Method for exploiting natural gas hydrates by means of hot water injection by aid of row type horizontal wells

Abstract

The invention discloses a method for exploiting natural gas hydrates by means of hot water injection by the aid of row type horizontal wells, and belongs to the field of technologies for exploiting natural gas hydrates. The method includes arranging row type horizontal well networks for target reservoirs by the aid of geological data and carrying out matched well completion operation for the target reservoirs by the aid of the geological data; carrying out depressurization exploitation by the aid of the horizontal wells after well completion is carried out until economic benefits are unavailable; carrying out fracturing operation on the horizontal wells after decompression exploitation is carried out; arranging ground supply systems and downhole movable electric systems at water injectionwells; injecting hot water into the natural gas hydrate reservoirs by the aid of the water injection wells; collecting natural gas and produced water from production wells. The method has the advantages that the method is applicable to reservoirs with poor formation communication, high reservoir thicknesses and low natural gas hydrate saturation; the reservoirs can be movably heated by the downhole movable electric heating systems, the heating locations, heat output power and the water drainage and gas production speeds can be changed, accordingly, the natural gas hydrate reservoirs can be optimally exploited, the gas production efficiency can be improved, and the economic benefits can be increased.

Description

technical field [0001] A method for exploiting natural gas hydrate by hot water injection in row-type horizontal wells belongs to the technical field of exploiting natural gas hydrate, and in particular relates to a method for exploiting natural gas hydrate by comprehensively utilizing a heating method and a decompression 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....

AI Technical Summary

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

Images