Prediction of Saturation Pressure of Fluid

A method comprising:

• operating a processing system comprising a processor and a memory including computer program code, wherein operating the processing system comprises:
• fitting a model to a transmittance response of a fluid as a function of pressure to obtain a fitted response;
• obtaining a filtered response, a first-order derivative, and a second-order derivative from the fitted response;
• obtaining a first energy ratio function and a second energy ratio function based on the first-order derivative and the second-order derivative, respectively, wherein:
• the first energy ratio function and the second energy ratio function are respective ratios of a first term to a second term;
• the first term is based on a first sliding window along the respective first-order derivative or the second-order derivative;
• the second term is based on a second sliding window along the respective first-order derivative or the second-order derivative;
• and
• the first sliding window is adjacent to and along pressures less than the second sliding window;
• detecting an inflection pressure at a maximum peak of the first-order derivative;
• detecting a downward curve pressure at a trough of the second-order derivative nearest to and greater than the inflection pressure;
• detecting a characteristic change pressure from a collection of pressures nearest to and greater than the downward curve pressure, wherein the collection of pressures comprises first identified pressures at respective peaks of the first energy ratio function and second identified pressures at respective peaks of the second energy ratio function;
• detecting an intersection pressure at an intersection of a first line and a second line, wherein:
• the first line is based on the fitted response at the inflection pressure and the first-order derivative at the inflection pressure;
• and
• the second line is based on the fitted response at the characteristic change pressure and the first-order derivative at the characteristic change pressure;
• and
• estimating a dew point pressure of the fluid based on at least one of the inflection pressure, the downward curve pressure, the characteristic change pressure, and the intersection pressure.