require_once($_SERVER["DOCUMENT_ROOT"] . "/bitrix/modules/main/classes/general/csv_data.php");

$filePath = $_SERVER['DOCUMENT_ROOT'] . '/upload/users.csv';
$fp = fopen($filePath, 'w+');
@fclose($fp);

$fields_type = 'R'; //дописываем строки в файл
$delimiter = ";";   //разделитель для csv-файла
$csvFile = new \CCSVData($fields_type, false);
$csvFile->SetFieldsType($fields_type);
$csvFile->SetDelimiter($delimiter);
$csvFile->SetFirstHeader(true);


$arUsers = array();
$csvFile->SaveFile($filePath, array("LOGIN", "ACTIVE", "NAME", "LAST NAME", "E-MAIL", "DATE_REGISTER", "ID", "Раздел регистрации", "UTM_CAMPAIGN", "UTM_TERM", "UTM_CONTENT", "UTM_SOURCE", "UTM_MEDIUM", "Баллы за рефералов", "Реферальный код"));

$res = CUser::GetList(($by="id"), ($order="desc"), [], ["SELECT"=>["LOGIN", "ACTIVE", "NAME", "LAST_NAME", "EMAIL", "DATE_REGISTER", "ID", "UF_SECTION_REGISTR", "UF_UTM_CAMPAIGN", "UF_UTM_TERM", "UF_UTM_CONTENT", "UF_UTM_SOURCE", "UF_UTM_MEDIUM", "UF_POINTS_REF", "UF_REF_PARENT"]]);
while($arUser = $res->Fetch()) {
    $arUsers[] = [
        $arUser["LOGIN"],
        $arUser["ACTIVE"],
        $arUser["NAME"],
        $arUser["LAST_NAME"],
        $arUser["EMAIL"],
        $arUser["DATE_REGISTER"],
        $arUser["ID"],
        $arUser["UF_SECTION_REGISTR"],
        $arUser["UF_UTM_CAMPAIGN"],
        $arUser["UF_UTM_TERM"],
        $arUser["UF_UTM_CONTENT"],
        $arUser["UF_UTM_SOURCE"],
        $arUser["UF_UTM_MEDIUM"],
        $arUser["UF_POINTS_REF"],
        $arUser["UF_REF_PARENT"]
    ];
}

foreach($arUsers as $row)
{
    $csvFile->SaveFile($filePath, $row);
}