Casing while drilling runs the well casing itself as the drillstring, eliminating a separate drilling and casing-running step. It creates distinct patenting territory because it combines casing-string mechanics, drillable-bit design, casing-drive systems and wellbore-integrity concerns that do not arise in conventional drill-then-case operations. That combination is why searches for this topic pull in wear, clearance and wellbore-strengthening terms alongside the core casing-while-drilling and drillable-bit language, rather than sitting cleanly inside one existing drilling-technology class.

The dataset ranks 80 assignees across 321 records, and ownership is concentrated: the top-ranked assignee alone holds 62 records, with the fifth-place assignee at 19 and tenth place at 11. The top five combined account for 46.1% of all 321 records in scope, and the top ten for 67.3%, so a small number of companies control most of the core filing activity while a long tail files only occasionally.

Filing activity peaked in 2017 at 18 records and has declined since. Comparing 2021 (17 filings) to 2024 (4 filings), the last year that can be treated as complete once publication lag is accounted for, filings fell 76%. Figures for 2025 and 2026 will rise as pending applications publish, so the near-term years should not yet be read as continuing the decline — but the 2021–2024 trend itself is a genuine contraction, not a lag artefact.