HOUSTON — Demand in the Permian basin for an MWD system with both electromagnetic (EM) and mud-pulse (MP) data transmission capabilities is increasing. ReedHycalog, a business unit of National Oilwell Varco’s Wellbore Technologies segment, developed the BlackStar II dual-telemetry MWD tool for use in such applications.
The BlackStar II dual-telemetry MWD tool combines the capabilities of both EM and MP data transmission to provide continuous drilling in challenging Permian drilling conditions. The dual-telemetry tool’s modular design allows flexibility in configuring the toolstring to maximize operational capabilities, allowing directional, drilling, and formation data to be measured downhole and transmitted to surface as either EM waves or pressure pulses. When using low-frequency EM waves, the tool sends information to the surface through the earth’s crust. The information is received at a surface antenna, decoded, and processed by a computer and distributed to the driller’s readout display without the encumbrance of mud or wire transmission. EM tools have no moving parts, allowing for use in air-drilling conditions or high lost-circulation material environments where mud-pulse (MP) tools are rendered inoperable. In addition, surveys can be transmitted during connections, minimizing the nonproductive time associated with conventional MP tools.
The dual-telemetry tool enables directional drillers to achieve the higher telemetry speeds and reductions in survey time made possible by EM telemetry, without risking a trip out of hole for signal interruption. Unlike other dual-telemetry tools, the new tool is fully retrievable, which reduces the risk of costly lost-in-hole events. When designing the tool, one of NOV’s primary objectives was to enable customers to utilize their existing inventory of nonmagnetic collars, mud pulsers, and universal bottomhole orientation subs, thereby reducing the investment necessary to offer dual-telemetry capabilities. The tool’s enhanced functionality and improved cost-effectiveness is ideal for use in the Permian, where flexibility is key and diverse power management options present directional drillers with a distinct advantage.
A directional provider used the dual-telemetry tool to address signal strength and battery-life concerns on a long lateral. Previous attempts to utilize EM telemetry with other tools had been unsuccessful, but with the new tool, variable voltage and current output allowed flexibility to extend the signal range into the lateral. Battery consumption was optimized, allowing the tool to reach total depth at more than 13,000 ft, and successful EM transmission provided directional and gamma measurements much faster than conventional mud-pulse update rates. Additionally, the operator eliminated nonproductive time due to the dual-telemetry redundancy of the system, effectively eliminating the need to trip for an equipment change.