Yemen's Houthi militant group is closing in the the city of Marib, in a key oil producing region, and observers say it may soon turn it attention to Shabwa, the country's other main oil centre.
"The Houthis are making rapid gains in Marib and have made it clear they want to take control of the oil and gas resources, and the power plant," said Peter Salisbury from non-governmental organisation International Crisis Group.
Since capturing the Rahabah and Mahliyah districts, west of Marib city, from government forces in September, the Houthis have pushed on to the outskirts of city capturing the Jabal Murad district and other areas. Around 54,000 people have been displaced in the past two months in the wake of the advance, Marib's deputy governor Abd-Rabbu Meftah told state-run Saba news agency this week, and Marib city's population has been swollen to 3mn.
The Houthis have begun circling the city from the west, but could decide to push directly on to oil production facilities that are around 65km to the east. These include a central processing unit that connects oil and gas fields in block 18, once Yemen's most prolific oil-producing block. Prior to the outbreak of the civil war in 2014, state-owned Safer produced around 2,4bn ft³/d (24.7bn m³/yr) of natural gas, 40,000 b/d of crude and 28,000 b/d (880,000 t/yr) of LPG from the block.
Marib also hosts a 10,000 b/d refinery, a power plant and one of the country's few LPG bottling plants.
If they are successful this would deal a blow to the Saud-led military coalition that has been fighting the militant group for more than six years. It would open the way for the Houthis to take over the neighbouring Shabwa governorate and provide them with additional revenues and political capital in any future negotiations over Yemen's future.
Advancing on Shabwa could be quicker too, Salisbury said.
"Shabwa has a different tribal, political makeup that is more divided than Marib," he said. "Some northern Sheb tribes might even welcome the Houthis."
Shabwa is home to some of Yemen's most productive oil and gas sites and to the Yemen LNG terminal, which used gas from Marib's block 18 as feedstock for the 6.7mn t/yr liquefaction facility that was operated by a TotalEnergies-led consortium until it closed in 2015.
Argus understands that the UAE has withdrawn its forces from a base inside the LNG complex. The base has been a source of tension between the UAE and the local Shabwa government, which had hoped to restart gas exports.
"Moving out… makes it less likely the gas plant might be shot up in a fight over control", said another analyst, who did not wish to be named. "But the UAE will likely just shift its weight to Rayan, outside Mukalla." This is further east along the coast in the Hadramawt governorate.
Restarting LNG exports from Balhaf looks unlikely, with the Houthis set to capture both the upstream gas source and maybe starting a push for the Shabwa province.

