Do we need to apply for a Visa? Do you have offices in Saudi Arabia, Khobar City?

Yes, you need to apply for a L type. According to Chinese embassy, you should submit your applications to the appointed companies.
1. Foreign Affairs and Business Service Office
Payless Building, Beside Samba Bank, King Abdullah Road, Alworod District, Riyadh, K.S.A

2. Chinese Competitive Spirit Company
Ground Floor, Sada, 1 Business Center Olaya District, Riyadh

3. Alsandross International Est
Bin Salem Trading Center, Al Takhassusi Street, next to Emirates Airlines office, Riyadh