Innovative Technique for Flowline Plug Remediation

Lee, Jeremy; Hampton, Brian Jeffrey; Alapati, Rama; Sanford, Elizabeth Aubray; O'Brien, Shawn

doi:10.4043/otc-20171-ms

Cited by 3 publications

(4 citation statements)

References 0 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Although the methane hydrate deposits are considered a future energy resource, they have been a risk for the energy industry when transporting hydrocarbon fluids through subsea flowlines operating at high pressure and low temperatures for deep and remote offshore fields. ,, Since Hammerschmidt suggested the occurrence of gas hydrates in gas transport pipelines with an equation for injecting methanol, the risk of hydrate formation in subsea flowlines was prevented by adding thermodynamic hydrate inhibitors (THIs) such as methanol and monoethylene glycol (MEG). These thermodynamic hydrate inhibitors shift the hydrate equilibrium conditions toward lower temperatures and higher pressures, thus avoiding hydrate formation under flowline conditions. ,, However, the injection of THIs demands large infrastructure such as storage tanks, a complex regeneration process, injection pumps, and subsea distribution pipelines. Moreover, the presence of electrolyte ions in the formation water may induce operational issues such as scale deposition and MEG loss. − As such, the oil and gas industry is seeking alternative solutions that are more efficient and offer economic benefits.…”

Section: Introductionmentioning

confidence: 99%

“…These thermodynamic hydrate inhibitors shift the hydrate equilibrium conditions toward lower temperatures and higher pressures, thus avoiding hydrate formation under flowline conditions. 1,6,7 However, the injection of THIs demands large infrastructure such as storage tanks, a complex regeneration process, injection pumps, and subsea distribution pipelines. Moreover, the presence of electrolyte ions in the formation water may induce operational issues such as scale deposition and MEG loss.…”

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

Kinetic Hydrate Inhibition Performance of Poly(vinyl caprolactam) Modified with Corrosion Inhibitor Groups

et al. 2017

View full text Add to dashboard Cite

Multifunctional polymers were designed and synthesized that contain both a kinetic hydrate inhibitor and corrosion inhibitor groups. This was achieved by modifying a copolymer of vinyl caprolactam and acrylic acid (PVCap-co-AA) where the acid groups were converted to known corrosion inhibitor groups including imidazole (APIM) and quaternary ammonium (ATCH) moieties. Therefore, all of the resulting polymers had the same molecular weight, end groups, and overall composition which allowed for accurate determination of the performance of these inhibitors. Their performance as kinetic hydrate inhibitors was evaluated by determining the hydrate onset time, growth rate, and resistance to flow using a high pressure autoclave. The experimental results show that both PVCap-co-APIM and PVCap-co-ATCH were able to delay hydrate nucleation; however, PVCap-co-APIM was better than PVCap-co-ATCH. The performance of new KHICIs was evaluated and compared with that of a commercial KHI, Luvicap, with three different cooling rates: for high and medium cooling rates, Luvicap delayed hydrate nucleation for a longer time compared to the new KHICIs. At low cooling rate, one of the KHICIs (PVCap-co-APIM) showed better performance than Luvicap. PVCap-co-APIM also performed better than Luvicap and PVCap-co-ATCH in decreasing the hydrate growth rate. Hydrate growth rate and resistance to flow were also studied during the hydrate formation to investigate the effect of the inhibitors on the growth of hydrate particles in the liquid phase. PVCap-co-APIM successfully suppressed hydrate growth in the early stage of hydrate formation, whereas PVCap-co-ATCH resulted in fast growth of the hydrate phase. For all of the studied cooling rates, PVCap-co-APIM showed stable resistance to flow even with increasing hydrate fraction in the liquid phase; however, PVCap-co-ATCH showed a torque surge in the early stage of hydrate formation when a fast cooling rate was used, which suggests that the ATCH group has a negative effect on the hydrate inhibition performance. These results provide a proof-of-concept that the modified PVCap-co-APIM, or related structures, that contain both kinetic hydrate inhibitor and corrosion inhibitor groups can be used as multifunctional inhibitors for offshore oil and gas fields.

show abstract

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Kinetic Hydrate Inhibition Performance of Poly(vinyl caprolactam) Modified with Corrosion Inhibitor Groups

et al. 2017

View full text Add to dashboard Cite

show abstract

“…Gas hydrates are nonstoichiometric crystalline compounds in which water molecules encage gas molecules via hydrogen bonding under low temperature and high pressure conditions. − Such conditions are found in subsea flowlines that transport hydrocarbons such as methane, ethane, and propane with produced water to processing facilities. As the formation of gas hydrates in subsea flowlines may lead to solid blockages that cause costly production stoppages and remediation processes, the energy industry has been injecting alcohol- or glycol-based hydrate inhibitors into these lines to thermodynamically shift the hydrate formation conditions. − Mono ethylene glycol (MEG) has been a popular choice of inhibitor for offshore gas fields due to its negligible loss to the hydrocarbon phase, while methanol has been used in offshore oil fields due to its low cost. However, these conventional inhibitors require a large infrastructure for storage with regeneration and high operational expenditures due to their large injection volume, which can be as high as 40–60 wt %, to the aqueous phase.…”

