Пример реализации класса для работы с PHPExcel

<?error_reporting(E_ALL);
ini_set('display_errors', TRUE);
ini_set('display_startup_errors', TRUE);

require($_SERVER["DOCUMENT_ROOT"]."/bitrix/modules/main/include/prolog_before.php");
require($_SERVER["DOCUMENT_ROOT"]."/local/lib/PHPExcel/PHPExcel.php");

class GenerateReportAboutUsersBP{

    private $bp_id, $objPHPExcel;

    function __construct($bp_id){

        $this->bp_id         = $bp_id;
        $this->objPHPExcel  = new \PHPExcel();
    }

    public function generate(){

        $sheet      = $this->objPHPExcel->getActiveSheet();

        $arResult   = $this->getUsers();

        $bpName     = $this->getBpName();

        if( count($arResult) > 0 ){

            $this->objPHPExcel->getActiveSheet()->mergeCells("A1:H1");
            $this->objPHPExcel->getActiveSheet()->setCellValue("A1", $bpName);
            $this->objPHPExcel->getActiveSheet()->getStyle("A1")->getAlignment()->setHorizontal(PHPExcel_Style_Alignment::HORIZONTAL_CENTER);

            $styleArray = array(
                'font'      => array(
                    'bold'      => false,
                    'size'      => 15,
                ),
                'borders'   => array(
                    'allborders' => array(
                        'style' => PHPExcel_Style_Border::BORDER_THIN,
                    )
                )
            );

            if(count($arResult[0])==1){
                $this->objPHPExcel->getActiveSheet()->mergeCells("A2:H2");
            }

            foreach(array_keys($arResult[ key($arResult) ]) as $i=>$title){
                $this->objPHPExcel
                    ->getActiveSheet()
                    ->setCellValueByColumnAndRow($i, 2, $title)
                    ->getStyle()
                    ->applyFromArray($styleArray);
            }

            $this->objPHPExcel
                ->getActiveSheet()
                ->getRowDimension('1')
                ->setRowHeight(40);

            foreach (range('A', $this->objPHPExcel->getActiveSheet()->getHighestDataColumn()) as $col) {

                $this->objPHPExcel
                    ->getActiveSheet()
                    ->getStyle($col."1")
                    ->applyFromArray($styleArray);

                $this->objPHPExcel
                    ->getActiveSheet()
                    ->getStyle($col."1")
                    ->getAlignment()
                    ->setVertical(PHPExcel_Style_Alignment::VERTICAL_CENTER);

                $this->objPHPExcel
                    ->getActiveSheet()
                    ->getStyle($col."1")
                    ->getFill()
                    ->setFillType(PHPExcel_Style_Fill::FILL_SOLID)
                    ->getStartColor()
                    ->setRGB('DCE6F4');

                $this->objPHPExcel
                    ->getActiveSheet()
                    ->getStyle($col."2")
                    ->applyFromArray($styleArray);

                $this->objPHPExcel
                    ->getActiveSheet()
                    ->getStyle($col."2")
                    ->getAlignment()
                    ->setVertical(PHPExcel_Style_Alignment::VERTICAL_CENTER);

                $this->objPHPExcel
                    ->getActiveSheet()
                    ->getStyle($col."2")
                    ->getFill()
                    ->setFillType(PHPExcel_Style_Fill::FILL_SOLID)
                    ->getStartColor()
                    ->setRGB('DCE6F4');

                $this->objPHPExcel
                    ->getActiveSheet()
                    ->getColumnDimension($col)
                    ->setAutoSize(true);
            }

            $row = 0;

            foreach($arResult as $arUser){

                $col = 0;

                if(count($arUser)==1){
                    $this->objPHPExcel->getActiveSheet()->mergeCells("A3:H3");
                }

                foreach($arUser as $val){

                    $this->objPHPExcel->getActiveSheet()->setCellValueByColumnAndRow($col, $row + 3, $val);

                    $col++;
                }

                $row++;
            }

            $objWriter = new \PHPExcel_Writer_Excel2007($this->objPHPExcel);
            $objWriter->setPreCalculateFormulas(false);

            header('Content-Type: application/vnd.openxmlformats-officedocument.spreadsheetml.sheet');
            header('Content-Disposition: attachment; filename="'.$this->bp_id.'.xlsx"');
            header('Cache-Control: max-age=0');

            $objWriter->save("php://output");

        }
    }

    public function getUsers(){

        \CModule::IncludeModule('bizproc');
        \CModule::IncludeModule("iblock");

        $getBpID = \COption::GetOptionString("main", "BP_DOC");

        $allIDValues = "";
        $allIDValuesList = [];
        $allElementsList = [];
        $allResultList = [];
        $arFilter = array(
            "IBLOCK_ID" => $getBpID,
            "CHECK_PERMISSIONS" => "N",
            "SHOW_NEW" => "Y",
            "ID" => $this->bp_id
        );
        $rsElements = \CIBlockElement::GetList(
            array(), $arFilter, false, false, array("ID","IBLOCK_ID","NAME","DATE_CREATE","CREATED_BY","PROPERTY_SROK","PROPERTY_KOGO")
        );
        while($obElement = $rsElements->GetNextElement()) {
            $data = $obElement->GetFields();
            $allIDValues .= $data["ID"].", ";
            $allElementsList[$data["ID"]] = $data;
        }

        $allIDValues = mb_substr($allIDValues, 0, -2);

        $connection = \Bitrix\Main\Application::getConnection();
        $sqlHelper = $connection->getSqlHelper();
        $workflow_id = "";

