Deep oil and gas reservoir and hydrate reservoir well group collaborative exploitation method
By utilizing the heat transfer technology of deep oil and gas reservoirs in natural gas hydrate mining and combining well group structure adjustment, the problem of insufficient heat in hydrate mining is solved, efficient mining is achieved and cost is reduced, and cost is met.
Patent Information
- Application Number
- CN202310673722.2
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2023-06-08
- Publication Date
- 2024-12-10
AI Technical Summary
The existing natural gas hydrate mining methods are costly and have low single well yields. Especially during the hydrate decomposition process, the decomposition rate is reduced due to the lack of heat, making it difficult to achieve cost-effective commercial mining.
The coordinated mining method of deep oil and gas reservoirs and hydrate well groups is adopted. By laying horizontal and vertical wells in the target area, the heat carried by oil and gas fluids is used to supply heat to the hydrate layer, and combined with the pressure-down mining technology, the well group structure is adjusted to Improve heat transfer efficiency.
It effectively overcomes the problem of decomposition rate reduction caused by heat transfer in the later stage of hydrate decomposition, reduces drilling costs, and achieves efficient hydrate mining, with high economic benefits and flexible production adjustment capabilities.
Smart Images
Figure CN119102557A_ABST
Abstract
Description
Technical Field
[0001] The invention relates to the technical field of natural gas hydrate development, and in particular to a method for coordinated exploitation of deep oil and gas reservoirs and hydrate reservoir well groups. Background Art
[0002] At present, my country has a huge total reserve of natural gas hydrates. The prospective resources of natural gas hydrates in the northern slope of the South China Sea alone reach tens of billions of tons of oil equivalent. Its industrial development is of great significance to improving my country's energy consumption structure, ensuring national energy security and achieving the "dual carbon" strategic goals. In view of the characteristics of natural gas hydrates and the geological conditions of the occurrence area, the mainstream mining methods currently proposed include pressure reduction method, heat injection method, inhibitor injection release and CO2 replacement method. Among them, the heat injection method, inhibitor injection method and CO2 replacement method have high costs and do not meet the requirements of economic and efficient hydrate development. They are not currently used in China. A domestic company used the pressure reduction method for two trials of hydrates in the sea area. The well types were vertical wells and horizontal wells. The single well production of the two exploitations was low and the production decline rate was fast. This is because the hydrate decomposition process requires heat absorption. If the surrounding formations cannot provide sufficient heat, the hydrate decomposition will be slow or stop. Therefore, in order to realize the commercial exploitation of hydrates, it is crucial to introduce an economical and efficient heat supplement method based on pressure reduction exploitation. Summary of the invention
[0003] In view of the shortcomings of the prior art, the object of the present invention is to provide a method for coordinated exploitation of deep oil and gas reservoirs and hydrate reservoir well groups, comprising:
[0004] Step 1: determine the target area, select the area where the hydrate layer and the deep oil and gas layer are coupled and coexisting, and the thickness of the hydrate layer meets the target requirements;
[0005] Step 2: arranging horizontal wells and vertical wells. Arranging horizontal wells in the hydrate layer of the target area and setting multiple vertical wells around the horizontal wells. The vertical wells penetrate the overlying rock layer, the hydrate layer and the intermediate layer from top to bottom in sequence and extend to the deep oil and gas layer.
[0006] Step 3: Horizontal well and vertical well operation transformation. Horizontal wells are located in the hydrate layer section for perforation and reservoir transformation operations, and vertical wells are located in the deep oil and gas layer section for perforation and reservoir transformation operations;
[0007] Step 4: Oil, gas and hydrate production. First, start the oil and gas production in the vertical well. The oil and gas fluids flow through the vertical well to the wellhead for production. At the same time, the heat carried by the oil and gas fluids is exchanged in the hydrate layer, continuously supplying heat to the hydrate layer. At the same time, the hydrate production well is depressurized to produce hydrates.
[0008] Furthermore, in step 1, the target thickness of the hydrate layer is greater than or equal to 15 m.
[0009] Furthermore, in step 2, the number of the vertical wells is greater than or equal to 4.
[0010] Furthermore, the horizontal section of the horizontal well is located in the hydrate layer, and in the middle of the hydrate layer.
[0011] Furthermore, when the gas production rate of the horizontal well in the hydrate layer reaches 300m 3 / d, close the horizontal wells in the hydrate layer, increase the gas production rate of the deep oil and gas vertical wells, increase the fluid flow rate in the vertical heat exchange section of the vertical wells to increase the heat, and restart the horizontal wells in the hydrate layer for production when the temperature of the hydrate layer rises.
