Uzbek media reports say residents of  number of villages have been evacuated in Baysun district of Surkhandarya region due to hydrogen sulfide leak.

The Ministry of Emergency Situations of Uzbekistan was cited as reporting that on September 1 at 3:17 pm during drilling operations at the 604th well of the 25 Years of Independence gas field (M-25) in Kulkamysh mahalla, a hydrogen sulfide leak occurred due to a violation of the technological process.

To ensure the safety of the public, residents living near the field were evacuated to a safe place, the report says.

“No cases of casualties or deaths of citizens have been recorded.  The situation is under complete control.  There is no room for panic.  Representatives of the relevant organizations have arrived at the scene, specialists are carrying out all the necessary work,” the Ministry of Emergency Situations noted.

Photographs distributed by official government agencies showed smoke coming from the drilling rig.  One of the videos on social networks shows firefighters working near the rig.

According to The Tashkent Times, the press service of the Surkhandarya governor’s office reported that the region governor Ulugbek Kosimov arrived in the Baysun district together with representatives of other organizations and departments. The situation is reportedly under complete control.

The public was reportedly requested not to panic, and social media activists were asked not to distribute materials that cause panic among the public.

In line with the instruction for safe conduct of work during the exploration and development of oil, gas and gas condensate fields with a high content of hydrogen sulfide, a plan for the elimination of possible accidents (PLA) associated with the release of hydrogen sulfide is drawn up for each facility, containing:

• diagrams of the arrangement of people, equipment and mechanisms;
• access roads and evacuation routes for people;
• dangerous areas of accumulation and spread of hydrogen sulfide;
• storage areas for personal protective equipment (PPE) and respiratory protective equipment (RPE);
• list of officials and institutions that must be immediately notified of the accident.

Hydrogen sulfide is a toxic gas that acts directly on the nervous system. It can paralyze the olfactory nerve, causing a person to stop smelling the gas. This often leads to severe poisoning due to the inability to promptly recognize and stop contact with the toxic source.

The maximum permissible concentration (MPC) of hydrogen sulfide in the air of the working area is 10 mg/m3, in a mixture with hydrocarbons (C1-C5) - 3 mg/m3 (GOST 12.1.005). The maximum permissible concentration of hydrogen sulfide in the air of populated areas is 0.008 mg/m3 (CH245).

The M25 field is the largest undeveloped gas field in Uzbekistan.  Estimated gas reserves are more than 150 billion cubic meters of raw gas. Most of the gas reserves have a high content of carbon dioxide and hydrogen sulfide.

In April 2017, the government of Uzbekistan signed a production sharing agreement with a consortium of investors - Gas Project Development Central Asia (formerly a joint venture of Gazprom and Gazprombank), Altmax Holding (Cyprus) and Uzneftegazdobycha on the investment block "Uzbekistan Mustakilligi" with additional exploration and development of the gas field "Mustaqillikning 25 Yilligi" with the construction of a gas processing complex in the Surkhandarya province.

The cost of the entire complex was estimated at US$5.8 billion.  The cost of the gas chemical complex was US$2.9 billion (in April 2021, the project was estimated at $2 billion).  The complex will have a production and processing capacity of 5 billion cubic meters of gas per year.

The project is being implemented under a PSA for a period of 35 years, the operator is Surhan Gas Chemical Operating Company foreign-invested company.

Drilling operations are carried out by Eriell, the design, supply of equipment and construction of a gas processing plant, infrastructure facilities, a gas collection, preparation and transportation system on a turnkey basis - Enter Engineering.

In 2021, VEB.RF and Gazprombank provided $900 million in a loan for the export of Russian equipment for the Mustaqillikning 25 Yilligi gas field in Surkhandarya.

US$1.45 billion was invested as of November 2023 in the development of the field, drilling operations were completed at 20 wells, 11 gas wells were successfully tested. Foundation work and construction of metal structures are almost complete.

In addition to gas production and processing, the GPP was to include a sulfur granulation and solidification unit, which is designed to convert liquid sulfur into solid sulfur in two possible configurations: granulated sulfur (for sale) and lump sulfur (for storage). This unit was planned to be located on a separate site directly adjacent to the GPP. The production volume was estimated at 460 thousand tons per year.

The project technology documents noted that the specificity of the Baysun gas processing complex is the significant content of so-called acidic components in the extracted raw materials (gas) - hydrogen sulfide (H2S) and carbon dioxide (CO2), strong corrosive impurities, which under certain conditions pose a serious threat to steel pipelines and equipment in contact with them, damage and / or destruction of which can be accompanied by environmental pollution, product losses, material damage and other negative consequences.

Another negative (and life-threatening for humans and animals) feature of hydrogen sulfide is its exceptional toxicity, which is why it belongs to the 2nd hazard class.