The line-by-line budget cuts have been exhausted industrywide. Pressured to reduce costs everywhere possible, operators seek the rare technologies and techniques that improve both efficiency and effectiveness without the corresponding creep in opex.

Capturing bypassed reserves
An operator working in the San Juan Basin in New Mexico sought one of those technological gems for a 5 ½-in. casing exit in a gas-producing development well. In hopes of accessing bypassed reserves and reviving production in this mature asset, the operator planned a 4.75-in. 10-degree sidetrack from the 5 ½-in. 17-lb/ft (25.2-kg/m) parent casing into the mixed sand and shale reservoir. This new dual-lateral drilling project—including the described sidetrack plus a second lateral out of the shoe—would produce from the same formation.

Working with a previous service provider, the client had executed three similar jobs with an average casing-exit and milling time of 14 hours per job. For this well the operator set a goal of a single-trip job with a total operational time of 12 hours or less. It requested use of a retrievable hydraulic-set system to avoid the additional time and costs associated with mechanically setting the whipstock anchor with a bridge plug.

Choosing the right solution

After an extensive review of the job specifications, Weatherford recommended the newly released Quick-Cut Pro service, which consists of the field-proven QuickCut casing-exit system, the AccuView collaboration system, a highly trained onsite specialist and a remote team of experts.

This real-time technology integrates well planning with real-time data and lessons learned from thousands of casing exits. This database is used to optimize key performance indicators such as ROP, pressure and flow rate in the planning phase, which are then displayed on the rig floor in an easy-to-interpret graphic user interface on a portable computer display. The simple-to-use plug-and-play technology requires no technician for installation and is ready to operate in 15 minutes or less on virtually any rig.

During operations the system securely delivers useful job-specific real-time information to the onsite and remote casing-exit experts. These data not only help to ensure that the casing exit is milled according to plan foot-by-foot but also that the operation is completed quickly, safely and economically.

The QuickCut Pro service, powered by AccuView software, contributed significantly to the efficiency of the casing-exit operation by enabling real-time data display and enhancing communication between onsite rig personnel and the offsite Weatherford team of experts. (Images courtesy of Weatherford International)

Remote collaboration

The Weatherford specialist on site began by inputting the pre-job plan into the AccuView system, which created an asset manager-controlled template that includes preloaded documents such as a job-hazard analysis, lifting plans, technical manuals and checklists. Once connected to the secure onsite network, the system began secure data transmission to offsite personnel, which included a top-tier casing-exit expert based in Houston.

The rig crew tripped the system into the well to the planned kickoff depth of 793 m (2,603 ft) and oriented the hydraulic MultiCatch whipstock for setting. Using the flow rate and nozzle calculations from the planning phase, the crew brought the pumps online and then increased flow rate to initiate the setting sequence. After holding for two minutes, they lowered the weight with the expectation that the anchor had been set. However, the system indicated no weight loss, meaning that no solid anchor setting was achieved.

The crew then pulled the string back up to depth and increased the flow slightly; still no anchor was set. Another attempt at a slightly higher flow rate yielded the same result. Unable to achieve the expected result based on pre-job plans, the onsite crew and operator turned to the experts in Houston for troubleshooting.

The expert, with real-time access to all operational details of the job and to thousands of “what-if” scenarios modeled on data from similar operations, immediately suggested an actionable solution to mix 20 bbl of high-viscosity 11.4-lb potassium chloride mud, pump it downhole at the maximum possible rate and then proceed as planned.

The onsite crew pumped the mud mixture downhole as recommended and held for three minutes. After the crew pulled up on the string, the anchor took weight and sheared off at 14,000 lb. Weight was then set to 20,000 lb per procedure. The crew marked the pipe, set down to 20,000 lb again and the system landed on the mark.

After picking up the pipe to neutral weight, the team set milling parameters and milled from 791 m to 793 m (2,595.5 ft to 2,603 ft). Sweeps at every 0.6 m (2 ft) of the borehole produced the expected amount of metal returns. As the QuickCut system milled the window and rathole, the software displayed all operational parameters in real time to onsite Weatherford experts and in Houston. Parameters were adjusted on the fly to minimize the load applied to the milling assembly, which helped to maintain a better-than-average ROP of 1.83 m/hr (6 ft/hr) throughout the process.

Once milling was complete, the crew marked the pipe in the system and milled the rathole from 793 m to 795 m (2,609 ft). Next, it reamed the window from 791 m to 795 m multiple times using a low torque and weight. The assembly slid through with the pump with no rotation, and then with no pump or rotation, which indicated a clean window. Finally, the crew pumped 10 bbl of sweep fluid and pulled the assembly out of the hole.

Time and cost savings

The operator originally sought to reduce milling time from the offset average of 14 hours to 12 hours, which equates to an about 15% decrease in rig time. The Weatherford system milled the window and rathole in a single trip in just over 3 hours. The total milling time was 9 hours faster than the client had required, a 78.5% reduction compared to the nearby well average, representing a record for the field.

Efficient problem-solving was the key to the drastic reduction in rig time. The issue encountered when setting the whipstock anchor would typically have required tripping out of the hole or would have resulted in significant downtime associated with phone calls between the job site and the Houston-based subject matter expert to discuss the problem. Because the system enabled real-time collaboration between the onsite crew and a remote team of experts, the team identified an efficient solution that incurred no nonproductive time. In addition to providing a flawless one-trip casing exit, the operation had zero recorded safety incidents.

Already among the most efficient means of mature field revitalization, sidetracking with the QuickCut Pro service helped the operator to boost well and reservoir profitability with minimal investment. Further, the service established a repeatable benchmark for casing exits in the field, which will enable the operator to reduce rig time and associated costs even more in future jobs. And because the problem-solving and predictive capabilities of the service are enhanced with each operation, the data and lessons learned from this job can be applied to improve casing-exit efficiency across the industry.