The ranking covers 49 companies, and the leading assignee holds 9 of the 95 records in scope, with the fifth-ranked company at 7 and the tenth-ranked at 4. Ownership is concentrated at the top but not dominated by a single player: the top 5 assignees together hold 42.1% of all records and the top 10 hold 63.2%. Below that handful, the remaining companies each hold small numbers of filings, so a practitioner should expect a fragmented field rather than one gatekeeper.

Filing peaked in 2017 at 13 records and declined afterward, with the 2021-to-2024 span down 92%, from 12 records to 1. Because publication lags filing by roughly 18 months, the most recent one to two years in any patent dataset are always undercounted, so the 2025-2026 figures should not yet be read as confirmation of further decline. Taken together, the safest reading is that the foundational claim space filled early and later years show fewer new filings, not that interest in EGS itself has disappeared.

E21B, the earth and rock drilling and wellbore subclass, appears in 57.9% of the 95 records in scope, making it by far the busiest classification. F03G (spring, weight and miscellaneous motor art) and F24T (geothermal systems) follow at 25.3% and 23.2% respectively, while materials-focused classes such as C09K and C01B sit in single digits to low double digits. Because a record can carry more than one IPC class, these percentages add up to more than 100% and describe claim density per subclass rather than a strict partition of the field.

US9062545B2, titled 'High strain rate method of producing optimized fracture networks in reservoirs,' is the most-cited record in this corpus at 79 citations. It addresses methods for shaping fracture networks under high strain rate conditions, a foundational technique relevant to hydraulic stimulation generally, not only geothermal applications. High citation counts in a searched corpus tend to favour older, foundational filings, so the figure should be read as a measure of influence on later filings rather than a claim of current market dominance.

The technology composition data shows E21B drilling mechanics heavily claimed at 57.9% of records, while materials and separation classes such as C09K (10.5%), F24J (9.5%), B01D (5.3%) and C01B (3.2%) carry far fewer filings. That gap suggests working-fluid chemistry, filtration and separation steps tied to stimulation are comparatively under-claimed relative to the mechanical fracturing methods themselves. A first claim drafted around a specific working-fluid formulation or a separation step integrated into the stimulation cycle is more likely to find open space than another claim on fracture-network mechanics.