CN107191154B - Wellhead back pressure regulating method and device - Google Patents
Wellhead back pressure regulating method and device Download PDFInfo
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- E21B34/00—Valve arrangements for boreholes or wells
- E21B34/02—Valve arrangements for boreholes or wells in well heads
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- E—FIXED CONSTRUCTIONS
- E21—EARTH OR ROCK DRILLING; MINING
- E21B—EARTH OR ROCK DRILLING; OBTAINING OIL, GAS, WATER, SOLUBLE OR MELTABLE MATERIALS OR A SLURRY OF MINERALS FROM WELLS
- E21B44/00—Automatic control systems specially adapted for drilling operations, i.e. self-operating systems which function to carry out or modify a drilling operation without intervention of a human operator, e.g. computer-controlled drilling systems; Systems specially adapted for monitoring a plurality of drilling variables or conditions
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Abstract
The invention discloses a wellhead back pressure regulation method and a device, wherein the method comprises the steps of acquiring a back pressure value of a wellhead and an opening degree value of a throttle valve in real time, and respectively calculating a back pressure deviation of the wellhead and an opening degree deviation of the throttle valve; when the back pressure deviation is larger than a preset back pressure coarse adjustment threshold value, regulating and controlling the wellhead back pressure based on the opening deviation of the throttle valve, so that the throttle valve reaches the opening set value of the throttle valve; and when the back pressure deviation is smaller than or equal to a preset back pressure coarse adjustment threshold value, regulating and controlling the wellhead back pressure based on the opening deviation of the throttle valve and the back pressure deviation of the wellhead so that the wellhead back pressure reaches the preset precision range of a wellhead back pressure set value. The method realizes undisturbed switching between the opening control and the back pressure control, and the pressure is stable and free of fluctuation during switching. The method has the capability of quick adjustment in case of large deviation and accurate regulation and control in case of small deviation, and has good control effect. The control method is simplified, the implementation is easy, and the control effect is stable.
Description
Technical Field
The invention relates to the field of petroleum drilling process control, in particular to a wellhead back pressure regulating and controlling method and device.
Background
With the rapid development of the petroleum industry, the requirements of actual exploration and development on various drilling technologies are higher and higher. The drilling technology is continuously developing towards the direction of automation and intellectualization, and a large number of novel automatic intellectualized drilling technologies are continuously emerging and widely applied to various operation sites. Fine pressure control drilling technology is one aspect of automated drilling for automatic monitoring of bottom hole pressure.
The fine pressure control drilling refers to the safe drilling realized by monitoring the pressure of a shaft in real time through a data monitoring system and wellhead equipment. In the equipment of the pressure-controlled drilling system, the control of the back pressure of a wellhead is realized by adjusting the pressure-controlled drilling throttle valve on the throttle manifold, the balance of the wellhead pressure in the whole drilling process is kept, and the pressure-controlled drilling system is a key component for realizing pressure control in pressure-controlled drilling hardware equipment.
At present, the control method of wellhead back pressure mainly has the following problems: on one hand, the control of the throttle valve has the characteristics of nonlinearity and time-varying uncertainty, while the traditional method directly establishes a method for adjusting the back pressure to the hydraulic pressure, does not consider the characteristics of nonlinearity and time-varying in the system, and has poor control effect. On the other hand, the throttle valve is adjusted to perform bidirectional action of the hydraulic cylinder, but in practice, a feedback control method of pressure and bidirectional action of the hydraulic cylinder is difficult to establish, so that the adjustment precision during the actual operation of the fine pressure control drilling is reduced.
In summary, there is a need to improve the conventional back pressure control method to solve the above problems.
Disclosure of Invention
One of the technical problems to be solved by the present invention is to improve the existing back pressure control method to improve the adjustment precision.
In order to solve the technical problem, an embodiment of the application firstly provides a wellhead back pressure regulation and control method, which comprises the steps of obtaining a back pressure value of a wellhead and an opening value of a throttle valve in real time, and respectively calculating a back pressure deviation of the wellhead and an opening deviation of the throttle valve; when the back pressure deviation is larger than a preset back pressure coarse adjustment threshold value, regulating and controlling the wellhead back pressure based on the opening deviation of the throttle valve, so that the throttle valve reaches the opening set value of the throttle valve; and when the back pressure deviation is smaller than or equal to a preset back pressure coarse adjustment threshold value, regulating and controlling the wellhead back pressure based on the opening deviation of the throttle valve and the back pressure deviation of the wellhead so that the wellhead back pressure reaches the preset precision range of a wellhead back pressure set value.
