Continuous circulation system for oil and gas well and usage thereof

Abstract

The invention relates to continuous circulation system that is constituted by multifunction injection system, in well circulation system and ground returning system. The injection system includes drilling fluid that has three densities, two or three mud pumps, and high pressure gas injection device. By the method of injecting two drilling fluids that have different density and fast mixing, or injecting high pressure gas, the in-well liquid column pressure would be adjusted fast and flexibly. The in-well circulation system includes double tube well structure and in-well drilling column, and supplies three flowing channels as the returning channel or injecting channel. The ground returning system includes well head control combination, casing head and gas-liquid-solid separating device. The continuous circulation system is constituted by eight purposes and improves the safety of the well.

Description

Technical field: [0001] The invention relates to a continuous circulation system used for drilling, well completion and workover of oil and gas wells and its application method. It is also suitable for drilling, completion and workover operations in geothermal, hydrological and mineral fields. Background technique: [0002] During the drilling process of oil and gas wells, the circulation system consists of three parts: the surface injection part, including tanks (pools) and pumps; the well circulation part, including the drill string, drill bit and wellbore; device, solid phase separator, etc. The drilling fluid circulation method currently used is: the mud pump sucks drilling fluid with a predicted density from the tank (or pool), and after pressurization, it is transported to the drill bit through the inner diameter flow channel of the hollow drill string, and reaches the bottom of the well through the nozzle of the drill bit, and then Enter the annular space between th...

AI Technical Summary

Problems solved by technology

[0003] The biggest defect of this circulation method is: once the drill string is disconnected (such as artificially disconnected, including tripping and connecting a single root; such as fault disconnection, including accidents such as stuck, broken, dropped, punctured, blocked, etc. ), the circulation will be interrupted; when the drill string is not in the well (such as when the drill string is pulled out, the drill string cannot be lowered, etc.), the circulation in the well cannot be realized

During the workover process, there will be low-pressure reservoirs, low pressure, easy damage, and even lost circulation

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