Plugging Orphan Wells Underwater: Why Marine Operations Are a Different Beast Entirely

When most people think about orphan oil and gas wells, they picture rusting wellheads hidden in fields, forests, or forgotten corners of rural America. Those land-based wells are indeed a massive environmental challenge, but they are only part of the story. Beneath our rivers, wetlands, bayous, and coastal waters lies another category of orphan wells that presents a far more complex operational problem.

How many orphan wells are underwater?

There is no single federal database that neatly categorizes "underwater orphan wells," but we can triangulate credible estimates using available data. Recent studies suggest there are roughly 14,000 unplugged, non-producing wells in the Gulf of Mexico alone, and approximately 90% of those wells are in shallow water, making them accessible by lift boats or jack-up rigs.

Beyond the Gulf, inland waterways represent an even murkier challenge. States such as Louisiana, Pennsylvania, and Ohio have thousands of legacy wells located in wetlands, riverbeds, and bayous. Estimates suggest that up to 35 percent of all orphan wells nationwide may be located near or within water sources, even if they are not fully submerged. These wells pose heightened environmental risks and are often difficult to access.

Same Goal, Different Execution

Whether on land or underwater, the objective of plugging a well is the same: isolate the hydrocarbon-bearing formations and permanently stop leaks. The execution, however, changes dramatically once water enters the equation.

On land, crews can typically drive trucks directly to the well site. Equipment is staged on a dirt pad. The wellhead is visible and accessible. Cement trucks, wireline units, and support vehicles can come and go with relative ease.

In underwater environments, access becomes the first major hurdle. Equipment must be positioned using barges, lift boats, jack-up rigs, or, in some cases, cranes operating from shore. Every pump, tank, and tool must be loaded onto a vessel, or lifted or carried to a staging platform, secured, and carefully coordinated. As long as work can be reached from the shore, complexity remains manageable. However, once operations exceed "the reach from the beach," everything escalates into a fully floating operation with exponentially more moving parts.

Even the final step looks different. On land, casing is typically cut three feet below ground level and buried. In water, the casing must be cut below the mudline (i.e., riverbed or seafloor) to prevent hazards to fishing nets, anchors, or vessel traffic. Regulations vary by state, but the intent is the same: eliminate future risks long after the crew has left.

Specialized Equipment and Risks

Marine plugging operations require assets that simply are not part of a standard land-based toolkit to create stable work platforms by anchoring legs into the seafloor and raising the deck above the water.

In certain conditions, caissons can be used to dewater a well area, temporarily creating a dry workspace. As projects grow more complex, remotely operated vehicles (ROVs) and commercial divers may be needed for inspection, cutting, and debris removal, although safety trends increasingly favor ROVs over diver intervention.

Weather adds another layer of uncertainty. Rain might slow a land operation, but waves, tides, wind, and rapidly fluctuating river levels can completely shut down marine work. You simply cannot jack up a vessel safely in high seas.

Corrosion is also a relentless adversary. Marine wells, especially those exposed to saltwater, often suffer severe degradation. In some cases, the outer conductor pipe is so compromised that it cannot support the weight of a blowout preventer, requiring costly structural reinforcement before plugging can even begin.

Why do so many underwater wells remain untouched?

A land-based orphan well might cost $20,000 to $100,000 to plug. A shallow-water marine well often starts at around $200,000 and can easily exceed $1 million. Vessel day-rates alone can run from $10,000 to $50,000 per day. And that's before cement, crews, containment systems, or specialized tooling are added.

This cost differential explains why many state programs, even when supported by federal funding, have historically avoided in-water wells. The "bang for the buck" calculation often favors plugging multiple land wells rather than a single marine well, even though the environmental stakes underwater can be higher.

Containment is another critical factor. On land, a release can often be managed by excavating soil. In water, even a small "burp" requires immediate deployment of oil spill booms and skimmers, as surface sheens spread rapidly. Best-practice marine operations demand secondary and tertiary containment planning from day one.

Looking Below the Waterline

Measuring methane and monitoring plug integrity underwater presents its own technical challenges. Gas interacts with the water column before reaching the surface, complicating detection and quantification. Yet understanding these emissions is essential for identifying failed plugs and subsurface anomalies that could undermine long-term environmental protection.

The Road Ahead

Marine orphan wells represent one of the most complex frontiers in environmental remediation. They demand specialized assets, careful planning, and a willingness to confront higher risk and cost. Solving the orphan well crisis in America will eventually require serious, sustained attention below the waterline.

Ignoring these wells does not make the problem disappear; it simply pushes the risk out of sight.

Curtis Shuck, Founder and Chairman of Well Done Foundation, brings more than 30 years of experience across public service and the private sector, leading oil and energy transportation, logistics, and capital project development in the Pacific Northwest and Mid-Continent, including executive leadership roles at Red River Oilfield Services. Well Done Foundation launched their Marine Division in late 2025. He began his career as a roustabout on Alaska's North Slope and now lives in Shelby, Montana.