Hydrogen sulfide formation in oil and gas

Abstract

Hydrogen sulfide (H2S) can be a significant component of oil and gas upstream production, where H2S can be naturally generated in situ from reservoir biomass and from sulfate-containing minerals through microbial sulfate reduction and (or) thermochemical sulfate reduction. On the other hand, the technologies employed in oil and gas production, especially from unconventional resources, also can contribute to generation or delay of appearance of H2S. Steam-assisted gravity drainage and hydraulic fracturing used in production of oil sands and shale oil/gas, respectively, can potentially convert the sulfur content of the petroleum into H2S or contribute excess amounts of H2S during production. A brief overview of the different classes of chemical reactions involved in the in situ generation and release of H2S is provided in this work. Speciation calculations and reaction mechanisms are presented to explain why thermochemical sulfate reduction progresses at faster rates under low pH. New studies regarding the degradation of a hydraulic fracture fluid additive (sodium dodecly sulfate) are reported for T = 200 °C, p = 17 MPa, and high ionic strengths. The absence of an ionic strength effect on the reaction rate suggests that the rate-limiting step involves the reaction of neutral species, such as elemental sulfur. This is not the case with other thermochemical sulfate reduction studies at T > 300 °C. These two different kinetic regimes complicate the goal of extrapolating laboratory results for field-specific models for H2S production.

Evaluation of sulfide emissions from a hydraulic system at the Blue River Dam

“…In crude oil reservoirs, conversion of elemental and organic sulfur to sulfate, then sulfide, is common. The high organic environment creates an ideal environment for reductive microbial reactions and abiotic thermochemical reductive reactions that result in the formation of hydrogen sulfide (Marriott et al 2015). Modern production methods, including steam assisted gravity drainage and hydraulic fracturing, can actually stimulate sulfide transformation in the production process.…”

High-Pressure Hydrogen Sulfide Experiments: How Did Our Safety Measures and Hazard Control Work during a Failure Event?

“…Naturally, H 2 S can be formed from the anaerobic decomposition of organic matter buried underground or in shallow medium such as swamps [8]. It can also coexist with oil and gas in subsurface reservoirs depending on the geological history and location of the reservoir [9,10]. Natural gas containing an appreciable quantity of H 2 S (usually >16 ppm) is normally referred to as sour gas, while crude oil with >0.5% sulfur (including H 2 S) is considered to be sour oil [11].…”

“…Several producers are shifting to the production of sour oil and gas reserves due to the continued depletion of sweet reservoirs and improving separation technology. Shale gas reserves, one of the major unconventional natural gas sources, are also known to contain H 2 S that may not show up on initial well testing [10].…”

Synthesis and evaluation of hexamethylenetetramine quaternary ammonium salt as corrosion inhibitor

“…However, the introduction of high concentration acid would cause pitting hydrogen embrittlement and weightlessness corrosion on the construction equipment and pipes . Worse still, iron ions that are acid‐corroded may damage the formation and reduce formation permeability . The corrosion not only threatens the integrity and safety of the equipment but also causes a considerable economic loss in oilfield production .…”