$17.0 million, on NGLs of 93% resulting in an increase in revenue of $9.7 million, and on natural gas of 63% resulting in an increase in revenue of $33.0 million.
Production expenses
Production expenses increased $31.4 million, or 105%, from $29.8 million for the six months ended June 30, 2021 to $61.2 million for the six months ended June 30, 2022. The increase is primarily attributable to the increased production associated with the addition of the Vacuum Properties and Andrews Parker properties of $26.9 million as well as increased maintenance costs and other cost increases.
On a per unit basis, production expenses increased from $8.74 per Boe sold for the six months ended June 30, 2021 to $14.52 per Boe sold for the six months ended June 30, 2022. The increase is primarily related to the increased costs per Boe from the acquired Vacuum Properties and Andrews Parker properties due to the acquired properties having a higher percentage of oil production, which is more expensive on a Boe basis than natural gas production. Additionally, increased maintenance costs and other cost increases contributed to the increase per Boe.
Taxes, transportation, and other
Taxes, transportation, and other increased $24.0 million, or 100%, from $24.0 million for the six months ended June 30, 2021 to $48.0 million for the six months ended June 30, 2022. The increase is primarily attributable to the increased production associated with the addition of the Vacuum Properties and Andrews Parker properties of $11.6 million as well as an increase in oil, NGLs, and natural gas prices.
On a per unit basis, taxes, transportation, and other increased from $7.02 per Boe sold for the six months ended June 30, 2021 to $11.40 per Boe sold for the six months ended June 30, 2022. The increase is primarily related to the higher commodity prices and change in production mix.
Depreciation, depletion, and amortization
Depreciation, depletion, and amortization increased $0.9 million, or 5%, from $18.8 million for the six months ended June 30, 2021 to $19.7 million for the six months ended June 30, 2022. The increase is primarily attributable to the increased production associated with the addition of the Vacuum Properties and Andrews Parker properties in the fourth quarter of 2021 of $5.9 million partially offset by a reduction of $5.0 million from our other assets as a result of a lower average DD&A rate partially offset by higher production.
On a per unit basis, depreciation, depletion, and amortization decreased from $5.52 per Boe sold for the six months ended June 30, 2021 to $4.68 per Boe sold for the six months ended June 30, 2022. The decrease is primarily related to changes in reserves.
General and administrative
General and administrative (“G&A”) expenses decreased $2.0 million, or 80%, from $2.5 million for the six months ended June 30, 2021 to $0.5 million for the six months ended June 30, 2022. The decrease is primarily attributable to a reduction of $6.1 million from headcount reductions partially offset by $4.1 million of decreased cost recoveries.
On a per unit basis, G&A expense decreased from $0.72 per Boe sold for the six months ended June 30, 2021 to $0.12 per Boe sold for the six months ended June 30, 2022. The decrease is primarily related to decreased costs and increased production partially offset by decreased cost recovery.
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