PHASE 5 (1981 – 2001)
Oil and gas exploration continued both onshore and offshore during this phase.
In 1979, Phillips Petroleum appraised the South Tano discovery and made gas and condensate find on the satellite 1S-3AX structure down dip of the main field.
They went ahead to further appraise the South Tano find by drilling IS-4X in 1981. They declared the South Tano discovery sub-commercial.
About the same time, Phillips Petroleum again appraised the North Tano find discovered earlier by Volta Petroleum.
They drilled the 1N-1X well in 1980 and 1N-2X well in 1981. These wells encountered both oil and gas. However, they declared this field too as non-commercial and relinquished the block.
The government at that time then decided to establish an institutional capacity, as well as the statutory and legal framework that would accelerate the country’s Exploration and Production (E & P) efforts. Subsequently, the current petroleum exploration & production, the petroleum income tax and the GNPC laws (PNDC Laws 84, 188 and 64) were enacted.
PNDCL 64 (1983) established the Ghana National Petroleum Corporation (GNPC) as a statutory body from the then Petroleum Department under the Ministry of Mines and Energy. This was to provide the requisite institutional framework to handle the country’s E & P activities. GNPC started operations in 1985.
PNDCL 84 (1984) established the legal and fiscal framework for the conduct of petroleum Exploration and Production activities in Ghana. GNPC was to become a virtual one-stop shop for investors in the upstream petroleum industry in Ghana.
Similarly, the Petroleum Income Tax Law, PNDCL 188 provided for a separate tax regime for petroleum exploration and production in Ghana.
As the sole statutory body to spearhead the search for commercial oil and gas to meet the country’s needs and let her be a net exporter of hydrocarbons, GNPC pioneered E & P activities. It sought for funds through various means to finance its activities.
One achievement of the fund raising efforts was that, in the Mid 80’s, the Canadian government, acting through Petro Canada International Assistance Corporation (PCIAC), expended considerable funds to support GNPC. In addition to helping to establish, equip and train personnel for GNPC’s research Laboratory, they also acquired extensive 2D seismic data in the offshore Tano/Cape Three Points basin in 1984 (PCIAC – 84 -97, 98 &99 vintages). These datasets are still some of the best in the basin. PCIAC also drilled 13 wells in the Tano basin – two (2) South Tano appraisal wells (ST-5 and ST-6), and eleven (11) shallow depth onshore wells (Ghancan wells).
In 1989, GNPC funded the acquisition, processing and interpretation of the first 3D seismic data over the South Tano Field with the firm conviction that the field is viable for national development. Following interpretation of the 3D seismic data and the studies undertaken to determine the viability of the Integrated Tano Fields Development Project (ITFDP) to use the gas for power generation, GNPC drilled three wells over the South Tano field – one (1) exploratory well ST–8 (1991), and two (2) appraisal wells ST-7H (1992) and ST-9H (1994). Both appraisal wells were horizontal wells. GNPC had by this time (1994) acquired one drillship and at least three other rigs in addition to other infrastructure to help facilitate the development of the Tano fields.
As part of the ITFDP, GNPC ordered a power barge to utilise the anticipated gas from the Tano fields. The infrastructure for the power barge and power transmission lines to link to the national grid was installed at Effasu-Mangyea in the Jomoro district in the Western region with funds that GNPC had secured.
GNPC also funded other seismic operations from 1989 to 1991. These included:
The shallow marine 2D seismic surveys in the Tano, Saltpond and Accra/Keta basins
The 2D land seismic survey in onshore Tano and Accra/Keta basins
The 2D seismic data over the Saltpond field
The 2D seismic (GNCT-88 vintage) in the Tano/Cape Three Points area
The Saltpond Field, which started production in 1978, was shut-in during the mid eighties by Primary Fuels Incorporated (PFI). PFI had acquired AgriPetco’s interest in the Saltpond Field. The latter had pulled out due to low, uneconomic production rates. Finally, PFI pulled out after drilling three wells; one gas well and two dry wells that did not meet their expectations.
Other companies operated in Ghana at various times during this period and made some finds:
In 1989, a consortium led by Atlantic Richfield Company Limited (ARCO) found gas with their Central Tano – 1 (CTS-1) well. Then they found heavy oil in the same year with their North West Tano – 1 (NWT-1) well. The CTS-1 find was declared sub-commercial while the exact accumulation of the NWT-1 was not determined because it was not mapped either before or after the well. However, recent mapping by GNPC personnel suggested that it could be worth looking at again.
In 1999, Hunt Oil Company found oil with their WCTP-2X well in deepwater. Hunt Oil declared the find non-commercial and subsequently pulled out in 2002.
Dana Petroleum Plc also found heavy oil with their WT-1X well drilled in 1999.
Other companies such as Nuevo Energy Resources, AGIP, Diamond Shamrock, Devon Energy and Fusion Oil (West Oil) all undertook exploration activities in Ghana’s coastal and offshore sedimentary basins during this period. These activities provided the National Oil Company (GNPC) with a lot of geological/geophysical data. The staff of GNPC also gained much experience in dealing with the operations of international Oil Companies.
Presented below is the list of wells drilled in this phase.