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Understanding the Reservoir Heterogeneity for Flow Characterization: From Integrated Case Study of Advanced Logging Applications from Mumbai High Carbonates, India

Madhu M. Panigrahi1, Chandramani Shrivastva2, R. D. Chourasiya1, Arnab Ghosh2, Koushik Sikdar2, and Rudal Singh1
1ONGC, Mumbai, India
2DCS, Schlumberger, Mumbai, India

Predictive understanding of the fluid flow through carbonates depends upon the post depositional effects which tend to introduce heterogeneity in reservoir properties. The multi-layered complex carbonate reservoirs of Mumbai High field are no exception.

This study aims at integration of advanced logging applications viz. magnetic resonance, borehole imaging, formation testing and sonic data along with the conventional open hole logs to understand the facies variation in carbonates that gives rise to heterogeneities in terms of petrophysical properties and therefore reservoir performance.

The study well has been producing oil with 28% water cut for past one year. The borehole images help in identifying the fractures, vugs, dissolution channels and their orientation and attributes. Incorporating these details is imperative to model the flow behaviour more realistically. Dissolution activities enhance the connectedness of the vugs and fractures, therefore providing a pathway for fluid flow. This connectedness is a raw permeability indicator and has been calibrated with magnetic resonance porosity and formation tester mobility. Image derived secondary porosity and magnetic resonance data are used to partition the porosity in micro, meso and macro component. Selective attenuation in acoustic energy is validated by vugs and fractures on image logs. An attempt has been made to understand the effect of injector wells in the nearby area on the production data in context of geological model conceptualized.

Integration of these dataset develops a methodology for identification of high permeability streaks in the reservoirs that needs to be implemented to understand the fluid flow behavior in heterogeneous carbonate systems. The production data calibrated with the study results attests the methodology for further development wells.

Presentation GEO India Expo XXI, Noida, New Delhi, India 2008©AAPG Search and Discovery