Estimation of Shale Gas and Oil Properties Based on Field Data
Distinguished Lecturer Tao Yang, Statoil
Reservoir fluid composition and PVT properties play important role in liquid rich shale development. Accurate estimation of reservoir fluid richness has significant impact on drilling target and well completion. Traditional PVT properties are widely used for reservoir management, production optimization, and economic evaluation.
Unfortunately PVT data from shale reservoirs is rarely available in public literature due to difficulty to obtain representative in-situ fluid samples in extremely low permeability reservoir. This makes understanding shale PVT a very challenging task. Statoil spent two years’ time to collect large amount of PVT samples and measure PVT properties for Eagle Ford field. Wide range of reservoir fluids from dry gas, gas condensate, volatile oil to black oil had been collected and studies thoroughly.
Based on the large PVT database from more than 50 wells, a new methodology was developed to estimate in-situ reservoir fluid composition and corresponding PVT properties based on readily available field data. Only providing one of following field data (either API gravity of surface condensate/oil, gas-oil ratio, surface gas composition, or mud logging data) is sufficient to derive majority PVT properties, including reservoir fluid composition, saturation pressure, formation volume factors, and NGLs.
The new method proposed in this presentation is a technical breakthrough for shale gas and oil properties with many applications with significant improvements. Thanks to reservoir fluid self-consistency in shale plays, it is very practical to estimate reasonable PVT properties based on existing field data without large sampling and laboratory programs.
Tao Yang is reservoir technology specialist at Statoil. He holds BSc and PhD degrees in chemical engineering. Before joining Statoil, Tao Yang worked at Pera a/s - a leading reservoir engineering consulting company in Norway. From association with Prof. Curtis Whitson (Recipient of SPE Anthony F. Lucas Gold Medal 2011), he gained vast industrial experiences from global reservoir engineering consulting projects for more than 200 fields.
Tao Yang has publications in prestigious journals and reviews papers for several technical journals (technical editor of SPE Reservoir Evaluation & Engineering and editorial board member of Journal of Petroleum Science and Engineering). He served as co-chairman and steering committee member for numerous workshops and conferences (including the successful SPE ATW Complex Reservoir Fluids in 2011, 2012 and 2014). He received the SPE Outstanding Technical Editor Award in 2009 and the SPE North Sea Regional Technical Award - Reservoir Description and Dynamics in 2011.