Rallen Australia is attempting to overturn a court order granting Tamboran Resources subsidiary Sweetpea Petroleum access to Tanumbirini station in the gas-rich Beetaloo Basin.
Sweetpea previously won the legal right to explore parts of the 5000sq km property, 600km southeast of Darwin, in the NT Civil and Administrative Tribunal.
But Rallen's lawyer Noel Hutley SC says the tribunal erred when it interpreted parts of the legislation, and failed to balance Rallen and Sweetpea's competing interests in the five-year agreement.
"The exercise of assessing what should have been in the access agreement was infected by legal error," he told the Supreme Court in Darwin on Monday.
"The whole decision is bad ... It should be sent back to the tribunal for reconsideration."
Rallen has eight grounds of appeal, including the argument that the decision failed to provide sufficient protection for the water infrastructure on Tanumbirini, which the cattle are reliant on in the dry season.
"To have an explorer argue that cutting the surface of the land up to access the assets below doesn't result in interference is something we struggle with," lawyer Kathy Merrick said outside court.
Workers started clearing land, sinking bores and building roads at the station in May.
"Sweetpea's operations are already causing havoc. They have cut our fences, bulldozed access routes and flouted their own plans for protecting our stock," Rallen co-director Pierre Langenhoven said before the hearing started.
He estimates it's likely to cost Rallen between $5 million and $8.5 million, depending on the number of the wells sunk.
"At the moment there's one well, it doesn't look like much, but when there's 190 wells on the property, it's a totally different story and then it's too late," Mr Langenhoven said.
He said paddocks would be cut by multiple well pads and compression stations joined by roads and gas pipelines.
"There will be no space for the cattle in that paddock," he said.
"I don't have an issue with them sharing the land but I have an issue with them dictating how we can use the land. They have been very disrespectful."
Mr Langenhoven said Sweatpea also planned to build an 18m wide access road across a protected Aboriginal sacred site called Newcastle Creek.
The pastoralist leases 1.1 million hectares of land across six NT stations, with 70,000 head of Brahman cattle. It has spent $200 million in the past four years developing the properties.
Tamboran has an agreement with the Northern Land Council, the native title holders of the area and a permit for exploratory fracking in parts of Tanumbirini and the neighbouring Beetaloo station.
The company says pastoral and exploration lease holders granted overlapping land access have co-existed successfully over many decades for the mutual benefit of their industries, traditional owners and the environment.
"Rallen, as a pastoral lease holder, have no right to attempt to block lawful exploration activities approved under our land access agreement, however, we respect the rights of Rallen," a spokesman said.
The Beetaloo is one of a number of gas fields the previous Morrison government planned to develop to help boost the economy and secure Australia's energy supply.
It caused concern among many in the territory, who fear it could jeopardise efforts to meet the nation's emissions reduction target and contaminate groundwater in a series of linked aquifers.
About 90 per cent of the NT's water supply comes from groundwater.
The hearing continues on Tuesday.
