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$res=[];
 $dbEl = \CIBlockElement::GetList(array('sort' => 'asc'), array('IBLOCK_ID'=>14,), false, false, Array('ID','NAME','CODE','IBLOCK_SECTION_ID'));      
while ($obEl = $dbEl->Fetch()) 
{
   $res[$obEl['ID']]['ID']=$obEl['ID'];
   $res[$obEl['ID']]['NAME']=$obEl['NAME'];
   $res[$obEl['ID']]['CODE']=$obEl['CODE'];
   $res[$obEl['ID']]['SECTION_ID']=$obEl['IBLOCK_SECTION_ID'];
   $res[$obEl['ID']]['GROUP']=[];
   $db_old_groups = \CIBlockElement::GetElementGroups($obEl['ID'], true);
   while($ar_group = $db_old_groups->Fetch()){
      $navChain = \CIBlockSection::GetNavChain($ar_group["IBLOCK_ID"], $ar_group["ID"]);
      while ($arNav=$navChain->GetNext()){
         $res[$obEl['ID']]['GROUP'][$ar_group["ID"]][]=$arNav['ID'];
      }               
   }
}
echo "<pre>";print_r($res);echo "</pre>";