Filings in this dataset are moderately concentrated: the five most active assignees together hold 18.6% of the 2,051 records in scope, and the ranked leader alone accounts for 156 records. That leaves the large majority of records spread across a long tail of filers, including oilfield-service companies, national oil companies and specialist storage developers. No single company controls the field outright, so freedom-to-operate analysis needs to look beyond the top names to this longer tail.

Filing rose steadily from 56 records in 2017 to a peak of 117 in 2022, then eased slightly to 78 by 2024 — a -5% change from the 82 filed in 2021, which reads as a plateau rather than a downturn. Figures for 2025 and 2026 are still incomplete because grants and publications typically trail the original filing date by about 18 months. Treat any apparent drop in the most recent one to two years as a data-lag artefact, not a real slowdown.

Earth and rock drilling for wells (IPC class E21B) dominates, appearing on 48.9% of the 2,051 records, reflecting how much of the field is about wellbore hardware, valves and control-line architecture rather than chemistry alone. Materials for miscellaneous applications (C09K) is the next largest at 15.8%, covering additives and conformance agents used to manage injection profiles. Smaller clusters in water treatment, separation and organic chemistry classes each sit under 9%, marking narrower but still active sub-fields.

US12228022B1, assigned to FMC Technologies and published 2025-02-18, claims a method of diverting part of a carbon dioxide stream into a slipstream line and using that slipstream to operate control modules at a well site. It specifically covers using CO2 itself as the actuation medium for wellsite equipment tied to an injection tree. It does not automatically block control architectures that use a different actuation medium, such as hydraulic or electric control lines, or that route the diverted CO2 for purposes other than equipment control — a clause-by-clause comparison against the granted claims is still needed for any specific design.

The thinnest documented branches by IPC share are water and wastewater treatment tied to injection operations (C02F, 4.0% of records), and organic-compound classes C07C (3.8%) and C07D (3.7%), all well below the dominant drilling-control and materials clusters. Only 10 co-assignee pairs exist across the whole dataset, indicating limited cross-company collaboration even in these narrower areas. Combining a specific treatment or compound step with a wellhead control-loop trigger, rather than claiming either element alone, is one plausible way to stake out unclaimed ground in these branches.