If your marriage is registered correctly, chances of an annulment are slim, at best. A messy process procedes.
If your Spanish is good, you can read the article on the right column of this page: http://www.divorcioperu.com/anulacion.php
If you need a good lawyer for a divorce, let me know (I am in the process of, but for different reasons!)
If not, here's a rough Google translation, below. However, you have to PROVE everything and there will be an investigation. If your partner is not cooperative, you may be in for a lonnnnnng process.
Church Court may grant an annulment after a thorough investigation of the reasons presented by the plaintiff (the filing the petition). During the investigation, the court communicates with both parties to hear their arguments.
Among the reasons that may lead to the annulment:
Lack of canonical procedure if one party is Catholic and needs to be married in the presence of a priest, deacon or bishop.
The existence of an impediment that can not be dispensed. (Eg marriage between siblings).
The presence of an intention contrary to the marriage at the time of the wedding.
The presence of a psychological factor that one or both has been prevented from making a commitment in conscience.
The inability to assume the primary responsibilities of marriage.
The use of force or deception to carry one or both marriage.
The court decides cases based generally in the diocese where the plaintiff lives.