One assignee leads the ranked list with 44 families, well ahead of the fifth-placed company at 21 and the tenth at 11. Several of the other entries in the ranking trace back to related corporate entities that filed under different legal names over time, which is typical after mergers or internal restructuring. The gap between the leader and the rest suggests the core sensing and location methods were staked out early, leaving later entrants to compete on narrower calibration or integration claims.

Filings peaked at 26 in 2018 after rising from 12 in 2017, and the tracked span from 2021 (7) to 2024 (0) shows a full -100% drop. However, 2024 is the most recent year in this dataset that can be treated as complete, because publication typically lags filing by around 18 months. Read the 2025-2026 figures as still filling in rather than as evidence the field has gone quiet.

Geophysics and gravity surveying (G01V) appears on 80.7% of the 197 records in scope, and earth and rock drilling (E21B) on 58.9%, meaning most filings combine subsurface sensing with well operations. Smaller but active classes include materials for miscellaneous applications and AI-based computing, each on 5.1% of records. Control and regulating systems (G05B) is the thinnest tracked class at 1.5%, which may indicate room for claims tied to automated stimulation control.