National Iranian South Oil Company                                                                                    Petro Hortash Engineering & Drilling Co.

    Kala Naft Tehran Co.                                                                                                            Iranian Offshore Oil Company

    South Pars Oil & Gas Co.                                                                                                       Weatherford (Iran)

       Naft Kave                                                                                                                           Arvandan Oil & Gas Co.         

      Barsha Drill Tools FZE.                                                                                                          National Iranian Drilling Company

     Persia Drilling Oil & Gas Company                                                                                           Exploration Oil

          CNPC (Iran)                                                                                                                         Oriental Oil Kish