How Completion Designs Affect Limited Entry Perforating
Data Science & Analytics

How Completion Designs Affect Limited Entry Perforating

Rosemary Jackson  •  

Limited Entry: “Take what you can measure, then inside the tool suite of Petro.ai, model and calculate all the unknowns so that you can get an accurate estimate of the pressure that’s being experienced by the rock,” Dr. Brendon Hall, VP of Geoscience assures us.

Extreme Limited Entry: This method focuses on engineering the completion design so that injections of sand and water at extremely high pressures work in a dynamic fracturing process. The process affects the variables during the stimulation, widening the perforations. "Achieving the pressure design goal can be difficult to maintain. Petro.ai models that perforation erosion so you can estimate the treating pressure and that tool inside the platform is the Treating Pressure Prediction App,” Dr. Hall continues. 

Petro.ai is uniquely situated to address the aggressive, dynamically changing parameters that are necessary to monitor when applying a completions design that incorporates extreme limited entry perforating. Petro.ai models all the known pressure changes in the well and the important shifting components including stress shadow and perf erosion to create an accurate prediction of the treating pressure needed.

Kyle LaMotta, VP of Analytics, explains, “The idea for limited entry is smaller fracs so that there’s more stimulation near the well bore. The limitation in ‘limited entry’ is how far those fracs are extending. To do that you need to design for a specific pressure at the perforation.

Coming up with that pressure value is one hurdle. The next is measuring to determine if you’ve achieved that pressure value.

treating pressure perf erosion

If you’re thinking about a completions design, the components include the perforation size, number of perforations, number of perforations per cluster, and your fluid component which is the type of fluid, the density, the viscosity, the type of proppant and the amount of proppant that you’re using. Then, the pressures that you need to use must be determined. All those components are dynamic and could change throughout the job. The job might be 2 hours long. You’re probably going to stick with one fluid system, but you’ll be changing the proppant intensity.

“As you’re pumping, you’re sandblasting those perforations, changing that hole size. You’re turning lots of dials and things are happening dynamically so it’s hard to know if that 1500 psi, or whatever number you determined for limited entry, is changing or not due to the dynamic nature and the interdependency of the variables. What Petro.ai can do is help calculate the knowns and then you can track what that pressure is.

“So, if it’s 1500 psi at the beginning of the job, by midway, it may not be staying at 1500 psi. You may need to make an adjustment by increasing the treating pressure to keep that pressure up at the eroding perforations.

predicted treating pressure

"Petro.ai dynamically models to show for a given treating pressure what the response is downhole. So, if the perfs are eroding, that’s indicated by the pressure dropping and you need to increase the treating pressure to continue maintaining that limited entry desired pressure.

“It’s tough because it’s not static. That’s why people have a hard time because companies rely on history or they have static simulators and different reporting methods. Petro.ai is an interactive tool more than a report.

Petro.ai is a tool that has inputs and knobs that you can turn to see the effect. Right now, it’s a look back tool so you can look at a previous stage and see the treating pressure. You can see all of the different pressure jobs throughout the well and then you can derive an accurate prediction on what the treating pressure needs to be in this similar location.

If Petro.ai sees a good match then we know that our perf erosion model is good, the stress shadow model is good and we’re accounting for all the pressure drops in the system.You can take that design and apply it to a new well. You can pump this new job in a similar fashion. You’ve got similar perf designs that resemble this well or this stage and then you can apply that to the new well.”

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