Well drilling method of through tubing of gas lift under-balanced coiled tubing

Abstract

The invention relates to a well drilling method of a through tubing of a gas lift under-balanced coiled tubing, which is applied in the technical field of petroleum well drilling. The through tubing operation way of the coiled tubing is adopted for carrying out under-balanced well drilling or low-pressure well drilling on target well sections at the lower part in a shaft with a drilled upper borehole, wherein the target well sections are a vertical well, a directional well or a horizontal well. The method has the following effects: the adoption of the through tubing operation of the coiled tubing can form three circulation channels by utilizing the coiled tubing, an oil tube and a sleeve, and a matching pipe column has good universality, does not need a special drilling column or an inner tube and does not need to use a rotary blowout preventer and other special equipment; a gas injection channel and a slurry injection channel are independent mutually, thereby being capable of more conveniently controlling the well bottom pressure and the under-pressure value and using an underground power drilling tool and a slurry pulse measurement system which are applicable to slurry well drilling to carry out well drilling operation and trajectory control; and the method does not need to be connected with a single and can keep the continuous circulation during the tripping process and the drilling process, and realize the full-process controllable under-balanced well drilling operation and the full-process controllable low-pressure well drilling operation.

Description

technical field [0001] The invention relates to a technology for underbalanced drilling in oil fields, in particular to a technology for realizing gas-filled underbalanced drilling by using coiled tubing to operate through oil pipes. It is also suitable for low-pressure drilling operations in low-pressure reservoirs and coalbed methane. Background technique [0002] At present, the underbalanced drilling technology refers to the drilling technology in which the bottom hole pressure of the drilling fluid circulation system is lower than the pore pressure of the formation during the drilling process, so that the fluid in the production layer enters the wellbore in a controlled manner and circulates it out of the well. has been more and more widely used. The main function and significance of underbalanced drilling are: ①It is beneficial to discover and accurately evaluate the reservoir in time; ②It can effectively protect the reservoir and significantly reduce the damage to th...

AI Technical Summary

Problems solved by technology

The main problems are: ①The cycle needs to be interrupted in the process of connecting the single root: after the pump needs to be stopped, the back pressure valve in the drill string should be used to block the backflow in the drill string, the standpipe should be opened to release the pressure, then the buckle should be disconnected, the single root should be connected, and then closed The standpipe pressure relief valve can be used to start the pump and re-establish the circulation; ②It is also necessary to interrupt the circulation during the tripping process; ③When the jacking force is large, it is also necessary to use the snubbing tripping device

When drilling in abnormally high-pressure formations or gas formations, the interruption of circulation will easily lead to the formation fluid continuously entering the well, and eventually develops into the upward movement and expansion of gas, which will cause the pressure in the well to continue to rise, which will easily induce risks and accidents of out-of-control well control, endangering operation safety

[0006] Another problem with using conventional drill strings to implement underbalanced drilling is: in the implementation of gas underbalanced (including the use of nitrogen, natural gas, diesel engine exhaust, aerated mud, foam and atomization, air and other media) to carry out directional drilling or When drilling horizontal wells, special downhole dynamic drilling tools and measurement-while-drilling systems are required, and downhole dynamic drilling tools and mud pulse measurement systems (MWD) suitable for mud drilling cannot be used

However, this technology requires the use of special devices such as special double-walled drill pipes, rotary inflatable faucets, and downhole gas-liquid mixers; the process of connecting single pipes not only interrupts the circulation, but also becomes very complicated due to the need to solve the connection and sealing of the double channels , which largely limits the practical application of the technique

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