METHOD AND SYSTEM FOR AUTOMATED ADJUSTMENT OF DRILLING MUD PROPERTIES

Description

FIELD OF THE INVENTION

[0001] The present invention relates to a method and system for automated adjustment of drilling mud properties in a mud recirculation system of a rig for drilling an underground wellbore.

BACKGROUND OF THE INVENTION

[0002] During drilling of underground wellbores for the production of crude oil and/or natural gas a drilling fluid, generally known as drilling mud, is circulated in downward direction through the interior of the drill string and then in upward direction through the surrounding annulus to lift drill cuttings to the surface, to clean and cool the drill bit, to stabilize the borehole, to lubricate the rotating drill string and to provide hydrostatic head for preventing well kicks.

[0003] At the wellhead the drill cuttings are removed from the drilling mud in a mud cleaning assembly and the mud volume is adjusted by adding fresh mud and the composition of the re-injected mud is adjusted by adding mud additives in a mud treatment assembly to generate desired mud properties, such as mud density, viscosity and pH.

[0004] A fluid handling system is described in WO 97/42395 A1, specifically for underbalanced drilling operations. A control unit determines or computes values of a number of operating parameters of the fluid handling system and controls the operation of the various devices based on such parameters according to programs and models provided to the control unit. The control unit, which receives signals from sensors, is coupled to the various devices in the system for controlling the operations of the devices, including control valves. The control unit periodically or continually determines the required drilling fluid mix as a function of one or more of the selected operating parameters and operates a control valve to discharge a correct amount of additive materials to obtain the desired mix.

[0005] WO 97/42395 A1 further discloses methods for the automated adjustment of drilling mud properties in a mud recirculation system of a rig for drilling an underground wellbore. WO 02/50398 A1 discloses a closed loop drilling system. WO 2010/085401 A1 discloses mixing additives with drilling fluid in a mud tank.

[0006] At the moment, there is no integrated solution utilizing a combination of integrated hardware and software that makes use of the measurement data to predict the downhole condition and control the mud properties in order to mitigate or avoid operational issues.

[0007] There is a need for an improved mud additive injection control system and method which overcome the drawbacks of the prior art.

[0008] Furthermore there is a need for a more efficient mud system management that minimizes waste and use of materials used to treat the mud and minimize operational downtime, due to for example a stuck drill pipe and/or drill pipe vibration, and operational issues, such as lack of well control and/or borehole instability due to the failure of keeping the mud properties at the desired specification.

SUMMARY OF THE INVENTION

[0009] In one aspect of the invention, there is provided a method for automated adjustment of drilling mud properties as defined in claim 1.

[0010] In another aspect of the invention, there is provided a system for automated adjustment of drilling mud properties as defined in claim 12.

[0011] These and other features, embodiments and advantages of the method and system as proposed herein are described in the accompanying claims, abstract and the following detailed description of non-limiting embodiments depicted in the accompanying drawing, in which description reference numerals are used which refer to corresponding reference numerals that are depicted in the drawing.

[0012] Objects and other features depicted in the figure and/or described in this specification, abstract and/or claims may be combined in different ways by a person skilled in the art.

BRIEF DESCRIPTION OF THE DRAWING

[0013] The systems and methods will be described hereinafter by way of example in more detail with reference to Figure 1, which is a schematic representation of a drilling assembly provided with an automated mud additive injection control system. No limitations are intended to the details of construction or design herein shown, other than as described in the claims below.

DETAILED DESCRIPTION OF THE DEPICTED EMBODIMENT

[0014] A method and system are proposed for automated adjustment of drilling mud properties in a mud recirculation system. Such mud recirculation system may form part of a drilling assembly for excavating an underground wellbore. The mud recirculation system may be applied on a rig for drilling an underground formation.

[0015] In one proposed method for automated adjustment of drilling mud properties in a mud recirculation system of a rig for drilling an underground wellbore, hierarchal primary and secondary optimization and control loops are induced to control an automated mud treating assembly which injects additives that continuously keep density, viscosity, pH and other mud properties within the specifications. Rather than that these specifications are set by an operator, a tertiary model-based optimization and control loop may be run to set the specifications.

[0016] This may be implemented by three nested optimization and control loops as follows: the tertiary optimization and control loop determines specifications for mud properties comprising density, viscosity, pH and optionally other mud properties on the basis of a model which optimizes desired downhole properties of the injected mud for assessed downhole drilling conditions. These mud property specifications are fed as setpoints to the secondary optimization and control loop, which determines the required additives to achieve the desired setpoint mud properties. The required additives as computed by the secondary loop then become the setpoints for the primary control loops, which open additive injection valves to achieve the required additives. The tertiary optimization and control loop may also determine setpoints of flow rate of the circulated mud stream, which may be fed directly to the pump control system without intervention by the secondary and primary optimization and control loops.

[0017] The mud properties may be measured by a sensor assembly that measures density, viscosity, pH and/or other properties of the mud in the mud recirculation system at the rig upstream and/or downstream of the automated mud treating assembly, which sensor assembly may comprise an upstream sensor assembly comprising primary and secondary untreated mud property sensors for monitoring the properties of the untreated mud flowing from a cuttings removal system to the automated mud treating assembly. The primary untreated mud flux property sensor may be arranged in the mud recirculation system between the secondary untreated mud flux property sensor and the mud treating assembly.

[0018] The automated mud treating assembly may comprise additive injection control devices, suitably injection control valves, that are controlled by the primary optimization and control loop to meet the injection rates of each additive set by set by the secondary optimization and control loop that is connected to the tertiary optimization and control loop that determines the appropriate ranges or setpoints for density, viscosity, pH and other mud properties in order to meet multiple operational objectives, such as maximizing cutting transport capabilities of the drilling mud and maintaining wellbore mechanical stability.

