Aphrons are specially stabilized micro-bubbles created in situ to aid in suppressing the loss of drilling fluid into high-permeability formations. Water-based aphrons are designed for aqueous drilling fluids, while oil-based aphrons are designed for non-aqueous fluids. In both cases, the micro-bubbles are composed of a core of gas or liquid stabilized by proprietary polymers and surfactants, which can aggregate to form a tough, elastic barrier to loss of drilling fluid in permeable zones. Some of these zones are typified by water-wet sands that are susceptible to fluid seepage and differential sticking. Others are characterized by laminated sand and shale sequences, which are expensive to drill with conventional drilling fluids or underbalanced drilling rig equipment.

The authors describe how use of water-based and oil-based aphrons in drilling fluids can mitigate losses of drilling fluids downhole.

Keywords:
jamin effect, society of petroleum engineers, application, concentration, drilling fluids and materials, capillary pressure, viscosity, spe 80208, surfactant layer, drilling fluid formulation
Subjects:
Drilling Fluids and Materials, Drilling fluid selection and formulation (chemistry, properties), Drilling fluid management & disposal
Copyright 2003, Society of Petroleum Engineers
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