Elimination of Biogenic Hydrogen Sulfide in Underground Gas Storage. A Case Study

Abstract

The paper reports microbiological study of Sulfate Reducing Bacteria activity in underground gas storage and preventive action against H2S formation. Complex research was performed on natural gas reservoir in Swarzow, where one of a few gas storages in Poland had been arranged. The presence of hydrogen sulfide in the 10-th cycle of UGS exploitation gave impact to search a new effective methods which might limit the microbial processes of sulfate reduction in the reservoir. Having the long-term experience, in 1995–96 operation of biocide treatment in SWARZOW UGS was completed with success. Selective biocides (quaternary ammonium compounds) were applied into the reservoir for the first time in Poland, in accordance with patented technology worked out in Oil and Gas Institute, Department of Microbiology. In 1997–98 the biocide injections to exploitation wells were repeated. These operations conduced to the total elimination of Sulfate Reducing Bacteria from the formation waters and caused partial reduction of H2S content in natural gas recovered from the reservoir. In 2003 the new technology based on synergetic action of biocide, represented by triazine derivatives, and H2S Scavenger (Sulfa Clear) was implemented for the first time in underground environment. Practical application of this technology on 2 objects of UGS was finished with a great success. Content of hydrogen sulfide in the recovered gas and formation waters now accords with European Standards. The paper also discusses microbiological studies of processes observed in the natural gas reservoir in Wierzchowice, which is the largest store in Poland. Its final capacity will be ca. 4,3 billion cubic meters of natural gas. The research was conducted between the 1st and the 8th cycle of UGS exploitation. Present investigations were performed in the monitoring system and included microbiological and chemical analysis of formation waters and drilling fluids. Active strains of H2S producing bacteria (Desulfovibrio sp. and Desulfotomaculum sp.) isolated from the reservoir, have been used for testing biocides selected to protect exploitation wells of WIERZCHOWICE UGS. Introduction Microbiological research and technologies based on selected microorganisms are widely applied in the world oil industry and environment protection. Balanced industrial development and ecosystem safety are taken into account in all exploration and exploitation operations realized on oil and gas reservoirs and the underground gas storage. It also concerns applied technologies, performance on storage's wells and application of chemicals during drilling processes. Toxic substances are excluded now and replaced by new environmental friendly, biodegradable compounds (for example biocides). The research concerning processes of hydrogen sulfide formation were initiated on the object of natural gas reservoir SWARZOW UGS. The first Underground Gas Storage was created in the south of Poland in a depleted deposit of natural gas with appropriate geological conditions and exploitation parameters. The bedrock of UGS is Cenomanien sandstone (thickness is 6,0 - 12,5 m) and Kimmeridgian limestone directly underneath it. In the gas-bearing part of the limestone-dolomite the thickness is 10,0 - 13,5 m. This part of the limestone is separated from the series of limestone and dolomite (total thickness about 250 m) by a 7 m rider of marls slate. The sandstone and the gas-bearing part of the limestone form one dynamic system. They are screened above by Cretaceous marls and Miocene slates. From the other side they are separated by 7-m interval of slate rider, which probably function as a complete seal. The UGS in Swarzów is a small reservoir, but from 1970 was used to cater for the most urgent needs of gas transport in the south-eastern Poland at that time. At the present time this object is one of a few gas storages, but it is still necessary in polish gas industry1,2. Due to the lack of field experience, the storage was an experimental unit at the beginning. The research was conducted prior to its construction on the process of extrusion of the formation water that entered the deposit during and after the operation. In 1979, locally - produced and methane - rich imported gas began to pumped into the UGS. Neither of them contained H2S. In the 10th cycle of the UGS operation (February 1989), high percentage of hydrogen sulfide was recorded in the gas recovered from the reservoir. Since then microbiological research has been conducted and action taken to prevent formation of H2S.

Relevance of Deep-Subsurface Microbiology for Underground Gas Storage and Geothermal Energy Production

“…Moreover, hydrogen sulfide reacts with ferrous iron to form iron sulfide, which precipitates and can cause clogging of the operation equipment. Microbial mediated formation of hydrogen sulfide has been found repeatedly in gas and oil reservoirs [34,80] pointing to the impact of sulfate reduction in UGS facilities. When all other electron acceptors are depleted methanogenesis and/or homoacetogenesis will appear, which are less favorable processes from a thermodynamic point of view [18].…”

Testy biocydów i neutralizatorów H2S jako dodatków do płuczek wiertniczych i płynów szczelinujących

“…Szczególnie niekorzystnie oddziałuje grupa beztlenowych bakterii zdolnych do wykorzystania siarczanów i innych utlenionych związków siarki jako końcowego akceptora elektronów, zwanych bakteriami redukującymi siarczany (SRB). Ze względu na fakt, że produktem ich metabolizmu jest siarkowodór, istnieje ogromna potrzeba stosowania środków biobójczych (czyli biocydów) w celu ograniczenia ich rozwoju (Raczkowski et al, 2004). Biocydy mają eliminować także inne mikroorganizmy szkodliwe z punktu widzenia przemysłu naftowego (Turkiewicz et al, 2013).…”

Biomonitoring Studies and Preventing the Formation of Biogenic H2S in the Wierzchowice Underground Gas Storage Facility

“…As part of biomonitoring tests, the following are performed: (i) microbiological tests (quantitative method, serial dilution method, and sequencing method) of formation waters focused on the presence of SRB (sulphate reducing bacteria), capable of producing H 2 S in the reservoir [5,[14][15][16][17][18][19] (ii) microbiological tests (qualitative method and sequencing method) of formation waters for the presence of bacteria which oxidize hydrogen sulphide and reduced sulphur compounds [14,15,[20][21][22], (iii) analyses of the chemical content of hydrogen sulphide and sulphides in formation waters, (iv) research on the effectiveness of biocides [6,23] and hydrogen sulphide scavengers in relation to biogenic hydrogen sulphide and determination of their dosage in UGS conditions based on microbiological and chemical tests of reservoir fluids [6,[23][24][25][26][27][28], (v) analysis of the composition of gas pumped and recovered from UGS, and (vi) analysis of the composition of gas pumped and recovered from UGS.…”