Note 18. Commitments and Contingencies Lease Obligations We executed two office leases during the nine months ended September 30, 2018. In June 2018, we executed a new lease for corporate office space that has escalating payments. The estimated commencement date is January 1, 2019 and the lease terminates on December 31, 2026. The lease for our current corporate office is expected to terminate on December 31, 2018. In August 2018, we executed a new lease for our Fort Worth office with a start date of October 1, 2018 and terminating on September 30, 2021, with a penalty-free early termination clause after two years. The table below reflects our estimated minimum commitments as of September 30, 2018 related to our office leases (in thousands): Remaining 2018 2019 2020 2021 2022 Thereafter Office Leases $ 390 $ 2,249 $ 2,285 $ 2,254 $ 2,066 $ 8,621 Litigation &amp; Environmental We are party to various ongoing and potential legal actions relating to our entitled ownership interests in certain properties. We evaluate the merits of existing and potential claims and accrue a liability for any that meet the recognition criteria and can be reasonably estimated. We did not recognize any liability as of September 30, 2018 and December 31, 2017. Our estimates are based on information known about the matters and the input of attorneys experienced in contesting, litigating, and settling similar matters. Actual amounts could differ from our estimates and other claims could be asserted. Klein v. Graham, et al. : On August 2, 2018, James M. Klein filed a derivative action in the Delaware Court of Chancery against seven of the Companys directors and one of its former directors (the Director Defendants), NGP Energy Capital Management, LLC, CP VI Eagle Holdings, L.P. (the Carlyle Investor), and (as a nominal defendant only) the Company. The complaint asserts claims relating to the Companys entry into a Preferred Stock Purchase Agreement with the Carlyle Investor, dated May 10, 2017. The lawsuit seeks monetary damages and attorneys fees. The Company believes the claims are entirely without merit and intends to vigorously defend against them. On October 2, 2018, a stipulation of dismissal without prejudice was granted as it relates to Messrs. Clarkson and Sims. From time to time, we could be liable for environmental claims arising in the ordinary course of business. We did not record environmental obligations at September 30, 2018 and at December 31, 2017. Firm Gas Transportation Service Agreement The Company had a firm gas transportation service agreement with Regency Intrastate Gas LLC as discussed in our 2017 Form 10-K. In connection with the NLA Divestiture, we transferred this agreement to Tanos. Dedicated Fracturing Fleet Services Agreements A discussion of these agreements are included in our 2017 Form 10-K. Interruptible Water Availability Agreement The Company entered into an interruptible water availability agreement with the Brazos River Authority (BRA) that began on February 1, 2017 and ends on December 31, 2021. The agreement provides us with an aggregate of 6,978 acre-feet of water per year from the Brazos River at prices that may be adjusted periodically by BRA. The agreement requires annual payments to be made on or before February 15 of each year during the term of the agreement. We recorded a payment of $0.5 million and $0.4 million during the nine months ended September 30, 2018 and 2017, respectively.