Background: Through hydraulic fracturing quality control on-site we detected issues with granular breaker running consistently and worked with a producer and the pressure pumping company to switch to a compatible liquid-add breaker going forward, and set expectations on-site with the frac crew.
Pictured above: The breaker hopper on the blender unit. A key piece of equipment that can have an outsized impact on the success of your frac and your well performance.
Plan for chemical over and under-pumping, breaker concentration issues have happened on your wells and will happen again. Develop acceptable tolerances and make the call ahead of time when to shut down and when to keep pumping to reduce stress and decision making on-the-fly
On-site equipment operators should be coached on how to handle chemical over and under-pumping so they respond in a predictable way
Discuss chemical options (such as liquid-add breaker) with your chemical provider and pressure pumping company, it may be worth paying more for chemical if it reduces formation damage, improves flow back and reduces variability in treating behaviour
Example: Breaker Not Running At All
Looking through the data-van data for a frac can help you identify stages where breaker hasn't been run properly. This is a great indication that a higher level of quality control is needed on-site.
The breaker concentration curve for solid-add breakers is based on an auger rpm in the breaker hopper. Here is an example of what a breaker concentration (L/m3) curve should look like:
When it's running, it's running mostly within +- 10% of program (green).
But on the following stage there's no record in the data-van data of any breaker running:
This means the auger was likely not turning, and no breaker was being fed into the well for this stage. This stage will likely not flow back, as it will remain polymerized until flow back, followed by the gellant likely caramelizing over time. An unintentional polymer flood and a complete waste of good reservoir.
So how do we mitigate this type of issue and make sure it doesn't impact future stages?
On-Site Communication to Ensure Smooth Execution
Whether the issue is with solid granular breaker or liquid add chemicals a big part of the solution is communication. The equipment operators need to know that while they’re being monitored more closely than usual, mistakes are only human. The important thing is that when issues happen there is a plan to communicate and correct them going forward.
Key points when communicating QC goals with blender/chemical van operators:
If a chemical is over or under-pumped, a stage is skipped, or there are issues placing proppant: averaging across all stages to meet programmed concentrations is not the goal
Increasing transparency increases trust: If chemicals aren’t running properly and you need support to fix an issue, communicate it over the radio instead of silently (and more slowly) trying to fix the issue yourself, it's valuable data for the producer and frac supervisor
The goal is to run at a programmed concentration as often as possible, but if there’s a drop-in chemical rate, chem and blender operators shouldn't be deciding when to batch chemical at the end of a stage (we've seen this happen), and should not increase concentration on following stages to average out to the correct chemical totals for the well (we've seen this happen too)
Good communication with the back end of the frac can help reduce early gel breaks and potentially issues with proppant suspension and transport. In the worst case this can cause proppant to drop out in the wellbore: stuck coil, hours reversing and cleaning out.
Could you see how preventing some of these reactions above could reduce screen-outs?
How Quality Control Reduces Breaker Issues
Once the frac fluid disappears down the well, there’s little you can do to mitigate issues with the frac chemistry, so it’s important to catch the issues as quickly as possible, the only way is through on-site testing and quality control:
Break test every stage at formation temperature in a hot bath. This can identify stages that aren’t breaking properly (polymer remaining in the formation) and can inform flowback timing decisions, tracer analysis, and well performance expectations
Manually check the breaker hopper frequently to catch granular feed issues as soon as possible so they can be corrected
Have an on-site focal for chemical consistency: QC personnel can facilitate communication with blender and chem van operators through shift changes and during the fast-paced on-site operations, so it doesn’t get overlooked
Bucket-test all liquid-add chemicals. Pump into a bucket with appropriate backpressure on the chemical pumps and calculate the pump rate, compare to the metered rate. Pump calibration should be a given, but it’s not safe to assume chemical pumps are calibrated regularly
Improve cold-weather procedures. Sharing best practices and preventative strategies (more on this below)
Why Solid Granular Breaker Issues Happen
There is a lot of equipment and processes to manage during a frac, and the priority is to ensure the proppant is being placed. This means there’s more focus on crosslinker, gellant, and proppant feeding properly.
