Missa Keswal Oil Field Potwar, Pakistan, a Failure Turned into Success

Agha Sher Hamid Zaman and Shahid Aziz Zahidi

Missa Keswal oil and gas field is located 70 km SSE of Islamabad in the eastern part of Potwar basin. On surface, it is a thrust bounded anticline striking in SW-NE direction. First seismic work was carried out in 1980, followed by drilling of an unsuccessful well. Another well was drilled after an improved seismic programme which resulted in discovery of oil and gas in seven different reservoir units of Cambrian, Permian, Paleocene, Eocene and Miocene age. Among these, three reservoir units namely Jutana, Baganwala and Kussak of Cambarian age had never produced in the Potwar basin earlier. The field had original, in place, proven reserves of 37.650 MMSTB of oil and 27.900 BSCF of gas. Current production from three wells is around 4500 barrels of oil and 7.3 MMSCFD of gas a day. This production comes from fractured limestone and porous sandstone rocks.

It is an exploration case history, making a comparison between old and new seismic work. Low density of seismic profiles, inaccurate acquisition and processing parameters and lack of local interpretation experience contributed to earlier failures. Interpretation of new seismic data reveals that strata of platform sequence display a duplex geometry overlain by a passive roof complex of Siwaliks sequence as against earlier interpretation of a pop up structure. Closed area at Eocene level is 30 sq. kms., structure is bounded by a main thrust fault in the strike direction. Few orthognal faults exist which may provide lateral barriers to the flow during production. Probably upward migration of oil from the underthrusted block of the duplex has contributed to the occurrence of a multi-reser oir system in the upper block.

AAPG Search and Discover Article #91019©1996 AAPG Convention and Exhibition 19-22 May 1996, San Diego, California