Field2, Field3, Field5, Field6, Field8, Field9, Field11, Field12, Field16 can be discarded?
Field14 does not have data, Field15 has data.
If I understand correctly, result from this example will be 51 fields and one record.
You need to pivot 3 sets of data. This is a CROSSTAB query. CROSSTAB requires 3 fields. I think will need another field with a common value on each row. Each import will need this field populated, number 1 will serve. Can use the ID field for this. An UPDATE query can populate the field. This will be RowHeading field.
For one method of CROSSTAB for multiple sets of values review http://allenbrowne.com/ser-67.html#MultipleValues
Another approach is to do 3 separate CROSSTAB queries then join them on the ID field.
Here is one of the CROSSTAB queries:
TRANSFORM First(Sheet1.Field4) AS FirstOfField4
GROUP BY Sheet1.ID
Use the query that joins the 3 crosstabs as source for inserting record into the final table.