Key Takeaways

• Class II injection wells fall under the EPA's Underground Injection Control (UIC) program and require annual reporting, mechanical integrity testing, and detailed records of injection volumes and pressures.
• Missed deadlines and failed mechanical integrity tests can trigger civil penalties exceeding $25,000 per day per violation, plus mandatory well shut-ins.
• Accurate injection profiling and pressure data — the kind produced by production logging — are central to demonstrating compliance and passing integrity tests.
• Operators in Kansas, Texas, and the Permian Basin often work under state-delegated primacy programs, so requirements vary by jurisdiction.

What Are the EPA Reporting Requirements for Injection Wells?

Injection wells used for enhanced oil recovery and saltwater disposal are regulated as Class II wells under the EPA's Underground Injection Control (UIC) program, established by the Safe Drinking Water Act. Operators must report annual injection volumes, monitor injection pressures, perform periodic mechanical integrity tests (MITs), and maintain records that demonstrate the well is not endangering underground sources of drinking water (USDWs).

The core purpose of these requirements is groundwater protection. Every Class II well must prove — through testing and documentation — that injected fluids stay confined to the authorized injection zone and do not migrate into freshwater aquifers. For operators running disposal and waterflood programs across the Mid-Continent and Gulf Coast, UIC compliance is not optional paperwork; it is a license-to-operate issue.

Understanding the UIC Program and Class II Wells

The UIC program divides injection wells into six classes. Class II covers wells associated with oil and gas production: enhanced recovery (EOR) injection, saltwater disposal (SWD), and hydrocarbon storage. Most operators interact with the program through two well types — disposal wells that handle produced water and injection wells that maintain reservoir pressure or sweep oil toward producers.

Authority for the program is split. The EPA directly administers UIC in some states, while others — including Texas (through the Railroad Commission) and Kansas (through the Kansas Corporation Commission) — have been granted primacy and run their own programs under EPA oversight. This means a Texas SWD well and a federally regulated well in another state can face different forms, deadlines, and pressure-test intervals even though both answer to the same Safe Drinking Water Act framework.

Permitting and Area of Review

Before injection begins, an operator must secure a permit that defines the authorized injection zone, maximum surface injection pressure, and an "area of review" — typically a quarter-mile radius — within which all penetrating wellbores must be evaluated for potential fluid migration pathways. Older, improperly plugged wells inside the area of review are a frequent compliance flag and a common reason permits are delayed or denied.

Key Deadlines and Data You Must Track

Most Class II programs require an annual report summarizing monthly injection volumes, maximum and average injection pressures, and the source of injected fluids. Annual reports are commonly due in the first quarter for the prior calendar year, but exact dates depend on your regulating agency. Falling behind on these submissions is one of the most common — and most avoidable — violations.

At a minimum, operators should be continuously tracking:

• Injection volumes — daily or monthly barrels injected, recorded per well.
• Injection pressure — surface pressure must stay below the permitted maximum to avoid fracturing the confining zone.
• Annulus pressure — monitored to detect tubing or packer leaks between integrity tests.
• Mechanical integrity test results — typically required every five years, sometimes more often for disposal wells.
• Fluid analysis — characterizing what is being injected, especially for disposal operations.

Mechanical Integrity Testing: The Heart of Compliance

A mechanical integrity test (MIT) proves two things: that there is no significant leak in the casing, tubing, or packer (internal integrity), and that there is no fluid movement into a USDW through channels behind the casing (external integrity). Failing either part means the well must be shut in until repairs restore integrity. MITs are usually required on a five-year cycle, but agencies can demand them after any workover or anomaly.

Internal integrity is commonly demonstrated with a standard annulus pressure test. External integrity — proving fluids are not channeling up behind the casing — is where diagnostic logging earns its keep. Temperature logs, radioactive tracer surveys, and oxygen-activation logging can map where injected fluid actually goes downhole. This is precisely the kind of injection analysis that turns a routine test into actionable reservoir intelligence.

Why Injection Profiling Matters

An injection well can pass a pressure test yet still be sending most of its fluid into one thief zone instead of the intended interval. A flow profile built from production logging data shows the distribution of injected fluid across the perforations, confirms zonal conformance, and provides defensible documentation that injection is contained. Eagle Reservoir Services uses advanced temperature and spinner processing to build these profiles even when conventional data is limited, helping operators satisfy regulators and improve sweep efficiency at the same time.

Penalties for Non-Compliance

The consequences of UIC violations are steep. Under the Safe Drinking Water Act, civil penalties can exceed $25,000 per day, per violation, and serious or willful violations can escalate to criminal liability. Beyond fines, regulators can order immediate well shut-ins — halting disposal capacity and forcing operators to truck produced water or curtail production across an entire field.

The most common violations are mundane: late or missing annual reports, exceeding permitted injection pressure, failing to run an MIT on schedule, and inadequate area-of-review documentation. Nearly all of these are preventable with disciplined record-keeping and a logging program that keeps integrity data current. For operators across Oklahoma, Kansas, and the Permian Basin, building compliance into routine well monitoring is far cheaper than reacting to a notice of violation.

Building a Compliance-Ready Monitoring Program

The operators who stay out of trouble treat UIC reporting as a year-round process, not a year-end scramble. That means automated volume and pressure recording, a calendar of MIT due dates tied to each permit, and periodic diagnostic logging to verify zonal conformance before a regulator asks for it. Pairing production logging with casing inspection gives a complete view of both where fluid is going and whether the barriers containing it remain sound.

If you operate Class II wells and want confidence that your integrity data will hold up to regulatory scrutiny, the team at Eagle Reservoir Services can help. Call (337) 852-9674 or contact our reservoir engineering team to discuss a monitoring and diagnostics program tailored to your field.

Frequently Asked Questions