Hi Rico: The values of the property field(s) are stored in a single field called "Properties". You can export this field, however, it will be difficult to figure out the name of the fields like so. The example below shows the value of 2 property fields that were added to the opportunity record.

First you have to activate the developer mode, 

and then go to the model where you have the data,

 selecting the data you need to extract, clicking on export,
 
look for the created fields, I imagine that you created them with odoo studio so they usually start with x_studio_ (field)

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