Visual Binary Testing of Hydrogen Sulfide Dissolved in Return Underground Local-Water of Oil and Gas Condensate Fields E.A. Reshetnyak*†, N.N. Nemets‡, O.S. Chernyshova§, A.V. Panteleimonov†, V.M. Ostrovskaya§§
	* Corresponding authors †V.N. Karazin National University, 4 Svoboda Sq., Kharkiv, 61022, Ukraine; *е-mail: reshetnyak@karazin.ua; ‡Ukraine Research Institute of Nature Gas “UkrNDIgaz”, 20 Gimnazicheskaya naberezhna Str, Kharkiv, 61010, Ukraine; §SSI "Institute for Single Crystals" NAS of Ukraine, 60 Nauky Ave, Kharkiv, 61072, Ukraine; §§Federal Autonomous Enterprise "25 State research institute of the Ministry of Defence of Russian Federation", 10 Molodogvardeyskaya Str, Moscow, 121351, Russian Federation
	Methods Objects Chem. Anal., 2019, 14(3), p. 146-152 https://doi.org/10.17721/moca.2019.146-152
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Abstract

In order to screen samples of return underground local-water of oil and gas condensate fields for the presence of dissolved hydrogen sulfide, it was proposed to use single comparison sample for visual binary testing of H₂S. Two indicator reactions occurring in solutions were selected — the formation of a stabilized suspension of MnS and CdS. Suspensions prepared in the presence of borate buffer (pH 9.18) and gelatin (stabilizer) are stable during the twenty four hours; a difference in the turbidity of suspensions can be observed near the normalized concentration of hydrogen sulfide (с_lim = 15 mg L^-1). When establishing the concentration of H₂S in the comparison samples, a statistical approach was applied; the estimated values of the threshold concentration of H₂S (c_comp.) are less than the normalized level on the value which providing the risk of a false-negative test result not more than 5% - 11.6 mg L-1 for MnS and 13.4 mg L^-1 for CdS. Preference was given to a test system based on a stabilized suspension of CdS, because for this reaction, a narrower interval of unreliability and the value of c_comp. is nearer to the value of the с_lim. The correctness of the visual binary testing of H₂S in the samples of the analyzed water was confirmed by spectrophotometric method with p-phenylenediamine.

Keywords: hydrogen sulfide, oil and gas condensate fields, return underground local-water, visual binary testing, stabilized suspension, spectrophotometry, p-phenylenediamine

Article language: Rus