Evaluation of formation damage and filter cake removal with a new LPM drilling fluid additive

Abstract

This study evaluates the LPM-FBR drilling fluid additive's performance in minimizing formation damage and facilitating filter cake removal in fractured and high-permeability cores. Using a Formation Damage System Apparatus, two experimental studies were conducted to address the challenge of balancing fluid loss control and formation damage mitigation in fractured reservoirs. The first study, comparing a base saltwater mud with and without LPM-FBR on a 1231 mD fractured sandstone core, showed that LPM-FBR significantly enhanced fluid loss control. It withstood 552 psi overbalance pressure with minimal fluid loss (85.6 mL over 6 h), effectively sealing fractures. However, it reduced return permeability from 1500 to 47.8 mD. The second study, using a 2000 mD fractured core, demonstrated LPM-FBR's effectiveness in limiting filtrate invasion to 5.7 mL over 4 h at 600 psi overbalance. Subsequent cleaning with caustic soda proved ineffective, severely impairing return permeability to 19–28 mD. A breaker solution with a high flow rate of water flushing showed more promise in filter cake removal. This research highlights the trade-offs between fluid loss control and formation damage when using LPM-FBR muds. While excelling in minimizing fluid losses under high overbalance conditions, the additive poses challenges in post-drilling permeability restoration. These findings underscore the need for comprehensive removal procedures to mitigate long-term productivity impairment in fractured reservoirs, contributing valuable insights for optimizing drilling fluid design and post-drilling cleanup strategies.

Keywords

• Drilling mud
• Formation damage
• Filter cake Removal
• Loss-prevention material
• Wellbore cleaning