Laboratory analyses of the oil samples indicate the oil has a gravity of 18.5 degrees API.
The U.S. giant will pay $3 billion to take over the Calgary firm.
The sale of Nexen Inc. to CNOOC, valued at over $15 billion, would be the largest-ever foreign acquisition by a Chinese company.
British Columbia Premier Christy Clark has written to the premier of Alberta, saying she will be available next week for possible talks in Calgary.
Over the initial 48 hour flow period the TT-13 well produced at an average oil rate of 2,959 barrels of oil per day.