Powershell script:
if(!(Get-PSSnapin Microsoft.SharePoint.PowerShell -ErrorAction:SilentlyContinue)) 
{ 
    Add-PsSnapin Microsoft.SharePoint.PowerShell 
}
$webURL = "http://sp-test/sites/RU_test"
$docLibraryName = "Documents"
$User = 'i:0#.w|micro\administrator'
$web = Get-SPWeb $webURL
$docLibrary = $web.Lists[$docLibraryName] 
$audit = $docLibrary.Audit
$auditEntries = $audit.GetEntries()
$targetUserId =  $web.AllUsers | Where{$_.UserLogin -eq 'i:0#.w|micro\administrator'} 
$Output = @()
foreach($entry in ($auditEntries | Select -unique))
{
    $FileName = $entry.DocLocation
    $userId = $entry.UserId
    $userEntry = $web.AllUsers | Where{$_.ID -eq $userId}
    $userName = $userEntry.UserLogin
    $Output+=New-Object -TypeName PSObject -Property @{
        FileName = $FileName
        userName = $userName
        Occurred = $entry.Occurred
        Event = $entry.Event
    } | Select-Object FileName,userName,Occurred,Event
}
$Output | Export-Csv -Path 'C:\Temp\audit.csv' -NoTypeInformation -Encoding unicode -Delimiter "`t"Happy Coding!