Preferably, before regulating and controlling the wellhead back pressure based on the opening deviation of the throttle valve to enable the throttle valve to reach the opening set value of the throttle valve, the method further comprises the following steps: establishing a throttle valve opening characteristic curve; and calculating the opening of the throttle valve corresponding to the set value of the wellhead back pressure based on the characteristic curve of the opening of the throttle valve, and taking the opening of the throttle valve as the set value of the opening of the throttle valve.
Preferably, the step of regulating and controlling the wellhead back pressure based on the opening deviation of the throttle valve to enable the throttle valve to reach the opening set value of the throttle valve comprises the following steps: acquiring the opening value of the throttle valve in real time, and calculating the opening deviation of the throttle valve according to the opening set value of the throttle valve and the acquired opening value of the throttle valve; when the absolute value of the opening deviation is larger than a preset deviation reference value, adjusting the throttle valve at the maximum speed to regulate and control the wellhead back pressure; and when the absolute value of the opening deviation is less than or equal to a preset deviation reference value, regulating the throttle valve in a PID mode to regulate and control the wellhead back pressure.
Preferably, the throttle opening degree characteristic curve is established according to the following expression:
wherein, XSPVIs the opening value of the throttle valve, CvThe characteristic values of the throttle valve are a, b, c, d and e, and constant coefficients are used.
Preferably, before regulating and controlling the wellhead back pressure based on the opening deviation of the throttle valve and the back pressure deviation of the wellhead, the method further comprises the following steps of: establishing a wellhead back pressure control model; calculating the control quantity of the pressure based on the wellhead back pressure control model and the wellhead back pressure deviation acquired in real time; and normalizing the control quantity of the pressure to obtain a control output quantity of the pressure, and using the control output quantity of the pressure as an opening set value of a throttle valve.
The embodiment of this application still provides a well head back pressure regulation and control device, includes: the detection unit is used for acquiring a back pressure value of a wellhead and an opening degree value of the throttle valve in real time and calculating a back pressure deviation of the wellhead and an opening degree deviation of the throttle valve respectively; the quick adjusting unit is used for adjusting and controlling the wellhead back pressure based on the opening deviation of the throttle valve when the back pressure deviation is larger than a preset back pressure rough adjusting threshold value, so that the throttle valve reaches an opening set value of the throttle valve; and the fine adjustment unit is used for adjusting and controlling the wellhead back pressure based on the opening deviation of the throttle valve and the wellhead back pressure deviation when the back pressure deviation is less than or equal to a preset back pressure coarse adjustment threshold value, so that the wellhead back pressure is within a preset precision range of a wellhead back pressure set value.
Preferably, the quick adjustment unit acquires an opening setting value of the throttle valve according to the steps of: establishing a throttle valve opening characteristic curve; and calculating the opening of the throttle valve corresponding to the set value of the wellhead back pressure based on the characteristic curve of the opening of the throttle valve, and taking the opening of the throttle valve as the set value of the opening of the throttle valve.
Preferably, the quick adjustment unit regulates wellhead back pressure according to the following steps: acquiring the opening value of the throttle valve in real time, and calculating the opening deviation of the throttle valve according to the opening set value of the throttle valve and the acquired opening value of the throttle valve; when the absolute value of the opening deviation is larger than a preset deviation reference value, adjusting the throttle valve at the maximum speed to regulate and control the wellhead back pressure; and when the absolute value of the opening deviation is less than or equal to a preset deviation reference value, regulating the throttle valve in a PID mode to regulate and control the wellhead back pressure.
Preferably, the quick adjustment unit establishes the throttle opening characteristic curve according to the following expression:
wherein, XSPVIs the opening value of the throttle valve, CvThe characteristic values of the throttle valve are a, b, c, d and e, and constant coefficients are used.
Preferably, the fine adjustment unit acquires an opening setting value of the throttle valve according to: establishing a wellhead back pressure control model; calculating the control quantity of the pressure based on the wellhead back pressure control model and the wellhead back pressure deviation acquired in real time; and normalizing the control quantity of the pressure to obtain a control output quantity of the pressure, and using the control output quantity of the pressure as an opening set value of a throttle valve.
Compared with the prior art, one or more embodiments in the above scheme can have the following advantages or beneficial effects:
by establishing the three-layer feedback back pressure regulation and control method, undisturbed switching between opening control and back pressure control is realized, and the pressure is stable and free of fluctuation during switching. The method has the capability of quick adjustment in case of large deviation and accurate regulation and control in case of small deviation, and has good control effect. The control method is simplified, the implementation is easy, the control effect is stable, and the requirement of fine regulation and control of wellhead back pressure in the pressure-controlled drilling technology can be met.
Additional advantages, objects, and features of the invention will be set forth in part in the description which follows and in part will become apparent to those having ordinary skill in the art upon examination of the following or may be learned from practice of the invention. The objectives and other advantages of the invention will be realized and attained by the structure particularly pointed out in the written description and claims hereof as well as the appended drawings.
