A method for exploiting natural gas hydrate by steam injection

Abstract

The invention discloses a method for exploiting natural gas hydrate by steam injection. The method uses an effective well pattern combination, which can effectively improve the heat utilization rate of steam injected into the reservoir, improve the production efficiency of the reservoir, and improve the recovery rate and development effect of hydrate. Compared with the existing method for exploiting natural gas hydrate by steam injection, the method of the present invention improves the injection capacity, improves the heating efficiency, increases the gas output, and reduces the sand-carrying output during the liquid production process. risk. The application of the combustible ice steam injection exploitation method provided by the present invention can improve the development efficiency of combustible ice, and improve the current shortcomings of low and unsustainable natural gas hydrate development efficiency.

Description

technical field [0001] The method belongs to the technical field of natural gas hydrate exploitation, in particular to a method for exploiting natural gas hydrate by steam injection. 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 by the combination of water and natural gas under medium-high pressure and low-temperature conditions, and is distributed in the permafrost of deep seabed or land. It is called "combustible ice" because it looks like ice and can burn in case of fire. [0003] At least three basic conditions must be met to form combustible ice: temperature, pressure and raw materials. First of all, combustible ice is formed below 0°C, and will decompose once it exceeds 20°C, while the seabed temperature is generally maintained at about 2 to 4°C, which is the most suitable for the formation of combustible ice; secondly, the pr...

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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

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