Showing papers on "Sour gas published in 1995"

Sour gas and water chemistry of the Bridport Sands reservoir, Wytch Farm, UK

Abstract: Abstract Co-produced waters and gaseous H2S were sampled at four wells at Wytch Farm oil field, UK, over a one year period. The chemical and stable isotopic (H, O) compositions of the waters were determined, plus the sulphur isotopic composition of dissolved sulphate and gaseous sulphide. Formation waters contain about 70 000 mg 1−1 total dissolved solids (TDS) and are evolved meteoric waters; there is a 10% fieldwide variation in TDS. H2S was formed by (bacterial?) reduction of formation-water sulphate. A high but variable fraction of the sulphide has been subsequently lost, perhaps by reaction with abundant Fe-bearing minerals. At least some, and possibly a significant fraction, of the sulphide in the reservoir is dissolved in formation water. Simple mass-balance models show that when reservoir sulphide is pre-dominantly within formation water, the concentration of H2S in produced gas will increase dramatically with increasing water cuts. In this case, increasing concentrations of H2S in produced gas do not necessarily imply that souring has been caused by production practices. Seawater breakthrough is recognized and quantified in one well using chemical and stable isotopic data. K, Mg and SO4 are all lost from injected seawater during its passage through the reservoir. Geochemical modelling and isotopic data fail to identify the fate of the missing sulphate, although the isotopic data tentatively suggest that some may have been converted to sulphide. However, the levels of sulphide produced from the breakthrough well are no higher than in other wells, suggesting that reduction of seawater sulphate contributes a small percentage of fieldwide H2S production.

Methods for sweetening hydrocarbons

Abstract: Sour natural gas, containing H2S and organic sulfide contaminants, is contacted with a sweetening composition comprising an aqueous solution of a substantially equimolar mixture of OC1- and HO2- (preferably NaOC1 and NaOOH) for a time sufficient to oxidize the sulfides to an odorless form. The solution has a pH of 9.0 - 10.5, an oxidation normality of 0.001 - 0.1. The solution may be produced by mixing C12 into a dilute aqueous solution of NaOH at about pH 10.5 until the pH reaches a level of about 9.5 - 10.5, or produced electrochemically in a diaphragm cell having a bipolar electrode in the same compartment as the anode, collecting the effluent gas from the cell and absorbing said effluent gas into a dilute aqueous solution of NaOH at about pH 9.5 - 10.5. The treatment may be run as an adjunct to a metal chelate redox treatment to improve the oxidation by the redox catalyst and to improve the catalyst regeneration. The treatment may be run in batch, in a scrubbing tower, or in-line in a flowing gas stream with solids removal provided.

Gri testing of SulFerox (trade name) for the direct treatment of high-pressure natural gas at NGPL`s Kermit, Texas site. Final report, April 1995

Abstract: Removal of hydrogen sulfide (H2S) from sour gas is vital to the natural gas industry. About 14% of gas reserves are sour, and 15% of gas produced requires sulfur removal. Direct treatment of high-pressure sour gas with liquid redox processes has potential to reduce sulfur emissions and costs compared to conventional amine/Claus/SCOT technologies. However, these potential benefits and operability have not been commercially proven. For these reasons, GRI funded a pilot unit project with Radian Corporation and with the assistance of Natural Gas Pipeline Company of America. SulFerox was the first of a series of technologies to be evaluated. ARI-LO-CAT II will be evaluated next.

Oxidation of hydrogen sulfide by an enrichment from sour water coproduced with petroleum

Abstract: We have previously demonstrated that the chemoautotroph and facultative anaerobeThiobacillus denitrificans may be readily cultured aerobically or anoxically in batch and continuous reactors on hydrogen sulfide under sulfide-limiting conditions. A sulfide-tolerant strain ofT. denitrificans (strain F) was isolated by enrichment and recently used in a successful field test of a microbial process for the treatment of sour water coproduced with petroleum at an Amoco Production Co. site in Wyoming. Prior to the initiation of this field test, it was determined that the sour water at this site contained low concentrations of indigenous autotrophs, which could grow on thiosulfate as an energy source. Samples of this sour water have now been used to produce an enrichment culture for sulfide oxidizers. This enrichment has been characterized with respect to hydrogen sulfide oxidation, response to oxygen, pH and temperature optima, and sulfide tolerance. The enrichment was shown to be strictly aerobic and to grow on sulfide as an energy source with complete oxidation of sulfide to sulfate. The enrichment has a tolerance of sulfide comparable to that ofT. denitrificans strain F. However, the enrichment has a higher optimum temperature (35°C) than strain F and was shown to oxidize sulfides over a much broader range of pH values (3.5–10).