[0019] Optionally, the primary, secondary and tertiary optimization and control loops operate at different time scales and hierarchies, whereby:

• the tertiary optimization and control loop is the master of the secondary optimization and control loop and operates at the highest time scale or lower sampling rate; and
• the secondary optimization and control loop is governed by, also called the slave of, the tertiary optimization and control loop and operates at the lower time scale or higher sampling rate than the tertiary optimization and control loop but higher time scale and lower sampling rate than the primary optimization and control loop which is governed by, also called the slave of, the secondary optimization and control loop.

[0020] The tertiary optimization and control loop may comprise an optimization module that determines the ranges or the setpoints of the primary treated mud properties given the objective functions of the tertiary optimization and control loop such as ensuring sufficient cutting transport, wellbore mechanical stability and given estimates of:

a) drill string torque and drag;

b) borehole stability and permeability;

c) size, volume, weight, density and composition of drill cuttings; and

d) downhole mud velocity, pH, viscosity, density and composition.

[0021] The ranges of the mud property values as determined by the optimization module of the tertiary loop may suitably be included as the desired ranges to be honoured by a multivariable control algorithm in the secondary control loop. The multivariable control algorithm suitably provides a setpoint for the injection rate of each one of the injected mud additives. The multivariable control algorithm may be a Model Predictive Controller (MPC) algorithm that casts the multivariable control problem as an optimal control problem with an objective function of minimizing the deviation of the primary treated mud properties from the desired ranges given the minimum and maximum amount of additives to be added at each cycle and the models between mud properties to be controlled and additives as well as the drilling and mud flux circulation rates, which casts the mud properties control problem into a multivariable optimization solution with constraints over a selected time horizon that take into account the amount of time required for the mud to be circulated through the borehole and back to the drilling rig at earth surface.

[0022] The multivariable control MPC algorithm may be provided with models identifying mathematical relationships between the additives, mud properties and measured variations in drilling rates that affect variations in drill cuttings concentration.

[0023] The proposed method may be implemented in a system for automated adjustment of drilling mud properties in the mud recirculation system.

[0024] An example of an implementation of an automated mud treatment system and method is illustrated with reference to Figure 1. Figure 1 shows a drilling assembly 1 comprising a drill bit 2 that is rotated by a drill string 3 as illustrated by arrows 4 to excavate an underground borehole 5.

[0025] Drilling mud 6 is pumped down through the drill string 3 as illustrated by arrows 7 and up through the surrounding annulus 8 as illustrated by arrow 9 to lift drill cuttings 10 to the earth surface 11, where the drill cuttings are removed from the returned mud 6 in a mud shaker and filter assembly 12.

[0026] The cleaned mud 6 is subsequently transported via a mud recirculation conduit 13 and a top drive swivel 14 back into the drill string 3. Even though the mud is recirculated, and as such there is strictly speaking no begin and end to the circuit, for the purpose of interpretation of terms such as "upstream", "downstream", and for defining the order in which certain parts of equipment are configured relative to each other in the mud circulation system, the mud share and filter assembly 12 is taken to be "the end" of the mud recirculation cycle, which is considered to be the most "downstream" end of the cycle. The most "upstream" end of the cycle is the transition from the mud share and filter assembly 12 into the mud recirculation conduit 13.

[0027] The mud recirculation conduit 13 is connected to a mud mixing tank 15 in which additional mud can be added from a mud tank 16 and in which the mud is mixed by a mixer 17 to homogenize the mud 6 before it is pumped back into the drill string 3 by a mud pump assembly 17,18. The mud mixing tank 15 may be referred to as untreated mud mixing tank 15, as it is located upstream of a mud treating assembly 20 to which the mud recirculation conduit 13 is furthermore connected. In this mud treating assembly 20 mud additives 21-24 are injected into the mud, to ultimately adjust mud properties, such as density, viscosity and pH.

[0028] The mud treating assembly 20 is suitably equipped with an automated additive injection control system 25 that automatically adjusts the injection rates of each of the mud additives 21-24 on the basis of measurements of the properties of untreated mud 6 upstream of the treating assembly 20 by primary and secondary untreated mud property sensors 26-27 and measurements of the treated mud 6 downstream of the treating assembly 20 by primary and secondary treated mud property sensors 28-29. An untreated mud mixing tank 15 may be arranged in the mud recirculation system 13 between the primary and secondary untreated mud property sensors 26-27.

[0029] The primary and secondary untreated and treated mud property sensors 26-27 and 28-29 form part of a hierarchical closed loop control system which contains two closed loops 30-31, where loop 30 is configured as a primary or master control loop and the other loop 31 is configured as a secondary or slave control loop. Both closed loop 30-31 make use of assemblies of substantially similar mud property sensors 26-29, located in predefined positions upstream and downstream of the mud treating assembly 20, providing necessary data for mud property monitoring and control.

[0030] The automated mud treating system 25 may comprise an additive injection optimization module comprising a computer programmed with algorithms known as Wells Advanced Kernels (WAKs) and a mathematical optimization module to provide the secondary multivariable control loop (for example the MPC alogrithm) with specifications for mud properties such as density, viscosity, pH and optionally other mud properties based on advanced drilling parameters modelling and real time data. Setpoints for circulation flow rate, which may also be computed, may be fed directly to the rig mud pump assembly 17,18. Given the specifications for the mud properties, the secondary multivariable control loop then computes the required mud additives 21-24. The required mud additives 21-24 as computed by the secondary optimization and control loop become the set points for the primary closed loop control system 30, which adjusts the valve openings accordingly to meet the setpoints of each of the mud additives 21-24.

