10. COMMITMENTS AND CONTINGENCIES

Commitments

The Company leases corporate office space in Houston, Texas; Tulsa, Oklahoma; and Denver, Colorado as well as a number of other field office locations. In addition, the Company has lease commitments for certain equipment under long-term operating lease agreements. The office and equipment operating lease agreements expire on various dates through 2024. Rent expense was approximately $8.7 million, $3.7 million and $1.3 million for the years ended December 31, 2013, 2012 and 2011, respectively. Approximate future minimum lease payments for subsequent annual periods for all non-cancelable operating leases as of December 31, 2013 are as follows (in thousands):


2014	$	8,540
2015		9,062
2016		8,855
2017		9,047
2018		9,299
Thereafter		23,828


Total	$	68,631

As of December 31, 2013, the Company has drilling rig commitments as follows (in thousands):


2014	$	37,672
2015		11,275
2016		—
2017		—
2018		—
Thereafter		—


Total	$	48,947

As of December 31, 2013, early termination of the drilling rigs commitments would require termination penalties of $30.2 million, which would be in lieu of paying the remaining drilling commitments of $48.9 million.

The Company has various other contractual commitments for, among other things, pipeline and well equipment, seismic, and infrastructure related expenditures.


2014	$	15,388
2015		—
2016		—
2017		—
2018		—
Thereafter		—


Total	$	15,388

The Company has entered into various long-term gathering, transportation and sales contracts in its Bakken / Three Forks formations in North Dakota which are not included in the tables above. As of December 31, 2013, the Company had in place nine long-term crude oil contracts and two long-term natural gas contracts in this area. Under the terms of these contracts, the Company has committed a substantial portion of its Bakken / Three Forks production for periods ranging from five to ten years from the date of first production. The sales prices under these contracts are based on posted market rates. The Company believes that there are sufficient available reserves and supplies in the Bakken / Three Forks formations to meet its commitments, as the proved reserves from this area represent approximately 67% of its total proved reserves.

Additionally, as of December 31, 2013, the Company had one long-term natural gas transportation contract and one long-term natural gas gathering contract in the Woodbine formation in East Texas which are not included in the tables above. The rate under the transportation contract was negotiated based on market rates and the contract term is five years from the date of first production. Under the gathering contract, the Company has committed substantially all of its natural gas production from specific wells in the area, until a contracted volume amount is reached, in exchange for the construction of a gathering system. The contract term is five years from the date of first production.

Historically, the Company has been able to meet its delivery commitments.

Contingencies

From time to time, the Company may be a plaintiff or defendant in a pending or threatened legal proceeding arising in the normal course of its business. While the outcome and impact of currently pending legal proceedings cannot be determined, the Company's management and legal counsel believe that the resolution of these proceedings through settlement or adverse judgment will not have a material effect on the Company's consolidated operating results, financial position or cash flows.