Benjamin Boakye, a director at the country's Africa Center for Energy Policy, said 20 percent of the country's potential reserves have been explored and new investors are needed to exploit the remaining 80 percent.
Boakye was quoted by the Platts energy news website as saying efforts by the Ghanaian government to expand exploration are short of what's needed to prevent "favoritism and cronyism."
"The laws need to be tightened up," he said Thursday.
Ghana's government expects to draw in at least $20 billion in new investments in the next five years
Deputy Energy Minister Benjamin Dagadu was quoted as saying evaluation of new bids was "ongoing."
The Tweneboa-Enyenra-Ntomme off the coast of Ghana should deliver its first oil by 2016. At its peak, it is expected to produce about 80,000 barrels per day. The Jubilee field off the coast could eventually produce more than 125,000 bpd, operator Tullow Oil says.