Drawings
The accompanying drawings are included to provide a further understanding of the technology or prior art of the present application and are incorporated in and constitute a part of this specification. The drawings expressing the embodiments of the present application are used for explaining the technical solutions of the present application, and should not be construed as limiting the technical solutions of the present application.
FIG. 1 is a schematic flow chart of a wellhead back pressure regulation method according to an embodiment of the invention;
FIG. 2 is a schematic diagram of a three-level regulation method of wellhead back pressure regulation according to an embodiment of the present invention;
FIG. 3 is a schematic diagram of dual PID opening feedback for a wellhead back pressure regulation method according to an embodiment of the invention;
FIG. 4 is a schematic view of a throttle opening adjustment model according to an example of the present invention;
fig. 5 is a schematic structural diagram of a wellhead back pressure regulating device according to another embodiment of the invention.
Detailed Description
The following detailed description of the embodiments of the present invention will be provided with reference to the accompanying drawings and examples, so that how to apply the technical means to solve the technical problems and achieve the corresponding technical effects can be fully understood and implemented. The embodiments and the features of the embodiments can be combined without conflict, and the technical solutions formed are all within the scope of the present invention.
In order to meet the requirement of fine pressure control drilling technology on the control precision of wellhead pressure, the regulation characteristic of the throttle valve needs to be adapted, and the regulation characteristic is particularly nonlinear and time-varying. Specifically, the requirements of quick adjustment of a large opening degree and accurate adjustment of a small opening degree can be met, and the problem of bidirectional adjustment of the opening degree of the throttle valve is solved. The pressure rough adjustment can be quickly carried out by combining with the characteristic curve of the throttling valve, and the mutual cooperation of pressure control and opening degree control is realized to realize the real-time fine adjustment of the wellhead pressure.
Fig. 1 is a schematic flow chart of a wellhead back pressure regulation method according to an embodiment of the present invention. As shown in the figure, the regulation and control method comprises the following steps: and S110, acquiring a back pressure value of the well mouth and an opening degree value of the throttle valve in real time, and respectively calculating a back pressure deviation of the well mouth and an opening degree deviation of the throttle valve. And S120, when the back pressure deviation is larger than a preset back pressure coarse adjustment threshold value, regulating and controlling the wellhead back pressure based on the opening deviation of the throttle valve, so that the throttle valve reaches the opening set value of the throttle valve. And S130, when the back pressure deviation is smaller than or equal to a preset back pressure coarse adjustment threshold value, regulating and controlling the wellhead back pressure based on the opening deviation of the throttle valve and the wellhead back pressure deviation, so that the wellhead back pressure is within a preset precision range of a wellhead back pressure set value.
This is explained in detail below with reference to the schematic diagrams of fig. 2 and 3.
As shown in fig. 2, the regulation and control method includes outer layer pressure feedback control and inner layer opening degree feedback control, the primary control loop is a pressure feedback control loop, and the secondary control loop is an opening degree feedback control loop, wherein the opening degree feedback control realizes rough regulation of wellhead pressure, and the pressure feedback control realizes fine regulation of wellhead pressure. Specifically, the coarse adjustment and the fine adjustment are performed in steps. And switching is carried out through a preset back pressure coarse adjustment threshold value. For example, if the preset back pressure deviation is set to 0.25MPa, the opening degree feedback control is performed when the back pressure deviation is greater than 0.25 MPa. And judging again that the back pressure deviation is less than 0.25MPa, and implementing pressure feedback control. And when the wellhead pressure is equal to the wellhead back pressure set value, stopping adjustment.
When only the opening degree feedback control is adopted, the outer ring pressure feedback control is temporarily not operated. As shown in fig. 2, the method for obtaining the opening set value of the throttle valve according to the wellhead back pressure set value includes the following steps: firstly, establishing a throttle opening characteristic curve, then calculating the throttle opening corresponding to a wellhead back pressure set value based on the throttle opening characteristic curve, and taking the throttle opening as the opening set value of the throttle.
The throttle opening characteristic curve is used to characterize the correspondence between characteristic values of the throttle valve and opening values of the throttle valve. The characteristic value of the throttle valve is obtained according to the definition of expression (1):
in the formula, CvThe characteristic value of the throttle valve is a dimensionless quantity for reflecting the flow capacity of the throttle valve. Q is the discharge capacity of the drilling fluid in m3H is used as the reference value. Rho is the density of the drilling fluid and the unit is g/cm3. Δ P is the differential pressure across the throttle in MPa.