[0031] The automated drilling mud treating system 20, 25 is able to adjust mud properties more accurately than manually controlled drilling fluid additive systems that may still be present on the drilling rig 33 for start-up and/or as a back-up in case of malfunctioning of the automated mud treating system 20,25. The automated additive injection control system 20,25 automatically adjusts during at least part of the drilling operations the drilling fluid additive injection rates to adjust the mud properties to a desired set-point based on a predefined reference signal.

[0032] The mud treating system 20 is arranged in an additives and mud mixing tank 34, which is designed in such a way to ensure sufficient mixing quality and appropriate response time to bring the mud properties back to a desired specification, and a set of physical actuators, such as additive injection pumps and control valves (not shown), for automatic addition of the mud additives 21-24. The size of the mixing tank 34 may suitably be determined by taking into account the following aspects:

• the minimum residence time required by the characteristics of the drilling mud to ensure a homogeneous mixture when additives are added; and
• the balance between the response time required by the secondary multivariable control loop to bring the properties of the primary untreated mud to the desired values or ranges while ensuring that the addition of the additives as the result of the controller's actions does not lead to major fluctuations in the steady state or transient values of the primary treated and secondary untreated mud properties.

[0033] The flow rates of the mud additives 21-24 into the additives and mud mixing tank 34 are regulated by the automated additive injection control system 25, which uses the data generated by the mud flux property sensor assemblies 26,27 about the untreated mud 6 returned from the borehole 5 is compared to reference signals or desired specifications of the mud properties, which can originate from operators or from an automatic set point optimization module based on the Wells Advance Kernel (WAK) prediction. Any deviations (error signals) from the desired setpoints will trigger the control algorithm to compute required amount of additives 21-24 to be added to the mud 6 and these computations are sent to the control valves of the mud treating assembly 20, 25.

[0034] The automated mud treating system 20,25 may furthermore be provided with an MPC algorithm, which casts the mud properties control problem into a multivariable optimization solution with constraints over a certain time horizon to take into account the amount of time required for the mud 6 to be circulated through the borehole 5 and back to the surface 11. The MPC algorithm is a control approach that takes the time horizon and input constraints into account.

[0035] The MPC algorithm may be provided with models identifying mathematical relationships between the additives, mud properties, and also measured disturbances such as variations in drilling rates that affect variations in drill cuttings 10 concentration. The effects of disturbances can change the relationship between the additives 21-24 and mud properties, which may be automatically corrected by the MPC algorithm.

[0036] There are two options to correct the models in the MPC algorithm:

I) One option is to correct the model by adding a filter, for example a Kalman Filter, that corrects and updates the model continuously based on measurement data.

II) Another option is to use an automatic model-rebuilding mechanism if the amount of updates from the Kalman Filter is too big. The automatic model-rebuilding mechanism is carried out by varying the additive signals systematically in such a way that meaningful mathematical relationships can still be derived without disturbing the drilling operations. The input signals and measured mud properties resulting from this systematic variation is then used to derive a new model for the control algorithm.

[0037] The required mud property specification and associated additive injection setpoints in the automated mud treating system 20,25 can be updated automatically by means of an optimization algorithm. Given the mud weight and the viscosity profile of the mud, the Wells Advanced Kernels (WAKs) may provide a prediction of the cutting transport state, the equivalent circulating density, and, optionally, the torque and drag profile along the borehole 5 and, also optionally, the elastic borehole stability. The mathematical models between the mud properties and these parameters can be derived by feeding the kernels with mud property values and fit models between the mud properties and the cuttings transport, drill string torque and drag and borehole stability. Given the selected mathematical model(s) and operational objective(s), such as maximize borehole cleaning and maximize borehole stability and applying a linear or nonlinear optimization algorithm, the appropriate setpoints for the mud additive injection rates can be derived automatically from the selected model(s).

[0038] Therefore, the method and system described herein are well adapted to attain the ends and advantages mentioned as well as those that are inherent therein.

[0039] The particular embodiments disclosed above are illustrative only, as the present invention may be modified, combined and/or practiced in different but equivalent manners apparent to those skilled in the art having the benefit of the teachings herein.

[0040] It is therefore evident that the particular illustrative embodiments disclosed above may be altered, combined and/or modified and all such variations are considered within the scope of the present invention as defined in the accompanying claims.

Claims

1. A method for automated adjustment of drilling mud properties in a mud recirculation system of a rig (33) for drilling an underground borehole (5), the method comprising:

- circulating drilling mud through the borehole and back to the rig at earth surface, whereby the drilling mud flows through an automated mud treating assembly (20,25);

- injecting mud additives into the mud with the automated mud treating assembly (20,25), to ultimately adjust mud properties;

- inducing hierarchal primary and secondary optimization and control loops (30, 31) to adjust injection rates of mud additives (21-24) into the drilling mud being circulated , to continuously keep mud properties, comprising density, viscosity, pH and optionally other mud properties, within specifications set by a model-based tertiary optimization and control loop, characterized in that the tertiary optimization and control loop comprises an optimization module that determines the ranges or the setpoints of the primary treated mud properties given objective functions of the tertiary optimization and control loop such as ensuring sufficient cuttings transport, wellbore mechanical stability and estimates of:

a) drill string (3) torque and drag;

b) borehole stability and permeability;

c) size, volume, weight, density and composition of drill cuttings (10); and

d) downhole mud velocity, pH, viscosity, density and composition.

2. The method of claim 1, wherein the primary optimization and control loop (30) governs opening and closing of additive injection control valves of the automated mud treating assembly (20, 25) to meet injection rates of each additive (21-24) set by the secondary optimization and control loop (31) that is connected to the tertiary optimization and control loop that determines the appropriate ranges or setpoints for the mud properties in order to meet multiple operational objectives, such as maximizing cuttings transport capabilities of the drilling mud (6) and maintaining wellbore mechanical stability.

