Cost-Effective Reservoir Evaluation and Oil Recovery via Biodegradation assessment from Gas Data in Al Shaheen Field

Summary The assessment of oil quality variations and alteration in the low permeability carbonate reservoirs of Al Shaheen field are crucial steps for completion strategies, and offer significant economic benefits, providing a cost-effective approach to reservoir evaluation beneficial to oil upstream. In Al Shaheen field the heterogeneity of oil quality observed within the same reservoir is mainly ascribable to oil biodegradation. These facts enhance the risk of having a low oil productivity during the production phase lateral oil biodegradation assessment and quality prediction is done by mean of geochemistry tools, by integrating ratios from mud gas (C1–C8) and liquid hydrocarbons (C9–C35) obtained from the drilled cuttings using a thermal extraction technology. All ratios show good correlation in describing biodegradation levels for a better assessment, and put the basis for getting a better predictive tool for oil APIs and properties prediction. The proposed oil biodegradation assessment method is a proper tool to help in the determination of the completion design. The qualitative assessment of the hydrocarbons and the identification of the geochemical compositional variation integrating gas and liquid geochemical data from surface samples allow a good understanding of lateral drain variability. Identifying sweet spots via biodegradation is a key for maximum production.