Development of a simple correlation utilizing field data and the standing-katz gas Z-factor method for predicting the oil formation volume factor at undersaturated conditions
Το work with title Development of a simple correlation utilizing field data and the standing-katz gas Z-factor method for predicting the oil formation volume factor at undersaturated conditions by Tyrakis Nikolaos is licensed under Creative Commons Attribution 4.0 International
Bibliographic Citation
Nikolaos Tyrakis, "Development of a simple correlation utilizing field data and the standing-katz gas Z-factor method for predicting the oil formation volume factor at undersaturated conditions", Master Thesis, School of Mineral Resources Engineering, Technical University of Crete, Chania, Greece, 2016
https://doi.org/10.26233/heallink.tuc.66913
The Oil Formation Volume Factor, Bo, is used in almost all the Reservoir and Production Engineering calculations for converting subsurface fluid volumes to surface ones. The knowledge of its value is a prerequisite for evaluating reliably initial hydrocarbon volumes in place, predicting hydrocarbon recovery and future reservoir performance and identifying the drive mechanism.The values of the Oil Formation Volume Factor are measured during the PVT study and they become usually available several months after the well has been tested. In the meanwhile, crucial reservoir engineering decisions have to be made by the Operator, including the estimation of the reserves and the future production plans for which values of Bo are provided by widely used correlations which only require data that are measured in the field during the Well Test (solution GOR, API, Sg, Tres). Given that these correlations are equations fitted against experimental data of oils from certain origin and composition, their accuracy is doubtful.The present master thesis deals with the development of a simple correlation, called liquid Z-factor based method, using fundamental relationships, for the determination of the Bo at undersaturated conditions. The correlation expresses the Bo as a function of data that are measured in the field during the Well Test and the reservoir density at reservoir pressure. The DAK representation of the Standing-Katz Z-factor chart was used for the computation of the crude oil density, and an Excel spreadsheet was developed to incorporate all the above calculations.A literature review was conducted to qualify 5 correlations currently used by the oil industry. These correlations were also included in the Excel spreadsheet.The field data of reservoir oils from all over the world was used for testing the performance of the developed correlation against the performance of the other well-known correlations.The results are very encouraging, since, the proposed method proved not only comparable but even more accurate and applicable in a wider range of Bo than the other presented correlations.