Underground real-time control system for density of drilling fluid

Abstract

The invention relates to an underground real-time control system for the density of drilling fluid. The underground real-time control system for the density of the drilling fluid comprises a drilling rig, an air compressor, a slurry pump, an intermediate transmission device, an electromagnetic valve, a packer, a wireless receiver and a ground control system, wherein the intermediate transmission device consists of an inner barrel and an outer barrel, which are coaxially arranged; the air compressor is connected to an air inlet of the inner barrel; the slurry pump is connected to a fluid inlet of the outer barrel; the tail end of the inner barrel is connected with an inner drill rod; the tail end of the outer barrel is connected with an outer drill rod; the tail end of the outer drill rod is connected with a drill collar; the tail end of the inner drill rod is fixedly arranged at the bottom of the drill collar; the tail end of the inner drill rod is connected with the electromagnetic valve; the packer is arranged on the outer drill rod; a wireless density sensor and a wireless pressure sensor are arranged at the bottom of the drill collar; the wireless receiver is connected with the ground control system. According to the system, the advantages of three drilling technologies, i.e. an overbalance drilling technology, an under-balanced drilling technology and a managed pressure drilling technology, are fully utilized, so that an underground pressure difference can be switched between an overbalanced state, an under-balanced state and a near-balanced state, the drilling rig can safely and efficiently reach a destination layer, the non-production time can be reduced, and the drilling cost can be lowered.

Description

technical field [0001] The invention relates to a downhole drilling fluid density control system, in particular to a downhole real-time control system for drilling fluid density. Background technique [0002] Since the formation itself has pressure, which increases with the increase of the well depth, in order to maintain the stability of the wellbore wall, it is initially overbalanced drilling, that is, the drilling fluid with a higher density is used to keep the bottom hole pressure higher than the formation pressure, so that the pressure in the annulus of the wellbore The drilling fluid column supports the borehole wall. However, due to the excessive pressure of the hydrostatic column of drilling fluid on the drill bit, it is not conducive to the bit to break the rock. Therefore, the biggest disadvantage of overbalanced drilling is slow drilling speed and drilling fluid loss to pollute the formation. In the 1960s and 1970s, underbalanced drilling technology began to appe...

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Problems solved by technology

[0004] The purpose of the present invention is to provide a real-time downhole control system for drilling fluid density, which is used to solve the problem that the current common g

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