Heavy Crude Oil Sampling and Assay For Refinery Capacity Planning: Design, Plan and Execution In A Supergiant Green Field

Abstract

Assessing heavy oil composition of a green field, with an accepted level of uncertainty so it can be used for refinery capacity planning is a critical challenge. Knowledge of heavy crude oil properties is vital to understand potential adverse impact on process performance and total costs of the whole value chain, downstream (corrosion, catalyst deactivation, fouling and pumping) and upstream (corrosion, fouling, obstruction, producibility, lifting, pumping and transportation). The usefulness of heavy oil properties is highly dependent upon how samples are representing the bulk of hydrocarbon resources that will be developed and the reliability of the sampling procedure which becomes even more challenging when performed in a geologically complex, multilayered, supergiant green field with wide variations of fluid properties vertically and aerially. In this paper we present a field case with the methodology used to design, plan and execute a heavy oil sampling and essay for refinery capacity planning and the lessons learned, in an area of the field representing the first phase of development, in a supergiant heavy oil green field located in north of Kuwait. This heavy oil sampling and essay was planned and executed under high levels of uncertainty, using previous crude assays, PVT data from appraisal and thermal pilot wells and reservoir static and dynamic model. Extensive statistical analysis was applied to understand and map uncertainties related to sampling, completeness and representativeness of laboratory tests vs. accepted international standards. The methodology was applied by a multidisciplinary project team involving specialists from upstream and downstream who performed the work using project management tools to design and implement the execution of sampling in the field. The project took near one year to complete and results are now used for refinery capacity planning at short and midterm. Lessons learned were documented so the future sampling and assays can be improved as data from more wells is going to be available during execution of development phase.