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Home / Issue Archive / 2009 / June #6 / Just a Spoonful of Sugar: Finding Profit in Sour Gas Fields

№ 6 (June 2009)

Just a Spoonful of Sugar: Finding Profit in Sour Gas Fields

Natural gas unanimously occupies a place ahead of other fossil fuels for its superior hydrogen content and lower emissions. Globally, there will be no shortage of gas anytime soon, with reserves estimated at around 165 tcm.

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   Though this might sound comforting, there is a blot on this idyllic landscape.  Only one blight spoils this idyllic landscape: about one third of the natural gas reserves contain high carbon dioxide and hydrogen sulfide concentrations, which considerably hinder commercial development of such deposits.  Gas containing hydrogen sulfide is toxic, highly corrosive and can significantly harm the environment. Its treatment requires the application of sophisticated technologies  and adds substantial costs.  However, at present, the world structure of natural gas reserves is changing for the worse. Clean and easily accessible feedstocks have run low.  Almost 50 percent of global reserves are considered difficult to produce, requiring heavy spending.

   Consequently, more and more companies all over the world are interested in developing sour gas fields, i.e. gas containing hydrogen sulfide, carbon dioxide and other gas impurities.  For example, Abu Dhabi Gas Industries Ltd. announced its intention to invest about $25 billion in the construction of two large gas processing plants and ten new onshore pipelines with a total length of 1,500 kilometers. Abu Dhabi Gas joined ConocoPhillips and began development of the Shakh gas field, which contains 30 percent hydrogen sulfide.  In the long run, such unconventional hydrocarbon sources may be of significant importance in the world fuel balance.  There are over 400 sour gas fields in the world, and about 130 are located within the European part of Russia.  Currently, development of such fields is impeded by engineering and environmental problems.  Their development requires solving complicated tasks to ensure engineering and environmental safety and economic efficiency.  One of the major tasks is to utilize produced sulfur, which is not in high demand at present.

   The Scientific Research Institute of VNIIGAZ, a Gazprom subsidiary, conducted the international conference, “Best Practices and Prospects for Sour Gas Fields Development.”
Alexander  Kalinkin, Deputy Head of Gazprom’s Department of Gas, Gas Condensate and Oil Production,  described Gazprom as “the world’s largest gas company.”  Its share in the global gas reserves is 17 percent, and in within Russia, 60 percent. Gazprom provides about 20 percent of the world’s gas and 85 percent of Russian domestic supply.  The company’s proved reserves are estimated at about 30 tcm with 12 percent falling at hydrogen-sulfide containing fields.  About 25 percent of reserves being developed by the company are located within sour gas fields.

   The Orenburg and the Astrakhan gas condensate fields are the largest Russian hydrocarbon fields containing hydrogen sulfide. The Orenburg field is at the stage of declining production; it has been operated for more than 30 years. The Astrakhan gas condensate field is more promising, with only 6 percent of its reserves withdrawn.  Total natural gas reserves in the Astrakhan dome fold make over 5 tcm with a resource potential exceeding 7 tcm, which is comparable with the reserves of major Gazprom fields in Western Siberia.  Production potential at the Astrakhan field is estimated at 50-60 bcm per year.

   Dmitri Lyugai, VNIIGAZ’s Deputy General Director, outlined in his conference speech how the Institute’s specialists analyzed potentials for increasing gas production at the Astrakhan field.  The analysis also included solutions for dealing with both sulphur and sulphur-free production.  Gas production and processing at the existing plant is possible with the condition that the plant’s emissions comply with established rates for air pollutants.These apply mainly to sulfur dioxide emitted by Claus sulfur recovery units. To comply with environmental standard emission rates, gas producers are required to introduce modern technologies to treat Claus unit exhaust gases.  The talk also covered development of long-term sulfur sequestration, as well as incineration and subsequent disposal in underground formations.  Technologies that deal with sulfur output include injecting  separated sour gases back to reservoirs and also producing sulfuric acid.  The Institute’s scientists concluded  that they had to develop a flexible processing chain, which would enable either to produce final products or  to dispose of sulfur depending on the market trends.

   Professor Anatoly Dmitrievskiy, head of the RAS Oil and Gas Research Institute, described an advanced technology for supersonic gas separation in order to separate primary products from hydrogen sulfide-containing gases. Units employing this technology must maintain an output gas flow containing up to 2 percent hydrogen sulfide.  A package unit’s throughput capacity will be at least 1.5 bcm  per year.  A total of eight units will match Astrakhan Gas Processing Plant’s current capacity.  Dmitrievskiy noted that the Astrakhan field must solve the following problems: ensure swift and high-quality well rehabilitation, eliminate fluid migration and cross-flows between deposits, and to shore up the reliability of well-abandonment procedures.

   A representative of BASF reported on the advantages of applying titanium catalysts to separate primary gases from hydrogen sulfide.  Use of similar equipment has achieved impressive results, providing strong evidence for development of titanium technologies.

   Robin Matton of UOP N.V. discussed technologies using absorption processes such as the BenFieldТМ  (hot potash cleaning) process, the Amine Guard FS process using special solvents, cryogenic processes, various sulfur absorbers, and special membranes that produce high-quality treatment results.

   Gases containing hydrogen sulfide are so corrosive that equipment and pipelines made of regular materials break down very quickly.  SUMITOMO has become a ground-breaker in the area of developing new materials capable of withstanding such aggressive environments.  In his report, the company’s representative discussed the experience of creating oil and gas field pipes for use in sour and corrosive conditions.

   Zemfira Stoye discussed about new developments by Noble Products using quenching technologies for stainless steel to be operated in corrosive services.  Various parts and assemblies were treated with these technologies and demonstrated good results during operations in heavily corrosive service conditions.

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