3. The method of claim 1 or 2, wherein the mud properties are measured by a sensor assembly (26-29) that measures the mud properties of the mud in the mud recirculation system at the rig (33) upstream of the automated mud treating assembly (20, 25).

4. The method of claim 1 or 2, wherein the mud properties are measured by a sensor assembly (26-29) that measures the mud properties of the mud (6) in the mud recirculation system at the rig (33) downstream of the automated mud treating assembly (20, 25).

5. The method of claim 3, wherein the sensor assembly (26-29) comprises an upstream sensor assembly (26, 27) comprising primary and secondary untreated mud flux property sensors (26,27) for monitoring the properties of the untreated mud (6) flowing from a cuttings removal system to the automated mud treating assembly (20, 25), wherein the primary untreated mud flux property sensor (26) is arranged in the mud recirculation system between the secondary untreated mud flux property sensor (27) and the mud treating assembly (20, 25).

6. The method of any one of the preceding claims, wherein:

- the primary (30), secondary (31) and tertiary optimization and control loops operate at different time scales and hierarchies;

- the tertiary optimization and control loop is the master of the secondary optimization and control loop (31) and operates at the highest time scale or lower sampling rate; and

- the secondary optimization and control loop (31) is governed by the tertiary optimization and control loop and operates at the lower time scale or higher sampling rate than the tertiary optimization and control loop but higher time scale and lower sampling rate than the primary optimization and control loop (30) which is governed by the secondary optimization and control loop (31).

7. The method of claim 5 or 6, wherein the sensor assembly (26-29) further comprises a downstream sensor assembly (28, 29) comprising primary and secondary treated mud property sensors (28,29) for measuring density, viscosity, pH and/or other properties of the treated mud (6) in the mud recirculation system at the rig (33) downstream of the mud treating assembly (20, 25), wherein the primary treated mud flux property sensor (28) is arranged in the mud recirculation system between the mud treating assembly (20, 25) and the secondary treated mud property sensor (29); and wherein:

- the primary optimization and control loop (30) is connected to a sensor assembly that measures the actual injection rate of each additive in the automated mud treating assembly (20, 25);
the secondary optimization and control loop (31) is connected to the sensor assembly (26-29) that measures the primary untreated and treated mud properties;
the tertiary optimization and control loop is connected to the primary untreated mud sensor assembly (26, 27) and optionally to the secondary untreated mud sensor assembly (28, 29).

8. The method of any one of claims 5 to 7, wherein the primary treated mud flux property sensor (28) forms part of the secondary optimization and control loop (31) and the secondary treated mud flux property sensor (29) forms part of the tertiary optimization and control loop.

9. The method of claim 8, wherein the ranges of the mud property values as determined by the optimization module are included as the desired ranges to be honoured by a multivariable control algorithm in the secondary control loop (31).

10. The method of claim 9, wherein the multivariable control algorithm is a Model Predictive Controller (MPC) algorithm that casts the multivariable control problem as an optimal control problem with an objective function of minimizing the deviation of the primary treated mud properties from the desired ranges given the minimum and maximum amount of additives (21-24) to be added at each cycle and the models between mud properties to be controlled and additives (21-24) as well as the drilling and mud flux circulation rates.

11. The method of claim 10, wherein the multivariable control algorithm is provided with models identifying mathematical relationships between the additives (21-24), mud properties and measured variations in drilling rates that affect variations in drill cuttings concentration.

12. A system for automated adjustment of drilling mud properties in a mud recirculation system of a rig (33) for drilling an underground borehole (5), the system comprising a mud recirculation conduit (13) and an automated mud treating assembly (20,25) comprising additive injection control devices that are controlled by hierarchal primary and secondary optimization and control loops to adjust injection rates of mud additives (21-24) into the mud recirculation conduit (13), arranged to continuously keep mud properties, comprising density, viscosity, pH and optionally other mud properties, within specifications set a model-based tertiary optimization and control loop, characterized in that the tertiary optimization and control loop comprises an optimization module that determines the ranges or the setpoints of the primary treated mud properties given objective functions of the tertiary optimization and control loop such as ensuring sufficient cuttings transport, wellbore mechanical stability and estimates of:

a) drill string torque and drag;

b) borehole stability and permeability;

c) size, volume, weight, density and composition of drill cuttings (10); and

d) downhole mud velocity, pH, viscosity, density and composition.

13. The system of claim 12, wherein the additive injection control devices are additive injection control valves, and wherein the primary optimization and control loop governs opening and closing of the additive injection control valves, to meet the injection rates of each additive set by the secondary optimization and control loop (31) that is connected to the tertiary optimization and control loop that determines the appropriate ranges or setpoints for the mud properties in order to meet multiple operational objectives, such as maximizing cuttings transport capabilities of the drilling mud (6) and maintaining wellbore mechanical stability.

14. The system of claim 12 or 13, wherein the system comprises a sensor assembly (26-29) that measures the mud properties of the mud (6) in the mud recirculation system at the rig (33) upstream and/or downstream of the automated mud treating assembly (20, 25).

15. The system of any one of claims 12-14, wherein the mud treating assembly (20, 25) comprises an additives (21-24) and mud mixing tank (34), the size of which is determined by two aspects:

- the minimum residence time required by the characteristics of the drilling mud (6) to ensure a homogeneous mixture when additives (21-24) are added; and

- the balance between the response time required by the secondary multivariable control loop (31) to bring the properties of the primary untreated mud (6) to the desired values or ranges while ensuring that the addition of the additives (21-24) as the result of the controller's actions does not lead to major fluctuations in the steady state or transient values of the primary treated and secondary untreated mud properties.

