pressure differential can be formed between hydrate reservoir 7 and gas reservoir 4. Under the action of the pressure differential between hydrate reservoir 7 and gas reservoir 4, free gas in gas reservoir 4 can return to hydrate reservoir 7 along connecting well 2, carrying heat energy to promote hydrate decomposition, thereby achieving coordinated development of gas reservoir 4 and hydrate reservoir 7. Natural gas generated by hydrate decomposition and free gas in gas reservoir 4 return to hydrate reservoir 7, enter the wellbore through perforations, and are produced by central well 3.

[0059] S107. During the second round of constant pressure production, the gas production rate of the central well 3 is monitored until the single-well daily gas production of the central well 3 decreases to a second preset gas production, and then production is stopped.

[0060] In the embodiment of the present invention, the above-mentioned well group is used to exploit the gas reservoir 4 and hydrate reservoir 7 to be exploited. Depending on the actual conditions of the gas reservoir 4 and hydrate reservoir 7 to be exploited, multiple well groups provided by the embodiment of the present invention can be arranged to jointly exploit the gas reservoir 4 and hydrate reservoir 7 to be exploited, thereby improving the recovery efficiency of the gas reservoir 4 and hydrate reservoir 7.

[0061] In the embodiment of the present invention, the number of the connecting wells 2 and the number of the central wells 3 arranged in the above-mentioned well group can be selected according to the actual situation of the gas reservoir 4 and the hydrate reservoir 7 to be mined, as long as the recovery rate of the gas reservoir 4 and the hydrate reservoir 7 can be better improved. In order to better illustrate the well group provided by the embodiment of the present invention, this embodiment is described in detail as follows for the sake of ease of understanding, taking the well group including two connecting wells 2 and one central well 3 as an example: Figure 2As shown, the two connecting wells 2 are arranged around the central well 3. Before mining, three vertical wells are drilled to form a well group consisting of two connecting wells and one central well.

[0062] The present invention designs a well group consisting of a connecting well 2 and a central well 3. The well group is used to first reduce the pressure of the natural gas hydrate reservoir 7 for exploitation. The reservoir pressure is continuously reduced, and the position of the packer 8 in the connecting well 2 is changed. The free gas in the gas reservoir 4 can return to the natural gas hydrate reservoir 7 along the connecting well 2 under the action of the pressure difference, and at the same time carry heat energy to promote the decomposition of the hydrate, thereby realizing the coordinated development of the gas reservoir 4 and the hydrate reservoir 7.

[0063] The method for collaborative development of gas reservoirs and hydrate reservoirs provided in an embodiment of the present invention can be applied to the exploitation of natural gas hydrate reservoirs with underlying gas reservoirs. Through a well group consisting of connecting wells and central wells, the thermal energy of the gas reservoir is used to promote the depressurization and development of production capacity of the natural gas hydrate reservoir. Specifically, a packer is installed in a connecting well at a position corresponding to the bottom of the hydrate reservoir, and a first round of constant-pressure production is carried out on the hydrate reservoir using a well group, namely the connecting well and the central well. The bottomhole pressure during the first round of production is controlled to be lower than the original pressure of the hydrate reservoir, so that hydrates in the hydrate reservoir decompose under the action of the pressure difference, and the decomposed natural gas enters the wellbore through the perforations and is produced by the well group, and the pressure of the hydrate reservoir continuously decreases. After the first round of production, the position of the packer in the connecting well is changed and the packer is installed at a position corresponding to the top of the hydrate reservoir in the connecting well. A second round of constant-pressure production is carried out using the central well, and the bottomhole pressure during the second round of constant-pressure production is controlled to be lower than the original pressure of the hydrate reservoir. After the first round of pressure reduction production, due to the reduction in the hydrate reservoir pressure, the free gas in the gas reservoir can return to the hydrate reservoir along the connecting well under the action of the pressure difference between the hydrate reservoir and the gas reservoir, while carrying heat energy to promote the decomposition of hydrates, which can significantly increase the gas production rate and hydrate decomposition rate of the gas reservoir, realize the coordinated development of the gas reservoir and the hydrate reservoir, and provide a new technical idea for significantly increasing the production capacity of natural gas hydrate reservoirs.

[0064] In a specific embodiment, during the first round of constant pressure production, the bottom hole pressure is 0.30.7 times the original pressure of the hydrate reservoir.

[0065] In a specific embodiment, the daily gas production of the central well 3 and the connecting well 2 is gradually reduced to 500

[0066] 1000m 3 / d, the first round of constant pressure mining ends.

[0067] In a specific embodiment, the daily gas production of the central well 3 is gradually reduced to 500-1000m 3 / d, the second round of constant pressure mining ends.

[0068] In a specific embodiment, during the second round of constant pressure production, the bottom hole pressure is 0.30.7 times the original pressure of the hydrate reservoir.

