Gas-lift reverse circulation well drilling system and automatic control method

Abstract

The invention discloses a gas-lift reverse circulation well drilling system and an automatic control method. The system comprises a wellhead device, an in-well drilling tool, a flow line, a gas injecting pipeline, a drilling liquid injecting pipeline and an automatic control system, wherein the in-well drilling tool comprises a drill bit, a downhole electromagnetic PWD, a drill collar, a lower single-wall drill rod, a gas-water mixer, a double-wall drill rod, an air injection valve and an upper single-wall drill rod; each of the gas injecting pipeline and drilling fluid injecting pipeline is provided with an automatic throttle valve, a pressure gauge, a flowmeter and an automatic pressure relief valve; the automatic control system comprises a signal receiver, a computer, a display, a PLC (programmable logic controller) and a parameter input module; and during the gas lift reverse circulation drilling process, the automatic control system monitors the bottom pressure in real time, adjusts the gas injection quantity parameter and the drilling fluid injection parameter and realizes the automatic and accurate control of the bottom pressure. The system has the beneficial effects that the well control risk is reduced by matching with conventional well control equipment at a well mouth; and the bottom hole pressure is accurately controlled to prevent the occurrence of lost circulationand overflow.

Description

technical field [0001] The invention relates to the technical field of oil and gas drilling, in particular to a gas lift reverse circulation drilling system and an automatic control method. Background technique [0002] During the drilling process, due to reasons such as unknown underground pressure system and complex geological conditions, lost circulation occurs from time to time, and even serious lost circulation occurs, which leads to complex downhole situations such as overflow, pipe sticking, and well wall collapse, causing a large number of Economic loss may also pollute the environment. There are many leakage prevention and control drilling technologies, including gas drilling technology, foam drilling technology, clear water strong drilling technology, mud cap drilling technology, etc. All these technologies have certain limitations: due to their own characteristics, gas drilling technology has a large water output. 1. The application of the stratum prone to collap...

AI Technical Summary

Problems solved by technology

[0004] The purpose of the present invention is to solve the problem of difficult drilling in lossy formations, and to provide a gas lift reverse circulation drilling system and automatic drilling system that reduces lost circulation and overflow, reduces well control risks, and is especially suitable for lossy formations with developed fractures and caves. Control Method

Images