Improved Reservoir Description Using Surface Oil Viscosity Data

Abstract

Subsurface oil viscosity data are usually 110t readily

available for most reservoirs, as they are expensive to

acquire. On the other hand, surface oil viscosity is

routinely measured and therefore readily available for

all producing wells. A method has been developed for

converting the surface viscosity to reservoir viscosity

data, using SPDC's "Field A" as a case study.

Surface oil viscosity data from all producing wells in

"Field A" where collected from SPDC-West

Production Chemistry laboratory and converted to

reservoir viscosity using a simple method that utilises

relevant PVT data. The method allows a better and

more detailed subsurface description of reservoir

viscosity in line with facies variations. The study also

shows that reservoir oil viscosity could be lower in

some sands than previously estimated. This gave a

significant impact on reserves in one of the reservoirs

where scope to increase the booked reserves by about

60 MMstb was observed. Opportunity to also -increase

constrained offtake from 2300 bid to 3000 bid in some

planned new wells was also observed.