Advanced MPD Techniques for Ballooning Control: Effective Management of Wellbore Breathing and Overbalance Optimization Allowed Successful Navigation Through the 12 in. Section to Achieve Target Depth – Case Study

Abstract

This study explores advanced managed pressure drilling (MPD) techniques to address well-control challenges caused by wellbore ballooning, compounded by high formation-charged mud volumes and aggressive mud contamination. The goal is to demonstrate successful unconventional MPD applications for depleting charged mud volumes during conventional well control operations. The approach aims to mitigate formation breathing effects and reduce overbalance pressure on weak formations to successfully drill the 12 in. section to the planned total depth (TD).

Due to aggressive flow behavior and mud weight reduction from saltwater influx, a methodical approach was implemented to reduce charged volumes in the well through controlled reductions in bottomhole equivalent circulating density (BH ECD). Each pressure decrement stabilized the well and returned charged volumes to the wellbore. Maintaining pressure balance was crucial, with steps executed under controlled conditions followed by circulation in standpipe pressure (SPP) control mode to keep constant bottomhole pressure (CBHP) despite non-homogeneous annular fluids.

The ballooning release technique required precise execution to ensure well stability. Critical requirements included establishing baseline parameters before circulation initiation. These parameters were references for stable conditions, enabling accurate monitoring and adjustments. Given the well's pressure sensitivity, SPP control during influx circulation was essential.

Successful execution of all decrement steps combined with SPP-controlled circulation reduced BH ECD from 150.2 to 146.7 pcf. This reduction decreased overbalance on the low-pressure formation, mitigating the risk of severe or total losses. The well was drilled to TD through careful parameter management while maintaining acceptable loss rates. This methodical approach preserved wellbore stability, minimized operational risks, and ensured optimal well control throughout drilling operations.