(EN) Disclosed are methods of determining the effectiveness of an asphaltene deposition inhibitor in oilfield applications. Such methods typically comprising the steps of introducing an oil well fluid into a microfluidic/millifluidic system; introducing a mixture of an asphaltene deposition inhibitor and carrier into the microfluidic/millifluidic system; introducing a precipitating agent, typically comprising heptane, into the microfluidic/millifluidic system; and optionally introducing toluene into the microfluidic/millifluidic system; then observing the presence or absence of asphaltene aggregation within the microfluidic/millifluidic system.