In the world of oil and gas production, the term "under travel" refers to a specific phenomenon related to the movement of the rod string within a well. It occurs when the travel of the rod string at the pump (bottom of the well) is less than the surface rod travel. This discrepancy can have significant implications for well productivity and requires careful monitoring and troubleshooting.
What is Rod String Travel?
Imagine a fishing rod. When you cast the line, the rod bends and the line travels a certain distance. Similarly, in an oil well, the rod string – a series of connected rods that act like a piston – is pumped up and down to lift the oil to the surface. The rod string travel refers to the total distance the rod string moves within the wellbore.
Why Under Travel Happens
Under travel occurs due to various factors, including:
Impact of Under Travel
Under travel can significantly impact well production:
Monitoring and Addressing Under Travel
Early detection of under travel is crucial to mitigating its negative impact. Regular monitoring through:
Once detected, addressing under travel requires careful investigation and analysis to determine the root cause. This may involve:
Conclusion
Understanding the concept of "under travel" in oil and gas production is essential for optimizing well performance and minimizing operational costs. By monitoring rod string travel, analyzing well production data, and effectively addressing the underlying causes, operators can ensure optimal well performance and minimize the negative consequences of under travel.
Instructions: Choose the best answer for each question.
1. What does "under travel" refer to in oil and gas production?
a) The movement of oil and gas within the wellbore. b) The travel distance of the rod string at the surface. c) The difference between the rod string travel at the surface and at the pump. d) The amount of oil produced from a well.
c) The difference between the rod string travel at the surface and at the pump.
2. Which of the following factors can contribute to under travel?
a) Efficient pump operation. b) Low fluid viscosity. c) Smooth wellbore geometry. d) Broken rods in the rod string.
d) Broken rods in the rod string.
3. What is a potential consequence of under travel?
a) Increased oil production rates. b) Reduced operating costs. c) Improved pump efficiency. d) Potential damage to equipment.
d) Potential damage to equipment.
4. Which method is NOT used for monitoring under travel?
a) Surface rod travel measurement. b) Downhole pressure readings. c) Wellbore temperature monitoring. d) Production rate analysis.
c) Wellbore temperature monitoring.
5. What is the first step in addressing under travel?
a) Replacing the entire rod string. b) Increasing the pumping speed. c) Investigating the root cause. d) Shutting down the well.
c) Investigating the root cause.
Scenario: You are an engineer monitoring an oil well. You notice a significant decrease in oil production and a discrepancy between surface rod travel and downhole pump travel, indicating under travel.
Task:
**Potential causes:** * **Pump malfunction:** The pump may be worn out, damaged, or not functioning properly. * **Rod string issues:** Broken rods, worn-out couplings, or stuck rods can hinder movement. * **Fluid conditions:** High viscosity, gas interference, or presence of sand could be hindering the pump's ability to lift oil. **Investigation:** * **Pump malfunction:** Inspect the pump using downhole cameras or other tools to assess its condition. * **Rod string issues:** Run a logging tool to check for broken or stuck rods, or analyze surface rod travel data for inconsistencies. * **Fluid conditions:** Analyze the produced fluid for viscosity, gas content, and sand content. **Solutions:** * **Pump replacement/repair:** If the pump is malfunctioning, it needs to be repaired or replaced. * **Rod string repair/replacement:** Broken rods or worn-out couplings need to be repaired or replaced. If the rod string is stuck, it may need to be freed using specialized tools. * **Fluid management:** If high viscosity, gas, or sand is causing the issue, implementing production techniques like gas lift or artificial lift could be necessary.