[0012] Furthermore, a portion of the horizontal well located in the hydrate layer is provided with a plurality of horizontal well perforations.
[0013] Furthermore, the portion of the vertical well located in the deep oil and gas layer is provided with a plurality of vertical well perforations.
[0014] Furthermore, a thermal insulation layer is provided in the portion of the vertical well located in the middle stratum.
[0015] Furthermore, the thermal insulation material of the thermal insulation layer is a nano thermal insulation board.
[0016] Furthermore, the thickness of the thermal insulation layer is 18 mm-22 mm.
[0017] In summary, the beneficial technical effects of the present invention are as follows: the present invention promotes the exploitation of hydrate reservoirs by utilizing the heat carried by the fluid when exploiting deep oil and gas reservoirs, effectively solving the problem of reduced decomposition rate caused by heat transfer in the later stage of hydrate decomposition, and overcoming the high cost of traditional heat injection methods; utilizing deep oil and gas reservoir production wells to effectively reduce drilling costs, and has strong application value in actual exploitation operations; through the setting of well groups, it is easy to make adjustments according to production conditions in the later stage to meet production requirements; while exploiting deep oil and gas, efficient hydrate exploitation is achieved, with high economic benefits. BRIEF DESCRIPTION OF THE DRAWINGS
[0018] The above and other objects, features and advantages of the present invention will become more apparent through the following description of the embodiments of the present invention with reference to the accompanying drawings. The accompanying drawings are only used for the purpose of illustrating the preferred embodiment mode and are not to be considered as limiting the present invention. In addition, the same reference symbols are used to represent the same components throughout the accompanying drawings.
[0019] Figure 1 It is a schematic diagram of the steps of the method of the present invention;
[0020] Figure 2 It is a schematic diagram of a well group for cooperative production of horizontal wells and vertical wells of the present invention;
[0021] Figure 3 It is a top view of the well group of horizontal wells and vertical wells for cooperative production according to the present invention;
[0022] In the figure, 1. overlying rock formation, 2. hydrate layer, 3. interlayer (intermediate formation), 4. deep oil and gas layer, 5. vertical well, 6. horizontal well, 7. heat exchange section of vertical well, 8. horizontal section of horizontal well, 9. horizontal well perforation, 10. heat, 11. vertical well perforation. DETAILED DESCRIPTION
[0023] The present invention is further described in detail below in conjunction with 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 described herein. On the contrary, 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. It should be noted that the embodiments of the present invention and the features in the embodiments can be combined with each other without conflict.
[0024] Reference Figure 1 As shown, a method for coordinated exploitation of a deep oil and gas reservoir and a hydrate reservoir well group disclosed in the present invention comprises: step one, determining a target area, selecting a coupled symbiotic area of a hydrate layer and a deep oil and gas layer, wherein the thickness of the hydrate layer meets the target requirement; step two, laying out horizontal wells and vertical wells, laying out a horizontal well in the hydrate layer of the target area, and setting up a plurality of vertical wells around the horizontal well, wherein the vertical wells sequentially penetrate the overlying rock layer, the hydrate layer and the intermediate stratum from top to bottom, and extend into the deep oil and gas layer; step three, operational transformation of the horizontal wells and the vertical wells, wherein the horizontal wells are located in the hydrate layer section for perforation and reservoir transformation operations, and the vertical wells are located in the deep oil and gas layer section for perforation and reservoir transformation operations; step four, oil and gas and hydrate exploitation, firstly starting the oil and gas exploitation of the vertical well, wherein the oil and gas fluid flows through the vertical well to the wellhead for exploitation, and at the same time, the heat carried by the oil and gas fluid is exchanged in the hydrate layer, and heat is continuously supplied to the hydrate layer, and at the same time, the hydrate production well is depressurized to exploit hydrates. It should be understood that horizontal wells are used for hydrate production, and vertical wells are used for oil and gas production.
[0025] In this embodiment, in step 1, the target thickness of the hydrate layer is greater than or equal to 15m. In this embodiment, in step 2, the number of vertical wells is greater than or equal to 4. In this embodiment, the horizontal section of the horizontal well is located in the hydrate layer and in the middle of the hydrate layer. In this embodiment, when the gas production rate of the horizontal well in the hydrate layer reaches 300m 3 / d, close the horizontal wells in the hydrate layer, increase the gas production rate of the deep oil and gas vertical wells, increase the fluid flow rate in the vertical heat exchange section of the vertical wells, increase the heat, and restart the horizontal wells in the hydrate layer for production when the temperature of the hydrate layer rises. In this embodiment, the portion of the horizontal well located in the hydrate layer is provided with a plurality of horizontal well perforations. In this embodiment, the portion of the vertical well located in the deep oil and gas layer is provided with a plurality of vertical well perforations. In this embodiment, a thermal insulation layer is provided in the portion of the vertical well located in the middle formation. In this embodiment, the thermal insulation material of the thermal insulation layer is a nano thermal insulation board. In this embodiment, the thickness of the thermal insulation layer is 18mm-22mm.