Ansprüche

1. Verfahren zum automatisierten Einstellen der Bohrschlammeigenschaften in einem Schlammrückführungssystem einer Bohranlage (33) zum Bohren eines unterirdischen Bohrlochs (5), das Verfahren Folgendes umfassend:

- Umwälzen von Bohrschlamm durch das Bohrloch und zurück zur Bohranlage an der Erdoberfläche, wobei der Bohrschlamm durch eine automatisierte Schlammbehandlungsanlage (20, 25) fließt;

- Einspritzen von Schlammadditiven in den Schlamm mit der automatischen Schlammbehandlungsanlage (20, 25), um letztendlich die Schlammeigenschaften anzupassen;

- Induzieren hierarchischer primärer und sekundärer Optimierungs- und Regelkreise (30, 31), um die Injektionsraten von Schlammadditiven (21-24) in den umgewälzten Bohrschlamm einzustellen, um die Schlammeigenschaften, die Dichte, Viskosität, pH-Wert und optional andere Schlammeigenschaften umfassen, kontinuierlich innerhalb der durch einen modellbasierten tertiären Optimierungs- und Regelkreis festgelegten Spezifikationen zu halten, dadurch gekennzeichnet, dass der tertiäre Optimierungs- und Regelkreis ein Optimierungsmodul umfasst, das die Bereiche oder die Sollwerte der Eigenschaften des primären behandelten Schlamms bei objektiven Funktionen des tertiären Optimierungs- und Regelkreises bestimmt, wie z. B. Sicherstellen eines ausreichenden Bohrkleintransports, der mechanischen Stabilität des Bohrlochs und der Abschätzung der folgenden Punkte:

a) Drehmoment und Widerstand des Bohrstrangs (3);

b) Stabilität und Durchlässigkeit des Bohrlochs;

c) Größe, Volumen, Gewicht, Dichte und Zusammensetzung des Bohrkleins (10); und

d) Bohrlochschlammgeschwindigkeit, pH-Wert, Viskosität, Dichte und Zusammensetzung.

2. Verfahren nach Anspruch 1, wobei der primäre Optimierungs- und Regelkreis (30) das Öffnen und Schließen der Additiv-Einspritzsteuerventile der automatisierten Schlammbehandlungsanlage (20, 25) regelt, um die Einspritzraten jedes Additivs (21-24) zu erfüllen, die vom sekundären Optimierungs- und Regelkreis (31) eingestellt werden, der mit dem tertiären Optimierungs- und Regelkreis verbunden ist, der die geeigneten Bereiche oder Sollwerte für die Schlammeigenschaften bestimmt, um mehrere Betriebsziele zu erreichen, wie z. B. Maximieren der Fähigkeiten des Bohrkleins zum Transport des Bohrschlamms (6) und Aufrechterhalten der mechanischen Stabilität des Bohrlochs.

3. Verfahren nach Anspruch 1 oder 2, wobei die Schlammeigenschaften durch eine Sensorbaugruppe (26-29) gemessen werden, die die Schlammeigenschaften des Schlamms im Schlammrückführungssystem an der Bohranlage (33) stromaufwärts der automatischen Schlammbehandlungsanlage (20, 25) misst.

4. Verfahren nach Anspruch 1 oder 2, wobei die Schlammeigenschaften durch eine Sensorbaugruppe (26-29) gemessen werden, die die Schlammeigenschaften des Schlamms (6) in dem Schlammrückführungssystem an der Bohranlage (33) stromabwärts der automatischen Schlammbehandlungsanlage (20, 25) misst.

5. Verfahren nach Anspruch 3, wobei die Sensorbaugruppe (26-29) eine stromaufwärtige Sensorbaugruppe (26, 27) umfasst, die primäre und sekundäre Flusseigenschaftssensoren für unbehandelten Schlamm (26, 27) zur Überwachung der Eigenschaften des unbehandelten Schlamms (6) umfasst, der von einem Bohrklein-Entfernungssystem zur automatischen Schlammbehandlungsanlage (20, 25) fließt, wobei der primäre Flusseigenschaftssensor für unbehandelten Schlamm (26) im Schlammrückführungssystem zwischen dem sekundären Flusseigenschaftssensor für unbehandelten Schlamm (27) und der Schlammbehandlungsanlage (20, 25) angeordnet ist.

6. Verfahren nach einem der vorhergehenden Ansprüche, wobei:

- die primären (30), sekundären (31) und tertiären Optimierungs- und Regelkreise mit unterschiedlichen Zeitskalen und Hierarchien arbeiten;

- wobei der tertiäre Optimierungs- und Regelkreis der Master des sekundären Optimierungs- und Regelkreises (31) ist und mit der höchsten Zeitskala oder einer niedrigeren Abtastrate arbeitet; und

- der sekundäre Optimierungs- und Regelkreis (31) durch den tertiären Optimierungs- und Regelkreis gesteuert wird und mit der niedrigeren Zeitskala oder höheren Abtastrate als der tertiäre Optimierungs- und Regelkreis arbeitet, jedoch mit einer höheren Zeitskala und niedrigeren Abtastrate als der primäre Optimierungs- und Regelkreis (30), der durch den sekundären Optimierungs- und Regelkreis (31) gesteuert wird.