A throttle opening characteristic curve is established based on the offline identification. Specifically, a throttle opening control experiment is carried out, the discharge capacity, the density and the pressure difference before and after the throttle at each opening of the throttle are measured and recorded, and then C is calculated according to an expression (2)vDifferent C can be obtainedvThe correspondence between the values and the different opening values of the throttle valve. And performing curve fitting on the corresponding relation based on a polynomial fitting algorithm to obtain a throttle valve opening characteristic curve. In one embodiment of the present invention, the throttle opening characteristic curve has a form as shown in expression (2):
in the formula, XSPVIs the opening value of the throttle valve expressed in percentage with respect to the full-opening stroke of the throttle valve. and a, b, c, d and e are fitting coefficients, and different values are taken according to different actual drilling processes.
Assuming that the pressure at the inlet of the throttle valve is equal to the wellhead back pressure set value and the pressure at its outlet is equal to atmospheric pressure, Δ P is approximately equal to the wellhead back pressure set value. Therefore, the throttle opening corresponding to the wellhead back pressure set value can be calculated according to the expression (2), and the throttle opening is used as the opening set value of the throttle to implement opening feedback control.
The opening feedback control loop controls a hydraulic cylinder of the throttle valve by adopting an electro-hydraulic proportional valve, and in one embodiment of the invention, a nonlinear feedback control method is further established aiming at the characteristics of nonlinearity and time variation of the throttle valve.
Because bidirectional adjustment of the hydraulic throttle valve is required, bidirectional electro-hydraulic proportional valves are used for hydraulic control in both directions. In order to realize the purpose of accurately and rapidly regulating and controlling the opening of the throttle valve, double PID opening feedback control is adopted. Specifically, as shown in fig. 3, when the deviation between the opening setting value of the throttle valve and the opening value obtained by measurement is large, the maximum control value SPV is directly output to the electro-hydraulic proportional valve, and the opening of the throttle valve is adjusted at the fastest speed. When the deviation between the opening set value of the throttle valve and the opening value obtained through measurement is small, PID feedback regulation is adopted for accurate control, wherein PID1 corresponds to one coil A of the electro-hydraulic proportional valve, PID2 corresponds to the other coil B of the electro-hydraulic proportional valve, and in actual operation, whether the maximum control value SPV output is adopted or PID output is adopted is determined by judging the deviation between the opening set value of the throttle valve and the opening value obtained through measurement, namely the relation between the opening deviation and a preset deviation reference value. Further, whether the opening degree deviation is output by PID1 or PID2 is determined by determining whether the deviation is positive or negative.
The above-described opening degree control process can be described by expressions (3) to (6) as follows.
Calculating the absolute value of the opening deviation of the throttle valve according to the opening value of the throttle valve obtained by real-time measurement, as shown in expression (3):
in the equation, sp (k) is a set value of the opening degree of the throttle valve at the current time k. PV (k) is a measure of the throttle opening at the current time k, edIs the deviation between the opening setting value of the throttle valve and the measured opening value, e (k) is the absolute value of the opening deviation at the current time k.
Further, in the embodiment of the present invention, in order to adapt to the regulation characteristic and nonlinearity of the throttle valve, the control is performed in a stepwise manner according to the magnitude of the absolute value of the opening deviation, specifically, when the absolute value of the opening deviation is greater than a preset deviation reference value, the throttle valve is regulated at the maximum speed so that the opening of the throttle valve is changed. And when the absolute value of the opening deviation is less than or equal to a preset deviation reference value, regulating the throttle valve in a PID mode to change the opening of the throttle valve. The adjustment process is shown in expressions (4), (5) and (6).
When e (k)>efgThe output quantity u (k) of the electro-hydraulic proportional valve is controlled to be:
in the formula, efgThe deviation reference value can be selected according to performance parameters of the throttle valve in practice. The SPV is a value of a control quantity that controls the electro-hydraulic proportional valve to adjust the throttle valve at a maximum speed. The positive sign and the negative sign in the above formula represent the adjusting direction of the electro-hydraulic proportional valve.
When e (k) is less than or equal to efgAnd then, controlling the electro-hydraulic proportional valve to output an output quantity u (k) at the moment k as follows:
in the formula, u1(k) and u2(k) are output quantities respectively for controlling two coils (coil A and coil B) of the electro-hydraulic proportional valve to output. When the PID method is adopted for adjustment, u1(k) and u2(k) may be specifically in the form shown in expression (6):
wherein e (k) is the absolute value of the opening deviation at the current k time, e (k-1) is the absolute value of the opening deviation at the k-1 time, and Kp1,Ki1,Kd1The proportional, integral, differential term coefficients, Kp, of the PID control algorithm (PID1) for u1(k), respectively2,Ki2,Kd2Proportional, integral, differential term coefficients for the PID control algorithm (PID2) u2(k), respectively.
