1. Smart ESD with Frac Hit Early Warning
Protects rod-pumped vertical oil wells from frac hits by early detection of atypical fluid entry
Bill Elmer, VP of Engineering
August 2, 2017

2. What is a Frac Hit?
A frac hit is typically described as an interwell communication event where an offset well, often termed a parent well in this setting, is affected by the pumping of a hydraulic fracturing treatment in a new well, called the child well.
Aril 2017 SPE Journal of Petroleum Technology (Volume 69 Issue 4), “Oil and Gas Producers Find Frac Hits in Shale Wells a Major Challenge”

3. The problem is increasing
Infill drilling and downspacing programs mean more frac hits.
Frac hits are known to be strong enough to damage production tubing, casing, and even wellheads.
Some wells impacted by frac hits never fully recover and, in the worst cases, permanently stop producing after taking frac hits.
Picture of rod string sanded up inside production tubing as shown in April 2017 SPE Journal of Petroleum Technology (Volume 69 Issue 4), “Oil and Gas Producers Find Frac Hits in Shale Wells a Major Challenge” has been removed for copyright reasons

4. Prevention solutions are of limited value
Notifying other nearby operators of an impending hydraulic fracturing operation
Watching pressures in offset wells during frac treatments
Looking at density changes in produced fluids
Live video of the offset wellhead

5. Needed: An early detection method to identify increased flowrate in the wellbore before it manifests at surface
Watching the casing pressure?
When the casing is connected to a flowline that prevents the pressure from rising, pressure will not immediately rise from fluid entry due to gas present in casing annulus
Shut in the casing to measure the pressure increase during the frac job?
If the casing is only rated for low pressures (2000 psi), will likely cause a casing failure if a frac hit occurs

6. An Effective Method for Detecting Frac Hits
Real time velocity indicator of increased fluid entry into wellbore
Not delayed by travel time to surface
Not masked by a flowline that easily handles this flow increase
Simple method
Casing valve regularly closed for short periods to measure a small buildup in casing pressure
Indicator is delta pressure / delta time
Separate indicators tracked for when well pumping than when not
Casing pressure immediately bled down, and cycle repeated
Need a cost-effective alternative to expensive flow measurement devices to determine this velocity
The real time velocity indicator in Encline’s Smart ESD with Frac Hit Early Warning provides a cost-effective solution

7. Why is this real time velocity indicator an accurate method to detect a “Frac Hit”?
Entry of gas and liquid from the perforations into the wellbore is normally a very steady-state process
Consequently, velocity of gas up the annulus is very steady
Measuring and trending this velocity in real time, and comparing to historic velocities should be an excellent method to detect a frac hit

8. From “Tubing Anchors Can Restrict Production Rates and Pump Fillage” by J.N. McCoy, Ken Skinner, & Lynn Rowlan of Echometer; and Tony Podio; presented at 2015 Southwestern Petroleum Short Course

9. Encline Smart ESD products are IoT-enabled
The basic Smart ESD device:
Allows remote ESD and shutdown reset
Has four digital inputs designed for common pump shutdowns, such as:
Beam vibration switch
Low flowline pressure
High flowline pressure
High Enviro-pot, separator, or tank level
Installs between the timer or RPC wiring and motor contactor, and will stop pump operation if any of the above are tripped
Provides local annunciation of shutdown, and web / Scada
Hosts real-time actionable webpage of pumping unit status
Stays in operators firewall, no cloud
Communicates in multiple Modbus languages
Communicates over ethernet or serial ports

10. Smart ESD with Frac Hit Early Warning
Utilizes two analog inputs to collect tubing pressure and casing pressure data
Utilizes two digital outputs to control valves on the tubing and casing outlets
Casing valve reverts to fail open position when frac hit detected to prevent casing over-pressure (collection of velocity indicator stops)
Tubing valve will close when frac hit detected to prevent filling with frac fluids
Pump operation will stop when frac hit detected
Alarmed through Scada system, with local annunciation

11. Precision wired 8” x 10” Nema 4X Cabinet houses all components

12. Final Thoughts
Many older vertical wells are endangered by offset hydraulic fracturing operations.
Encline’s Smart ESD with Frac Hit detection offers operators a cost-effective way to:
Turn off the pumping unit and shut the tubing when unknown frac hits are determined to be happening
For wells with high casing pressure ratings, the casing can also be closed
Annunciate common pumping unit shutdown systems
Locally, over Scada, or real-time actionable webpage
Remotely reset these shutdowns using secure passcodes
Quantify normal fluid entry rates through use of a Velocity Indicator, calculating averages and variances, and storing this historical data onboard
Quantify abnormal fluid entry rates through statistical comparison of current Velocity indicators to the historical average and variance values
Provide for low cost collection of tubing and casing pressure data

13. What do we need help with?
Wells to test, so that we can tune our Velocity Indicator and Variance calculations
An active horizontal drilling program in a field with existing vertical conventional rod pumped wells
Preferably have ethernet access, allowing webpage access and ability to revise product software

14. For additional information:
Please contact us at enclinelift.com or
Bill Elmer or
VP of Engineering and R&D
David Elmer
VP of Business Development
Jacob Wright
Product Support Engineer
John Elmer
President