[0026] Reference Figure 1-3 As shown, it is a specific preferred embodiment of a method for coordinated exploitation of deep oil and gas reservoirs and hydrate reservoir well groups disclosed in the present invention:
[0027] Step 1, such as Figure 1 As shown, according to the scale and daily production of the deep oil and gas layer 4, the scale and permeability of the hydrate layer 2 and other reservoir parameters, the selected hydrate layer thickness is 15m, and a hydrate production well (horizontal well 6) is deployed in the center of the hydrate layer, and four deep oil and gas production wells (vertical wells 5) are deployed at appropriate distances around the horizontal section 8 of the hydrate production well (horizontal well 6), and four deep oil and gas production wells (vertical wells 5) are deployed to form a square grid well;
[0028] Step 2, such as Figure 2 As shown, the hydrate production well (horizontal well 6) penetrates the overburden stratum 1 and uses the hydrate production well horizontal section 8 in the middle of the hydrate layer 2; the deep oil and gas production well (vertical well 5) penetrates the overburden stratum 1, the hydrate layer 2 and the intermediate stratum 3, and extends to the deep oil and gas layer 4; taking into account the different lithologies of the hydrate layer 2 and the deep oil and gas layer 4, the overpressure perforation with sand control components is selected in the horizontal section 8 of the hydrate production well to form the horizontal well perforation 9, and the ultra-high temperature perforation is selected in the deep oil and gas production well (vertical well 5) located in the deep oil and gas layer 4 to form the vertical well perforation 11;
[0029] Step three, according to the actual situation of each well and the geological characteristics of the hydrate layer 2 and the deep oil and gas layer 4, select appropriate fracturing materials and scientifically design construction parameters. The hydrate layer 2 is hydraulically fractured by using seawater-based fracturing fluid through the horizontal section 8 of the hydrate production well, and the deep oil and gas production well (vertical well 5) is hydraulically fractured by using high-temperature resistant weighted fracturing fluid to fracture the deep oil and gas layer 4; an insulation layer is set in the part of the deep oil and gas production well (vertical well 5) located in the middle formation, and the insulation material of the insulation layer is selected from nano insulation board, and the thickness of the insulation layer is 20mm. The insulation layer can reduce the loss of heat carried by the oil and gas fluid in the deep oil and gas production well (vertical well 5) in the middle formation, so that more heat is transferred to the hydrate layer, and better heat energy is provided for hydrate decomposition.
[0030] Step 4: The oil and gas fluid in the deep oil and gas layer 4 returns through the deep oil and gas production well 5, and the heat 10 carried enters the hydrate layer 2 through the vertical heat exchange well section 7 located in the hydrate layer 2, providing heat compensation in the hydrate production process and promoting hydrate decomposition; the hydrate production well (horizontal well 6) is depressurized and produced in the hydrate layer 2 through the hydrate production well horizontal section 8, and the gas and water produced by the decomposition are produced through the hydrate production well (horizontal well 6) wellbore; in this embodiment, when the gas production rate of the hydrate production well (horizontal well 6) is 300m 3 / d, the hydrate production well (horizontal well 6) is closed, the gas production rate of the deep oil and gas production well (vertical well 5) is increased, the fluid flow rate in the vertical heat exchange well section 7 is increased, the accumulation of heat 10 is increased, and when the temperature of the hydrate layer 2 rises again, the hydrate production well (horizontal well 6) is restarted for production.
[0031] In this embodiment, a well group is used to exploit hydrates. Five wells closely connect the deep oil and gas layer 4 and the hydrate layer 2 through heat transfer in the vertical heat exchange well section, forming a joint application system. The well group is also easy to adjust according to production conditions in the later stage. In the well group, the central hydrate production well is the main well, and the four adjacent wells are defined as auxiliary wells. A main well and its corresponding auxiliary wells are called a well group. According to the influence of the geological conditions of the sea area where the plan is implemented and the constraints of the ground conditions, the number of auxiliary wells is not limited to 4, more or less than 4, and the shape of the well network is not necessarily square. Therefore, the well group used in the present invention changes with the specific terrain conditions of the target reservoir, and is not limited to the standard five-well group.
