System Design Principles
1) Emulsion Stability & Wettability Control:
The selection of a stable water-in-oil (W/O) emulsion system is based on emulsification efficiency and wettability tests to optimize a composite emulsifier package.
A suitable wetting agent ensures surface wettability reversal of solid particles (e.g., weighting materials, drill cuttings).
2) Rheology Optimization:
A low-viscosity, high-yield-point (LV-HY) fluid is achieved by selecting an optimal rheology modifier, ensuring high yield point-to-plastic viscosity (YP/PV) ratio for effective hole cleaning in ERD wells.
3) System Performance Requirements:
The formulated OBDF must exhibit thermal stability (up to 180°C), contamination resistance, stable rheology, and LV-HY properties to meet ERD operational demands.
Key Component Optimization:
1. Emulsifier Selection:
A composite ("one-drum") emulsifier system is critical for forming a stable W/O emulsion.
Dual emulsifiers (primary + secondary) enhance interfacial film strength compared to single emulsifiers.
Optimal primary-to-secondary emulsifier ratio (0.8–1.0) achieves >90% emulsification efficiency.
2. Wetting Agent Selection:
ME-OWET (an amide-based wetting agent) demonstrates superior thermal stability (180°C) and ensures effective wettability reversal of barite particles.
3. Rheology Modifier Selection:
ME-MOD maintains consistent apparent viscosity (AV), plastic viscosity (PV), and yield point (YP) before/after aging, with minimal YP/PV ratio variation (stable at 180°C).
4. Fluid Loss Control Agent Selection:
ME-BLACK LIG (a lignite-derived additive) provides calcium/clay & seawater contamination resistance, non-viscosifying effects, and thermal stability (180°C).