Section: Introductionmentioning

confidence: 99%

Hydrate Growth Inhibition by Poly(vinyl caprolactam) Released from Microcarriers under Turbulent Mixing Conditions

et al. 2018

View full text Add to dashboard Cite

Core−shell microcarriers were microfluidically prepared by using water-in-oil-in-water double-emulsion drops as a template. The aqueous core contained a kinetic hydrate inhibitor (KHI) of poly(vinyl caprolactam) (PVCap), and the shell was made of a cross-linked polymer. To make the microcarriers selectively release PVCap at temperatures where hydrate formation occurs under a constant shear flow, the relative shell thickness to the radius of the microcarrier was set to 0.11. The hydrate inhibition performance of PVCap released from the microcarriers was investigated using continuous cooling and constant subcooling in a high-pressure autoclave. Longer hydrate onset times were observed for the PVCap microcarriers compared to bulk water, suggesting that hydrate nucleation was inhibited by PVCap released from the microcarriers. The obtained subcooling temperature for the PVCap microcarriers was 11.3 °C, which was close to that of the PVCap bulk solution at 10.8 °C. The hydrate growth was faster for the PVCap microcarriers than for bulk water, but the effective growth period was shorter, resulting in a lower hydrate fraction in the liquid phase. Although the PVCap microcarriers performed successfully under continuous cooling, limited performance was observed with constant subcooling. Successful hydrate inhibition was sometimes observed, but fast hydrate formation was also observed over repeated experiments. This result is because microcarriers are designed to rupture under a constant shear flow. Thus, more studies are required to improve the design of microcarriers to release the inner KHI solution, even in cold-restart operations. Nevertheless, microcarriers provide a flexible way to inject KHI into subsea flowlines, as many different types of KHIs can be simultaneously delivered at a proper dose using a set of distinct microcarriers.

show abstract

“…They are formed through hydrogen bonding between water molecules that enclathrate guest molecules at high pressures and low temperatures. These conditions are found in subsea oil and gas flowlines, as the production of offshore oil and gas fields have been moving into deeper and remote regions. − Industry practice has relied on the injection of vast quantities of alcohol- or glycol-based thermodynamic hydrate inhibitors (THIs) to completely prevent hydrate formation in subsea flowlines; , however, handling large amounts of THI in remote offshore fields significantly increases the capital and operational expenditures, thereby adversely affecting the economics of field development. Consequently, hydrate prevention strategies are now moving toward hydrate risk management, through delaying nucleation of hydrate crystals, or the prevention of the agglomeration of the hydrate particles.…”

Section: Introductionmentioning

confidence: 99%

Performance of Poly(N-isopropylacrylamide)-Based Kinetic Hydrate Inhibitors for Nucleation and Growth of Natural Gas Hydrates

et al. 2017

View full text Add to dashboard Cite

Hydrate prevention strategies for offshore flowlines are now moving toward hydrate risk management by delaying its nucleation and growth using water-soluble polymers, known as kinetic hydrate inhibitors (KHIs). This study investigates the natural gas hydrate inhibition performance of three poly(N-isopropylacrylamide) (PNIPAM)-based KHIs [poly(Nisopropylacrylamide-co-acrylic acid (PNIPAM-co-AA), poly(N-isopropylacrylamide-co-cyclopentylamine (PNIPAM-co-Cp), and poly(N-isopropylacrylamide-co-tert-butylamine (PNIPAM-co-C 4 t)] by determining the hydrate onset time, growth rate, and resistance to flow using a high-pressure autoclave. These data are compared to three control groups [water, Luvicap solution, and polyvinylpyrrolidone (PVP)] under various cooling rates (0.25, 0.033, and 0.017 K/min). The results show that the nucleation of hydrate crystals was delayed in the presence of the KHI candidates as assessed using the onset time at different cooling rates. The effect of the KHI candidate on the hydrate growth characteristics was also studied by determining the initial growth rate and torque changes with an increasing hydrate fraction in the liquid phase. The obtained results confirmed that the synthesized PNIPAM-based KHIs showed a high subcooling temperature, which is comparable to those of commercial KHIs. The modification of the base polymer (PNIPAM-co-AA) improves the kinetic inhibition performance for PNIPAM-co-Cp (13.9, 12.5, and 7.8 K for 0.25, 0.033, and 0.017 K/min cooling rates, respectively) but results in decreased performance for PNIPAM-co-C 4 t (9.6, 9.9, and 7.6 K for 0.25, 0.033, and 0.017 K/min cooling rates, respectively). After the hydrate onset, PNIPAM-co-C 4 t showed a slower growth rate and more stable torque during the hydrate formation than PNIPAM-co-Cp, suggesting its potential role as a crystal growth inhibitor. These results suggest that the performance of PNIPAM-based KHIs can be evaluated with the holistic investigation on nucleation and growth of hydrate crystals.

show abstract

Innovative Technique for Flowline Plug Remediation

Cited by 3 publications

References 0 publications

Kinetic Hydrate Inhibition Performance of Poly(vinyl caprolactam) Modified with Corrosion Inhibitor Groups

Kinetic Hydrate Inhibition Performance of Poly(vinyl caprolactam) Modified with Corrosion Inhibitor Groups

Hydrate Growth Inhibition by Poly(vinyl caprolactam) Released from Microcarriers under Turbulent Mixing Conditions

Performance of Poly(N-isopropylacrylamide)-Based Kinetic Hydrate Inhibitors for Nucleation and Growth of Natural Gas Hydrates

Contact Info

Product

Resources

About