Read text file and store in db respecting the order

Summary:

Hi, please I would like your help with the following:

I receive a file with this pattern:

line to remove 

line to remove 

line to remove 

<invoice>

****

****

****

</invoice>

line to remove 

line to remove 

line to remove 

<invoice>

****

****

****

****

****

****

</invoice>

line to remove 

line to remove 

line to remove 

<invoice>

****

</invoice>

--------------------------------------------------

The goal is to get a file with format similar to:

<invoices>

<invoice>

****

****

****

</invoice>

  <invoice>

****

****

****

****

****

****

</invoice>

<invoice>

****

</invoice>

</invoices>

I have thought of reading as csv and storing the file in db. and then cleaning up with pl*sql. Any simpler idea will be welcome.