Reservoir Fluid Characterization and Application for Simulation Study

Abstract

The paper presents a methodology to develop and apply an equation-of-state (EOS) multi-fluid model for a field in Tunisia. The EOS model was developed by matching measured PVT data for a near-critical oil sample. The fluid characterization was used to estimate contamination level in oil-based-mud contaminated MDT samples, calculate decontaminated sample composition, estimate zone composition based on clean-up test measured oil-gas ratio, estimate fluid composition of some layers where samples were not available, and study the effect of gas condensate blockage and capillary number on simulated well performance. In this field, reservoir fluids range from lean gas condensate to rich gas condensate and volatile oil. Clean up tests were conducted for all four zones encountered in the well, and oil-gas ratios were measured. During the clean up test of one zone, a near critical oil sample was collected and standard PVT experiments were conducted. Oil based mud (OBM) contaminated MDT samples were collected from six of the nine non-communicating layers, with OBM contamination levels between 20–65 wt% STO. An EOS model was developed after matching measured PVT data on the near-critical oil sample. The MDT samples were decontaminated using measured mud composition. The calculated decontaminated "clean" sample compositions were used in a reservoir simulation model to initialize the layer from which the MDT sample was taken. The developed EOS model was also used to estimate the fluid composition of different zones and layers without fluid samples. The zone fluid compositions were calculated based on measured test OGR. The EOS model, zone fluid compositions, decontaminated MDT samples, and layer mobilities were used to estimate fluid composition of the layers without samples. This paper provides a methodology that can be used in any other field.

An effective characterization procedure for petroleum reservoir fluids using molecular type methods and cubic equations of state

“…T A B L E 5 Specifications of the reservoir fluids used in this study [47,48] Oil Normal boiling point values of plus fractions have been calculated using the distillation curve method. [52] T A B L E 6 The sequence of computational steps for seven different characterization procedures [37] Proposed model in Equation (5) Proposed model in Equation…”

“…Jhaveri and Youngren [46] Proposed model in Equations ( 7)- (10) 2 SAP Hosseinifar and Shahverdi [37] Proposed model in Equation (5) Proposed model in Equation…”

“…Based on this, the fluid characterization procedure is essential as an engineering solution to solve the problem. [4][5][6] Undoubtedly, the type of equation of state directly affects the performance of characterization methods. Many researchers in recent years have developed interesting characterization approaches based on the statistical equations of state.…”