[0069] In a specific embodiment, drilling the connecting well 2 through the hydrate reservoir 7 to the first preset position of the gas reservoir 4 includes:

[0070] The connecting well 2 penetrates the hydrate reservoir 7 and is drilled to a distance from the top of the gas reservoir 4. Location.

[0071] In a specific embodiment, drilling the central well 3 to the second preset position of the hydrate reservoir 7 and perforating the hydrate reservoir 7 includes:

[0072] The central well 3 is drilled to a distance from the top of the hydrate reservoir 7. location and perforating in the hydrate reservoir 7.

[0073] In a specific embodiment, the connecting well 2 and the central well 3 are both completed by perforation, and the perforation points are spaced 5 to 10 meters apart.

[0074] In a specific embodiment, the oil pipe 9 is made of heat-insulating material to reduce the loss of heat carried by free gas in the gas reservoir.

[0075] In a specific embodiment, the lowered oil pipe 9 is made of glass fiber, and its thermal conductivity is less than 0.04 W / m·K.

[0076] In order to better illustrate the method for collaborative development of gas reservoirs and hydrate reservoirs provided by the embodiment of the present invention, this embodiment is described through a specific example for ease of understanding. The specific steps include:

[0077] S201. Based on the geological and structural environment of the block, select a natural gas hydrate reservoir 7 with an underlying gas reservoir 4 as a measure area, wherein the thickness of the hydrate reservoir 7 is not less than 15 m;

[0078] S202, reference Figure 2 As shown, two connecting wells 2 and a central well 3 are drilled, wherein the connecting well 2 penetrates the hydrate reservoir 7 and is drilled to the top of the gas reservoir 4. Position, and perforation is performed in the hydrate reservoir 7 and gas reservoir 4 respectively. The oil pipe 9 is made of glass fiber with a thermal conductivity of less than 0.04W / m·K. The central well 3 is drilled to the top of the hydrate reservoir. Perforation is carried out at the location, with the interval between each perforation point being 5m;

[0079] S203, reference Figure 2As shown, a packer 8 is installed at a position corresponding to the bottom of the hydrate reservoir in the two connecting wells 2;

[0080] S204, reference Figure 2 As shown, the well group (i.e., two connected wells 2 and central well 3) adopts constant pressure production, and the bottom hole pressure is 0.5 times the original pressure of the hydrate reservoir. Under the action of the pressure difference, the hydrate decomposes, and the decomposed natural gas enters the wellbore through the perforations and is produced by the well group;

[0081] S205, continuously record the gas production rate, when the daily gas production of a single well decreases to 1000m 3 / d, change the position of the packer 8, refer to Figure 3 As shown, the packers 8 in the two connected wells 2 are installed at positions corresponding to the top of the hydrate reservoir. The central well 3 is used for constant pressure production, and the bottomhole pressure is 0.5 times the original pressure of the hydrate reservoir. After the pressure reduction development, the pressure of the hydrate reservoir decreases, and the free gas in the gas reservoir 4 can return to the hydrate reservoir 7 along the connected well 2 under the action of the pressure difference, while carrying heat energy to promote the decomposition of the hydrate reservoir 7, thereby achieving coordinated development of the gas reservoir 4 and the hydrate reservoir 7.

[0082] S206, such as Figure 2 As shown in the figure, the gas production rate is continuously recorded. When the gas production of the central well decreases to 1000m3 in 3 days, the gas production rate is gradually reduced to 1000m3. 3 / d, stop mining.

[0083] Example 2

[0084] Based on the same inventive concept, an embodiment of the present invention further provides a method for collaborative development of a gas reservoir and a hydrate reservoir, which is implemented using a well group, wherein the well group includes a central well 3 and at least one connecting well 2 arranged around the central well 3;

[0085] The system includes: an oil pipe lowering device, a perforating device, a production device and a gas production monitoring device;

[0086] The oil pipe lowering device is used to lower the oil pipe 9 between the hydrate reservoir 7 and the gas reservoir 4;

[0087] The perforating device is used to drill the connecting well 2 through the hydrate reservoir 7 and the oil pipe 9 to a first preset position of the gas reservoir 4, and perform perforations in the hydrate reservoir 7 and the gas reservoir 4 respectively; and to drill the central well 3 to a second preset position of the hydrate reservoir 7, and perform perforations in the hydrate reservoir 7;

