For decades, active magnetic ranging meant a stop-start rhythm: drill ahead, pull out, run wireline to take a ranging measurement, pull out again, run back in to drill. Ranging-while-drilling collapses that cycle, and on a relief well, the time it saves is measured in days.
The tyranny of the round-trip
Traditional wireline ranging is accurate but slow. Every measurement requires tripping the drillstring, rigging up wireline, taking the survey, and tripping back in. On a deep intercept that sequence repeats many times, and each cycle is hours of rig time during which no progress is made toward the target.
On a relief well, where every hour of an active blowout carries environmental and financial cost, that delay is the most expensive thing on the program.
Keeping the bit on bottom
Ranging-while-drilling moves the measurement into the bottom-hole assembly itself. Gunnar's DeadAhead™ uses wired drillpipe to range continuously as the well advances, no tripping, no wireline, no waiting.
More power, earlier locate
Wired pipe delivers far more electrical power downhole than wireline can, roughly 10× the current injection of an analogous wireline tool in DeadAhead™. More power means a stronger injected signal, which means the target is detected earlier and tracked more confidently all the way to intercept.
On a North Dakota well, DeadAhead™ held five to ten feet of separation across 5,500 feet of continuous ranging and intercepted at the exact planned depth, the world's first commercial wired-pipe AMR-while-drilling deployment, saving roughly two weeks of rig time and about two million dollars.
On a subsequent deployment in Texas, the DeadAhead™ system identified the target about 350 feet away and let us converge and intercept in a matter of hours.
Why it compounds offshore
Onshore the savings are real; offshore they are transformative. With rig day-rates an order of magnitude higher, eliminating round-trips and shortening the critical path can save tens of millions on a single intercept.
- Wireline ranging forces repeated, time-consuming drillstring round-trips.
- Ranging-while-drilling measures from the BHA continuously, no tripping, no waiting.
- Wired pipe delivers ~10× the current injection, for an earlier locate and confident tracking.
- Proven on North Dakota and Texas intercepts; savings compound dramatically offshore.