Carbon Management Technology Conference,
7-9 February 2012,
Orlando, Florida, USA
Enhanced oil and gas recovery is going to be the future option for Pakistani
reservoirs sooner or later, when conventional gas deposits will be running
short and oil reservoirs will not be able to continue production under their
current depletion mechanisms.
Reservoir analysed in this study is one of the four vertically stacked heavy
oil reservoirs in an oilfield of Potwar region and producing at lower
production rate. This work is an attempt to screen the subject reservoir for
future decisions. First fluid characterisation was executed using experimental
PVT data. History match was performed using available production and reservoir
data. Since flowing bottom-hole pressures were unavailable, they were generated
using Guo Ghalambor correlation using tubing head pressure information.
Afterwards, reservoir screening was performed using available criteria in the
literature and updated with world EOR survey. Screening dictated the
application of miscible carbon dioxide flooding for the subject reservoir. Also
the reservoir pressure was above bubble point, showing the feasibility for CO2
injection. Minimum miscibility pressure was estimated empirically using Alston
et al. correlation and numerically by slim-tube simulation. MMPs resulted from
both methods well agreed.
Three scenarios were made to analyse the performance of reservoir under the
influence of revitalization planning. Additional producer was placed in the
subject reservoir, which ceased flow after 16 years adding 1 MMSTB of oil to
the reserves. Injecting water enhanced the life of the reservoir to 24 years
yielding 2.8 MMSTB of oil while the application of CO2 miscible flooding
incremented 3.7 MMTSB of oil in the same duration as waterflood.
Results inferred from this study will prove to be a breakthrough in the field
of R&D for welcoming enhanced oil recovery in Pakistan. It also encourages
the industry look ahead to the revitalization of mature and aging oil
Field XYZ under study was located in Potwar Region of Pakistan which is home to
various oilfields which are producing from light to heavy oils.
The Potwar Basin has been actively explored for hydrocarbons since 1870 and
first success came in 1914 when Attock Oil Company discovered oil at Khaur. The
Dhulian, Joyamir and Balkassar field were then discovered by the same company
in 1918, 1943 and 1945 respectively. In 1978 Amoco was granted the exploration
license in the Northern Potwar. In 1982, the concession was granted to the
Occidental of Pakistan, who discovered oil from the Eocene formations and later
from Paleocene and Permian horizons. Similarly, NOC1 was also granted
exploration license in the Northern Potwar Deformed Zone (NPDZ), where it
drilled several exploratory, appraisal as well as development wells
In 1990, with the help of 3D Seismic Survey for the first time in the history
of Pakistan, Rajpet1 field was explored. Fig. 1 is showing the horizon map of a
reservoir in Rajpet oilfield.
Geologically, Rajpet structure is NE-SW trending anticline. The producing part
of the structure is pop up block formed between two thrust faults. The closed
area is about 12 sq.km bounded by 1800 m.sec contour 2.
Field had four vertically stacked reservoirs and to-date 5 wells had been
drilled in this field and 4 were producing (as on 31-12-2010)