Side-by-side horizontal well exploitation method of natural gas hydrates

Abstract

The invention provides a side-by-side horizontal well exploitation method of natural gas hydrates and belongs to the technical field of natural gas hydrate exploitation. The method comprises the steps that combined with geological data, a side-by-side horizontal well net is arranged in a target reservoir, and matched well-completion practices are conducted, and after well completion, depressurizing exploitation is conducted through the horizontal wells until no economic benefits; fracturing operation is conducted on horizontal wells after depressurizing exploitation, then a ground supply system and an insulated tubing heating system are arranged in a water injection well, hot water is injected into the natural gas hydrate reservoir through the water injection well, and nature gas and produced water are collected through a production well. The method is suitable for the reservoir which is poor in connectedness, thick in storage and low in natural gas hydrate saturation, the reserves of the available natural gas hydrates can be improved by arranging the horizontal wells which are distributed side by side in the target reservoir, and the insulated tubing heating system is utilized to achieve hot water injection for exploitation so that the heating efficiency can be improved, the heat loss can be reduced, the gas production efficiency can be improved, and the economic benefit can be improved.

Description

technical field [0001] A method for exploiting natural gas hydrate row-type horizontal wells belongs to the technical field of natural gas hydrate exploitation, and in particular relates to a method for exploiting natural gas hydrate by comprehensively utilizing a heating method and a depressurization method. Background technique [0002] Natural gas hydrate (NGH for short) is a non-stoichiometric clathrate compound formed by natural gas and water at a certain low temperature and high pressure, also known as "combustible ice". 1m 3 Natural gas hydrate can contain 164m 3 methane gas and 0.8m 3 of water. "Combustible ice" is a secondary product of natural gas, and its application range is roughly the same as that of natural gas. It is a typical oil substitute. "Combustible ice" is extremely flammable. Under the same conditions, the energy generated by the combustion of "combustible ice" is dozens of times higher than that of coal, oil, and natural gas. It is known as "the ...

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Problems solved by technology

However, the decomposition driving force provided by the depressurization method alone is small, and the decomposition of natural gas hydrate causes the temperature to drop. When the temperature drops below 0°C, it will also cause ice blockage and stagnation of natural gas hydrate decomposition. CN 20111048906.4 discloses a drainage The natural gas hydrate is exploited by depressurization and heating at the same time, which continuously promotes the decomposition of hydrate. The above two methods use the gas escaping after the hydrate is decomposed, and the water falls due to its own weight. The water pump discharges the water out of the natural gas hydrate production well. But in fact, the decomposed gas carries a large amount of water vapor when it escapes, and the escape speed is very slow, and the extraction efficiency is very low

Moreover, in CN 20111048906.4, horizontal wells are used for combustion and heating. It is unsafe to burn and heat in natural gas hydrate exploitation wells. There are combustible gases inside and outside the natural gas hydrate exploitation wells. It is very dangerous to use open flames for direct heating.

In CN 201310398998.0, microwave generators are used to heat and exploit natural gas hydrates, and the decomposition of natural gas hydrates is promoted by heating. However, the use of vertical wells limits the heated volume of heated natural gas hydrates, and it is more convenient to fix the microwave generators on the upper part of the packer. Further limit the heating volume of gas hydrate

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