One assignee leads the ranked field with 175 records, well ahead of the fifth-place company at 48 and tenth place at 15. This dataset’s ranking covers 69 companies in total, and the drop from the leader to the rest of the field is steep rather than gradual. Several of the largest names in the ranking are related corporate entities of the same oilfield-services group, filed under slightly different legal names across jurisdictions, so the effective concentration at the top is likely even higher than the raw ranking suggests.

Filings fell from 11 in 2021 to 3 in 2024, a -73% change over that span, after peaking at 18 in 2017. That said, publication typically lags filing by around 18 months, so the years closest to the present are always undercounted and should not be read as proof of an ongoing decline. The safest read is that the technology’s core measurement physics is well established, and filers are refining rather than staking new ground.

US9176252B2, assigned to Schlumberger Technology Corporation and filed in 2015, covers a method for estimating petrophysical parameters and invasion profiles by jointly inverting induction (electromagnetic) and pressure data, using a multiphase fluid flow simulator to constrain the inversion. It ties the inverted invasion profile to fluid flow physics and gravity segregation effects rather than treating resistivity inversion as a standalone electromagnetic problem. Anyone building a joint induction-pressure inversion workflow for invasion-profile estimation needs to check their approach against this claim scope specifically.