Collecting method of core gas in natural gas hydrate drilling field

Abstract

The invention relates to a collecting method of core gas in a natural gas hydrate drilling field. The collecting method comprises the following steps of: (1) step 1, cleaning a collected core sample in the drilling field and placing the cleaned core sample in an air collector, and fully filling saturated salt water and discharging air in the air collector under the thermostatic waterbath condition of an air chamber; step 2, selecting a gas collecting bottle the size of which is matched with the gas production rate of a core, and when the saturated salt water is filled in the thermostatic waterbath, connecting a bottle port of the gas collecting bottle with a gas collecting outlet of the air collector; and step 3, collecting release gas of the core sample under the gas condition set by the air chamber is in within the pre-set time, then screwing down a bottle cover of the gas collecting bottle under the thermostatic waterbath, and finishing the collection of the release gas of the core sample. The collecting method provided by the invention has the advantages that the processes of packaging the aquo-complex core sample, releasing the gas, collecting the gas, collecting gas in an oscillation manner and sealing and storing the gas are finished once, a series of pilot processes are simplified, and the work efficiency of gas collection is greatly improved.

Description

technical field [0001] The invention relates to the field of gas collection at a natural gas hydrate drilling site, and more specifically relates to a method for collecting hydrocarbon gas in rock cores at a natural gas hydrate drilling site and a method for identifying natural gas hydrate based thereon. Background technique [0002] Gas hydrate is a kind of high density (1 m 3 Can release 164 m 3 The clean energy of methane) is twice the sum of conventional energy resources such as coal, oil, and natural gas in the world, and has attracted great attention from many countries around the world. The original form of gas hydrate usually exists in the pores or crevices of drilled cores. When natural gas hydrates actually exist underground, the drilled cores will release a large amount of hydrocarbon gas when they reach the surface at normal temperature and pressure. Therefore, the amount of gas released from the core during drilling is one of the key parameters for quickly jud...

AI Technical Summary

Problems solved by technology

This method uses normal temperature mechanical oscillation to release gas. The advantages are: simple and fast field operation; the disadvantages are: (1) With the decomposition of hydrate and the release of gas, the pressure in the metal tank is increasing, which inhibits the hydrate. Decomposition, resulting in incomplete gas release; (2) The hydrocarbon gas released from the decomposition is mixed with the air in the reserved space on the top of the metal tank, causing a series of analysis errors

This method adopts natural static release at room temperature, draining water and taking air. The advantage is that the field operation is simple and the influence of air is eliminated; the disadvantages are: (1) The natural release speed is slow; (2) The decomposition and release of the sample is affected by the ambient temperature Larger, resulting in different degrees of hydrate decomposition and larger errors in gas release

[0006] To sum up, the above two methods existing in the prior art all have the advantages of simple field operation, but also have the disadvantages of slow decomposition, low efficiency, incompleteness, and being easily affected by ambient temperature, and may also be affected by The influence of air mixed with pollution, this kind of defect in the collection of gas released from the core in the prior art, makes the identification of natural gas hydrate in the prior art also have large errors, and can not be obtained quickly identify

Images