Some wells in the Middle East have “Cyclic Production” behavior. For example, they produce for 10 days and then need to be shut in for 7 days so the reservoir can recharge, after which the well can be opened again.
What causes this behavior? And what are the solutions for maintaining production from such wells?
Main Causes of Cyclic Production
1. High Drawdown:
When the well is opened, pressure drops quickly. If the reservoir cannot recharge the well fast enough, pressure continues to decline and production falls. Shutting in the well allows pressure to rebuild.
2. Low or Heterogeneous Permeability:
Many reservoirs have low or discontinuous permeability, making fluid movement to the wellbore slow. Thus, cyclic production helps balance reservoir recharge.
3. Low Reservoir Energy (Depletion):
In depleted reservoirs or those lacking strong drive mechanisms (e.g., gas cap or aquifer), continuous production is not sustainable.
4. Coning or Unwanted Water/Gas Production:
Continuous production can cause water or gas coning, lowering production quality. Cyclic production helps mitigate this.
Solutions to Maintain or Improve Production
1. Optimize Production and Shut-in Cycles (Using Well Test Data):
Use real well data to find the optimal balance between production time and shut-in duration (e.g., produce for 5 days, shut in for 3 days). Well test data can be used for this purpose. Use pressure transient analysis to better understand recharge rate, permeability, and reservoir characteristics.
2. Drawdown Control:
- Reduce production rate to prevent rapid pressure drop.
- Choke size optimization to manage drawdown levels.
3. Acid Stimulation:
If low rates are caused by near-wellbore damage or blockages, acidizing operation can restore performance.
ESP-Lifted Wells with Cyclic Production
In a situation where the installed ESP pump capacity is higher than the reservoir’s ability to feed the well, the pump will eventually shut down due to the drop in fluid level inside the annulus. This condition is technically referred to as Pump-Off. In such cases, pump operation must be controlled (by reducing the frequency to decrease the flow rate), although this may not be ideal!