[0088] The mining device is used to install a packer 8 at a position corresponding to the bottom of the hydrate reservoir 7 in the connecting well 2, and use the connecting well 2 and the central well 3 to perform a first round of constant-pressure mining to decompose the hydrates in the hydrate reservoir 7 under the action of the pressure difference; wherein, during the first round of constant-pressure mining, the bottom hole pressure is less than the original pressure of the hydrate reservoir; and, install the packer 8 at a position corresponding to the top of the hydrate reservoir 7 in the connecting well 2, and use the central well 3 to perform a second round of constant-pressure mining, so that the free gas in the gas reservoir 4 can return to the hydrate reservoir 7 along the connecting well 2 under the action of the pressure difference between the hydrate reservoir 7 and the gas reservoir 4, while carrying heat energy to promote the decomposition of the hydrates; wherein, during the second round of constant-pressure mining, the bottom hole pressure is less than the original pressure of the hydrate reservoir, and mining is stopped;

[0089] The gas production monitoring device is used to monitor the gas production rate of the connecting well 2 and the central well 3 during the first round of constant pressure production, until the daily gas production of the central well 3 and the connecting well 2 decreases to the first preset gas production; and, during the second round of constant pressure production, monitor the gas production rate of the central well 3 until the daily gas production of the central well 3 decreases to the second preset gas production.

[0090] In the embodiment of the present invention, the method for collaborative development of gas reservoirs and hydrate reservoirs corresponds to the method for collaborative development of gas reservoirs and hydrate reservoirs described in the above embodiment 1. Its specific implementation process can refer to the process of development using the method for collaborative development of gas reservoirs and hydrate reservoirs in the above embodiment 1. The repeated parts will not be repeated here.

[0091] Example 3

[0092] Based on the same inventive concept, the present invention also provides a well group for collaborative development of gas reservoirs and hydrate reservoirs, including: a central well 3 and at least one connecting well 2 arranged around the central well 3, the connecting well 2 penetrates the hydrate reservoir 7 and is drilled to a first preset position of the gas reservoir 4, and the central well 3 is drilled to a second preset position of the hydrate reservoir 7.

[0093] In a specific embodiment, the connecting well 2 penetrates the hydrate reservoir 7 and is drilled to a distance from the top of the gas reservoir 4. Location.

[0094] In a specific embodiment, the central well 3 is drilled to a depth of 100 m from the top of the hydrate reservoir 7. Location.

[0095] In the embodiment of the present invention, the gas reservoir and hydrate reservoir collaborative development well group corresponds to the gas reservoir and hydrate reservoir collaborative development method described in the above embodiment 1. Its specific layout and application process can refer to the development process of applying the gas reservoir and hydrate reservoir collaborative development method in the above embodiment 1. The repeated parts will not be repeated here.

[0096] In this document, relational terms such as first and second, etc., are used only to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Moreover, the terms "comprises", "includes" or any other variations thereof are intended to cover non-exclusive inclusion, so that a process, method, article or apparatus comprising a series of elements includes not only those elements, but also other elements not explicitly listed, or elements inherent to such process, method, article or apparatus. The orientation or positional relationship indicated by the terms "upper", "lower", etc. is based on the orientation or positional relationship shown in the accompanying drawings, and is only for the convenience of describing the present invention and simplifying the description, and does not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operate in a specific orientation, and therefore should not be understood as a limitation on the present invention.

[0097] Each embodiment in this specification is described in a progressive manner, and the same or similar parts between the embodiments can be referred to each other. Each embodiment focuses on the differences from other embodiments. It should be noted that, in the absence of conflict, the embodiments of the present invention and the features in the embodiments can be combined with each other. The present invention is not limited to any single aspect, nor to any single embodiment, nor to any combination and / or permutation of these aspects and / or embodiments. Each aspect and / or embodiment of the present invention can be used alone or in combination with one or more other aspects and / or other embodiments.

[0098] Finally, it should be noted that the above-described embodiments are only specific implementation methods of the present invention, which are used to illustrate the technical solutions of the present invention, rather than to limit them. The scope of protection of the present invention is not limited thereto. Although the present invention has been described in detail with reference to the above-described embodiments, those skilled in the art should understand that any person skilled in the art can modify or easily conceive of changes to the technical solutions described in the above-described embodiments within the technical scope disclosed by the present invention, or replace some of the technical features therein with equivalents. Such modifications, changes, or replacements do not deviate from the spirit and scope of the technical solutions of the embodiments of the present invention, and should be included in the scope of protection of the present invention. Therefore, the scope of protection of the present invention shall be subject to the scope of protection of the claims.