7. Verfahren nach Anspruch 5 oder 6, wobei die Sensorbaugruppe (26-29) ferner eine stromabwärts befindliche Sensorbaugruppe (28, 29) umfasst, umfassend primäre und sekundäre Flusseigenschaftssensoren für behandelten Schlamm (28, 29), zur Messung von Dichte und Viskosität, pH-Wert und/oder andere Eigenschaften des behandelten Schlamms (6) in dem Schlammrückführungssystem an der Bohranlage (33) stromabwärts der Schlammbehandlungsanlage (20, 25), wobei der primäre Flusseigenschaftssensor für behandelten Schlamm (28) im Schlammrückführungssystem zwischen der Schlammbehandlungsanlage (20, 25) und dem sekundären Flusseigenschaftssensor für behandelten Schlamm (29) angeordnet ist; und wobei:

- der primäre Optimierungs- und Regelkreis (30) mit einer Sensorbaugruppe verbunden ist, die die tatsächliche Einspritzrate jedes Additivs in der automatischen Schlammbehandlungsanlage (20, 25) misst;

- der sekundäre Optimierungs- und Regelkreis (31) mit der Sensorbaugruppe (26-29) verbunden ist, die die primären Eigenschaften des unbehandelten und behandelten Schlamms misst;

- der tertiäre Optimierungs- und Regelkreis mit der primären Sensorbaugruppe für unbehandelten Schlamm (26, 27) und optional mit der sekundären Sensorbaugruppe für unbehandelten Schlamm (28, 29) verbunden ist.

8. Verfahren nach einem der Ansprüche 5 bis 7, wobei der primäre Flusseigenschaftssensor für behandelten Schlamm (28) einen Teil des sekundären Optimierungs- und Regelkreises (31) darstellt und wobei der sekundäre Flusseigenschaftssensor für behandelten Schlamm (29) einen Teil des tertiären Optimierungs- und Regelkreises darstellt.

9. Verfahren nach Anspruch 8, wobei die Bereiche der Schlammeigenschaftswerte, wie durch das Optimierungsmodul bestimmt, als die gewünschten Bereiche, die durch einen multivariablen Regelalgorithmus in dem sekundären Regelkreis (31) eingehalten werden sollen, einbezogen werden.

10. Verfahren nach Anspruch 9, wobei der multivariable Regelalgorithmus ein modellprädiktiver (MPC) Regelalgorithmus ist, der das multivariable Regelproblem als ein optimales Regelproblem mit einer objektiven Funktion der Minimierung der Abweichung der primären Eigenschaften des behandelten Schlamms von den gewünschten Bereichen unter Berücksichtigung der minimalen und maximalen Menge an Additiven (21-24), die bei jedem Zyklus hinzuzufügen sind, und der Modelle zwischen den zu regelnden Schlammeigenschaften und den Additiven (21-24) sowie der Bohr- und Schlammflusszirkulationsraten darstellt.

11. Verfahren nach Anspruch 10, wobei der multivariable Regelalgorithmus mit Modellen versehen ist, die mathematische Beziehungen zwischen den Additiven (21-24), Schlammeigenschaften und gemessenen Variationen der Bohrraten identifizieren, die sich auf Schwankungen der Bohrkleinkonzentration auswirken.

12. System zur automatischen Anpassung der Bohrschlammeigenschaften in einem Schlammrückführungssystem einer Bohranlage (33) zum Bohren eines unterirdischen Bohrlochs (5), wobei das System eine Schlammrückführungsleitung (13) und eine automatisierte Schlammbehandlungsanlage (20, 25) umfasst, die Additiv-Einspritzsteuervorrichtungen umfasst, die durch hierarchische primäre und sekundäre Optimierungs- und Regelkreise gesteuert werden, um die Einspritzraten von Schlammadditiven (21-24) in die Schlammrückführungsleitung (13) einzustellen, die so angeordnet sind, dass die Schlammeigenschaften kontinuierlich beibehalten werden, die Dichte, Viskosität, pH-Wert und gegebenenfalls andere Schlammeigenschaften umfassen, innerhalb von Spezifikationen einen modellbasierten tertiären Optimierungs- und Regelkreis umfassen, dadurch gekennzeichnet, dass der tertiäre Optimierungs- und Regelkreis ein Optimierungsmodul umfasst, das die Bereiche oder die Sollwerte der primär behandelten Schlammeigenschaften bei gegebenen Zielfunktionen des tertiären Optimierungs- und Regelkreises bestimmt, wie z. B. Sicherstellen eines ausreichenden Bohrkleintransports, der mechanischen Stabilität des Bohrlochs und der Abschätzung der folgenden Punkte:

a) Drehmoment und Widerstand des Bohrstrangs;

b) Stabilität und Durchlässigkeit des Bohrlochs;

c) Größe, Volumen, Gewicht, Dichte und Zusammensetzung des Bohrkleins (10); und

d) Bohrlochschlammgeschwindigkeit, pH-Wert, Viskosität, Dichte und Zusammensetzung.

13. System nach Anspruch 12, wobei die Additiv-Einspritzsteuervorrichtungen Additiv-Einspritzsteuerventile sind und wobei der primäre Optimierungs- und Regelkreis das Öffnen und Schließen der Additiv-Einspritzsteuerventile regelt, um die Einspritzraten jedes Additivs zu erfüllen, die durch den sekundären Optimierungs- und Regelkreis (31) eingestellt werden, der mit dem tertiären Optimierungs- und Regelkreis verbunden ist, der die geeigneten Bereiche oder Sollwerte für die Schlammeigenschaften bestimmt, um mehrere Betriebsziele zu erreichen, wie z. B. Maximieren der Bohrklein-Transportfähigkeiten des Bohrschlamms (6) und Aufrechterhalten der mechanischen Stabilität des Bohrlochs.

14. System nach Anspruch 12 oder 13, wobei das System eine Sensorbaugruppe (26-29) umfasst, die die Schlammeigenschaften des Schlamms (6) in dem Schlammrückführungssystem an der Anlage (33) stromaufwärts und/oder stromabwärts der automatischen Schlammbehandlungsanlage (20, 25) misst.

