Shahriar Osfouri

The main objective of this research is to study the phenomenon of composition gradient in hydrocarbon reservoirs and to develop its thermodynamic modeling. With this point of view, this dissertation has been developed in 5 phases which first 4 phases provide the fields to have more reliable results from modeling, while in phase 5 using the results from preceding phases, modeling of compositional grading has been developed. In the first phase, screening and quality control of available samples have been investigated. To this end, using the data of more than 40 gas condensate samples, the range of acceptable fluctuations of parameters affecting the stability of well conditions is determined using statistical concepts. The results show that only for 11.5% of the samples all parameters were within the acceptable range.