Install-Package Oracle.DataAccess.x86

using (OracleBulkCopy bulkCopy = new OracleBulkCopy(conexion))
{
  bulkCopy.DestinationTableName = TABLA;
  bulkCopy.BatchSize = 100000;
  bulkCopy.BulkCopyTimeout = 20000;
  bulkCopy.WriteToServer(data);// checar https://docs.oracle.com/cd/E11882_01/win.112/e23174/OracleBulkCopyClass.htm#CHDHHABB para ver que formato es el mas adecuado para usted
  bulkCopy.Close();
  bulkCopy.Dispose();
  conexion.Dispose();
}