Jeff Knight and Thomas Vest, Diamondback Energy
Jeff Saponja, Oilfy
Sucker rod pumping for horizontal wells has advanced considerably over the past few years. Advancements in sucker rod pump technologies and bottomhole assembly (BHA) components/configurations have allowed for more efficient downhole gas separation and greater production drawdowns. The unintended consequence has been an escalation of solids in the produced fluids with increased failure frequencies.
Solids control while sucker rod pumping horizontal wells is risky, complex and tricky, especially for when lowering a pump into the curve or using Extended Dip Tube systems in the curve. Extended Dip Tube systems position the pump in the vertical or near vertical and place the gas separator deeper in the curve.
Lab and field studies confirm that gassy-slug flow moves solids as migrating dunes/beds. These dunes accumulate (over weeks and months during steady production) in the lower portion of the wellbore’s curve section where gravity starts limiting dune migration. The risk is any surge in gas rate, flow interruption, or shutdown instantly mobilizes the accumulation of solids as high-concentration solids slugs—overwhelming BHA’s and causing stuck/failed pumps.
A comprehensive systems solution was essential: advanced BHA’s paired with targeted operating practices to defeat solids slugging. The following solution has proved effective:
1. Apply operational practices to control and limit formation high concentration solids slugs:
a. Invoke a preventative maintenance casing flush program, especially after shutdowns
b. Employ operational practices that avoid gas rate surging and spiking
c. Employ rod pump controller logic that reduces slug flows
2. Design the BHA with technologies and configurations that limit slug flows.
3. Design the BHA with technologies that firstly “bust up” solids slugs and then separate solids for containment out of harm’s way. This includes a slug busting solids separator that operates at high inclinations (such as 90 degrees).
4. Design the pump to efficient convey solids through itself.
Results from implementation of this comprehensive approach with innovative solids control and separation technologies will be shared and discussed.