Method for exploiting natural gas hydrate through steam injection
A technology of natural gas and hydrate, which is applied in the fields of mining fluids, coal gasification, earth drilling, etc., and can solve the problems that the seabed combustible ice cannot be put into large-scale commercial mining, the risk of sand production, and the inability to produce gas and liquid in time, etc. Achieve the effects of improving low development efficiency, improving steam injection volume, and improving development efficiency
Active Publication Date: 2020-08-18
PETROCHINA CO LTD
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Problems solved by technology
[0009] Based on the above reasons, seabed combustible ice cannot be put into large-scale commercial mining so far.
[0010] The steam injection proposed in the prior art to develop natural gas hydrate has the following problems: 1) Natural gas hydrate generally exists as a cement in the reservoir, and the dense combination of water molecules reduces the permeability of the reservoir, thereby reducing the pressure of injected steam. Ability
2) The gas and liquid produced after the pyrolysis of natural gas hydrate cannot be produced in time, resulting in an increase in reservoir pressure and the risk of reservoir damage
3) During the drainage process, there will generally be a decrease in pressure, causing reservoir instability and sand production risks
Method used
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Embodiment 1
[0045] This embodiment provides a preferred steam injection method for recovering natural gas hydrate.
[0046] Description of reservoir properties:
[0047] The burial depth of the simulated reservoir I is 330m, the effective thickness of the reservoir is 50.0m, and the net-to-total thickness ratio is 0.92. The reservoir is loose sandstone cemented by hydrate crystallization. There is no pure mudstone interlayer inside the reservoir, and there is a good cap rock on the upper part of the reservoir; there is a coarse sandstone layer on the bottom, with a permeability of more than 10 Darcy and a formation pressure of 3.3MPa.
[0048] The production process of the method of steam injection to exploit natural gas hydrate is as follows:
[0049] 1) According to the geological characteristics and development status of the reservoir, make a preliminary evaluation:
[0050] The reservoir meets the following conditions: the shallower reservoir is 330m, the reservoir thickness is >20....
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The invention discloses a method for exploiting natural gas hydrate through steam injection. The method is characterized in that through an effective well pattern combination mode, the heat utilization rate of steam injected into a reservoir can be effectively improved, the production efficiency of the reservoir is improved, and the recovery rate and the exploitation effect of the hydrate are improved. Compared with an existing method for exploiting the natural gas hydrate, the method for exploiting the natural gas hydrate through steam injection has the advantages that the injection capacityis improved, the heating efficiency is improved, the gas yield is increased, and the sand-carrying output risk in the liquid production process is reduced; and through the method for exploiting the natural gas hydrate through steam injection, the exploitation efficiency of the natural gas hydrate can be improved, and the defects of low efficiency and discontinuity of natural gas hydrate exploitation at present are overcome.
Description
technical field [0001] The method belongs to the technical field of natural gas hydrate exploitation, and in particular relates to a method for exploiting natural gas hydrate by injecting steam. Background technique [0002] Combustible ice, that is, natural gas hydrate (Natural Gas Hydrate), the molecular structure is CH 4 ·H 2 O, is a solid cage-like crystalline compound formed when water and natural gas are mixed under medium-high pressure and low temperature conditions under certain conditions, and is distributed in the deep seabed or permafrost on land. Because it looks like ice and can burn when exposed to fire, it is called "combustible ice". [0003] The formation of combustible ice must meet at least three basic conditions: temperature, pressure and raw materials. First of all, combustible ice is formed below 0°C, and it will decompose once it exceeds 20°C, and the seabed temperature is generally maintained at about 2-4°C, which is most suitable for the formation...
Claims
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IPC IPC(8): E21B43/24E21B43/30E21B43/01E21B43/295E21B43/267
CPCE21B43/24E21B43/305E21B43/01E21B43/295E21B43/267
Inventor 郭二鹏蒋有伟
Owner PETROCHINA CO LTD