Method and system for regulating precision pressure-control well drilling throttle valve

Abstract

An embodiment of the invention provides a method and a system for regulating a precision pressure-control well drilling throttle valve. The method includes acquiring displacement of a mud pump of a precision pressure-control well drilling system, displacement of a back-pressure pump and opening values of the throttle valve at a current moment and within a preset duration before the current moment in real time; predicting opening values of the throttle valve within a preset number of sampling periods after the current moment in real time according to the acquired displacement of the mud pump, the acquired displacement of the back-pressure pump and the acquired opening values of the throttle valve; adjusting opening of the throttle valve within the preset number of sampling periods after the current moment so that the opening of the throttle value is equal to the predicted opening values of the throttle valve. Precision pressure-control well drilling requirements can be met by bottom hole pressures corresponding to the predicted opening values of the throttle valve. According to the scheme, the method and the system have the advantages that the opening values of the throttle valve within the preset number of sampling periods after the current moment are predicted according to the displacement of the mud pump, the displacement of the back-pressure pump and the opening values of the throttle valve at the current moment and within the preset duration after the current moment, and accordingly the precision pressure-control well drilling throttle valve regulation effectiveness can be improved.

Description

technical field [0001] The invention relates to the technical field of precision managed pressure drilling, in particular to a method and system for adjusting a throttle valve of fine managed pressure drilling. Background technique [0002] Fine managed pressure drilling technology is a technology that can realize balanced or near-balanced drilling. Its purpose is to determine the bottom hole pressure window, precisely control the annular pressure profile, maintain the pressure of the entire wellbore between the formation pore pressure and the fracture pressure, and solve the difficult problems in drilling. Its working process is as follows: In a closed circulation system, the drilling fluid enters the standpipe from the mud tank through the drilling pump and descends to the drill pipe, passes through the float valve and the annulus on the upper part of the drill bit, and then flows from the annular blowout preventer below the rotary control device flow out. Then through a...

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Problems solved by technology

[0003] The key to the normal work of fine MPD is to be able to control the opening of the throttle valve stably and accurately, and to achieve this goal, it is necessary to establish an accurate fine MPD control calculation model, but on the one hand, due to the consideration of multiple parameters , such as back pressure, fluid density, fluid rheology, annular liquid level, hydraulic friction and wellbore geometry, etc., even if the control calculation model is established, its structure is very complicated and it is difficult to achieve precise control; on the other hand , from the perspective of engineering application, the established control model needs to be simplified as much as possible, and it can still maintain good performance under the influence of uncertain factors, and the control algorithm is required to be simple and easy to implement, so as to meet the needs of real-time control, and the actual drilling process is often Non-linear, time-varying and uncertain; therefore, it is difficult to establish an accurate calculation model for fine MPD control

[0004] At present, the PID (proportional-integral-derivative) control method is used to control the adjustment of the throttle valve in the fine managed pressure drilling in the existing technology, but the PID control method can only adapt to the different drilling process with a set of fixed PID parameters. The deterministic factors are often not fully consistent with the multivariable coupling, nonlinear, large time-delay and other complex systems of the drilling wellbore formation system, and when the PID parameters change beyond a certain range, the performance of the drilling wellbore formation system will be significantly worse, or even impossible. Meet the requirements, so that in the process of controlling the opening of the throttle valve in the drilling wellbore formation system, the influence of uncertainties such as multivariable coupling, nonlinearity, and large time delay in the drilling wellbore formation system cannot be overcome, and the impact on fine MPD can be reduced. Effectiveness of throttle adjustment

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