RU2362011C1 - Installation for regulating bottom-hole pressure of drilling agent - Google Patents

Abstract

FIELD: oil and gas production.

SUBSTANCE: invention refers to oil production, notably, to process of boring wells and is designed for automatic regulation of bottom-hole pressure of drilling agent and to maintaining it at level of reservoir pressure. The installation is equipped with a boring pump with a regulating drive, with a bottom-hole pressure sensor, with a communication channel, with a receiver, with a control block and with a master of forecast bottom-hole pressure. Additionally the installation is equipped with a correcting link and an integrating block; also the control block is connected to the input of the integrating block, the output of the integrating block is connected with the input of the correcting link, while an output signal from the correcting link is fed to the input of the regulating drive of the boring pump.

EFFECT: upgraded accuracy and reduced time of regulation of bottom-hole pressure of drilling agent.

2 dwg

Description

The invention relates to the oil industry, and in particular to equipment and technology for drilling wells, and is intended to automatically control the bottomhole pressure of the flushing fluid and maintain it at the reservoir level.

A device for regulating a turbine drilling process is known, in which the regulation is made according to the hydraulic characteristic of the turbine, which has an unshocked mode of operation shifted towards lower revolutions by maintaining a constant pressure by regulating the flow of flushing fluid by the pump during chiselling by a pressure sensor that acts on the drive of mud pumps, the flow sensor, depending on the number of revolutions of the turbine, acts on the bit feed mechanism (see AS of the USSR No. 122104, 1958).

The disadvantage of this device is the low accuracy of regulation and the lack of the possibility of drilling at the equilibrium of reservoir and bottomhole pressures, and therefore the low speed of drilling wells. This is due to the fact that the pressure is controlled by ground-based devices and the flow rate of the flushing fluid is regulated in small stages to reduce the vibrations of the pipe string in order to stabilize the axial load, which does not allow equilibrium drilling.

The prototype is a device for controlling the drilling process, equipped with a mud pump with an adjustable drive. The disadvantage of this device is the error in the steady state caused by the use of a static controller (see AS of the USSR No. 935603, 1982).

The technical task is to create an accurate device for automatically controlling the bottomhole pressure of the drilling fluid directly in the process of drilling wells.

The technical result is an increase in accuracy and a reduction in the time for regulating the bottomhole pressure of the drilling fluid both during turbine and rotary drilling of wells.

It is achieved by the fact that the control device is additionally equipped with a correcting link and an integrating unit, while the control unit is connected to the input of the integrating unit, the output of the integrating unit is connected to the input of the correcting link, and the output signal from the correcting link is fed to the input of the adjustable drive of the mud pump.

The proposed device is shown in figure 1. The device comprises a bottomhole pressure sensor 1, a communication channel 2, a receiver 3, a control unit 4, a predicted drilling fluid pressure adjuster 5, an integrating unit 6, a damper 7, an adjustable actuator 8, and a mud pump 9.

The device operates as follows:

The output signal from the sensor 1 downhole pressure of the drilling fluid is fed to the input of the hydraulic communication channel 2 of the bottom with the wellhead. At the wellhead, the signal from the output of the communication channel is fed to the input of the receiver 3, where it is filtered from noise and amplified. The extracted and amplified useful signal, which is proportional to the bottomhole pressure from the receiver output, is supplied to one of the inputs of the control unit 4 and is compared with the signal supplied to the second input of the control unit from the predictor of reservoir pressure 5, the value of which is set based on the available data obtained as a result of drilling exploratory wells. By the magnitude of the received error signal in block 4, a control action is generated and fed to the input of the integrating block 6, where the integral component of the action is formed, which is fed to one of the inputs of the damper 7, designed to prevent sudden changes in the values of the control action, made in the form of an aperiodic first-order link . The output of the control unit is connected to the second input of the damper. The final control action formed in the damper 7 is fed to the input of the adjustable drive 8 connected to the mud pump, as a result of which the speed of the drive changes in accordance with the law of regulation and the value of the bottomhole pressure of the drilling fluid. This leads to the necessary change in the flow rate of the drilling fluid at the pump outboard and sets the required value of the pressure of the drilling fluid at the bottom of the well in the range of 0-1.5 MPa.

The proposed control device for the drilling process allows the drilling process to balance the reservoir and bottomhole pressure and change the bottomhole pressure by changing the flow rate of the drilling fluid. The bottomhole pressure of the drilling fluid is determined by the formula:

where: γ is the specific gravity of the drilling fluid, g / cm;

L is the depth of the well, m;

Q is the flow rate of the drilling fluid, m ³ / s;

α _KP - proportionality coefficient taking into account hydraulic pressure loss in the annular space.

From the difference between P _s and downhole reservoir pressures P _pl determined value of drilling fluid pressure on the face of the algorithm

,The control action is formed according to the PI-law of regulation,

,

- давление рассогласования, г/см;Where:

- mismatch pressure, g / cm;

k _P is the proportional coefficient of the controller settings;

k _And is the integral coefficient of adjustment of the controller.

To eliminate the static error, it is proposed to use the proportional-integral control law, for which an integrating unit is introduced into the control unit, generating a signal equal to the integral of the input value (mismatch) taken during the control time.

The transfer function of the system for automatic regulation of bottomhole pressure, implemented by the proposed device (figure 1) has the form:

Where

- передаточная функция объекта управления,

- transfer function of the control object,

- передаточная функция ПИ-регулятора.

- transfer function of the PI controller.

Based on laboratory studies, the proposed device for controlling the process of drilling wells was simulated and the main quality parameters for regulating the bottomhole pressure of the proposed device were determined. Transients obtained using the prototype and this device are provided in figure 2. Here, number 1 shows the transition process obtained using the prototype, and number 2 shows the transition process of the proposed device for controlling the bottomhole pressure of the drilling fluid, t1 and t2 are the control time. In both cases, the delay was taken equal to 4 s. The regulation time in the CAP equipped with the proposed device is no more than 17 seconds, the static error tends to zero.

This device allows to increase the accuracy of regulation of bottomhole pressure and reduce the time of this process.

Information source

1. USSR author's certificate No. 122104, 1958.

2. Copyright certificate of the USSR No. 935603, 1982 / (prototype).

Claims (1)

A device for controlling the bottomhole pressure of a drilling fluid equipped with a mud pump with an adjustable drive, a bottomhole pressure sensor, a communication channel, a receiver, a control unit and a predictor of reservoir pressure, characterized in that the device is additionally equipped with a correcting link and an integrating unit, while the control unit is connected to the input of the integrating unit, the output of the integrating unit is connected to the input of the correction link, and the output signal from the correction link is fed to the input adjustable drive mud pump.

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