In the prior art, the opening degree feedback control adopting a single PID control algorithm is only controlled by one output, and the requirement of bidirectional hydraulic control cannot be met. The opening degree feedback control of the embodiment of the invention is double-PID opening degree feedback, as shown in FIG. 3, whether PID1 output or PID2 output is determined by judging the positive and negative of the difference between the opening degree set value of the throttle valve and the measured opening degree value, and PID1 and PID2 respectively correspond to an electro-hydraulic proportional valve coil A and a coil B, so that the requirements of quick adjustment of large opening degree and fine adjustment of small opening degree can be met.
In the embodiment of the invention, the wellhead pressure of the outer layer is converted into the opening of the throttle valve of the inner layer based on the characteristic value of the throttle valve and the throttle valve opening adjusting model, and the coarse adjustment of the wellhead pressure is realized by directly adjusting the opening, which is beneficial to improving the speed of back pressure adjustment.
When the opening is adjusted to the opening set value of the throttle valve, the throttle valve can adjust the wellhead pressure to be close to the wellhead back pressure set value, and at the moment, the pressure feedback control loop and the opening feedback control loop of the outer ring are connected in series to realize series control, as shown in fig. 2.
The pressure feedback control loop is regulated and controlled based on the wellhead back pressure control model. The input of the wellhead back pressure control model is the wellhead back pressure deviation obtained through real-time measurement and calculation, and the output is the control quantity of pressure.
In one embodiment of the present invention, an incremental PID control algorithm is used to establish a back pressure control model, as shown in expression (7):
uu(k)＝Kp3[ee(k)-ee(k-1)]+Ki3ee(k)+Kd3[ee(k)-2ee(k-1)+ee(k-2)](7)
where ee (k) is the back pressure deviation at the current time k, ee (k-1) is the back pressure deviation at the time k-1, and ee (k-2) is the back pressure deviation at the time k-2. ee (k) can be calculated according to ee (k) -psp (k) -ppv (k), where psp (k) is a set value of wellhead back pressure at the current time k, ppv (k) is a wellhead back pressure value measured at the current time k, and Kp3,Ki3,Kd3Respectively are the proportional, integral and differential term coefficients of the PID control algorithm. uu (k) is the incremental value of the pressure. It should be noted that uu (k) calculated according to expression (7) is only a control increment, and the magnitude of the control amount of the pressure at the current time needs to be obtained according to the control amount of the pressure at the previous time.
Next, the obtained control amount of the pressure is normalized to obtain a control output amount of the pressure, and the control output amount of the pressure is transmitted to the opening feedback control circuit as an opening setting value of the throttle valve, thereby establishing a transmission relationship of the control amount between the main control circuit and the sub control circuit. The normalization process is a mathematical conversion method that converts the control amount of the pressure to the range of 0 to 1 (i.e., 0 to 100%), and the control output amount of the pressure obtained by the normalization process can be used to control other control targets. For example, if the range of the set value of the controlled object is 4 to 20, it is sufficient to convert the standard value within the range of 0 to 1 of the controlled output amount into the range of 4 to 20.
The wellhead back pressure regulation and control method is a three-layer feedback control method and can meet the technical requirements of high control precision and high response speed. The opening feedback control of the throttle valve is established on the innermost layer, and the rapid and accurate regulation and control of the opening of the throttle valve are realized. And (3) establishing a throttle valve opening characteristic curve in the middle layer, transmitting the outer layer feedback data to the inner layer hydraulic control system, and respectively adopting different regulation and control methods according to the opening deviation value to realize coarse adjustment of the wellhead pressure. The cascade control of the wellhead back pressure to the opening degree is realized in the outermost layer design, the wellhead back pressure value is compared with the set back pressure value according to actual detection, the back pressure deviation is generated, the deviation is converted into a target opening degree value through a wellhead back pressure model and is transmitted to a throttle valve opening degree control system, the opening degree of a throttle valve is adjusted through a hydraulic control system, the wellhead back pressure is enabled to reach the preset precision range of the wellhead back pressure set value, and finally fine adjustment of the wellhead set pressure is realized. The quick response requirement of well head back pressure control is met, and meanwhile, the adjusting precision is improved.
The control method can meet the requirements of throttle valve opening control and wellhead back pressure control. The device has the capability of quick adjustment in large deviation and accurate regulation and control in small deviation, and has good control effect. The undisturbed switching between the opening control and the back pressure control can be realized, and the pressure is stable and free of fluctuation during the switching. The control method is simplified, the implementation is easy, the control effect is stable, and the requirement of fine regulation and control of wellhead back pressure in the pressure-controlled drilling technology can be met.
In order to further clarify the adjustment process of the regulation method of the above embodiment, the following description is made with reference to an example.
