The Red Sea Puzzle Under Houthi Blockade: Saudi Tankers Quietly 'Disappear'
Following the Houthi blockade of the Red Sea, Saudi tankers have widely disabled their AIS systems to avoid attacks, plunging loading operations at key terminals such as Yanbu into a 'dark fleet' status and causing severe distortions in export data. Estimates of export volumes for the same period vary by millions of barrels per day among different agencies, creating unprecedented uncertainty for the IEA and OPEC in assessing global supply. Although Saudi Arabia has rerouted some crude northward to mitigate risks, its actual export scale and flow directions have vanished into a 'data black hole,' exacerbating volatility risks in oil pricing
Saudi Arabia's Red Sea oil exports are falling into a rare 'data black hole.' Tankers are massively disabling their Automatic Identification Systems (AIS) to evade attacks, making it difficult to track actual loading conditions at key oil export terminals such as Yanbu Port, thereby increasing uncertainty in global crude supply assessments.
According to Xinhua News Agency, Yemen's Houthi rebels warned international shipping companies on the 20th that vessels engaging in trade with Saudi ports could face military strikes, further expanding the scope of the maritime embargo against Saudi Arabia previously announced.
According to Reuters, since the blockade took effect on July 20, cargo loading at Saudi Arabia's Yanbu Port has frequently operated as 'dark ships.' George Morris, an analyst at vessel tracking firm Vortexa, stated that last week, no pickup operations at Yanbu Port had AIS enabled. Nhway Khin Soe, an analyst at Kpler, noted that in recent weeks, about 70% of loading operations on Saudi Arabia's west coast were in 'dark ship' status, and since July 23, every shipment from Yanbu Port has involved vessels lacking continuous AIS coverage.
Meanwhile, shipping security risks in the Red Sea persist. According to CCTV News, the Yemen Coast Guard issued a statement on the 11th local time, saying that Houthi forces launched a missile attack on a merchant vessel named 'Tahama' in the Bab el-Mandeb Strait that morning, killing six people, including crew members and Yemeni armed personnel, and injuring ten others.
Amidst compounded shipping risks and data gaps, the market not only struggles to confirm the actual scale of Saudi oil exports but may also be unable to accurately judge the global crude supply-demand gap, thereby increasing uncertainty in oil price determination.
Significant Divergence in Supply Data
The information vacuum caused by the blockade has directly reflected in the export estimates of different agencies.
Taking the week starting August 3 as an example, Vortexa estimated that crude oil exports from Yanbu Port dropped from 2.71 million barrels per day to 2.38 million barrels per day; Kpler's data showed a sharp decline from 4.04 million barrels per day to 1.78 million barrels per day; while AXSMarine's estimates indicated an increase from approximately 420,000 barrels per day to 850,000 barrels per day.
For the same port and the same time period, data provided by different agencies differ by millions of barrels per day.
Since vessel AIS data is a crucial foundation for tracking global crude oil trade and estimating supply-demand balance, the lack of data means that the IEA, OPEC, and market participants find it difficult to independently verify Saudi Arabia's actual export volumes. For one of the world's largest crude oil exporters, this 'data blind spot' may further amplify market misjudgments regarding supply surpluses or shortages.
Saudi Export Routes Shift Northward
Facing shipping risks in the Red Sea, Saudi Arabia is adjusting its crude oil export routes, with some crude being transported northward through the Suez Canal or Egypt's SUMED pipeline into the Mediterranean market.
Shipping data also shows a significant decline in vessel traffic through the Bab el-Mandeb Strait. Last week, an average of about 32 vessels passed through the strait daily, lower than the pre-blockade level of approximately 50 vessels per day before the Yemeni Houthi rebels announced the blockade.
Satellite image analysis further reveals a significant contraction in loading activities at Saudi Arabia's Red Sea crude terminals. Phileeppos, an independent maritime data analyst, stated that since the blockade took effect on July 20, loading activities at Saudi Red Sea terminals have dropped by about half; the average tanker inventory at the King Fahd and Muajiz terminals has also fallen from approximately 10 million barrels per satellite pass before the blockade to about 5 million barrels.
This indicates that Saudi Arabia is reducing shipping security risks by adjusting transport routes and reducing exposure at Red Sea ports, but at the same time, it makes it more difficult for the global market to track its actual crude oil flows.