        $sql = "SELECT * FROM b_bp_workflow_state WHERE DOCUMENT_ID_INT IN($allIDValues)";//AND STATE = 'InProgress'
        $recordset = $connection->query($sql);
        while ($record = $recordset->fetch())
        {
            $workflow_id .= "'".$record["ID"]."', ";
            $allIDValuesList[$record["ID"]] = $record["DOCUMENT_ID_INT"];
        }

        $workflow_id = mb_substr($workflow_id, 0, -2);

        $sql = "SELECT * FROM b_bp_tracking WHERE WORKFLOW_ID IN($workflow_id)";
        $recordset = $connection->query($sql);
        while ($record = $recordset->fetch())
        {
            if (strpos($record["ACTION_NOTE"], 'Ознакомление с документом пользователями из списка') !== false) {
                $newTitle = substr($record["ACTION_NOTE"], strpos($record["ACTION_NOTE"], '{=user'));
                $pieces = explode(", ", $newTitle);
                $arUsers = array();
                foreach ($pieces as $piecesKey => $piecesVal){
                    if (strpos($piecesVal, 'group_dr') !== false) {
                        $str = preg_replace("/[^0-9]/", '', $piecesVal);
                        unset($pieces[$piecesKey]);
                        $arUsersDep = CBPHelper::extractUsersFromExtendedGroup("group_dr".$str);
                        $arUsers = array_merge($arUsers,$arUsersDep);
                    }
                    else{
                        $str = preg_replace("/[^0-9]/", '', $piecesVal);
                        $pieces[$piecesKey] = $str;
                    }
                }
                $pieces = array_merge($pieces,$arUsers);
                $pieces = array_unique($pieces);
                $allResultList["ALL_USER"] = $pieces;
            }

            if(strpos($record["ACTION_NOTE"], 'ознакомился с документом') !== false){
                $pattern = '/\{(.+?)\}/';
                preg_match_all($pattern, substr($record["ACTION_NOTE"],3), $matches);

                $str = preg_replace("/[^0-9]/", '', $matches[0]);

                $comment = explode("документом:", $record["ACTION_NOTE"]);

                $dateEdit = $record["MODIFIED"]->toString();

                $allResultList["USER_VOTED"][$str[0]] = array("COMMENT"=>$comment[1],"DATE"=>$dateEdit);
            }
        }

        $arAllSection = array();
        $arFilter = Array('IBLOCK_ID'=>5, 'GLOBAL_ACTIVE'=>'Y');
        $db_list = \CIBlockSection::GetList(Array($by=>$order), $arFilter, true);
        echo $db_list->NavPrint($arIBTYPE["SECTION_NAME"]);
        while($ar_result = $db_list->GetNext())
        {
            $arAllSection[$ar_result['ID']] = $ar_result['NAME'];
        }

        $arAllUser = array();
        $user_filter = array("ID"=>implode("|", $allResultList["ALL_USER"]));
        $rsUsers = \CUser::GetList($by="ID", $order="desc", $user_filter, array("SELECT"=>array("UF_1C_PRFB0C9F4DC8C6","UF_DEPARTMENT","UF_1C_PRF508AFB5863A"), "FIELDS"=>array("ID","NAME","LAST_NAME"))); // выбираем пользователей
        while($rs = $rsUsers->GetNext()) {
            $rs["UF_DEPARTMENT"] = $arAllSection[$rs["UF_DEPARTMENT"][0]];
            $arAllUser[$rs["ID"]] = $rs;
        }

        $arAllResult = array();
        if(!empty($allResultList["ALL_USER"])){
            foreach ($allResultList["ALL_USER"] as $resultKey => $resultVal){
                $arAllResult[$resultVal] = array(
                    "№ п\п" => $resultKey+1,
                    "Фамилия Имя" => $arAllUser[$resultVal]["LAST_NAME"]." ".$arAllUser[$resultVal]["NAME"],
                    "Табельный номер" => $arAllUser[$resultVal]["UF_1C_PRFB0C9F4DC8C6"],
                    "Статус ознакомления" => (!empty($allResultList["USER_VOTED"][$resultVal]))?"Ознакомлен":"Не ознакомлен",
                    "Дата" => $allResultList["USER_VOTED"][$resultVal]["DATE"],
                    "Комментарии" => $allResultList["USER_VOTED"][$resultVal]["COMMENT"],
                    "Бюджет" => $arAllUser[$resultVal]["UF_1C_PRF508AFB5863A"],
                    "Подразделение" => $arAllUser[$resultVal]["UF_DEPARTMENT"],
                );
            }
        }
        else{
            $arAllResult[] = array(
                "Ошибка"=>"Документ в статусе 'Ожидание дополнительной информации'"
            );
        }

       return $arAllResult;
    }

    public function getBpName(){
        \CModule::IncludeModule("iblock");

        $getBpID = \COption::GetOptionString("main", "BP_DOC");

        $bpName = "";
        $arFilter = array(
            "IBLOCK_ID" => $getBpID,
            "CHECK_PERMISSIONS" => "N",
            "SHOW_NEW" => "Y",
            "ID" => $this->bp_id
        );
        $rsElements = \CIBlockElement::GetList(
            array(), $arFilter, false, false, array("ID","IBLOCK_ID","NAME")
        );
        while($obElement = $rsElements->GetNextElement()) {
            $data = $obElement->GetFields();
            $bpName = $data["NAME"];
        }
        return $bpName;
    }
}

$report = new GenerateReportAboutUsersBP($_REQUEST["bp_id"]);

$report->generate();
?>