15. System nach einem der Ansprüche 12-14, wobei die Schlammbehandlungsanlage (20, 25) einen Additivtank (21-24) und einen Schlammmischtank (34) umfasst, deren Größe durch zwei Aspekte bestimmt wird:

- die Mindestverweilzeit, die aufgrund der Eigenschaften des Bohrschlamms (6) erforderlich ist, um eine homogene Mischung bei der Zugabe von Additiven (21-24) zu gewährleisten; und

- das Gleichgewicht zwischen der Ansprechzeit, die der sekundäre multivariable Regelkreis (31) benötigt, um die Eigenschaften des primären unbehandelten Schlamms (6) auf die gewünschten Werte oder Bereiche zu bringen, wobei sichergestellt wird, dass die Zugabe der Additive (21-24) als Ergebnis der Aktionen des Reglers nicht zu größeren Schwankungen des stationären Zustands oder vorübergehenden Werten der Eigenschaften des primären behandelten und des sekundären unbehandelten Schlamms führt.

Revendications

1. Procédé d'ajustement automatisé des propriétés de boue de forage dans un système de recirculation de boue d'une installation de forage (33) permettant de forer un trou de forage souterrain (5), le procédé consistant à :

- faire circuler la boue de forage à travers le trou de forage et la faire revenir à l'installation de forage à la surface de la terre, la boue de forage s'écoulant ainsi à travers un ensemble automatisé de traitement de boue (20, 25) ;

- injecter des additifs de boue dans la boue à l'aide de l'ensemble automatisé de traitement de boue (20, 25), pour finalement ajuster les propriétés de boue ;

- induire des boucles primaires et secondaires hiérarchiques d'optimisation et de commande (30, 31) pour ajuster les taux d'injection d'additifs de boue (21-24) dans la boue de forage en circulation, afin de maintenir en continu les propriétés de boue, y compris la masse volumique, la viscosité, le pH et éventuellement d'autres propriétés de boue, dans les spécifications définies par une boucle tertiaire d'optimisation et de commande à base de modèle, caractérisée en ce que la boucle tertiaire d'optimisation et de commande comprend un module d'optimisation qui détermine les plages ou les points de consigne des propriétés de boue traitée primaire compte tenu des fonctions objectives de la boucle tertiaire d'optimisation et de commande, afin de garantir un transport de sédiments de forage, une stabilité mécanique de puits de forage et des estimations :

a) de couple et de traînée du train de forage (3) ;

b) de stabilité et de perméabilité du trou de forage ;

c) de taille, de volume, de poids, de masse volumique et de composition des sédiments de forage (10) ; et

d) de vitesse, de pH, de viscosité, de masse volumique et de composition de la boue de fond.

2. Procédé selon la revendication 1, dans lequel la boucle primaire d'optimisation et de commande (30) contrôle l'ouverture et la fermeture des soupapes de commande d'injection d'additifs de l'ensemble automatisé de traitement de boue (20, 25) afin de répondre aux débits d'injection de chaque additif (21-24) définis par la boucle secondaire d'optimisation et de commande (31) qui est reliée à la boucle tertiaire d'optimisation et de commande qui détermine les plages ou points de consigne appropriés pour les propriétés de boue afin d'atteindre de multiples objectifs opérationnels, tels que la maximisation des capacités de transport des sédiments de forage de la boue de forage (6) et le fait de maintenir la stabilité mécanique de puits de forage.

3. Procédé selon la revendication 1 ou 2, dans lequel les propriétés de boue sont mesurées par un ensemble capteur (26-29) qui mesure les propriétés de boue de la boue dans le système de recirculation de boue au niveau de l'installation de forage (33) en amont de l'ensemble automatisé de traitement de boue (20, 25).

4. Procédé selon la revendication 1 ou 2, dans lequel les propriétés de boue sont mesurées par un ensemble capteur (26-29) qui mesure les propriétés de boue de la boue (6) dans le système de recirculation de boue au niveau de l'installation de forage (33) en aval de l'ensemble automatisé de traitement de boue (20, 25).

5. Procédé selon la revendication 3, dans lequel l'ensemble capteur (26-29) comprend un ensemble capteur amont (26, 27) comprenant des capteurs de propriétés de flux de boues non traitées primaires et secondaires (26, 27) permettant de surveiller les propriétés de boue non traitée (6) s'écoulant d'un système d'élimination de sédiments de forage vers l'ensemble automatisé de traitement de boue (20, 25), le capteur de propriétés de flux de boue non traitée primaire (26) étant disposé dans le système de recirculation de boue entre le capteur de propriété de flux de boue non traitée secondaire (27) et l'ensemble de traitement de boue (20, 25).

6. Procédé selon l'une quelconque des revendications précédentes, dans lequel :

- les boucles primaires (30), secondaires (31) et tertiaires d'optimisation et de commande fonctionnent à différentes échelles de temps et à différentes hiérarchies ;

- la boucle tertiaire d'optimisation et de commande est maîtresse de la boucle secondaire d'optimisation et de commande (31) et fonctionne à l'échelle de temps la plus élevée ou à un taux d'échantillonnage inférieur ; et

- la boucle secondaire d'optimisation et de commande (31) est contrôlée par la boucle tertiaire d'optimisation et de commande et fonctionne à l'échelle de temps inférieure ou à un taux d'échantillonnage supérieur à la boucle tertiaire d'optimisation et de commande mais à une échelle de temps plus élevée et à une fréquence d'échantillonnage inférieure à celles de la boucle primaire d'optimisation et de commande (30) qui est contrôlée par la boucle secondaire d'optimisation et de commande (31).

