Abstract: Methods for optimizing petroleum reservoir analysis and sampling using a real-time component wherein heterogeneities in fluid properties exist. The methods help predict the recovery performance of oil such as, for example, heavy oil, which can be adversely impacted by fluid property gradients present in the reservoir. Additionally, the methods help optimize sampling schedules of the reservoir, which can reduce overall expense and increase sampling efficiency. The methods involve the use of analytical techniques for accurately predicting one or more fluid properties that are not in equilibrium in the reservoir. By evaluating the composition of downhole fluid samples taken from the reservoir using sensitive analytical techniques, an accurate base model of the fluid property of interest can be produced. With the base model in hand, real-time data can be obtained and compared to the base model in order to further define the fluid property of interest in the reservoir.