Blowout Preventer Stack Design Patents: Who Leads, Gaps 2026
- 30.3% concentration. the five leading assignees together hold 1,143 of the 3,772 records in scope, a share concentrated in a field with no shortage of single-filing entrants below them.
- Filings peaked in 2017 at 251 and have since fallen, with 2021's 169 dropping to 54 by 2024 (-68%) — though 2025-2026 counts are still filling in as publication catches up.
- 93.5% of records sit in E21B earth and rock drilling, but secondary classes in valves, fluid-pressure actuators and control systems point to where narrower, less-crowded claims still get filed.
Filing growth compares 2021 (169 records) with 2024 (54) — a three-year span. 2024 is the most recent year we treat as complete: publication lags filing by roughly 18 months, so 2025 onwards are still filling in and any growth rate that ends there would understate the field. Top-5 share is the combined record count of the five largest assignees divided by all 3,772 records in scope (CR5), not by the ranked leaders only.
What this landscape covers
Blowout preventer (BOP) stack design spans the mechanical, hydraulic and control-system claims that keep a wellbore sealed under pressure: ram-type and annular preventers, shear rams, bonnet seals, annular packing elements, working pressure ratings and riser connectors. The search underlying this page pulls 3,772 published records filed between 2015 and mid-2026 that combine a BOP-type term with a specific component or performance claim, so the set is weighted toward stack hardware and sealing mechanics rather than drilling operations generally.
Most of that hardware activity clusters in a single IPC subclass, which is expected for a mechanically defined component category, but a handful of secondary classes — valves, pumps, control systems and even digital data processing — mark where BOP claims increasingly overlap with automation and monitoring.
Filing trend and technology composition
Two views of the same 3,772-record set: how filing volume has moved year over year, and which IPC subclasses the claims fall into.
Filings rose to a 2017 peak, then declined
Filings climbed to a peak of 251 in 2017, then eased off; 2021 stood at 169 before falling to 54 by 2024, a -68% move over that span. Counts from 2025 onward are still incomplete because publication typically lags filing by around 18 months, so the most recent years should not be read as a continued decline yet.
E21B dominates; secondary classes mark adjacent claim activity
E21B (earth and rock drilling) covers 93.5% of the 3,772 records, consistent with a component defined by its wellbore function. Smaller shares in F16K (valves, 2.7%), F15B (fluid-pressure actuators, 2.7%), F16L (pipe fittings, 1.8%), G05B (control systems, 1.5%), B23D (shear/cutting mechanisms, 1.2%), F04B (pumps, 1.2%) and G06F (digital data processing, 1.0%) show where BOP claims extend into hydraulics, control logic and monitoring software.
Shares are the percentage of the 3,772 records in scope. A patent can carry several IPC classes, so the shares add up to more than 100%.
Go deeper on Blowout Preventer Stack Design with Eureka
This page is one run against one query. Ask Eureka your own question about blowout preventer stack design and every answer comes back with the patent numbers behind it.
Try EurekaRepresentative filing and most-cited prior art
Annular Blowout Preventer (BOP) Packing Unit with Integrated Secondary Sealing Compound
An annular blowout preventer includes a body, a piston disposed within the body, and a packing unit disposed adjacent the piston. The packing unit includes a packer body surrounding an opening, fabricated from a first material, with a second, less rigid material disposed between the packer body and the opening. The packer body and second material constrict the opening when the preventer is actuated, and the second material seals around a tool disposed within the opening, filling crevices or recesses on the tool's outer perimeter.Filed by Chevron U.S.A. Inc., published 2016-07-14.
