$resOrder = Bitrix\Sale\OrderTable::getList(
    array(
        'filter' => array('=USER_ID' => 1),
        'group' => array('PAYED'),
        'runtime' => array(           
            new Bitrix\Main\Entity\ExpressionField('IDS', 'GROUP_CONCAT(%s)', array('ID')),
        ),
    )
);