Drilling-while-drilling technology of compound double circulation underbalanced casing

Abstract

The invention relates to a compound double-circulation under-balanced casing pipe while-drilling drilling technology. The compound double-circulation under-balanced casing pipe while-drilling drilling technology is characterized in that a drilling and make-a-connection drilling technology is adopted, an air compressor and a water pump are started, vaporous water in a pipeline pushes an air hammer to work through an air inlet pipe, a compound double-circulation drilling tool is driven to work, finally vaporous water is drained through a chip removal device, a slush pump is started at the same time, slush enters the annular part of a casing pipe and the annular part of a drilling rod through an air exhaust box, flows to the well wall and the annular part of the casing pipe through a fairing, upwards returns to a wellhead slush tank and circulates repeatedly, and it is ensured that pressure of the well wall is balanced; when make-a-connection is performed, a three-way valve is opened, and vaporous water formed by the air compressor and the water pump is reversed by the three-way valve, enters a continuous air supplying system and enters the air inlet pipe through the continuous air supplying system to push the air hammer to work and drive the compound double-circulation drilling tool to work. The difficult problems such as collapse, air leakage, hole shrinkage, chip off-falling, deviation control, straight hitting, water coning, drilling tool jamming and blowout in the under-balanced drilling process are solved, and the drilling speed is greatly increased.

Description

technical field [0001] The invention relates to a drilling technology suitable for oil drilling, geothermal wells, power generation wells, coalfield escape wells and other drilling operations, in particular to a compound double-circulation underbalanced casing drilling-while-drilling technology. Background technique [0002] Underbalanced drilling, also known as negative pressure drilling, refers to a drilling technique in which the bottom hole pressure is lower than the formation pressure during drilling, and the fluid in the ground enters the wellbore in a controlled manner and circulates to the surface. At present, the relatively mature underbalanced drilling technology at home and abroad mainly adopts the air down-the-hole hammer drilling technology, and its technological process is as follows: (1). DTH hammer and drilling tools work. The air discharged from the drilling tool is used to cool the drill bit and carry cuttings back to the ground from the drill pipe and the...

AI Technical Summary

Problems solved by technology

Air DTH hammer drilling technology mainly exists: 1. As long as the under-balanced conditions are met, the drilled open hole wall is prone to collapse, diameter shrinkage, and block loss. The downhole water and gas will produce vaporized water, and the well wall will be eroded during the upward return process to accelerate the collapse. ;2. The hole diameter of the open hole is relatively large, the geological structure is relatively complex, and the well is relatively deep and other factors, the gas consumption is too large, resulting in high equipment costs, and the cuttings carried by the gas must be dry, otherwise the sticking of the drilling tool will cause the drill to stick; 3. When the water is produced from underground formations, the greater the water output, the greater the amount of gas required and the higher the pressure

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