| # | Publication no. | Patent title | Citations |
|---|---|---|---|
| 1 | US4046191A | Subsea hydraulic choke | 322 |
| 2 | US4626135A | Marine riser well control method and apparatus | 316 |
| 3 | US6230824B1 | Rotating subsea diverter | 279 |
| 4 | US6102673A | Subsea mud pump with reduced pulsation | 275 |
| 5 | US6325159B1 | Offshore drilling system | 259 |
| 6 | US6227300B1 | Slimbore subsea completion system and method | 219 |
| 7 | US4444250A | Flow diverter | 192 |
| 8 | US6668943B1 | Method and apparatus for controlling pressure and detecting well control problems during drilling of an offsh… | 190 |
| 9 | US4712620A | Upper marine riser package | 182 |
| 10 | US5735502A | BOP with partially equalized ram shafts | 179 |
Citation counts favour older records simply because they have had longer to accumulate citations within the searched corpus; treat them as a signal of influence on the field, not of current technical relevance.
Each row carries its publication number; clicking a row searches Eureka by that number.
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Reading the concentration, trend and classification data together points to where claim space is occupied and where a narrower filing still has room.
The top of the field is dense, the tail is long
The five leading assignees hold 1,143 of the 3,772 records in scope, and the top 10 extend that to 1,659 (44.0%). Below that threshold the ranking spreads across many single- or low-count filers, which is typical of a mature hardware category where large operators and service companies dominate core sealing and ram claims.
Volume has come off its 2017 peak
Filings peaked at 251 in 2017 and have declined since, with the 2021-2024 window showing a 68% drop from 169 to 54. Because publication lags filing by roughly 18 months, 2025 and 2026 figures are still incomplete and should not be read as confirmation the decline continues.
Core hardware claims sit in one subclass
E21B covers the overwhelming majority of records, which is expected given BOP stacks are defined by their drilling-well function. The smaller shares in valves, actuators, pipe fittings and control systems mark where component-level or software-adjacent claims are being filed alongside the core mechanical hardware.
Even top filers are pulling back
Recent-year momentum among the leading assignees is uniformly soft, with year-over-year declines recorded across several of the largest filers and some showing no filings at all in the latest year. That pattern is consistent with the broader post-2017 volume decline rather than a single company's retreat.
Eureka can read the same corpus for gaps instead of for coverage: under-claimed branches adjacent to blowout preventer stack design, with the prior art for and against each one.
Who holds the ground, and where it's open
Filing concentration sits with a small group of legacy oilfield equipment and service companies, several of which share filings through corporate affiliates. Below that top tier, claim activity thins out quickly.
A single filer leads by a wide margin
The top-ranked assignee holds 293 records, well ahead of fifth place at 151 and tenth at 78. That gap reflects decades of continuation filings across ram, packing and connector designs from an established BOP equipment manufacturer.
Affiliated entities file jointly
The strongest co-assignee pairing appears 89 times, with two related pairings each appearing 48 times. These patterns typically reflect a parent-subsidiary or joint corporate structure filing under related entity names rather than independent collaboration between competitors.
Legacy filers are slowing simultaneously
Momentum tracking across named leading assignees shows year-over-year declines ranging from roughly -50% to -100%, with several recording zero filings in the latest tracked year. This is consistent with the field-wide volume drop rather than isolated withdrawal by one company.
| Assignee | Recent year | YoY |
|---|---|---|
| Schlumberger Technology Corporation | 3 | -63% |
| Schlumberger Technology B.V. | 1 | -50% |
| Cameron International Corporation | 0 | — |
| Hydril USA Manufacturing LLC | 0 | — |
| Hydril Company | 0 | — |
| Hydril USA Distribution LLC | 0 | -100% |
| Transocean Sedco Forex Ventures Limited | 0 | — |
| Halliburton Energy Services, Inc. | 0 | — |
Where to take this
The dataset points to a field with dense core claims and a thinning but still-active edge. Two directions make sense depending on what you're deciding.
Check freedom-to-operate against the top holders
With 30.3% of records held by five assignees, any new ram or packing element design should be screened against that concentrated set before further development spend.
