Rotary pressure maintaining coring method for ocean drilling

Abstract

The invention relates to a rotary pressure maintaining coring method for ocean drilling. The method includes the following steps: 1) placing an inner tube assembly into an outer tube assembly at the bottom of a hole by a salvage spear head; 2) sending the inner tube assembly to the outer tube assembly by a rope for sitting clamping, then simultaneously drilling down to a bottom hole stratum, and performing rotary core sample coring through cooperation of an outer tube drill bit and a middle tube drill bit together; 3) driving a shear pin of an inner tube assembly b by the f salvage spear headto cut and removing clamping with the inner tube assembly, then sliding upward along an inner tube assembly a, allowing a core tube containing a core sample to slide upward into the inner tube assembly a, and giving thrust to a ball valve by a spring through a ball valve driving nipple, and driving the ball valve to slide downward and achieving overturn of 90 degrees; and 4) making the inner tubeassembly remove clamping from an appearance assembly and pulling out of a wellhead by the salvage spear head, taking out the core sample, and completing a pressure maintaining coring process. The method achieves rotary pressure maintaining sampling, can adapt to a quaternary system sedimentary stratum and bed rock, and is wider in application range.

Description

technical field [0001] The invention relates to the technical field of drilling, in particular to a rotary pressure-maintaining coring method for marine drilling of natural gas hydration. Background technique [0002] Obtaining gas hydrate samples through ocean drilling is a commonly used technology at present, and because gas hydrate is located in the harsh and inaccessible polar and deep-sea marine environment, especially because when it is brought to the surface, it will quickly decompose into gas hydrate The two components of the substance, namely liquid water and methane gas, are affected by this, usually the success rate of coring is not high, and even lead to coring failure, which also indirectly affects the efficiency of coring, so in order to ensure the success of coring, it is necessary to use a The coring operation is carried out by means of pressure. However, the marine environment is changeable, and the more times of coring failures, the longer the construction...

AI Technical Summary

Problems solved by technology

[0002] Obtaining gas hydrate samples through ocean drilling is a commonly used technology at present, and because gas hydrate is located in the harsh and inaccessible polar and deep-sea marine environment, especially because when it is brought to the surface, it will quickly decompose into gas hydrate The two components of the substance, namely liquid water and methane gas, are affected by this, usually the success rate of coring is not high, and even lead to coring failure, which also indirectly affects the efficiency of coring, so in order to ensure the success of coring, it is necessary to use a coring

The marine environment is changeable, and the more times of coring failures, the longer the construction time and the greater the construction risk, especially when coring in hard strata, it becomes more difficult

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