KANSAS—Historically, conventional geologic formations in the Mid-Continent have been active waterflooding targets. The industry’s focus may have shifted in recent years to horizontal resource plays, but the region’s geology obviously has not changed. What has worked historically is still applicable, and that includes waterflooding conventional wells.

What has changed, however, is the state of technology and operating practices. Like any kind of improved oil recovery project, the decision whether to waterflood comes down to economics. More specifically, it is ultimately driven by the expected tradeoff between recovering additional barrels over an extended productive lifecycle versus the additional capital costs and recurring operating costs of initiating and maintaining an active waterflood.

So how are technology and best practices changing the calculus? The answer encompasses multiple fronts, including design refinements, mechanical equipment improvements, and advanced chemical solutions, according to Jason Schmidt, consulting engineer with Schmidt Engineering Inc. His company has designed various Kansas waterfloods, including both fully engineered projects and smaller-scale applications where a single well was converted from a producer to an injector.

Along with evolving technology, there is also a mindset change among operators to think through the full lifecycle of a field from the outset. “In the past, waterflooding was something to consider after a field’s production was already in decline,” Schmidt explains. “But more producers are now beginning to think about pressure support and full-life reservoir management early on.”

Matt Osborn, president and chief executive officer of Eureka, Kansas-based Daystar Petroleum, seconds that idea. Osborn says he sees more attention to reservoir pressure and sweep from the start, up to and including factoring waterflood planning into initial drilling decisions.

“Keep drilling, and if a producing well disappoints, but there is porosity and permeability, convert it to an injector to start pressure maintenance early,” quips Osborn, whose company operates several Kansas waterfloods. “The more you plan ahead, the more likely ultimate recovery rates will be higher in the long run.”

In fact, the ideal approach to field development would be to drill wells based on expectations of future IOR and EOR, Schmidt observes. Developing conventional geology is rarely a textbook exercise and requires balancing between geologic understanding, operating judgment, and capital discipline. Taking the long view by considering optimal waterflood patterns, injection timing, and reservoir pressure support can extend a field’s commercial productivity for decades.

But, of course, economics guide decision making in any project. Schmidt is quick to acknowledge that topsy-turvy oil prices and the volatility precipitated by geopolitical events and conflicts make long-range economic planning and evaluations more challenging than ever.

Rethinking Economics

Tom Larson, proprietor of Larson Engineering Inc. in Olmitz, Kansas, applauds the trend toward earlier flood planning in the development stage, but he says the most important consideration remains ensuring that a waterflood can be built and operated profitably.

Despite waterflooding’s long history in the Sunflower State, Larson considers waterflooding an underutilized, cost-effective technology for adding reserves. “Even when technical conditions are right for waterflooding, traditional economic models may not show bottom-line financial benefits in some Kansas fields.”

Larson calls waterflooding “the most cost-effective way to add reserves,” and argues that much of what engineers learn about waterflooding in college textbooks does not neatly apply to Kansas. Instead of broad, homogeneous reservoirs, many Kansas fields are highly variable and built around cyclothems—alternating limestone and shale sequences—with localized sand development and marked heterogeneity. That variability can hinder waterflood operations, especially when multiple operators and royalty owners have to agree on unitization, allocations, and operating structure.

Larson says the traditional approach to waterflooding uses centralized flood facilities serving an entire field, making it necessary to unitize fields, consolidate production, and build large common facilities that require significant upfront capital. A better solution, he points out, is a decentralized model that installs small, economic injection pumps at each injection well.

“Existing lines can be reversed and used to transport water from the tank battery to the injection site,” he explains. “A saltwater tank and a small pump are placed at the injection well, eliminating much of the cost associated with new high-pressure lines and large centralized equipment.”

The advantage is immediate and practical, according to Larson. “This decentralized approach can allow operators to install a flood for a fraction of the cost of a traditional system, and it also gives operators flexibility in dealing with heterogeneous Kansas reservoirs.”

That flexibility is a big bonus considering that water may channel in an unexpected direction, offset wells may respond differently than predicted, and injected water may sweep one part of the field and bypass another. “We keep flood designs flexible,” Larson says. “If water starts moving in the wrong direction, we can easily adjust the injection pattern as needed.”

Moreover, if a waterflood is not sweeping as it should, the operator is not locked into an expensive, permanent setup. “The small injection plant can be moved. The pattern can be modified and injection adjusted as field performance dictates,” he adds.

Diaphragm Pumps

Larson’s experience in waterfloods led directly to equipment innovation. He has designed injection plants for Waterflood Equipment, a company that fabricates and installs diaphragm-pump-based injection systems. Diaphragm pumps are simple, affordable, easier to repair in the field, and less prone to leaking than triplex, horizontal and other pump types, Larson explains.

He points to another important detail: the pumps can be configured to help operators adjust injection pressures and rates in different parts of the reservoir. In some mature waterfloods, he says, an operator may be running the broader field at one pressure while individual injection wells in parts of the flood require a higher pressure to achieve the desired response. In those cases, smaller diaphragm pump-based systems can be used to selectively boost injection pressure at individual wells without reworking the entire fieldwide setup.

All of that reinforces a larger point Larson returns to repeatedly: “The barrel recovered with waterflooding can be the most economic barrel on the entire lease,” he states.

He notes other practical benefits once an IOR system is in place, including tax treatments and reduced water-hauling costs when produced water can be injected locally rather than disposed offsite. These benefits are not usually the first things operators think about when considering a waterflood, but in a mature conventional field, small economic advantages matter.

Schmidt agrees with the move toward distributed injection, and credits Larson with helping drive the approach. The appeal of replacing a single large central pump station with multiple smaller diaphragm pumps at the injection sites is easy to understand, he goes on.

First, it reduces infrastructure costs. Schmidt says the system avoids the need for extensive high-pressure lines because water can be moved to the location at lower pressure and then pressurized at the wellsite. “It is definitely a cost savings,” he comments.

Second, it simplifies maintenance and improves operating resilience. If a centralized system goes down, the entire flood can be affected. In a distributed setup, if one pump goes down, only one injector is lost, and the pump can be swapped quickly.

Third, Schmidt says it fits how many Mid-Continent operators build floods incrementally, field by field, with a close eye on cost.

Understanding The Reservoir

But even with better surface equipment, Schmidt says the foundation of any flood remains understanding the reservoir. Asked what an ideal modern waterflood design would look like, he starts with cores, logs, and simulation. In fact, Schmidt suggests that in a perfect world, core samples would be collected while drilling every well so that information could be directly correlated to well logs and a full waterflood simulation would be run to test pattern options and injection strategies.

Of course, budgets are never unlimited, which means operators have to use the best available tools to make the most of limited information to understand the target formation rock and subsurface characteristics. Advanced waterflood simulation software is using artificial intelligence to run multiple iterations much faster than a single human engineer could.

While AI cannot replace experience, Schmidt says it can reduce the time required to test various design and operating configurations, allowing engineers to evaluate more scenarios much more quickly.

Waterflooding innovations are taking multiple forms, from decentralized injection to new types of pumps and equipment to better subsurface analysis and surveillance. But in a region like Kansas with a mix of conventional reservoir targets, a deep bench of existing infrastructure, and operators who understand how to work incrementally, these innovations collectively serve to remind that one of the industry’s most established improved recovery methods still has plenty of room to improve and optimize to recover new reserves in old fields.