Claims

1. A method for collaborative development of gas reservoirs and hydrate reservoirs, characterized in that: The method is implemented by using a well group, wherein the well group includes a central well and at least one connecting well arranged around the central well; the method includes: An oil pipeline is run between the hydrate reservoir and the gas reservoir; Drilling the connecting well through the hydrate reservoir and the oil pipe to a first preset position of the gas reservoir, and performing perforations in the hydrate reservoir and the gas reservoir respectively; Drilling the central well to a second preset position of the hydrate reservoir and perforating the hydrate reservoir; A packer is installed in the connecting well at a position corresponding to the bottom of the hydrate reservoir, and a first round of constant pressure production is carried out using the connecting well and the central well to decompose hydrates in the hydrate reservoir under the action of a pressure differential; wherein the bottom hole pressure during the first round of constant pressure production is less than the original pressure of the hydrate reservoir; During the first round of constant pressure production, the gas production rates of the connecting well and the central well are monitored until the daily gas production of the central well and the connecting well decreases to a first preset gas production rate; The packer is installed at a position in the connecting well corresponding to the top of the hydrate reservoir, and a second round of constant-pressure production is carried out using the central well, so that free gas in the gas reservoir can return to the hydrate reservoir along the connecting well under the action of the pressure difference between the hydrate reservoir and the gas reservoir, while carrying heat energy to promote the decomposition of the hydrate; wherein the bottom hole pressure during the second round of constant-pressure production is lower than the original pressure of the hydrate reservoir; During the second round of constant pressure production, the gas production rate of the central well is monitored until the single-well daily gas production of the central well decreases to a second preset gas production, and then production is stopped.

2. The method for collaborative development of gas reservoirs and hydrate reservoirs according to claim 1, characterized in that: During the first round of constant-pressure production, the bottom hole pressure was 0.3 to 0.7 times the original pressure of the hydrate reservoir.

3. The method for collaborative development of gas reservoirs and hydrate reservoirs according to claim 1, characterized in that: The daily gas production of the central well and the connecting well is gradually reduced to 500-1000 The first round of constant pressure mining ends.

4. The method for collaborative development of gas reservoirs and hydrate reservoirs according to claim 1, characterized in that: The daily gas production of the central well is gradually reduced to 500-1000 The second round of constant pressure mining ends.

5. The method for collaborative development of gas reservoirs and hydrate reservoirs according to claim 1, characterized in that: During the second round of constant pressure production, the bottom hole pressure is 0.3 to 0.7 times the original pressure of the hydrate reservoir.

6. The method for collaborative development of gas reservoirs and hydrate reservoirs according to claim 1, characterized in that: Drilling the connecting well through the hydrate reservoir to a first preset position of the gas reservoir includes: The connecting well penetrates the hydrate reservoir and is drilled to a distance from the top of the gas reservoir. Location.

7. The method for collaborative development of gas reservoirs and hydrate reservoirs according to claim 1, characterized in that: The step of drilling the central well to a second preset position of the hydrate reservoir and performing perforation in the hydrate reservoir comprises: The central well is drilled to a distance from the top of the hydrate reservoir. location and perforated in the hydrate reservoir.

8. The method for collaborative development of gas reservoirs and hydrate reservoirs according to any one of claims 1 to 7, characterized in that: The connecting well and the central well are completed by perforation, and the perforation points are spaced 5 to 10 .

9. The method for collaborative development of gas reservoirs and hydrate reservoirs according to any one of claims 1 to 7, characterized in that: The oil pipe lowered is made of heat-insulating material.

10. The method for collaborative development of gas reservoirs and hydrate reservoirs according to claim 9, characterized in that: The oil pipe is made of glass fiber, and the thermal conductivity is less than 0.

04. .

11. A gas reservoir and hydrate reservoir collaborative development system, characterized in that: The method is implemented by using a well group, wherein the well group includes a central well and at least one connecting well arranged around the central well; The system includes: an oil pipe lowering device, a perforating device, a production device and a gas production monitoring device; The oil pipe lowering device is used to lower the oil pipe between the hydrate reservoir and the gas reservoir; The perforating device is used to drill the connecting well through the hydrate reservoir and the oil pipe to a first preset position of the gas reservoir, and perform perforations in the hydrate reservoir and the gas reservoir respectively; and to drill the central well to a second preset position of the hydrate reservoir, and perform perforations in the hydrate reservoir; The mining device is used to install a packer at a position corresponding to the bottom of the hydrate reservoir in the connecting well, and use the connecting well and the central well to perform a first round of constant-pressure mining to decompose hydrates in the hydrate reservoir under the action of the pressure difference; wherein, during the first round of constant-pressure mining, the bottom hole pressure is less than the original pressure of the hydrate reservoir; and, install the packer at a position corresponding to the top of the hydrate reservoir in the connecting well, and use the central well to perform a second round of constant-pressure mining, so that free gas in the gas reservoir can return to the hydrate reservoir along the connecting well under the action of the pressure difference between the hydrate reservoir and the gas reservoir, while carrying heat energy to promote the decomposition of hydrates; wherein, during the second round of constant-pressure mining, the bottom hole pressure is less than the original pressure of the hydrate reservoir, and mining is stopped; The gas production monitoring device is used to monitor the gas production rate of the connecting well and the central well during the first round of constant pressure production, until the daily gas production of the central well and the connecting well decreases to the first preset gas production; and, during the second round of constant pressure production, monitor the gas production rate of the central well until the daily gas production of the central well decreases to the second preset gas production.

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