Mita,
Thanks for that info. I am currently exploring the OpenSpirit plug-in for Petrel that you mention. It will be nice to see added support for this.
I was able to come up with a work-around for now where I create a tab delimited csv file out of an ERSI GIS vector polyline featureclass file (sub-surface contours) using the Data Interoperability Tool keeping only X,Y,Z attributes which Petrel will except as a general format. Unfortunately this does not include any other attributes. I am able to bring in other attributes as a Petrel Point Attribute file format which includes the X,Y,Z columns plus an addtional column for an attribute to use.
Thanks,
Michael