Breaker isn't critical to ensure your proppant is suspended long enough to circulate or move tools in the case of an issue (unless over-pumped, causing flash breaks). For this reason Breaker and the rest of the chemicals are secondary from the perspective of a lot of on-site personnel.
If things are running smoothly, breaker and many of the other chemicals are usually never scrutinized.
Top reasons granular breaker issues happen:
Granular breaker can accumulate moisture and cake into solid chunks or freeze in cold weather, requiring labor-intensive and safety-sensitive manual crushing
Inattention: the breaker hopper can run empty (and still show a rate because the auger is turning), the blender operator may not catch this for multiple stages
Running granular breaker when liquid add is possible, potentially a better solution (discuss suitability and the pros and cons with your chemical provider)
The blender operator can forget to switch on the breaker auger
It’s worth taking a second look at the type of breaker you’re pumping, how consistently it’s running, and if there are other options that could work in your application.
Planning for Winter
It’s worth mentioning a few quick words about winter planning. We’re blessed with brutal cold and blistering wind that can wreak havoc operations in the field, and frac execution is no exception.
Here are a few strategies and ideas that are worth revisiting when winter rolls around:
o Bump liquid-add breaker every few minutes to prevent freezing of lines (backflow through check valves can cause freezing even if the breaker has a very low freeze point)
o Inspect Granular Breaker: granular breaker can cake or freeze from humidity and low temperatures, breaker should ideally be inspected before bringing to site
o Running a few extra steam lines so the crew can quickly and more safely correct temperature-related issues including ice plugs and trapped pressure without manually disconnecting lines and rodding them
o Tarping at the blender. Chem lines and leaky check-valves can freeze, tarping helps to contain steam so they can be quickly thawed
Liquid-Add Chemicals can have Similar Issues
Solid granular breaker isn’t the only chemical on-site that can have these types of issues.
We’ve seen some interesting approaches on-site to pumping liquid-add chemicals. If we strap (track the level) in a tote and notify a chem van operator they’re over or under-pumping we’ve seen a few different undesirable approaches:
Continue to run concentrations below programmed, "set it and forget it"
Batch chemicals at the end of each stage to average out to the correct loading
Increase loadings on the following stages to average out to the correct loading
Fail to select a suitably sized chemical pump, there are multiple pump sizes with minimum and maximum pump rates, this can require more time and effort switching and flushing chemical lines, incorrectly sized pumps often pump erratically, swinging up and down in rate
Pump through worn chemical pumps that aren't able to pump at programmed rates consistently
Ideally, the chem-van operator will re-calibrate and replace worn components on their chemicals pumps and pump the programmed rate going forward.
Look forward to our upcoming article series on this subject.
Investigate Pros and Cons of Switching to a Liquid-add Breaker
Switching to a liquid add breaker isn’t possible in all circumstances, but it can dramatically impact the consistency of delivering the same amount of breaker to each stage.
The best strategy is to discuss the following points with your pressure pumping company:
Source water compatibility
Stability times: time to drop below set viscosity, 100cP in most cases
Break time: time to drop below 10 cP
Required shut-in times post-frac
Formation Temperature & Enzyme vs Oxidative breaker suitability
In the example from the start of this article, the operator successfully switched to a liquid-add breaker.
Breaker issues are avoidable with a solid plan.
Ensure good communication before the job when designing the frac, and good on-site communication facilitated by real-time lab testing for early diagnosis of issues.
Resources spent monitoring breaker during pumping are cheap insurance for potentially catastrophic loss of proppant suspension or proppant pack polymer damage. Post-frac reports aren’t a reliable source of data for identifying and diagnosing breaker issues.
If you’d like to discuss this content or how quality control could help in your application don’t hesitate to get in touch, you can reach me directly at:
Thanks for reading,