Adaptive Tension Limits for Winch Control System Reduce Disengagements in Automated Wireline and Slickline Operations in Complex Reservoirs
Authors: Meirkhan J. , Zhang Z. , Wang J. , Saboo S. , Baklanov N. 
Published: March 2024

Adaptive tension limits for the winch control system in automated wireline and slickline operations with backspool and slack controls are presented. The design addresses safety and access challenges for gravity conveyance that are exacerbated in complex reservoirs (deviated or tortuous). The solution significantly improves the reaction to tension events and can prevent cable and tool holdups by adjusting tension limits and tolerances dynamically. To navigate and minimize winch shutdowns, the controller utilizes the expected tool weight based on current wellbore conditions.

An in-house multiphysics wireline conveyance model that computes the cable tension profile given winch speed, well geometry, cable length, and other properties provides real-time dynamic tension prediction. To compensate for the uncertainty in input downhole parameters, a helper assimilation model continuously optimizes downhole parameters assessing an error between the predicted and measured tensions. Business logic further derives three levels for surface tension limits, with estimated head tension replacing the static and imprecise user input to provide the lower surface tension tolerance. Moreover, those tension limits change adaptively following variations in the well environment as the job proceeds based on expected surface and head tensions.

Unlike existing implementations, the presented winch controller uses three limits to execute winch slowdown, assertive winch deceleration, and winch stop. To prevent the cable slack further, the proposed controller stops the winch by detecting excessive time spent within the medium band. We analyzed incidents from the past where the automated system created wire pile-up at the drum side, and winchman abiding vigilance was required to spot and intervene in the problem within a few seconds to avoid further harm. In deviated wells, where the friction between the cable and the tubing is higher, a fast-moving winch will see a tension drop at some point; the lower tension shutdown limit may not be triggered because of being too low for the conditions. The new design, tested successfully at the facility in Texas, showcased improved conveyance, fewer alarms, smoother tension response, and adequate head tension estimation. This led to greater speed and efficiency. Field studies from highly deviated wells confirm that the expected head tension reliably detects low-tension anomalies during running-in-hole. Tests confirm the winch decelerates and stops if tension remains below the medium limit.

The probability of disengagements due to low-tension events increases as wells get deeper, fluid gets heavier, and trajectories become more deviated. The presented method significantly increases operation efficiency by minimizing the number of disengagements and reduces the risks of backspool and cable slack in deviated or complex reservoirs. The extended winch control autonomy has been demonstrated, leading to a fully autonomous system by which runs can be completed without disengagements.