A Study on Multi-Functional Oilfield Production Chemicals for Scale, Corrosion and Gas Hydrates

Oilfield production chemistry is a wide field which includes many different areas and related difficulties. In this work, focus is on mitigating scale, corrosion, and gas hydrates using chemical inhibitors. Production lines often require chemical treatment for several problems simultaneously, which may cause incompatibility issues. The development of multi-functional inhibitors is based on the idea of treating all three issues simultaneously and avoiding incompatibility. As a part of this development, the ability to test the corrosion inhibition of a compound was paramount. Using the Gamry EuroCell Electrochemical Cell a CO2 corrosion testing method was reviewed and optimized to reduce deviation and increase replicability. The optimized method was used to test various compounds to investigate which functional groups that could be interesting to include in future inhibitor syntheses. The major results found from this testing were that 500 ppm of a commercial imidazoline exhibited a corrosion inhibition efficiency of 85.4±2.2 %, and that none of the synergists by themselves tested achieved higher efficiency. The compound with highest efficiency was found to be sodium lignosulfonate which exhibited an efficiency of 95.9±1.6 %. An experimental polymer based on polymaleic anhydride reacted with 3,3-dibutylaminopropylamine (DBAPA) and vinylcaprolactam (VCap), abbreviated PMA:VCap-DBAPA, was tested as a CI, both by itself and with various synergists. While the polymer by itself at 500 ppm exhibited an efficiency of 18.1±6.6 %, this was increased to above 90 % by the addition of five separate synergists at 100 ppm, of which the highest was ammonium thiocyanate at 96.0±1.5 %. Overall, synergists with thiol functional groups seemed to generally provide good synergism with PMA:VCap-DBAPA. While synergists with functional groups embedded within a ring structure generally provided poor synergism with PMA:VCap-DBAPA. Two other projects to synthesise polymers with multi-functional character were also carried out. The synthesis of poly(1-oxy-3-lactam vinylene) was successful for polyoxyvinylcaprolactam (POVCap) and polyoxyvinylpiperidone (POVPip). Copolymers of POVCap and POVPip were tested as corrosion and gas hydrate inhibitors. It was found that a copolymer of 36 % POVCap and 64 % POVPip exhibited a hydrate onset temperature of 11.6±0.1 ºC, and corrosion inhibition efficiency of 15.4±3.6 % for pure POVPip. While corrosion results were somewhat higher for copolymers at different ratios, the increased efficiency is likely due to the insoluble part of copolymers with a high molar fraction of OVCap. None of the synergists tested managed to achieve a similar synergism with POVCap as with other polymeric caprolactam containing kinetic gas hydrate inhibitors. Finally, the synthesis of hyperbranched polyamine containing imidazolidine rings based on a publication from a Chinese group was unsuccessful. Many attempts were made with different variations of the synthesis, but none were found to produce the described product

Oxyvinylenelactam Polymers-A New Class of Lactam-Based Kinetic Hydrate Inhibitor Polymers

The deployment of kinetic hydrate inhibitors (KHIs) is a chemical method for the prevention of gas hydrate plugging in gas, condensate, and oil production flow lines. Polymers made using the monomer N-vinylcaprolactam (VCap) are one of the most common KHI classes. Alternative classes of polymers containing caprolactam groups are rare. Here, we present a study on oxyvinylenelactam polymers and copolymers with pendant piperidone or caprolactam groups. Low-molecular-weight homo- and copolymers were obtained. The nonrotating vinylene groups impart rigidity to the polymer backbone. Poly(oxyvinylenecaprolactam) (POVCap) was insoluble in water, but poly(oxyvinylenepiperidone) (POVPip) and OVPip:OVCap copolymers with 60+ mol % OVPip were soluble with low cloud points. KHI screening tests were carried out using the slow constant cooling method in steel rocking cells. POVPip was water soluble with no cloud point up to 95 °C but showed a poor KHI performance. In contrast, OVPip:OVCap copolymers with about 60–70 mol % OVPip were also water soluble and showed a reasonable KHI performance, better than that of poly(N-vinylpyrrolidone) but not as good as that of poly(N-vinylcaprolactam). Surprisingly, several additives known to be good synergists for VCap-based polymers showed negligible synergy or were antagonistic with the 62:38 OVPip:OVCap copolymer with regard to lowering the onset temperature of hydrate formation. However, a blend with hexabutylguanidinium chloride showed a strong effect to delay the onset of rapid hydrate formation.publishedVersio

