DRILLING CONTROL METHOD AND SYSTEM

• US 20120059521A1
• Filed: 03/01/2010
• Published: 03/08/2012
• Est. Priority Date: 03/02/2009
• Status: Active Grant

• Current Assignee: Sekal AS (Sumitomo Corporation)
• Original Assignee: Drilltronics Rig Systems AS (Sumitomo Corporation)
• Inventors: Cayeux, Eric, Iversen, Fionn
• Granted Patent: US 9,175,557 B2
• Time in Patent Office: Days
• US Class Current: 700/275
• CPC Class Codes: E21B 44/00 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

Abstract

Method and system for drilling control comprising a plurality of controllers adapted to control performance process parameters, on the basis of driller controls from a driller that provides this as instructions to said controllers, wherein the system further comprises sensors and means for obtaining process values, such as downhole pressure, temperature and torque, where- in the system is adapted to, continuously and/or repeatedly, calculate safeguard envelopes for performance process parameters on the basis of process values and drilling process models and that it is adapted to restrain said controllers from applying performance process parameters outside said safeguard envelopes as a result of driller instructions, and—a method and system for automatically triggering a remedying action in case of an evolving or existing critical situation, comprising calculation of process parameter boundaries which represent a critical condition for the well by using calibrated drilling process models, comprising (i) triggering an emergency action if a parameter exceeds said boundaries, said emergency action being intended to minimize the effect of said critical situation, (ii) then further analyzing the well in order to determine which remedying action to then be applied, the remedying action being intended to remedy the cause of said effect; (iii) if said remedying action is not capable of remedying the cause of said effect, then applying predetermined safe process parameters or shutting down.

Claims

1. A method of imposing safeguard during drilling of a well by the use of a drill rig having at least a speed controlled pipe string hoist, wherein performance process control parameters are controlled through machine controllers, wherein a driller drills a well by controlling said process control parameters through said machine controllers with driller instructions, and wherein process values are provided, to a safeguard calculation unit, where the safeguard calculation unit calculates safeguard limits for the process control parameters, derived from process limits, such that at least some of said safeguard limits constitute boundary values of performance process parameter-related safeguard envelopes, the method comprising the steps of:

restricting controller output to remain within said safeguard envelopes, as said controllers are adapted to keep said controller output within said safeguard envelopes, thereby preventing driller instructions that result in performance process parameters beyond said safeguard envelopes;

wherein said safeguard calculation unit comprises continuously calibrated drilling process models, which enable calculation of safeguards limits for said performance process control parameters, the calculation being based on at least one of wellbore pressure limits, wellbore stability limits, and mechanical tubing limits, as constraints, as well as current process values, and

iteratively calculating said safeguard calculations until the safeguard limits converge.

2. The method according to claim 1, wherein values and/or parameters are provided by application of one or more of the following systems:

i) a drilling machineries data acquisition system, which is an integrated part of a machine control system and which is adapted to provide control system values

ii) a mud logging system; and

iii) a downhole measurement data acquisition system, comprising downhole sensor tools for providing downhole measurements, such as downhole pressure, downhole temperature and survey measurements.

3. The method according to claims 1, further comprising the step of:

calibrating drilling process models, wherein for the calibration of hydraulics models, fluid flow friction factor calibration is performed by using unscented Kalman filtering or steady state model with zero point solver, wherein measured standpipe pressure and downhole pressure are applied for calibration.

4. The method according to claim 1, further comprising the step of:

calibrating drilling process models, wherein for the calibration of torque and drag model, tubular (drill string/casing/liner) sliding/rotating friction is estimated by using back calculation with a zero point solver, applying measured hook load and torque for model tuning.

5. The method according to claim 1, further comprising the step of:

continuously applying tubular velocity safeguards during running and pulling of a tubular, wherein

i) iterative calculation of tubular velocity limits is performed by forward calculations using calibrated hydraulics model from current process values, bounds given by pressure limits (PP or FP) in open hole section, and zero point solver; and

wherein

ii) tubular velocity limits are enforced through machine controllers.

6. The method according to claim 1, further comprising the step of:

performing continuous application of tubular mechanical safeguards during reaming and reciprocation, such as maximum overpull/setdown weight and rotating torque, wherein

i) bounds are given by elastic limits constraints and direct calculation of limits is performed using current configuration of wellbore trajectory and tubular length; and

wherein

ii) tubing mechanical limits are enforced through machine controllers.

7. The method according to claims 1, further comprising the steps of:

i) continuously or repeatedly predicting future process values on the basis of at least drilling process models and past or current process values;

ii) in that future, comparing predicted process values with current process values, as measured or otherwise provided; and

then iii) if current process values deviate outside predetermined allowed deviation values, input remedying instructions to said controllers in order to provide remedying performance process parameter from said controllers.

12. The method of claim 1, wherein the well produces one or both of gas and oil.

13. The method of claim 1, wherein the process values are measured, and are one of continuously or repeatedly input into the safeguard calculation unit.

8. (canceled)

9. A method for automatically triggering a remedying action in case of an evolving or existing critical situation, including calculation of process parameter boundaries which represent a critical condition for the well by using calibrated drilling process models, in the method comprising the steps of:

(i) triggering an emergency action if a parameter exceeds said boundaries, said emergency action being intended to minimize the effect of said critical situation,

(ii) then further analyzing the well in order to determine which remedying action to then be applied, the remedying action being intended to remedy the cause of said effect;

(iii) if said remedying action is not capable of remedying the cause of said effect, then applying predetermined safe process parameters or shutting down.

10. The method according to claim 9 for application of automatic remediating action on detection of packoff/bridging, wherein:

(a) limits for detecting indication of packoff or bridging are detected by one or more of rapid buildup of pump pressure; and

steady increase/erratic torque behavior, wherein detection is achieved by comparing predicted values, by using models, to actual behavior; and

(b) limits for triggering automated action with respect to pump pressure and torque behavior are calculated as a function of fluid flowrate, pipe torque and rpm; and

(c) immediate automatic action comprises a predefined %-wise reduction of flowrate; and

(d) if packoff is diagnosed due to continuously increasing pump pressure/torque or sustained erratic torque, automatic shutdown of pumps is performed; and

(e) if bridging is diagnosed by resulting stabilized torque variations/pump pressure, then flowrate is automatically increased to maximum allowable flowrate as a function of bridge, as defined by remediating algorithms with calculated input parameters.

11. A system for calculation of the acceptable threshold conditions before determining that the well has entered a critical situation, adapted to apply the calibrated drilling process models in said calculation, wherein, in case a parameter is exceeding the continuously updated conditions for a critical situation, an automatic action is triggered automatically to minimize the effect of the critical situation, wherein this automatic action can adapt itself as a function of the response of the well to the automatic action, the system comprising:

one or more machine controllers;

wherein machine controller algorithms for automatic triggering of remediating action are implemented directly in the machine controllers, and machine controller algorithms for dynamic remediating action are implemented directly in the machine controllers; and

wherein calculated setpoints/curves/surfaces defining triggering and dynamic remediating action are communicated to the machine controllers from the calculations through a central database; and

wherein the machine controllers are adapted to continuously compare measured process values with triggering limits, and wherein, if triggering limits are exceeded then remediating action is automatically triggered;

v) after triggering, remediating control is performed dynamically as a function of response, as defined by the setpoints/curves/surfaces defining appropriate dynamic remediating action.