16. Commitments

We have operating lease agreements for office space and office equipment. The lease for the majority of our office space terminates in December 2022. Minimum future lease payments due under noncancelable operating leases with terms in excess of one year as of December 31, 2013 are as follows (in millions): 2014–$1.3; 2015–$1.3; 2016-$1.3; 2017-$1.4; thereafter–$8.0.   

Total rent expense was approximately $2.6 million, $1.7 million and $1.9 million during 2013, 2012 and 2011, respectively.

Pursuant to the Purchase and Sale Agreement with Total E&P, we are required to fulfill security requirements related to ARO for certain properties through bonds or making payments to an escrow account or a combination. As of December 31, 2013, we were in compliance with the security amount requirement of $55.0 million. Additional security requirements are $9.0 million in 2014, $9.0 million in 2015, $6.0 million in 2016, $6.0 million in 2017 and $18.0 million in the 2018 to 2023 time period to a total security requirement of $103.0 million by 2023.

Pursuant to the Purchase and Sale agreement with Shell related to ARO for certain properties, we have bonds that are subject to re-appraisal in the 2015. The current security requirement of $74.0 million could be increased up to $94.0 million depending on certain conditions and circumstances.

We have additional bonding requirements primarily related to properties owned by our subsidiary, W&T Energy VI, LLC, which require bonds in compliance with requirements set by the BOEM.  These bonds are required as long as W&T Energy VI, LLC owns the properties, including completion of plugging and abandonment activities.

Total fees related to bonds, inclusive of the bonds in connection with Total E&P and Shell described above, were $5.0 million, $2.9 million and $2.6 million during 2013, 2012 and 2011, respectively.  The amount of future commitments is dependent on rates charged in the market place and when asset retirements are completed.  Estimated future fees related to bonds were based on current market prices and estimates of the timing of asset retirements, of which some wells and structures are estimated to extend to 2030.  Future costs are estimated as follows (in millions):  2014–$5.5 million; 2015–$5.7 million; 2016–$5.8 million; 2017–$5.7 million; thereafter– $48.4 million.  See Note 18 for additional information in connection with bond requirements.

Pursuant to an agreement with the Helix Well Containment Group, we are required to make payments to have access to certain equipment to respond to a subsea spill should a spill occur at a property we operate. As of December 31, 2013, future payments due are $1.9 million in 2014, $1.9 million in 2015 and $1.9 million in 2016. These payments may increase or decrease depending on whether the number of companies participating in the consortium changes.

We have no drilling rig commitments with a term that exceeded one year as of December 31, 2013 and our drilling rig commitments meet the criteria of an operating lease. Future payments of all drilling rig commitments as of December 31, 2013 were $21.5 million in 2013.