A Study on Multi-Functional Oilfield Production Chemicals for Scale, Corrosion and Gas Hydrates

Oilfield production chemistry is a wide field which includes many different areas and related difficulties. In this work, focus is on mitigating scale, corrosion, and gas hydrates using chemical inhibitors. Production lines often require chemical treatment for several problems simultaneously, which may cause incompatibility issues. The development of multi-functional inhibitors is based on the idea of treating all three issues simultaneously and avoiding incompatibility. As a part of this development, the ability to test the corrosion inhibition of a compound was paramount. Using the Gamry EuroCell Electrochemical Cell a CO2 corrosion testing method was reviewed and optimized to reduce deviation and increase replicability. The optimized method was used to test various compounds to investigate which functional groups that could be interesting to include in future inhibitor syntheses. The major results found from this testing were that 500 ppm of a commercial imidazoline exhibited a corrosion inhibition efficiency of 85.4±2.2 %, and that none of the synergists by themselves tested achieved higher efficiency. The compound with highest efficiency was found to be sodium lignosulfonate which exhibited an efficiency of 95.9±1.6 %. An experimental polymer based on polymaleic anhydride reacted with 3,3-dibutylaminopropylamine (DBAPA) and vinylcaprolactam (VCap), abbreviated PMA:VCap-DBAPA, was tested as a CI, both by itself and with various synergists. While the polymer by itself at 500 ppm exhibited an efficiency of 18.1±6.6 %, this was increased to above 90 % by the addition of five separate synergists at 100 ppm, of which the highest was ammonium thiocyanate at 96.0±1.5 %. Overall, synergists with thiol functional groups seemed to generally provide good synergism with PMA:VCap-DBAPA. While synergists with functional groups embedded within a ring structure generally provided poor synergism with PMA:VCap-DBAPA. Two other projects to synthesise polymers with multi-functional character were also carried out. The synthesis of poly(1-oxy-3-lactam vinylene) was successful for polyoxyvinylcaprolactam (POVCap) and polyoxyvinylpiperidone (POVPip). Copolymers of POVCap and POVPip were tested as corrosion and gas hydrate inhibitors. It was found that a copolymer of 36 % POVCap and 64 % POVPip exhibited a hydrate onset temperature of 11.6±0.1 ºC, and corrosion inhibition efficiency of 15.4±3.6 % for pure POVPip. While corrosion results were somewhat higher for copolymers at different ratios, the increased efficiency is likely due to the insoluble part of copolymers with a high molar fraction of OVCap. None of the synergists tested managed to achieve a similar synergism with POVCap as with other polymeric caprolactam containing kinetic gas hydrate inhibitors. Finally, the synthesis of hyperbranched polyamine containing imidazolidine rings based on a publication from a Chinese group was unsuccessful. Many attempts were made with different variations of the synthesis, but none were found to produce the described product

Multi-functional Flow Assurance Chemicals: Corrosion and Kinetic Hydrate Inhibition from Maleic Anhydride:N-Vinyl Caprolactam Copolymers and Synergists

Water-based flow assurance issues include corrosion, scale, and gas hydrate formation. Chemical solutions to mitigate these issues usually require separate inhibitors, which sometimes can lead to compatibility difficulties. Herein, we report studies on maleic-based copolymers to combat hydrate and corrosion with a view to optimizing for scale inhibition also. The product of maleic anhydride:N-vinyl caprolactam copolymer reacted with 3-dibutylaminopropylamine (MA:VCap-DBAPA) and its amine oxide derivative (MA:VCap-DBAPA-AO) were the kinetic hydrate inhibitor (KHI) polymers investigated. Due to limited CO2 corrosion inhibition (CI) by the polymers alone, various oxygen-, sulfur-, and nitrogen-based additives were screened for improved CO2 CI and possible KHI synergy. KHI performance screening tests were conducted under high pressure with a structure II-forming natural gas mixture in steel rocking cells using the slow (1 °C/h) constant cooling method. CO2 corrosion inhibition was measured by linear polarization resistance in a stirred 1 L CO2 bubble test apparatus using C1018 steel coupons and 3.6 wt % brine at 20.5 °C. Several sulfur-based additives improved the CI efficiency of the maleic polymers, especially butyl thioglycolate and 2-aminoethanethiol, without a negative effect on the KHI performance. For example, 2500 ppm MA:VCap-DBAPA plus 1000 ppm butyl thioglycolate gave an average hydrate onset temperature (To) of 4.4 °C (12.7 °C below the To for no additive) and 99.7% CI efficiency. In contrast to a classic fatty acid imidazoline surfactant corrosion inhibitor, butyl thioglycolate was also found to greatly enhance the CI efficiency of industrial KHIs, poly(N-vinyl caprolactam) (PVCap) and N-vinyl pyrrolidone:N-vinyl caprolactam copolymer, with no antagonism to the KHI performance of the polymer. In addition, butyl thioglycolate boosted the KHI performance of PVCap. The use of small synergists such as butyl thioglycolate avoids the use of classical surfactant corrosion inhibitors which can lead to tighter emulsions and poor overboard oil-in-water quality.publishedVersio

