Hydrate phase equilibria for the binary CO2+water and CH4+water mixtures in silica gel pore of nominal diameters 6, 30, and 100 nm were measured and compared with the calculated results based on van der Waals and Platteeuw model. At a specific temperature, three-phase hydrate-water-vapor (HLV) equilibrium curves for pore hydrates were shifted to the higher-pressure condition depending on pore s...

Antifreeze proteins (AFPs) prevent ice growth by binding to a specific ice plane. Some AFPs have been found to inhibit the formation of gas hydrates which are a serious safety and operational challenge for the oil and gas industry. Molecular dynamics simulations are used to determine the mechanism of action of the winter flounder AFP (wf-AFP) in inhibiting methane hydrate growth. The wf-AFP ads...

Gas hydrates are a vast energy resource with global distribution in the permafrost and in the oceans. Even if conservative estimates are considered and only a small fraction is recoverable, the sheer size of the resource is so large that it demands evaluation as a potential energy source. In this review paper, we discuss the distribution of natural gas hydrate accumulations, the status of the p...

Natural gas hydrate deposits are found in deep offshore environments. In some cases these deposits overlay conventional oil and gas reservoirs. There are concerns that the presence of hydrates can compromise the safety of exploration and production operations [Hovland and Gudmestad, 2001]. Serious problems related to the instability of wellbores drilled through hydrate formations have been docu...

Pentazocine and tripelennamine can be identified in urine as a part of routine screening for drug abuse. Pentazocine, pentazocine hydrate, and tripelennamine can be detected by thin-layer chromatography of chloroform/isopropanol extracts of heat- and acid-hydrolyzed urine. Gas chromatography is used for confirmation. Gas chromatographic/mass spectrometric studies (chemical ionization mode) show...

Introduction: The composition of the martian polar caps has long been debated with a consensus opinion that the north is composed predominately of water ice and the south a combination of solid CO2 and water ice [1]. Smythe and Miller [2] suggested that the polar caps may be composed of at least some CO2 hydrate, aka. clathrate, or compound gas hydrates [3, 4, 5, 6, 7]. Durham [8] predicted tha...

A fiber optic-based distributed sensing system (DSS) has been integrated with a large volume (72 l) pressure vessel providing high spatial resolution, time-resolved, 3D measurement of hybrid temperature-strain (TS) values within experimental sediment-gas hydrate systems. Areas of gas hydrate formation (exothermic) and decomposition (endothermic) can be characterized through this proxy by time s...

The objectives of coring and downhole logging at this site are tied to completing the transect of scientific drill sites across the Northern Cascadia Margin to further constrain models for the formation of marine gas hydrate in a subduction zone acretionary prism. The depth to the BSR rapidly becomes shallower around this site and is only half the depth (~125 mbsf) than at Site U1327 (~225) mbs...

Hanumantha Rao (1999) has published a quite valuable program to calculate the thickness of the gas hydrate stability zone (HSZ) in the marine environment. The method involved is based on the pressure–temperature equations developed by Miles (1995) from the gas hydrate phase equilibrium diagrams. Unfortunately, a bug occurs in the program, which may lead to some calculations appearing incorrect....

Vertical seismic profile (VSP) data from two drill sites on the Cascadia margin show low-velocity zones, indicative of free gas, beneath a bottom-simulating reflector (BSR). Offshore Oregon, at Ocean Drilling Program (ODP) Site 892, velocities drop from an average of 1750 m/s above the BSR to less than 1250 m/s below it. Sonic logs confirm that seismic velocity in the sediments adjacent to the ...