Run a freedom-to-operate search in Eureka →Scope claims toward the under-claimed branches
Control-logic, sensing and metallurgy-adjacent claims sit in smaller IPC subclasses than the core E21B hardware, suggesting narrower but less contested filing opportunities.
Explore white space with Eureka →Common questions on BOP stack design patents
Filing activity in this dataset is concentrated among a small group of established oilfield equipment and service companies, with the top-ranked assignee holding 293 of the 3,772 records in scope. The next four leading assignees bring the combined top-five share to 1,143 records, or 30.3% of the field. Below the top ten, which together hold 44.0% of records, filing activity spreads across many companies with far smaller counts, so freedom-to-operate work should prioritise the leading names first.
No — filings peaked at 251 in 2017 and have declined since, with the 2021 to 2024 window showing a 68% drop from 169 to 54 records. However, publication typically lags filing by around 18 months, so 2025 and 2026 counts in any dataset are still incomplete and should not yet be read as confirming a continued decline. The safest complete-year comparison currently available ends at 2024.
The core of this landscape sits in IPC subclass E21B (earth and rock drilling), which covers 93.5% of the 3,772 records because BOP stacks are defined by their wellbore-sealing function. Smaller but meaningful activity appears in valves and taps, fluid-pressure actuators, pipe fittings, control and regulating systems, cutting mechanisms, pumps, and digital data processing. These secondary classes mark where BOP claims intersect with hydraulics, automation and monitoring rather than pure mechanical sealing.
US20160201422A1, filed by Chevron U.S.A. Inc. and published 2016-07-14, claims an annular blowout preventer packing unit with an integrated secondary sealing compound — specifically a packer body of one material paired with a second, less rigid material that fills crevices around a tool passing through the seal. It is a useful reference point for anyone designing annular packing elements with dual-material sealing approaches, since its claims focus narrowly on that materials-pairing mechanism rather than the broader preventer body.
The secondary IPC classes point to it: control-logic sequencing for ram actuation, real-time sensing of packing element wear, riser connector fatigue monitoring, and shear ram cutting-edge metallurgy all sit in subclasses with far lower record counts than the core E21B hardware claims. These branches combine mechanical BOP function with sensing, control or materials-science elements that are less densely claimed than the base sealing and ram mechanisms, making them a more realistic target for a narrowly scoped new filing.
A single invention often generates multiple published documents — continuations, divisionals, and filings in different jurisdictions such as the US, EPO, WIPO/PCT, UK, Australia and Canada, all represented among the receiving offices in this dataset. Counting by patent family, as the assignee ranking in this landscape does, removes that duplication and gives a fairer picture of how many distinct inventions an assignee actually holds, rather than how aggressively they refiled or how many jurisdictions they pursued.
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Disclaimer. This page is generated from Patsnap Eureka data drawn from a limited snapshot of global patent and scientific-literature records, and is provided for general information and reference only.
Patent data carries inherent limitations: recent filings (typically the most recent 18–24 months) are under-counted due to standard publication lag; counts may be reported at either a patent-family or a patent-record basis and are not always directly comparable; classification, applicant-name, and citation data may contain errors, duplicates, or omissions; and the underlying search query defines and constrains the scope shown. As a result, the analysis may be incomplete or inaccurate and may not reflect the full technology landscape.
Nothing on this page constitutes an exhaustive prior-art, novelty, freedom-to-operate, or validity search, nor does it constitute legal, financial, investment, or professional advice, and it should not be relied upon as such. Any patent, commercial, or strategic decision should be verified independently and reviewed with qualified patent, legal, and domain professionals. Patsnap makes no warranties, express or implied, as to the accuracy, completeness, or fitness for any particular purpose of the information presented.
Machine translation. Assignee and organisation names originally recorded in Chinese, Japanese or Korean have been rendered into English by an AI translation step so that the tables stay readable. These renderings are best-effort and may not match a company’s registered English name; the original name is what the underlying patent record carries, and it is what any Eureka query launched from this page uses.