En empirisk studie av barrierer og suksesskriterier for geotermisk energi i Norge.

Geotermisk energi har et enormt potensial for energiutvinning, men er en relativt liten del av det norske energibildet i dag. Med den 25. klimakonvensjonen og dagens energiomstilling mot et lavutslippssamfunn i tankene, var hensikten med denne oppgaven å belyse de ulike barrierene og suksesskriterier som fremkommer i den geotermiske bransjen i dag. Dette blir utforsket gjennom oppgavens to problemstillinger: Hvilke barrierer forekommer i dag som direkte hindrer for vekst av geotermisk energi i Norge? Hvilke suksesskriterier foreligger det som vil kunne føre til videre vekst i den norske bransjen? Metoden vi brukte til å svare på problemstillingene var gjennom fem intervjuer med nøkkelpersoner fra det norske geotermiske miljøet, får å så analysere intervjuene gjennom en tematisk analyse, utdrag fra denne analysen blir presentert i resultatkapittelet. Disse resultatene ble satt opp mot eksisterende litteratur på de ulike temaene som ble funnet i analysen og sammen dannet dette grunnlaget for diskusjonen. Før oppgaven søker å svare på problemstillingene starter den med en innføring i geotermisk energi, hvordan den blir dannet og de ulike produksjonsteknikkene som finnes for uthenting av denne resursen. Dette er for at leseren skal få en enkel forståelse av selve resursen og de viktigste momentene rundt den, oppgaven går så inn på en studie av allerede etablert forskning hvor oppgaven søker et mer omfattende syn på dagens geotermiske industri og utfordringene som foreligger. Her blir særlig momenter som kom frem gjennom analysen lagt vekt på, da denne sammen med resultatet danner grunnlaget for diskusjonen. Av barrierene som kom frem ble det funnet at geotermisk energi må konkurrere mot veldig store og etablerte energikilder. Konkurransemessig kommer geotermisk energi frem som ukjent blant befolkningen når den blir satt opp mot andre energikilder, prisene på elektrisitet er lave, mens investeringskostnad og risiko for etablering av geotermiske anlegg er for høy i dag. Det kommer samtidig frem at de geologiske forholdene ikke er gunstige for etablering i Norge, noe som skyldes den harde berggrunnen og relativt kjølige temperaturgradienten. Det mangler klart definerte retningslinjer og lovverk, noe som fører til utfordringer rundt etablering. Blant suksesskriteriene ble det funnet at det offentlige burde fortsette å fokusere på å fremme teknologier som kan bidra til energiomstillingen, blant annet gjennom å gi økonomisk støtte som forbedrer konkurranseevnen til geotermisk energi. Bransjen i seg selv har stort potensial for forbedring, som for eksempel ved kontinuerlig forbedring av arbeidsprosesser, overføring av kunnskap fra petroleumsnæringen, og ny teknologi som kan utbedre energibrønnenes potensial og levetid. En av teknologiene som kom fram som interessant for Norge var hybridløsninger. Disse kriteriene er viktig for den geotermiske bransjen å fokusere på, for å sikre videre vekst i Norge. Denne oppgaven søker heller å opplyse om, enn å løse, utfordringene bransjen står ovenfor. Det håpes at oppgaven gjennom å påpeke barrierer og suksesskriteriene vil inspirere til videre arbeid for finne løsninger på disse problemstillingene