Shale fluid-preserving sealed coring device and method

Abstract

The invention discloses a shale fluid-preserving airtight coring device and method, comprising: a coring bit, an outer cylinder and a drill pipe joint connected in sequence, the drill pipe joint can drive the outer cylinder and the coring bit to rotate; There are sequentially connected ball valve assemblies, inner cylinders, multiple fluid collection tanks connected in series, and measurement-while-drilling devices; multiple fluid collection tanks are used to collect natural gas in the core; measurement-while-drilling devices are used to measure the concentration of natural gas in the fluid collection tanks Temperature and pressure; the shale fluid-preserving closed coring device also includes that one end of the suspension assembly is connected to the outer cylinder, and the other end is respectively connected to the measurement while drilling, multiple fluid collection tanks and the inner cylinder, so that when the outer cylinder rotates, The inner cylinder does not rotate. When coring and lifting the drill, the ball valve assembly is closed, and the gas in the fluid collection tank is not lost, which can effectively obtain the shale samples and the lost gas content of the closed coring, and improve the reliability of shale gas content and shale gas reserves. and economic evaluation to meet the needs of scientific research and production.

Description

technical field [0001] The invention belongs to the technical field of shale gas exploration and development, and more specifically relates to a shale fluid-preserving sealed coring device and method. Background technique [0002] Shale gas content is an important parameter for resource evaluation and area selection evaluation, and is also an important indicator of whether shale has industrial value and economic benefits. Accurately calculating the size of gas reserves is of great significance for deploying development plans. The gas content of shale is usually obtained by on-site desorption. All the free gas escapes, and the adsorbed gas is partially desorbed. Usually, the on-site desorption gas content consists of three parts: desorbed gas, lost gas and residual gas. The desorbed gas is calculated by desorption of the core, and the residual gas is obtained by crushing the core. The research on these two points has basically reached a consensus, and there are few objections...

AI Technical Summary

Problems solved by technology

However, the commonly used pressure-holding sealed coring technology is not suitable for shale gas (especially the sealed coring of deep high-temperature and high-pressure shale gas), so there is currently no closed coring device and Related engineering tests

[0004] The current technology mainly has the following deficiencies: (1) Although the temperature and pressure of conventional oil and gas closed coring can meet the requirements of shale gas, due to the existence of shale gas adsorption and occurrence, the temperature and pressure drop during drilling The resulting desorption of shale gas is inevitable, and a large amount of natural gas will be desorbed when the temperature is slightly lowered, and accidents such as pressure suppression and blasting will be caused if the temperature is slightly lowered. When the coring tool reaches the wellhead, remove the pressure cap on the joint of the blowout pipe, connect the blowout pipe, loosen the needle valve, and the pressure of the inner cylinder can be released, which avoids the pressure of the inner cylinder caused by core blockage and the occurrence of core damage. Shot blasting is not suitable for fluid-preserving sealed coring of shale gas; (2) Sealed coring devices for coalbed methane and methane hydrate are mostly used when the formation temperature and formation pressure are not high (coalbed methane: 10~ 20Mpa, 20~60℃; methane hydrate: 1~10Mpa, -10~28℃), which is significantly lower than deep shale gas 50~100Mpa, temperature 60~120℃, and is not suitable for the sealing of shale gas coring

Therefore, there is currently no example of application to high-temperature and high-pressure shale gas sealed coring

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