Enables drilling narrow pressure window wells by maintaining constant downhole pressure
The e-cd™ system is an Eni-patented process used as a standalone system or in conjunction with managed-pressure-drilling (MPD) operations to enable continuous circulation – which is the ability to maintain uninterrupted flow of drilling fluid to the well via the drillstring during connections while drilling and tripping out of the hole.
With continuous circulation, the pumps are never turned off while making connections during drilling or tripping. This keeps the bottomhole pressure constant during these activities, maintains fluid rheology and temperatures, and ensures that cuttings are kept moving at all times. Continuous circulation with the e-cd system improves the success rate for challenging projects such as wells with narrow pore pressure/fracture gradients, along with high-pressure/high temperature (HP/HT) wells and extended-reach wells.
Uninterrupted circulation with e-cd systems provides:
- Continuous hole cleaning and solids transport
- Reduced kick/loss conditions, with constant equivalent circulating density (ECD) and bottomhole pressure (BHP)
- Reduced loading of solids during pumps off
- Reduced stuck-pipe and packoff incidents
- Reduced ballooning effects
- Maintained formation integrity
- Improved borehole stability
- Reduced connection gas
- Extended life of bottomhole assemblies (BHAs) and avoidance of mud rheology modifications in high-temperature environments
- Compatibility with wireline/slickline intervention operations
- Complementary systems to backpressure-control MPD systems
The e-cd system is one of the most utilized sub-based continuous circulation systems in the industry, and it has arguably the highest global utilization and success rate of continuous circulation system connections.
The key attributes of the design’s success include:
- A proven and reliable dual metal-to-metal flapper valve configuration for both axial and radial sealing mechanisms
- An active sealing mechanism in axial directions without manual intervention on the rig floor
- A high-flow-rate, side-entry port