Canada-based oil company CGX Energy OYL.V will begin dredging and building the docks of a key deepwater port at Berbice, in eastern Guyana, planned to serve the South American nation's oil and agriculture sectors, the firm's chairman said on Wednesday.CGX Energy unit Grand Canal Industrial Estates in 2010 acquired a 50-year lease for a 55-acre parcel strategically located near the Berbice River for the project…