Setting the displacement of the drilling fluid to 72m3H, drilling fluid density 1.45g/cm3. The current measurement pressure is 1MPa, the measurement opening is 59.9%, the set back pressure value of the wellhead is 4MPa, and the wellhead back pressure control method needs to adjust the back pressure from 1MPa to 4MPa, efgThe yield was taken to be 3%. Root of herbaceous plantThe regulation process of the method according to the embodiment of the application is as follows:
(1) a throttle opening characteristic curve is established based on the offline identification.
A throttle valve performance regulation test is carried out in advance to obtain a characteristic value C of the throttle valvevExperimental data on the opening degree variation are shown in table 1:
TABLE 1C corresponding to the current openingvValue of
| Opening (%) | CvValue of | Opening (%) | CvValue of | Opening (%) | CvValue of |
| 0 | 0.00 | 35 | 25.45 | 70 | 106.82 |
| 5 | 1.87 | 40 | 36.45 | 75 | 113.30 |
| 10 | 2.31 | 45 | 48.84 | 80 | 117.35 |
| 15 | 3.06 | 50 | 61.92 | 85 | 119.04 |
| 20 | 5.28 | 55 | 74.96 | 90 | 119.20 |
| 25 | 9.64 | 60 | 87.21 | 95 | 119.43 |
| 30 | 16.39 | 65 | 98.01 | 100 | 119.50 |
Substituting the data in Table 1 into expression (2) to obtain a system of equations, and passing backCalculating the opening degree about CvThe curve equation for the values is:
the obtained throttle opening characteristic curve is shown in fig. 4.
(2) Setting PID parameters of throttle valve opening control:
PID parameters need to be adjusted and determined according to actual operation. For the convenience of explaining the flow, it is assumed that two coils of the electro-hydraulic proportional valve are not different, so that the two directional operating characteristics of the system are considered to be the same, and two PID parameters are set to be the same. Here a set of PID parameter coefficients is given: kp1＝Kp2＝2.1，Ki1＝Ki2＝0.2，Kd1＝Kd2Substituting the coefficient into expression (6) to obtain 0:
(3) setting an incremental PID parameter of a wellhead back pressure control model:
the incremental PID parameters need to be set and determined according to actual operation. For ease of explanation of the flow, a set of PID parameter coefficients is given here: kp3＝0.75，Ki3＝0.07，Kd3Substituting the coefficient into expression (7) to obtain 0:
uu(k)＝0.75[ee(k)-ee(k-1)]+0.07ee(k) (8-3)
(4) calculating C of the current timevThe value:
72m according to the current displacement3H, density 1.45g/cm3And the expected wellhead back pressure value is 4MPa, and the parameters are substituted into the expression (1) to calculate CvThe values of (A) are as follows: cv＝43.35。
(5) According toCvThe value of (A) is calculated to the opening value X to be adjustedSPV：
C is to bevSubstituting the expression (8-1) to obtain:
XSPV＝43.08％ (8-5)
(6) calculating the opening deviation:
substituting the calculation result of the formula (8-5) into the expression (3) to obtain:
e(k)＝abs(43.08％-59.9％)＝16.82％ (8-6)
(7) output of control amount for adjusting throttle opening:
when e (k)>efgAnd (4) outputting a control quantity u (k) by using an expression (4), so that the throttle valve regulates and controls the opening towards 43.08 at the maximum speed.
When e (k) is less than or equal to efgAnd (3) outputting the control quantity u (k) by using an expression (5), wherein the output control adopts a PID (proportion integration differentiation) method to carry out accurate regulation and control around 43.08.
(8) A new opening measurement value is obtained.
And (4) acquiring the latest throttle opening value according to the displacement sensor, and performing new calculation and control in the step (6) until the opening set value of the throttle is reached, so as to realize accurate regulation and control of the throttle opening.
(9) And calculating the back pressure deviation and the incremental value of the back pressure.
And calculating a back pressure deviation (ee (k) ═ PSP (k) — PPV (k)) according to the currently measured pressure value and a wellhead back pressure set value, and substituting the calculated back pressure deviation into an expression (8-3) to calculate an incremental value of the required control quantity of the pressure. However, uu (k) is an incremental output, and it is necessary to increase or decrease the original set value to obtain a control amount of pressure, and the obtained control amount of pressure is used as the opening degree set value of the throttle valve.
Assuming that the opening degree of the throttle valve is 43% and the throttle pressure is 3.7MPa when the pressure control is shifted to the first time after the rough adjustment of the opening degree control of the inner layer is completed, the set wellhead back pressure value of 4MPa and the above parameters are substituted into the expression (8-3) and ee (k) ═ psp (k) — ppv (k), the back pressure deviation ee (k) ═ 0.3 is calculated, and the control output uu (k) () 0.23 is obtained.
