A drilling system and drilling method based on subsea pump pressure control

Abstract

The invention relates to a drilling system and method based on subsea pump pressure control. The system is characterized by comprising a drilling ship; a drilling liquid supplying device and a control device are arranged on the drilling ship; the drilling liquid supplying device is connected with the liquid feeding end of a water faucet through a liquid manifold; the water faucet is fixedly connected to a derrick arranged in the middle part of the drilling ship; the liquid discharging end of the water faucet is in rotating connection with the top end of a drilling rod; a drill bit is fixedly connected to the bottom end of the drilling rod; an absorbing module sleeves the lower part of the drilling rod; two pipelines are symmetrically arranged on the outer pipe wall of the absorbing module; a throttle valve is arranged on the pipeline at one side; the control device is electrically connected to an electrical device positioned on the drilling ship; the electrical device is electrically connected with a motor through a control and power pipeline; the output end of the motor is connected with a subsea pump; an inlet of the subsea pump is connected with a hose and provided with a pressure flow sensor. According to the system, the opening degree of the throttle valve and the rotating speed of the subsea pump can be adjusted by a control panel device through the control and power pipeline, so that the pressure of a wellhead of a subsea drilling well is stable, and as a result, the well control risk caused by natural gas-water composition can be controlled.

Description

technical field [0001] The invention relates to a drilling system and a drilling method based on pressure control of a subsea pump, belonging to the field of marine mining engineering. Background technique [0002] Natural gas hydrate is a white solid crystalline substance, which can only exist under certain temperature and pressure conditions, and generally requires a temperature of about 0-10°C and a pressure higher than 10Mpa. If the temperature rises or the pressure drops, the Methane gas then escapes, and gas hydrates tend to dissociate. There may be a large number of natural gas hydrate layers in the deep water high pressure and low temperature environment. Due to the deep water temperature and pressure environment, the buried depth of natural gas hydrate is generally within 600m below the mud line. For conventional deep water drilling technology and equipment, it is still impossible to establish risers and prevent Well control systems such as injectors, so convention...

AI Technical Summary

Problems solved by technology

There may be a large number of natural gas hydrate layers in the deep water high pressure and low temperature environment. Due to the deep water temperature and pressure environment, the buried depth of natural gas hydrate is generally within 600m below the mud line. For conventional deep water drilling technology and equipment, it is still impossible to establish risers and prevent Well control systems such as injectors, so conventional drilling and well control operations cannot be implemented

Even if conventional deepwater drilling and completion well control equipment can be used, the installation and control of the kilometer-long riser and the complex blowout preventer system are quite complicated, resulting in most of the operation time being spent on the riser blowout prevention During the installation and recovery process of the drill system, the operating efficiency is extremely low, the cost of the drilling rig is high, and the economic benefit is poor

[0003] In addition, free gas usually exists under the natural gas hydrate caprock. When drilling into this formation, the free gas easily invades the wellbore and destroys the wellbore equilibrium condition, thus causing a series of well control problems.

When drilling the gas hydrate formation, the formation equilibrium conditions will be broken, causing the decomposition of gas hydrate. If the decomposition rate is not effectively controlled, it will destroy the stability of the gas hydrate formation and lead to the collapse of the wellhead. Therefore, Natural Gas Hydrate Drilling and Exploration Face Huge Risks

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