A new downhole machining system has been developed for lightweight intervention applications to remove wellbore obstructions and stuck valves, combining the precision of real-time bit position measurement with the power of push-pull forces up to 40,000 lbf. This tool builds on existing hardware from proven milling and shifting services, with added software features for advanced automation and control. This paper describes the new machining system and benefits for the operator to enable a reliable and robust contingency machining service. Conventional wireline milling tools use a tractor tool for weight-on-bit and torque reaction. These tractor-based milling systems can be efficient for removing obstructions over a long interval, but they are not ideal for milling hard metal targets. For example, a nipple milling operation might require many hours to mill, during which time the operator has no indication that the milling operation is progressing as planned since the tractor does not provide any measurement of milling progress. The new machining system provides the operator with a real-time measurement of milling progress with resolution down to 1/100-in. to quickly diagnose and correct any problems due to bit damage, engagement with the target, or cuttings accumulation. For known targets of multiple materials or interrupted geometry, or for bits with staged cutting features, the direct measurement of bit position enables automatic machining programs that can autonomously execute a predefined sequence of cutting parameters (weight, speed, and torque) that change with measured bit position. The machining progress and quality indicators are displayed in real time at surface using a graphic interface showing the machining target and current bit position. The machining tool uses the same anchor and linear actuator modules from wireline shifting service tools, combined with the same rotary motor and gearing modules from wireline milling service tools. Torque from the bit is transferred across the linear actuator module using a sleeve that is keyed above and below the piston. Both the linear actuator hydraulic motor and the rotary motor are equipped with rotor position and torque feedback and powered by a downhole inverter for maximum power efficiency, precise control of hydraulic pressure and bit position, and reverse operation for stall prevention and recovery. Test data are shared in this paper to compare the performance of the new machining tool with a high-performing tractor-based milling service tool. Examples are given for both isolation valve machining and nipple machining.

An automated wireline milling solution targeted for removal of wellbore obstructions of a varying type, from scale to metal, with built-in capabilities of autonomous cruise navigation between consecutive obstacles, is presented. This paper highlights design features that made a step change in the efficiency and usability of milling services. Control challenges are still common in downhole milling technology. Changes in milling target composition, cuttings accumulation around the target, drag forces from production flow, and other variations can reduce system efficiency and result in lost time or failed interventions. In the case of wireline milling technology, inclusion of intelligent on-board electronics in the downhole equipment presents an opportunity to actively control the milling process to optimize rate of penetration and implement additional protections to reduce operational risk. We describe a robotic toolstring that automatically and independently controls a wireline tractor using real-time feedback from a milling cartridge and other on-board sensors. Embedded control algorithms implement intuitive workflows derived from the combined experience of multiple experts in well intervention. With this automated wireline milling system, the user can initiate the milling process by defining certain milling parameters and then can monitor progress in real time while the downhole robotic tool regulates weight on bit and the milling motor. This new automated downhole control system significantly improves torque-on-bit and weight-on-bit controls yielding superior performance, such as rate of penetration and usability. Dynamic load conditions are handled in a high-speed distributed control loop downhole to get most of bit torque capacity across the entire speed range defined by the motor power curve. Tractor push force is adjusted quasi-instantaneously with changes in cutting conditions. Control responsiveness along with software solutions for tracking of motor stall preconditions and a torque limiter greatly reduce the occurrence of motor stalls arising due to the bit wedging in highly reactive targets. With stall avoidance and an automatic backing-off feature to reengage the bit in case of a sporadic torque spike, direct involvement of an operator is significantly minimized compared to the previous tool generation. Head-voltage stabilization is another factor positively impacting the overall power stability and performance of electromechanical tools downhole. Safety features are also in place to prevent cable twisting and protect assets from overcurrent and overtemperature conditions. The progressive design of the automated milling tool boosts operational efficiency and autonomy, minimizes human mistakes, and reduces risk of getting stuck during the service. Case histories demonstrate the first field jobs and system integration tests performed with this new tool.

A new type of wireline-powered debris removal system that efficiently captures and retains a wide variety of wellbore debris types is presented. The system's unique benefits and performance are demonstrated through modeling and testing in controlled conditions. Wireline-powered debris removal technology uses localized fluid circulation generated downhole to vacuum debris into bailers for capture. Challenges with conventional systems are related to the ability to continuously mobilize and separate a variety of debris including fine particulates and cohesive debris-binder mixtures. The new wireline debris removal system improves on previous technology by addressing the specific challenges of each of the debris types. This performance improvement is enabled by using a progressing cavity pump (PCP) to create powerful bidirectional suction pressure and a staged bailer configuration with parallel flow filters for maximum fill efficiency. Pump performance is compared analytically for a centrifugal pump and a PCP to demonstrate the benefits of the PCP for debris collection applications. These benefits include reverse pumping ability for unsticking the toolstring when operating in debris-filled wellbores. This pump analysis defines a suction pressure budget, which is used to analyze the performance and capabilities of the staged bailer system. The pressure losses and debris accumulation profile of the new top-fed parallel flow filter bailers is determined by using fluid dynamics models. Results of an extensive testing campaign are presented to validate model results. Actual collection performance is presented for a wide variety of debris types using the new debris removal system. The new wireline debris removal system's use of a PCP to generate the necessary vacuum and provide bidirectional capabilities for operational flexibility in combination with maximum debris recovery provided by staged bailers with parallel flow filters will bring new efficiencies and reliability to intervention operations.

An advanced jarring method was developed for deviated wells where conventional jarring is not possible. Comparing the results of jarring impact with this new method to jarring impact with conventional methods showed similar effectiveness. Rather than relying on gravity or energy stored in the cable (slickline or e-line), a high-performance, fully adjustable spring jar uses an accelerator to provide consistent energy storage and delivery during the jarring operation. However, this cannot be used in highly deviated wells because there may not be enough cable pull to energize the accelerator and perform an effective jarring event. To enable this, a wireline linear actuator can be used to pull and energize the accelerator and fire the jar effectively. In addition, having a jar and a linear actuator combined on the same run can allow for a more efficient fishing strategy by combining jarring and a straight pull or push. To prove the feasibility of this method, a system integration test was performed in which the linear actuator was used to fire the high-performance jar through an accelerator. In this test, the jarring force and the acceleration of the fish (the element being jarred) was measured and compared to standard jarring without the linear actuator. The measurements showed that it does not make a difference whether the jar is fired by the cable or by the linear actuator; the same force and acceleration (i.e., shock level) was imparted. This means that the linear actuator can be used to fire the jar without losing effectiveness. To achieve maximum efficiency, jarring and straight-pulling can be combined in the same run during which the two can be alternated to maximize results. This method is novel because it enables jarring in highly deviated wells and allows for jarring and straight-pulling on the same run, creating a more comprehensive fishing strategy.