Module 2: Sucker-Rod Pumping Systems

Beam units, rod strings, and downhole pump mechanics.

⏱ 60 minutes🎯 Beginner🎁 Free

🎯 Learning Objectives

  • Explain how beam units convert rotary to reciprocating motion.
  • Identify the function of the rod string and downhole pump valves.
  • Estimate production rate using Q ≈ A × Stroke × SPM × Fillage × 1440 × η.
  • List common operational issues (gas interference, wear) and mitigations.

📘 Key Terms

SPM Fillage Traveling valve Standing valve Polished-rod load

📎 Prerequisite

Module 1 — Intro to Artificial Lift
Time: ~60 min Level: Beginner Format: Video + reading + quiz

ℹ️ What & Why

Sucker-rod systems use a surface beam unit to drive a reciprocating downhole pump. They are the most widely deployed lift method, spanning low-rate land wells to large fields, thanks to simplicity, maintainability, and cost effectiveness.

⚙️ Principles of Operation

  • Beam/gearbox converts rotary motion to a vertical stroke at the polished rod.
  • Rod string transmits the motion to the downhole pump barrel & plunger.
  • Upstroke: traveling valve closes; fluid passes the standing valve and lifts.
  • Downstroke: traveling valve opens; chamber fills for the next cycle.

🧩 System Components

  • Surface unit (beam + gearbox) and prime mover (motor/engine).
  • Sucker-rod string (graded/tapered) to manage load and wear.
  • Downhole pump with traveling & standing valves.
  • Tubing anchor / seating nipple for pump placement.
  • Wellhead & polished-rod seal for load transfer and sealing.

📏 Operating Considerations

💡
Field Tip
Start with moderate SPM and tune for fillage & efficiency before increasing rate.
⚠️
Common Pitfall
Ignoring gas interference at the pump intake reduces fillage and increases loads. Add separation strategies where needed.

🧪 Worked Example — Estimating Rate

Formula

Q ≈ Aplunger × Stroke × SPM × Fillage × 1440 × ηvol

Given: Plunger Ø = 1.5 in → A = 1.767 in²; Stroke = 100 in; SPM = 8; Fillage = 0.85; ηvol=0.9.

Compute: Q ≈ 1.767 × 100 × 8 × 0.85 × 1440 × 0.9 / 231 ≈ ~850 bpd (approx.).

231 in³ = 1 gallon; 42 gal = 1 bbl. Use detailed corrections for slip/compressibility in practice.

Beam pumping unit showing major surface components
Figure 2.1 — Beam pumping unit with major components.
Sucker-Rod pumping unit schematic and linkage
Figure 2.2 — Sucker-Rod pumping unit schematic.

Tip: Click any figure to open the full-size image in a new tab.

✅ Quick Knowledge Check

1) Which component converts rotary to reciprocating motion?
The surface beam + gearbox provides the reciprocating stroke.
2) Low pump fillage is most commonly due to…
Gas at the intake reduces effective intake volume; separation helps.
3) Spot the mistake (Worked Example): Which change most directly increases Q?
Q scales with SPM and stroke while fillage & efficiency remain high.

🧾 Summary & Takeaways

  • Beam/gearbox creates a reciprocating stroke that drives the downhole pump.
  • Traveling/standing valves control intake and lift across strokes.
  • Rate scales with A, stroke, SPM, fillage, and volumetric efficiency.
  • Watch for gas interference, deviation wear, and excessive loads.
  • Tune SPM and separation first; then optimize rod design and pump size.

➡️ What’s Next

Up next: Module 3 — Electrical Submersible Pumps (ESP)
Recommended: skim a vendor beam-pump manual; review your field’s SPM/fillage trends.
Go to Module 3 →
Last updated: Aug 2025 • Author: Atlas ESP Academy
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