Hi Charles,
In my country we can create Resident Foreign Currency accounts in USD. But I'm not sure how it's done in Nigeria. Please check with your bank. 
Hi Charles,
As Shenan suggested, you may want to check with your local banks about opening a US dollar account. Once you do, you can look into wire transfer as an option to withdraw your Upwork earnings. Here are some details about timing and fees related to wire transfers.
~ Valeria
