High Performance Water-based Drilling Fluids—A High Efficiency Muds Achieving Superior Shale Stability While Drilling Deepwater Well with HPHT in South China Sea

Abstract

In deepwater drilling operation, low temperature, high pressure, gas hydrate, narrow density window are the major challenges for drilling fluids to meet, and with the increasing depth drilled, high temperature and high pressure condition was occurred in deepwater well. In the other side, Oil based muds (OBM) and synthetic based muds (SBM) are limited in using because of the strict environment rules in the South China Sea. In deepwater HTHP well, shale hydration, dispersion and Equivalent Circulation Density (ECD) caused by rheology change with high temperature difference are the two critical problems. Therefore, petroleum service institutes and companies take much time and money on research to develop a high performance water-based mud system (HPWBM) to solve these problems and improve drilling efficiency. In the paper, a new method to estimate amine derivatives was proposed, the specific test steps was introduced in detail, and secondly a High efficiency muds (HEM) are selected and the main properties were evaluated in lab such as rheological properties at lower temperature, shale inhibition and anti-accretion. Finally, the system was applied successfully in LS project in the South China Sea. The results showed that HEM system delivered high drilling performance such as shale stability, high pressure and high temperature (HPHT) resistance, lubricity and high rate of penetration (ROP) with no wellbore problems, and the system is suitable for deepwater HTHP well operation.