| ● | NGLs marketing revenues were $4 million for the nine months ended September 30, 2024. There were no NGLs marketing revenues for the nine months ended September 30, 2023. |
Marketing expense. Marketing expense decreased from $217 million for the nine months ended September 30, 2023 to $193 million for the nine months ended September 30, 2024, a decrease of $24 million, or 11%. Marketing expense includes the cost of third-party purchased natural gas, NGLs and oil as well as firm transportation costs, including costs related to current excess firm capacity. The cost of third-party natural gas purchases decreased $47 million between periods, partially offset by increased oil and NGLs purchases of $38 million and $4 million, respectively. The total cost of third-party commodity purchases decreased primarily due to lower natural gas marketing volumes and prices between periods, partially offset by higher oil prices and marketing volumes during the nine months ended September 30, 2024. Firm transportation costs decreased $19 million from $82 million for the nine months ended September 30, 2023 to $63 million for the nine months ended September 30, 2024, primarily due to the reduction in firm transportation commitments between periods.
Contract termination, loss contingency, settlements and other operating expenses. Contract termination, loss contingency, settlements and other operating expenses attributable to our marketing segment for the nine months ended September 30, 2023, relate to a $24 million payment for the early termination of our firm transportation commitment of 200,000 MMBtu per day on the Equitrans pipeline. Our marketing segment did not incur any contract termination, loss contingency, settlements and other operating expenses for the nine months ended September 30, 2024.
Antero Midstream Segment
Antero Midstream revenue. Revenue from the Antero Midstream segment increased from $782 million for the nine months ended September 30, 2023 to $819 million for the nine months ended September 30, 2024, an increase of $37 million. This increase is primarily due to higher gathering and processing revenues of $66 million, partially offset by lower water handling revenues of $29 million. The increased gathering and processing revenues between periods is primarily a result of the expiration of the growth incentive fee rebate program on December 31, 2023, increased throughput and annual CPI-based gathering and compression rate adjustments between periods. The decreased water handling revenues between periods is primarily due to lower fresh water delivery volumes and lower water handling volumes that are billed at cost plus 3%, partially offset by higher blending volumes and an increased fresh water delivery rate due to an annual CPI-based adjustment during the nine months ended September 30, 2024.
Antero Midstream operating expense. Total operating expense related to the Antero Midstream segment increased from $325 million for the nine months ended September 30, 2023 to $337 million for the nine months ended September 30, 2024, an increase of $12 million. This increase is primarily due to higher general and administrative expense, including equity-based compensation expense, and depreciation expense between periods as well as lower gains on asset sale during the nine months ended September 30, 2024.
Items Not Allocated to Segments
Interest expense. Interest expense increased from $85 million for the nine months ended September 30, 2023 to $91 million for the nine months ended September 30, 2024, an increase of $6 million or 7%, primarily due to higher average Credit Facility borrowings between periods and higher benchmark interest rates during the nine months ended September 30, 2024.
Income tax expense (benefit). For the nine months ended September 30, 2023, we had income tax expense of $46 million, with an effective tax rate of 17%, related to our income before income taxes of $272 million. For the nine months ended September 30, 2024, we had an income tax benefit of $2 million, with an effective tax rate of 9%, related to our loss before income taxes of $25 million. The decrease in the effective tax rate between periods was primarily due to the effects of noncontrolling interests and our loss before income taxes during the nine months ended September 30, 2024.
Capital Resources and Liquidity
Sources and Uses of Cash
Our primary sources of liquidity have been through net cash provided by operating activities, borrowings under our Credit Facility, issuances of debt and equity securities and additional contributions from our asset sales, including our drilling partnership. Our primary use of cash has been for the exploration, development and acquisition of oil and natural gas properties. As we develop our reserves, we continually monitor what capital resources, including equity and debt financings, are available to meet our future financial obligations, planned capital expenditure activities and liquidity requirements. Our future success in developing our proved reserves and production will be highly dependent on net cash provided by operating activities and the capital resources available to us.