(10) Inner ring opening adjustment
And (4) switching to the step (6) to perform opening feedback adjustment according to the new target opening value obtained in the step (9) until the adjustment is completed.
(11) Obtaining new pressure measurements
And (4) acquiring data of a throttle valve pressure sensor to obtain a new pressure measurement value, and transferring to the step (9) to perform pressure fine regulation until the wellhead back pressure reaches a preset precision range of a wellhead back pressure set value, such as 0.05.
Fig. 5 is a schematic structural diagram of a wellhead back pressure regulating device according to another embodiment of the invention. As shown in the figure, the detection unit 51 performs the operation of step S110, the fast adjustment unit 52 performs the operation of step S120, and the fine adjustment unit 53 performs the operation of step S130, which will not be expanded in detail here.
Those skilled in the art will appreciate that the modules or steps of the invention described above can be implemented in a general purpose computing device, centralized on a single computing device or distributed across a network of computing devices, and optionally implemented in program code that is executable by a computing device, such that the modules or steps are stored in a memory device and executed by a computing device, fabricated separately into integrated circuit modules, or fabricated as a single integrated circuit module. Thus, the present invention is not limited to any specific combination of hardware and software.
Although the embodiments of the present invention have been described above, the above descriptions are only for the convenience of understanding the present invention, and are not intended to limit the present invention. It will be understood by those skilled in the art that various changes in form and details may be made therein without departing from the spirit and scope of the invention as defined by the appended claims.
Claims (6)
1. A wellhead back pressure regulation method comprises the following steps:
acquiring a back pressure value of a wellhead in real time, and calculating the back pressure deviation of the wellhead;
acquiring an opening set value of the throttle valve, acquiring an opening value of the throttle valve in real time, and calculating an opening deviation of the throttle valve according to the opening set value of the throttle valve and the acquired opening value of the throttle valve;
when the back pressure deviation is larger than a preset back pressure rough adjustment threshold value, opening feedback control of the throttle valve is carried out based on the opening deviation of the throttle valve, so that the throttle valve reaches an opening set value of the throttle valve, and well mouth back pressure is regulated, wherein the step of obtaining the opening set value of the throttle valve comprises the following steps: establishing a throttle opening characteristic curve, calculating a throttle opening corresponding to a wellhead back pressure set value based on the throttle opening characteristic curve, and taking the throttle opening as an opening set value of a throttle;
when the back pressure deviation is smaller than or equal to a preset back pressure coarse adjustment threshold value, opening feedback control of the throttle valve is carried out based on the opening deviation of the throttle valve, and then the wellhead back pressure is enabled to reach a preset precision range of a wellhead back pressure set value, wherein the step of obtaining the opening set value of the throttle valve comprises the following steps: establishing a wellhead back pressure control model, calculating the control quantity of pressure based on the wellhead back pressure control model and the back pressure deviation of the wellhead acquired in real time, carrying out standardized processing based on the control quantity of the pressure to obtain the control output quantity of the pressure, and taking the control output quantity of the pressure as the opening set value of the throttle valve.
2. The method according to claim 1, wherein the performing the opening degree feedback control of the throttle valve based on the opening degree deviation of the throttle valve includes:
when the absolute value of the opening deviation is larger than a preset deviation reference value, adjusting the throttle valve at the maximum speed to regulate and control the wellhead back pressure;
and when the absolute value of the opening deviation is less than or equal to a preset deviation reference value, regulating the throttle valve in a PID mode to regulate and control the wellhead back pressure.
3. The method according to claim 2, characterized in that the throttle valve opening characteristic curve is established according to the following expression:
wherein, XSPVIs the opening value of the throttle valve, CvThe characteristic values of the throttle valve are a, b, c, d and e, and constant coefficients are used.
4. A wellhead back pressure regulation device comprising:
the detection unit is used for acquiring a back pressure value of a wellhead in real time, calculating a back pressure deviation of the wellhead, acquiring an opening set value of the throttle valve, acquiring an opening value of the throttle valve in real time, and calculating the opening deviation of the throttle valve according to the opening set value of the throttle valve and the acquired opening value of the throttle valve;
and the quick adjusting unit is used for performing opening feedback control on the throttle valve based on the opening deviation of the throttle valve when the return pressure deviation is greater than a preset return pressure coarse adjustment threshold value, so that the throttle valve reaches an opening set value of the throttle valve, and further regulating and controlling wellhead return pressure, wherein the step of obtaining the opening set value of the throttle valve comprises the following steps of: establishing a throttle opening characteristic curve, calculating a throttle opening corresponding to a wellhead back pressure set value based on the throttle opening characteristic curve, and taking the throttle opening as an opening set value of a throttle;
and the fine adjustment unit is used for performing opening feedback control on the throttle valve based on the opening deviation of the throttle valve when the return pressure deviation is less than or equal to a preset return pressure coarse adjustment threshold value, so that the wellhead return pressure reaches a preset precision range of a wellhead return pressure set value, wherein the step of acquiring the opening set value of the throttle valve comprises the following steps of: establishing a wellhead back pressure control model, calculating the control quantity of pressure based on the wellhead back pressure control model and the back pressure deviation of the wellhead acquired in real time, carrying out standardized processing based on the control quantity of the pressure to obtain the control output quantity of the pressure, and taking the control output quantity of the pressure as the opening set value of the throttle valve.