7. Procédé selon la revendication 5 ou 6, dans lequel l'ensemble capteur (26-29) comprend en outre un ensemble capteur aval (28, 29) comprenant des capteurs de propriétés de boues traitées primaires et
secondaires (28, 29) permettant de mesurer la masse volumique, la viscosité, le pH et/ou d'autres propriétés de boue traitée (6) dans le système de recirculation de boue au niveau de l'installation de forage (33) en aval de l'ensemble de traitement de boue (20, 25), le capteur de propriétés de flux de boue traitée primaire (28) étant disposé dans le système de recirculation de boue entre l'ensemble de traitement de boue (20, 25) et le capteur de propriété de boue traitée secondaire (29) ; et dans lequel :

- la boucle primaire d'optimisation et de commande (30) est reliée à un ensemble capteur qui mesure le débit d'injection réel de chaque additif dans l'ensemble automatisé de traitement de boue (20, 25) ;

- la boucle secondaire d'optimisation et de commande (31) est reliée à l'ensemble capteur (26-29) qui mesure les propriétés de boues primaires non traitées et traitées ;

- la boucle tertiaire d'optimisation et de commande est reliée à l'ensemble capteur de boue non traitée primaire (26, 27) et éventuellement à l'ensemble capteur de boue non traitée secondaire (28, 29).

8. Procédé selon l'une quelconque des revendications 5 à 7, dans lequel le capteur de propriétés de flux de boue traitée primaire (28) fait partie de la boucle secondaire d'optimisation et de commande (31) et où le capteur de propriétés de flux de boue traitée secondaire (29) fait partie de la boucle tertiaire d'optimisation et de commande.

9. Procédé selon la revendication 8, dans lequel les plages des valeurs de propriétés de boue telles que déterminées par le module d'optimisation sont incluses en tant que plages souhaitées à honorer par un algorithme de commande multivariable dans la boucle secondaire de commande (31).

10. Procédé selon la revendication 9, dans lequel l'algorithme de commande multivariable est un algorithme de dispositif de commande prédictif modèle (MPC) qui projette le problème de commmande multivariable comme un problème de commande optimale présentant une fonction objective de minimisation de l'écart des propriétés de boue traitée primaire par rapport aux plages souhaitées compte tenu de la quantité minimale et maximale d'additifs (21-24) à ajouter à chaque cycle et des modèles entre les propriétés de boue à commander et des additifs (21-24) ainsi que des taux de forage et de circulation de flux de boue.

11. Procédé selon la revendication 10, dans lequel l'algorithme de commande multivariable est doté de modèles identifiant les relations mathématiques entre les additifs (21-24), les propriétés de boue et les variations mesurées des taux de forage qui affectent les variations de la concentration de sédiments de forage.

12. Système d'ajustement automatisé des propriétés de boue de forage dans un système de recirculation de boue d'une installation de forage (33) permettant de forer un trou de forage souterrain (5), le système comprenant un conduit de recirculation de boue (13) et un ensemble automatisé de traitement de boue (20, 25) comprenant des dispositifs de commande d'injection d'additifs qui sont commandés par des boucles primaires et secondaires hiérarchiques d'optimisation et de commande pour ajuster les taux d'injection d'additifs de boue (21-24) dans le conduit de circulation de boue (13), agencé pour maintenir en continu les propriétés de boue, en particulier la masse volumique, la viscosité, le pH et éventuellement d'autres propriétés de boue, dans les spécifications définies par une boucle tertiaire d'optimisation et de commande à base de modèle, caractérisé en ce que la boucle tertiaire d'optimisation et de commande comprend un module d'optimisation qui détermine les plages ou les points de consigne des propriétés de boue traitée primaire compte tenu des fonctions objectives de la boucle tertiaire d'optimisation et de commande, afin de garantir un transport de sédiments de forage, une stabilité mécanique de puits de forage et des estimations :

a) de couple et de traînée du train de tiges ;

b) de stabilité et de perméabilité du trou de forage ;

c) de taille, de volume, de poids, de masse volumique et de composition des sédiments de forage (10) ; et

d) de vitesse, de pH, de viscosité, de masse volumique et de composition de la boue de fond.

13. Système selon la revendication 12, dans lequel les dispositifs de commande d'injection d'additifs sont des soupapes de commande d'injection d'additifs et dans lequel la boucle primaire d'optimisation et de commande contrôle l'ouverture et la fermeture des soupapes de commande d'injection d'additifs afin de répondre aux débits d'injection de chaque additif définis par la boucle secondaire d'optimisation et de commande (31) qui est reliée à la boucle tertiaire d'optimisation et de commande qui détermine les plages ou points de consigne appropriés pour les propriétés de boue afin d'atteindre de multiples objectifs opérationnels, tels que la maximisation des capacités de transport des sédiments de forage de la boue de forage (6) et le fait de maintenir la stabilité mécanique du puits de forage.

14. Système selon la revendication 12 ou 13, dans lequel le système comprend un ensemble capteur (26-29) qui mesure les propriétés de boue de la boue (6) dans le système de recirculation de boue au niveau de l'installation de forage (33) en amont et/ou en aval de l'ensemble automatisé de traitement de boue (20, 25).

15. Système selon l'une quelconque des revendications 12-14, dans lequel l'ensemble de traitement de boue (20, 25) comprend un additif (21-24) et un réservoir de mélange de boue (34), dont la taille est déterminée par deux aspects :

- le temps de séjour minimum requis par les caractéristiques de la boue de forage (6) pour assurer un mélange homogène lors de l'adjonction d'additifs (21-24) ; et

- l'équilibre entre le temps de réponse requis par la boucle secondaire de commande multivariable (31) pour amener les propriétés de boue non traitée primaire (6) aux valeurs ou gammes souhaitées tout en garantissant l'adjonction des additifs (21-24), car le résultat des actions du dispositif de commande n'entraîne pas de fluctuations majeures de l'état constant ou des valeurs transitoires des propriétés de boue traitée primaire et de boue non traitée secondaire.

Drawing