Managed Pressure Drilling: Operations Safety Measures
Question: How do you know is the managed pressure drilling Operation matrix is “safe”?
RCD Limit: 450 psi
LOT: 13 ppg
Min Influx allowed while drilling: 2 Bls*
Max Influx allowed while drilling: 5 Bls*
* Data as per company’s polices
Answer: Run IME and check safe influx values.
The objective Influx management Envelope (IME) determines if an influx can be run safely under certain conditions by running dynamically the influx control (Circulating out).
IME is a dynamic process, pump must to be on at normal drilling or circulating rate.
1-Identify what is the maximum allowable expanded at surface influx size that not exceed primary barrier limits.
2-Calculate influx at the bottom at time detection (flow)
Influx volumes< can be circulated within the primary barrier
Influx > required use of secondary barrier
1. Enter Data into Influx Management Envelope
RCD Limit :480 psi. Maximum RCD pressure in dynamic conditions.
Circulating : 100 psi. Under this pressure is safe to take influxes while circulating
Circulating Backpressure: 180 psi. During connection is safe to take influxes under this pressure.
Minimum Detection Limits: 2 bbls. According with company polices is under this amount is safe to circulate the influx with MPD equipment.
Maximum Detection Limits: 5 bbls. According with company polices is the Maximum volume of influx allowed to circulate the influx with MPD equipment.
After enter above data into IME, it shows this picture
Also the IME provides this information:
|297||2.0||If the MPD equipment detect and control an influx 2 Bbls under 297 psi is safe to circulate|
|233||5.0||If the MPD equipment detect and control an influx 5 Bbls under 233 psi is safe to circulate|
|283||4.0||If the MPD equipment detect and control an influx 4 Bbls under 283 psi is safe to circulate|
2. Run the above scenarios to confirm dynamically if those values are correct.
Adjusted Post Influx
Adjusted Post Influx Data
|KI Post||Volume Influx||Description|
|294||2.0||If the MPD equipment detect and control an influx 2 Bbls under 294 psi is safe to circulate|
|218||5.0||If the MPD equipment detect and control an influx 5 Bbls under 218 psi is safe to circulate|
|265||4.0||If the MPD equipment detect and control an influx 4 Bbls under 265 psi is safe to circulate|
This data table shows.
KI: Influx intensity (ppg)
Max Vol: shows the maximum influx at surface due gas expansion.
Gas (SCFM): Maximum gas at surface and we can decide if the influx can be also circulated through MPD separator.