Enhancing formation breakdown pressure using optimized drilling fluid additives with preventive wellbore...

Area of Science:

• Petroleum Engineering
• Drilling Engineering
• Wellbore Integrity

Background:

• Formation fracture pressure evaluation is critical for preventing induced fracturing and drilling fluid losses.
• Conventional approaches consider formation breakdown pressure (FBP) an intrinsic rock property, independent of drilling fluid characteristics.
• Lost circulation remains a significant challenge in oil and gas well drilling operations.

Purpose of the Study:

• To investigate the impact of drilling fluid sealing performance on formation breakdown pressure (FBP) and fracture reopening pressure (FRP).
• To evaluate the effectiveness of lost circulation materials (LCMs) in enhancing wellbore strengthening and preventing fluid losses.
• To assess the role of drilling fluid additives in improving the pressure-bearing capacity of formations.

Main Methods:

• Prepared twenty-five drilling fluid formulations with various lost circulation material (LCM) combinations.
• Evaluated fluid loss behavior and mud cake quality using an API filter press apparatus.
• Assessed the five best-performing drilling fluids using a wellbore strengthening evaluation device.

Main Results:

• The optimal LCM combination resulted in a thin, low-permeability mud cake with superior sealing properties.
• Significant increases were observed: up to 42% in formation breakdown pressure (FBP) and 95% in fracture reopening pressure (FRP).
• API filter press data showed qualitative agreement with wellbore strengthening test results, suggesting its utility as a preliminary screening tool.

Conclusions:

• Well-designed drilling fluids incorporating effective LCMs play a vital role in preventing lost circulation.
• Improving drilling fluid sealing performance demonstrably enhances wellbore strengthening and pressure-bearing capacity.
• API filter press tests offer a rapid, cost-effective method for preliminary screening of drilling fluid formulations for wellbore strengthening applications.