A method for removing hydrogen sulfide from gas streams

Abstract: The invention disclosed relates to a process for removing hydrogen sulfide from a gas stream, such as sour natural gas, with the formation of elemental sulfur as a by-product. By controlling the reaction conditions, the conversion of hydrogen sulfide is maximized, and the sulfur dioxide selectivity is controlled. Specifically, the sulfuric acid concentration and the reaction temperature may be balanced, depending on the desired product mix.

Partial oxidation of liquid hydrocarbon fuel or aqueous slurry of solid carbon fuel

Abstract: A partial oxidation process for the production of a stream of cooled and cleaned synthesis gas, reducing gas, or fuel gas substantially free from entrained particulate matter and slag. The hot raw gas stream from the partial oxidation gas generator is quench cooled with deaerated grey water in a quench tank to produce black quench water or cooled in a radiant and/or convection cooler. The cooled gas is scrubbed with deaerated grey water in a scrubbing zone to remove all of the entrained particulate matter and to produce black scrubbing waters. The black water is resolved in a flashing zone and reused by flashing it in two or three flash stages connected in series and separating the overhead flash vapors comprising vaporized grey water and sour gas from the bottoms comprising concentrated black water. The flash vapors from the first flash stage are used to heat a stream of deaerated grey water being recycled to the quench tank and gas scrubbing zone or to the gas scrubbing zone. The concentrated black water from the flashing zone is thickened in a clarifier and then filtered to produce filter cake which may be burned and grey water filtrate. The flash vapors from the second flash stage and optionally steam are introduced into a deaerator to strip dissolved oxygen from incoming make-up water, grey water condensate, and grey water filtrate. In another embodiment of the process, the flash zone comprises three flash stages.

Clad Steel Pipe for Corrosive Gas Transportation

Abstract: This paper describes the applicability and reliability of clad steel pipe and its welds in sour gas environments in comparison with those of 22%Cr-5.5%Ni3%Mo-0.15%N duplex stainless steel (ASTM A240 UNS31803) solid pipe. The example of practical applications of clad steel pipe for corrosive gas transportation is also presented.

Fixed-bed processes provide flexibility for COS, H{sub 2}S removal

Abstract: Mobil North Sea Ltd.`s Scottish Area Gas Evacuation (SAGE) plant at St. Fergus, Scotland, has been designed to process a broad range of contract gases. It is currently the only U.K. terminal capable of processing northern North Sea sour associated gas containing both H{sub 2}S and CO{sub 2}. A key element has been integration of fixed-bed processes for selective removal of COS and H{sub 2}S from the gas and liquid product streams. The result has been operating flexibility and significant capital savings. The terminal consists of two gas-processing trains that were completed in two phases. The first train, with capacity for processing 500 MMscfd of sweet gas from Beryl, was brought on-line in July 1992. The second phase, completed in March 1994, allowed sour gas from Brae to be treated. The paper describes these processes, sour gas drying, NGL purification, and gas sweetening.

Field evaluation of a solid-based H2S scavenger for treating sour natural gas. Topical report

Abstract: The Gas Research Institute (GRI) is sponsoring an evaluation program for H2S scavenging technologies as part of an overall sulfur removal/recovery research program. The evaluation of a solid-based scavenger (Sulfa Treat) is the second in a series of full-scale field evaluations. The report presents the results of the evaluation conducted at a production plant in central Texas treating approximately 17 MMscfd of natural gas with 7 to 9 ppmv of H2S and 2.8% CO2 at 500 to 900 psig.

Subquality natural gas sweetening and dehydration potential of the physical solvent N-formyl-morpholine

Abstract: Almost all gas produced in the United States requires processing before it is placed in the transmission system. For approximately 50% of the gas, this is just dehydration. The remainder, however, requires processing that is more complex and costly. A report to the Gas Research Institute states that about 30% of the proven gas reserves contained sufficient nitrogen, carbon dioxide or hydrogen sulfide to be classified as a subquality.

Microbially-enhanced redox solution reoxidation for sweetening sour natural gas

Abstract: About twenty five percent of natural gas produced in the United States is sour containing significant volumes of hydrogen sulfide and other contaminants. Liquid redox processes remove hydrogen sulfide from natural gas. Aqueous solution of chelated ferric ions oxidize the hydrogen sulfide to elemental sulfur. The reduced iron chelate is then oxidized by contact with air and recycled. This requires expensive equipment for regeneration, costly chemicals and the process is usually energy intensive. Recent studies show that the ferric ion regeneration rates are substantially enhanced in presence of acidophilic bacteria. The specific objectives of this project are to advance the technology and improve the economics of the commercial iron-based chelate processes utilizing biologically-enhanced reoxidation of the redox solutions used in these processes, such as LO-CAT II and SulFerox.