Operators Quantify How Completions Tweaks Drive Production
Authors: Pallanich Jennifer 
Published: August 2024

With every completion, operators can fine-tune their designs. More stages or fewer? More proppant or less?

But what actually drives production improvements? Operators are increasingly seeking low-cost means of determining just that, often pushing readily available data through analytical workflows to determine what’s working. And just what is it worth, anyway, to get the completion right?

As long-sought technology allowing operators to optimize their fractures in real time nears reality, the question arises of how much value a perfect fracture will bring to the bottom line.

Autonomous intelligent fracturing (AIF) capabilities require automated completions equipment responding to decisions that are based on low-cost, real-time measurements fed into optimization models which then determine the value of changing a stage’s design parameters to improve it. Hess wanted to know if it was worth pursuing such a technologically ambitious goal, Craig Cipolla, principal engineering advisor at Hess, told an Unconventional Resources Technology Conference (URTeC) audience in June.

To answer that question, Hess carried out modeling studies to estimate the value of the perfect stage, detailed in URTeC 4044071. That study used the uniformity index (UI), a metric that quantifies completion effectiveness of the stages.

While engineers design completions with a goal of reaching a perfect UI of 1.0, “very rarely do we see a uniformity index of 1. We see something less than that,” Cipolla said. “To understand the relationship between a very low UI, a perfect UI, and median UI, we didn’t have that range of field data to do that. So, we did a modeling study.”

The study was conducted on five Middle Bakken wells, where Hess’ fiber-optics data suggest current UIs are around 0.7. The study set a technically achievable perfect UI at 0.93—0.99, a baseline UI at 0.8, and a poor UI at 0.2–0.3 to estimate the “cost of not getting it right,” he said.

When the UI is poor (Fig. 1), some clusters may receive little fluid while in a perfect scenario, all clusters receive the same amount of fluid. Yet a perfect UI does not guarantee a cluster will fracture uniformly, so fracture morphology was also a consideration.

To predict the production improvement and value of the perfect frac stage for the five Middle Bakken wells, Hess used a fully coupled, calibrated hydraulic fracture-reservoir simulation model along with a second study using the same reservoir simulation model with pre-existing fractures. Fig. 2 illustrates fracture lengths and drainage patterns for perfect, low, and base case UIs.

The second method showed much less heterogeneity in fracture geometry than the fully coupled model. According to the paper, the first model’s results were the most realistic, and the second model made it possible to compare results and ensure conclusions weren’t dependent on fracture geometry details. Although the results in the two models varied, the study predicted that increasing a UI from 0.25 to 0.75 would deliver a 10% hike in first-year production. The paper went on to say the benefits of increasing the UI are less as the average UI improves.