Improved Autodriller Performance with Direct Drillstring Measurements in the Drawworks Control Loop
- I. M. Soukup (National Oilwell Varco M/D Totco) | M. S. Boudreaux (National Oilwell Varco M/D Totco) | R. Ramirez (National Oilwell Varco M/D Totco) | J. R. Anderson (NOV ReedHycalog) | J. Shim (University of Tulsa)
- Document ID
- Society of Petroleum Engineers
- SPE Annual Technical Conference and Exhibition, 9-11 October, San Antonio, Texas, USA
- Publication Date
- Document Type
- Conference Paper
- 2017. Society of Petroleum Engineers
- 1.12 Drilling Measurement, Data Acquisition and Automation, 1.6.1 Drill String Components and Drilling Tools (tubulars, jars, subs, stabilisers, reamers, etc), 1.12.4 Sensor Technology, 1.10 Drilling Equipment, 1.6 Drilling Operations
- Autodriller Performance Testing, Drillingstring Response, Direct Drillstring Measurements, Drawworks Control Loop, Control Stability
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Precise autodriller control is critical for minimizing drilling dysfunction, maximizing tool life, and optimizing drilling performance. Measurements made as part of the control loop have traditionally been located remotely from the drillstring, and therefore, suffer from physical system states that are not directly related to the forces on the bit. As an example, weight measurements from deadline anchors are influenced by forces and physical properties of the hoisting system, which include friction effects, mud hose forces, and mechanical stiffness. Direct drillstring measurements provide more representative and repeatable measurements of forces near the bit, achieved by decoupling the physical states which are external to the drillstring system. Moreover, recent developments in sensor technology have provided wireless communication to the drillstring, which enables continuous direct drillstring measurements while drilling.
Data from an integrated direct drillstring measurement system was recently implemented into the drawworks control system of a jackup rig drilling in the Gulf of Thailand. Two test methodologies were used to accurately evaluate performance between the direct drillstring and the deadline anchor (feedback loop sensors) for weight-on-bit (WOB) control: (1) the first method required alternating the sensor sources every 400-500 ft and (2) the second method involved changing the sensors after each completed well.
Performance was studied by acquiring data while drilling under WOB control and comparing statistical measures between each sensor set. Time-domain analysis for control error was calculated to examine stability, responsiveness, and general error trends. Broad spectrum control performance was analyzed through statistical metrics and evaluated across wells as a function of depth. This paper documents these various analyses, the comprehensive results of which indicate significant opportunities for improved autodriller control, and thus, drilling performance by using measurements directly coupled to the drillstring within the control loops.
To date, the limited number of wireless intelligent sensor systems has precluded widespread adoption of integrating direct drillstring measurements into the control loop. However, recent improvements in sensor systems and the associated technology discussed in this paper, and applied successfully in the field, demonstrate the need for advancements in the control system architecture of drilling rigs. System stability and sensitivity improvements enable greater weight control to the drillstring and better translate the forces at the bit for more representative, repeatable real-time drillstring measurements. Field tests have shown significantly improved autodriller control, reduced drilling dysfunction, and increased rate of penetration (ROP), particularly at deeper hole depths, verifying the technology's application in extended reach wells.
|File Size||3 MB||Number of Pages||21|