Control device for phases in wellbore of supercritical carbon dioxide drilled well

Abstract

The invention relates to a control device for phases in a wellbore of a supercritical carbon dioxide drilled well, which comprises a main circulation loop and a control system. The main circulation loop is formed by sequentially connecting a CO2 storage tank, a plunger pump, a heat exchange device, a vertical tube, a drill stem, a bit, the wellbore, a wellhead backpressure control system, a rotary separator and a refrigerating device through pipelines. The control system is electrically connected with a high-pressure gas cylinder, an electromagnetic valve, the heat exchange device, pressure sensors, temperature sensors and mass flow meters through an industrial personal computer. One pressure sensor, one temperature sensor and one mass flow meter are installed at each of an inlet and an outlet of the wellbore to monitor temperature and pressure of carbon dioxide drill fluid at a wellhead in real time. A software system is controlled by the industrial personal computer to send out control signals to control and adjust the wellhead backpressure control system and the heat exchange device in real time, the pressure and the pressure of the supercritical carbon dioxide drill fluid at the downhole are recalculated until the supercritical state judgment conditions are met, and accordingly the carbon dioxide drill fluid at the downhole can be constantly maintained at the supercriticalstate.

Description

Technical field: [0001] The invention relates to a set of supercritical carbon dioxide drilling wellbore phase state control devices, belonging to the technical field of petroleum drilling. Background technique: [0002] The sustained and rapid development of my country's economy has led to an increasing demand for oil and gas. The problem of insufficient supply of oil and gas production has become increasingly prominent. There are few good oil and gas resources left. Large-scale exploitation of unconventional and difficult-to-use oil and gas resources (such as shale gas and tight gas) inevitable. In order to improve the extraction efficiency of unconventional and difficult-to-develop oil and gas resources, fast and efficient drilling methods that avoid oil and gas reservoir pollution and are highly concerned. Supercritical carbon dioxide fluid not only has low viscosity and high diffusion coefficient similar to gas, but also has high density and good solubility similar to l...

AI Technical Summary

Problems solved by technology

[0004] Based on the properties of supercritical carbon dioxide, supercritical carbon dioxide drilling fluid will undergo phase changes due to changes in temperature and pressure during wellbore circulation, showing three phase states: gaseous, liquid, and supercritical. It has dual characteristics of gas and liquid, which is beneficial to increase the rate of penetration and protect the reservoir. It is an ideal phase state in the wellbore during drilling. Therefore, it is necessary to establish a set of phase state control devices in the wellbore for supercritical carbon dioxide drilling. The new technology lays the foundation, but there are no public reports of such control devices used in supercritical carbon dioxide drilling at home and abroad.

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