First Successful Utilisation of High Density Micronised Ilmenite in South East Asia

Abstract

The objective of this paper is to share the Operator's first experience in utilizing ilmenite in an offshore HPHT well as part of a low cost well initiative and the value obtained by utilization of such a weighting agent in particular towards lowering ECD. After extensive testing micronized ilmenite was used as the weighting agent for the synthetic based drilling fluid (SBM) for the B1 well. This well was classified as high complexity with a narrow margin window and with predicted maximum bottom hole pressure of 12,013 psi at 3,990 m TVDDF. Extensive laboratory testing was conducted to determine the optimum formulation for a 16 ppg SBM. Part of the methodology in the testing was conducting rheology comparisons between various weighting agents, manganese tetraoxide, barite and micronized ilmenite. The subsequent results were then run through hydraulics simulations to determine the best formulation for optimized hydraulics. Additional testing was conducted to determine the overall stability of the system including conducting static sag tests with a similar duration to the planned wireline logging operation. The primary drivers for using this fluid were to reduce ECD in a narrow margin environment and facilitate the taking of good wireline logs by providing optimum hole conditions without any sag. The micronized ilmenite system successfully achieved a similar rheology to manganese tetraoxide with low PV's of less than 50 cP at 17 ppg and a sag index of less than 0.52. These properties were at an OWR of 80:20. This led to both the successful drilling of the well and completing the required wireline logging with no fluids related NPT or issues related to sag. During logging, the mud was static for 5 days without problems. The mud weight of 17 ppg was the highest density, at that time, at which the micronized ilmenite system had been used.