How the tools behave in difficult mud

The lab and the rig are not the same place: lost-circulation material, heavy mud, gasified drilling fluid and hours of continuous vibration all change how a tool actually performs. Below is what each condition does and where our limits sit.

Hole conditions that shorten tool life

• Lost-circulation material (LCM) — LCM packs up at the valve port and in the flow restriction; at best the pulse amplitude drops, at worst the valve sticks. An LCM tolerance has to state material type, particle size and concentration together — a bare claim that a tool "passes LCM" is worth nothing.
• Sand content — Erosion of valve parts and restrictor rings by solids is cumulative, and it is what sets the service interval.
• High viscosity and high density — Pulse attenuation increases and the waveform spreads — one of the main reasons data is lost in long laterals.
• Gasified fluid and underbalanced drilling — The fluid becomes more compressible and pressure waves propagate differently; in severe cases a mud pulse cannot establish a working channel at all, and we recommend electromagnetic telemetry for those jobs.