5. The apparatus according to claim 4, wherein the performing the opening degree feedback control of the throttle valve based on the opening degree deviation of the throttle valve includes:
when the absolute value of the opening deviation is larger than a preset deviation reference value, adjusting the throttle valve at the maximum speed to regulate and control the wellhead back pressure;
and when the absolute value of the opening deviation is less than or equal to a preset deviation reference value, regulating the throttle valve in a PID mode to regulate and control the wellhead back pressure.
6. The apparatus according to claim 5, wherein the quick adjustment unit establishes the throttle opening characteristic curve according to the following expression:
wherein, XSPVIs the opening value of the throttle valve, CvThe characteristic values of the throttle valve are a, b, c, d and e, and constant coefficients are used.
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| CN109386243B (en) * | 2017-08-10 | 2021-04-27 | 中国石油化工股份有限公司 | Shaft pressure regulation and control method and system |
| CN112459747A (en) * | 2020-12-08 | 2021-03-09 | 中国石油天然气集团有限公司 | Control method of pressure-limiting and regulating valve for pressure-controlled drilling based on cubic spline curve |
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| CN1538036A (en) * | 2003-04-17 | 2004-10-20 | 雷宗明 | Automic control system for throttle well killing |
| CN2874018Y (en) * | 2006-04-04 | 2007-02-28 | 朱英杰 | Well head back pressure controller for petroleum production |
| JP4301323B2 (en) * | 2007-05-14 | 2009-07-22 | トヨタ自動車株式会社 | Control device for internal combustion engine |
| CN101634862B (en) * | 2009-07-31 | 2011-05-04 | 中南大学 | Control method of opening of large flow throttle valve for water |
| CN101694152B (en) * | 2009-10-30 | 2012-12-26 | 中国石油大学(北京) | Multi-level fine choke manifold and automatic control system |
| CN201593387U (en) * | 2010-02-03 | 2010-09-29 | 中国石油天然气集团公司 | Drilling annulus pressure precise control system |
| US10241483B2 (en) * | 2013-02-21 | 2019-03-26 | National University Corporation Nagoya University | Control device design method and control device |
| JP5714622B2 (en) * | 2013-02-21 | 2015-05-07 | トヨタ自動車株式会社 | Control device |
| CN103256015B (en) * | 2013-05-06 | 2015-10-21 | 中国石油大学(北京) | The wellhead back pressure control system of controlled pressure drilling and wellhead back pressure control method |
| CN103527169A (en) * | 2013-10-24 | 2014-01-22 | 陕西高新能源发展有限公司 | Throttle valve control system |
| CN103527168A (en) * | 2013-10-24 | 2014-01-22 | 陕西高新能源发展有限公司 | Throttle valve control system |
| CN105089528B (en) * | 2014-05-14 | 2018-10-16 | 中国石油天然气集团公司 | A kind of well head pressure control method and device for controlled pressure drilling |
| CN105320790A (en) * | 2014-07-28 | 2016-02-10 | 中国石油化工股份有限公司 | Design method of throttle valve with pressure drop linearly changed with opening degree as well as valve core |
| CN105320789B (en) * | 2014-07-28 | 2019-01-01 | 中国石油化工股份有限公司 | Discharge coefficient with the throttle valve of aperture linear change design method |
| CN104405362B (en) * | 2014-10-28 | 2017-04-26 | 中国石油集团西部钻探工程有限公司 | Automatic bottom hole pressure control device for under-balanced drilling and using method of device |
| CN104481436B (en) * | 2014-12-05 | 2017-05-10 | 中国石油天然气集团公司 | Method and system for regulating precision pressure-control well drilling throttle valve |
| CN204371220U (en) * | 2014-12-05 | 2015-06-03 | 中国石油天然气集团公司 | The regulating system of meticulous controlled pressure drilling choke valve |
| CN105045137A (en) * | 2015-08-12 | 2015-11-11 | 中国航空工业集团公司西安飞机设计研究所 | Adaptive PID control method and control system of executing mechanism |
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