IPTC 17238 5 resulting from reservoir charging events. No initial gas caps existed in the Burgan field. However, secondary gas caps were formed in the structurally high areas of Magwa and Ahmadi soon after production started. The PVT tables employed in the model were from previous studies. An attempt was made to enhance the PVT characterization with a conceptual PVT model utilizing all PVT data from 1946 to 1990. Systematic extrapolation with priority to early time data allowed generation of estimated PVT properties in areas of deficiency in PVT date coverage. However, it was unsuccessful due to the limited early time PVT data and the fact that the new PVT tables led to instability problems in flow simulation. The final model used the PVT tables from previous studies with some modifications in the dissolved gas-oil-ratio versus depth (RSVD) data. In view of the uncertainties predicated upon how well the existing fluid PVT data characterize a complex the size of the Greater Burgan, a comprehensive PVT campaign was put in place and is already underway, to significantly raise the quality and coverage of hard data to guide the next generation of development efforts on the field. Rock properties Laboratory routine core analysis (RCAL) and special core analysis (SCAL) formed the basis in generating relative permeability tables for oil-water and oil-gas systems. Reservoir Quality Index [RQI = 0.0314*(K/ φ ) 1/2 ] methodology, combined with the rock types defined in the geological modeling phase, were used extensively to produce robust workflows in assigning initial water saturation (Swi) in the dynamic model and defining end-points, Residual oil saturation (Sorw), Irreducible water saturation (Swirr). For oil-water system, only one set of normalized relative permeability curves was used, however, end-points in each cell were varied according to the cell’s RQI / rock type. Sorw values were assigned by reservoir whereas Swirr was calculated based on a RQI-related equation. Similarly, only one set of gas-oil relative permeability curves was used. It was treated in the same manner using critical gas saturation and residual oil saturation to gas. For consistency, end-point scaling option was used to scale the initial water saturation (Swi) and irreducible water saturation (Swirr) in each cell. Recurrent Data The 65 years of production together with 2278 wells/completions created a significant challenge in the preparation of the simulation input. Well-by-well, historical data such as deviation surveys, production (oil, water and gas), and completions/workovers were downloaded from the corporate database. Several applications and utility tools were developed and utilized to quality check and assemble the recurrent data into the correct and required simulation format. The team adopted a string-based concept to group production data into either tubing allocated or casing allocated. Five different production strings, namely Tubing (T), Casing (C), Both tubing and casing (B), Tubing Long (TL) and Tubing Short (TS) were assigned to all wells.
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- Winter '15
- Computer simulation, greater burgan field, Burgan field