[0032] In summary, the beneficial technical effects of the embodiments disclosed in the present invention are as follows: the present invention promotes the exploitation of hydrate reservoirs by utilizing the heat carried by the fluid when exploiting deep oil and gas reservoirs, effectively solving the problem of reduced decomposition rate caused by heat transfer in the later stage of hydrate decomposition, and overcoming the high cost of traditional heat injection methods; utilizing deep oil and gas reservoir production wells to effectively reduce drilling costs, and has strong application value in actual exploitation operations; through the setting of well groups, it is easy to make adjustments according to production conditions in the later stage to meet production requirements; while exploiting deep oil and gas, efficient hydrate exploitation is achieved, with high economic benefits.
[0033] It should be noted that, in this article, relational terms such as first and second, etc. are only used 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 "include", "comprise" or any other variants thereof are intended to cover non-exclusive inclusion, so that a process, method, article or device including a series of elements includes not only those elements, but also other elements not explicitly listed, or also includes elements inherent to such process, method, article or device. In the absence of further restrictions, the elements defined by the statement "comprise a ..." do not exclude the presence of other identical elements in the process, method, article or device including the elements.
[0034] Finally, it should be noted that: Obviously, the above embodiments are only examples for clearly explaining the present invention, and are not intended to limit the implementation methods. For ordinary technicians in the relevant field, other different forms of changes or modifications can be made based on the above description. It is not necessary and impossible to list all the implementation methods here. The obvious changes or modifications derived from this are still within the scope of protection of the present invention.
Claims
1. A method for collaborative exploitation of deep oil and gas reservoirs and hydrate reservoir well groups, characterized in that: include: Step 1: determine the target area, select the area where the hydrate layer and the deep oil and gas layer are coupled and coexisting, and the thickness of the hydrate layer meets the target requirements; Step 2: arranging horizontal wells and vertical wells. Arranging horizontal wells in the hydrate layer of the target area and setting multiple vertical wells around the horizontal wells. The vertical wells penetrate the overlying rock layer, the hydrate layer and the intermediate layer from top to bottom in sequence and extend to the deep oil and gas layer. Step 3: Horizontal well and vertical well operation transformation. Horizontal wells are located in the hydrate layer section for perforation and reservoir transformation operations, and vertical wells are located in the deep oil and gas layer section for perforation and reservoir transformation operations; Step 4: Oil, gas and hydrate production. First, start the oil and gas production in the vertical well. The oil and gas fluids flow through the vertical well to the wellhead for production. At the same time, the heat carried by the oil and gas fluids is exchanged in the hydrate layer, continuously supplying heat to the hydrate layer. At the same time, the hydrate production well is depressurized to produce hydrates.
2. The method for coordinated exploitation of deep oil and gas reservoirs and hydrate reservoir well groups according to claim 1, characterized in that: In the step 1, the target thickness of the hydrate layer is greater than or equal to 15 m.
3. The method for coordinated exploitation of deep oil and gas reservoirs and hydrate reservoir well groups according to claim 1, characterized in that: In step 2, the number of the vertical wells is greater than or equal to 4.
4. The method for coordinated exploitation of deep oil and gas reservoirs and hydrate reservoir well groups according to claim 1, characterized in that: The horizontal section of the horizontal well is located in the hydrate layer and in the middle of the hydrate layer.
5. The method for coordinated exploitation of deep oil and gas reservoirs and hydrate reservoir well groups according to claim 1, characterized in that: In step 4, when the gas production rate of the horizontal well in the hydrate layer reaches 300m 3 / d, close the horizontal wells in the hydrate layer, increase the gas production rate of the vertical wells in the deep oil and gas layer, increase the fluid flow rate in the vertical heat exchange section of the vertical well to increase the heat, and restart the horizontal wells in the hydrate layer for production when the temperature of the hydrate layer rises.
6. The method for coordinated exploitation of deep oil and gas reservoirs and hydrate reservoir well groups according to claim 1, characterized in that: The portion of the horizontal well located in the hydrate layer is provided with a plurality of horizontal well perforations.
7. The method for coordinated exploitation of deep oil and gas reservoirs and hydrate reservoir well groups according to claim 1, characterized in that: The part of the vertical well located in the deep oil and gas layer is provided with a plurality of vertical well perforations.
8. The method for coordinated exploitation of deep oil and gas reservoirs and hydrate reservoir well groups according to claim 1, characterized in that: A thermal insulation layer is provided in the portion of the vertical well located in the middle stratum.
9. The method for coordinated exploitation of deep oil and gas reservoirs and hydrate reservoir well groups according to claim 8, characterized in that: The heat-insulating material of the heat-insulating layer is a nano heat-insulating board.
10. The method for coordinated exploitation of deep oil and gas reservoirs and hydrate reservoir well groups according to claim 1, characterized in that: The thickness of the thermal insulation layer is 18mm-22mm.