The price of OPEC basket of fourteen crudes stood at $55.20 a barrel on Friday, compared with $55.59 the previous day, according to OPEC Secretariat calculations.
Oil prices fell on Monday, pausing for breath after posting gains of as much as 20 percent in the third quarter, after a survey pointed to a slight increase in OPEC production in September, according to Reuters.
Oil output from the Organization of Petroleum Exporting Countries (OPEC) also rose last month, gaining by 50,000 barrels per day (bpd).
Iraqi exports increased and production edged higher in Libya, one of the OPEC producers exempt from a deal to curb output and support prices.
The OPEC Reference Basket of Crudes (ORB) is made up of the following: Saharan Blend (Algeria), Girassol (Angola), Oriente (Ecuador), Zafiro (Equatorial Guinea), Rabi Light (Gabon), Iran Heavy (Iran), Basra Light (Iraq), Kuwait Export (Kuwait), Es Sider (Libya), Bonny Light (Nigeria), Qatar Marine (Qatar), Arab Light (Saudi Arabia), Murban (UAE) and Merey (Venezuela).