Drilling system and method for improving drilling efficiency in permafrost

Abstract

The invention discloses a drilling system and method for improving tundra drilling efficiency. The drilling method comprises the following steps of: adopting a downward drilling pipe column, starting a nitrogen gas compressor and a high-pressure pump unit; pumping liquid nitrogen into a shaft from a continuous oil pump, providing power to an underground motor, cutting shaft-bottom rocks by a PDC drill bit, and starting drilling operation; spraying out the liquid nitrogen through a spray nozzle of the drill bit to form liquid nitrogen jet flow which is matched with cutting of the PDC drill bit; upwards returning and circulating nitrogen gas along with rock debris to ground along an annular space, and recycling through a sand remover, a back pressure valve and a gas purifier; and drilling to a target layer, thereby completing drilling operation. Liquid-nitrogen fracturing effect is beneficial for expanding cracks generated inside rocks, so that rock breaking efficiency is effectively improved; the temperature of liquid nitrogen is extremely low, and liquid nitrogen is vaporized to absorb heat in an upward return process, so that decomposition of natural gas hydrates is effectively restrained, a well wall is kept stable, and underground complexity is prevented; and in an operation process, liquid nitrogen is recycled, so that the process is simple, is economical and is good in field applicability.

Description

technical field [0001] The invention belongs to the technical field of permafrost drilling for energy exploitation, and in particular relates to a drilling system and method for improving drilling efficiency in permafrost. Background technique [0002] Gas hydrates are ice-like crystalline substances formed by natural gas and water under high-pressure and low-temperature conditions, and are widely distributed in deep-sea sediments or land permafrost. Natural gas hydrate has become a hot spot in the development of the contemporary energy industry due to its large reserves, wide distribution, high energy density, clean and pollution-free. Especially in recent years, the energy shortage has been increasing day by day, which has made countries pay more attention to it, and have increased their efforts in exploration and development research. [0003] In recent years, my country has also successfully drilled natural gas hydrates in the Shenhu area of ​​the South China Sea, the p...

AI Technical Summary

Problems solved by technology

[0007] The purpose of the present invention is to provide a drilling system and method for improving the drilling efficiency in permafrost, aiming to solve the problem of downhole complexity and environmental pollution caused by the decomposition of natural gas hydrate in drilling in permafrost, and to realize permafrost on land Safe, rapid, economical and environmentally friendly drilling in layers

Images