Reducing Uncertainty in Hydrocarbon Pore Volume Estimation of Giant Multi-Layered Reservoirs, Saudi Arabia

Hussain M. Al Sabti
Saudi Aramco, Dhahran, Saudi Arabia

Integrated Reservoir studies coupled with leading edge technology that Saudi Aramco uses has had a profound impact on reducing the uncertainty of hydrocarbon pore volume estimates. Experienced, multidisciplinary teams have been assembled to apply geological, geophysical and petrophysical technology to perform fully integrated reservoir studies, which will expand and accurately define the pore volume base of Aramco's reservoirs. In the past few years, Aramco has implemented a major program to review existing Special Core Analysis studies and perform new petrophysical studies wherever deemed necessary. These data were interpreted to define and characterize rock types and then integrated with other geological and production data to better define the storage and flow capacity/characteristics of the reservoir. This presentation will discuss the multiple techniques used in this integrated approach with an emphasis on petrophysical techniques. Some of the examples that are described in this presentation are log-to-core calibration, saturation estimations using electrical property measurements, capillary pressure and saturation height functions and reservoir cutoffs techniques.

Special Core Analysis studies are used to characterize fit-for-purpose rock types; which may address problems of flow, saturation, residual oil saturation and water cut for examples. The petrophysical parameters associated with each rock type are then used to integrate core, log, performance, geological and simulated performance. Rock types tied to the geology and saturations are then distributed throughout the 3D Geocellular model using saturation-height models for an accurate estimate of hydrocarbons in place. Implementation of new technology such as NMR and ECS coupled with these advanced petrophysical models are very useful in relating core based petrophysical properties to reservoir scale attributes; lithology, reservoir quality, movable and bound fluids, transition zones and productive intervals for hydrocarbon production. This petrophysical approach to our integrated studies has resulted in substantial amount of hydrocarbon pore volume revision for many of our reservoirs.

AAPG Search and Discovery Article #90039©2005 AAPG Calgary, Alberta, June 16-19, 2005