Experimental set-up design for gas production from the Black Sea gas hydrate reservoirs Sukru Merey * , Caglar Sinayuc Middle East Technical University (METU), Department of Petroleum and Natural Gas Engineering, Ankara, Turkey article info Article history: Received 15 February 2016 Received in revised form 2 April 2016 Accepted 11 April 2016 Available online 25 April 2016 Keywords: CH 4 hydrate Black Sea hydrates Reactors Hydrate experiments HydrateResSim abstract Gas hydrate deposits which are found in deep ocean sediments and in permafrost regions are supposed to be a fossil fuel reserve for the future. The Black Sea is also considered rich in terms of gas hydrates. It abundantly contains gas hydrates as methane (CH 4 ~ 80e99.9%) source. In this study, by using the literature seismic and other data of the Black Sea such as salinity, porosity of the sediments, common gas type, temperature distribution and pressure gradient, the optimum gas production method for the Black Sea gas hydrates was selected as mainly depressurization method. It was proposed that CO 2 /N 2 injection as a production method from the potential Black Sea gas hydrates might not be favorable. Experimental set-up (high pressure cell, gas flow meter, water-gas separator, mass balance, pressure transducers and thermocouples) for gas production from the Black gas hydrates by using depressurization method was designed according to the results of HydrateResSim numerical simulator. It was shown that cylindrical high pressure cell (METU Cell) with 30 cm inner length and 30 cm inner diameter with a volume 21.64 L in this study might reflect flow controlled conditions as in the real gas hydrate reservoirs. Moreover, 100 mesh portable separator in METU cell might be very useful to mimic Class 1 hydrate reservoirs and horizontal wells in gas hydrate reservoirs experimentally. © 2016 Elsevier B.V. All rights reserved. 1. Introduction With the decline of the amount of gas in conventional gas res- ervoirs, unconventional gas reservoirs such as gas hydrates and shale gas reservoirs have become very popular recently (Kok and Merey, 2014). Gas hydrates are ice like crystalline structures formed by water and gas molecules at high pressure and low temperature values. They are defined as nonstoichiometric com- pounds, which means the ratio of the atoms present in the composition is not a simple integer (Carroll, 2009). Hydrocarbon molecules such as methane (CH 4 ), ethane (C 2 H 6 ), propane (C 3 H 8 ) and i-butane (i-C 4 H 10 ) form their own hydrate (simple hydrate) at high pressure and low temperature conditions when there is enough water in the system. Similarly, carbon dioxide (CO 2 ), hydrogen sulfide (H 2 S), nitrogen (N 2 ), oxygen (O 2 ) and other gases form hydrate at their hydrate equilibrium conditions (Sloan and Koh, 2007). According to the gas in place calculations of Johnson (2011) in hydrate bearing sands in the world, there is a huge range of gas hydrate resource between 133 and 8891 tcm. It can be concluded that even the most conservative estimates of the total quantity of gas in gas hydrate are much larger than the conventional gas re- sources (404 tcm) and shale gas (204e456 tcm) (Chong et al., 2015). The magnitude of this resource can make hydrate reservoirs a substantial future energy resource. Currently, there are mainly four gas production methods from gas hydrate reservoirs: depressur- ization, thermal stimulation, chemical injection, and CO 2 injection. Depressurization is thought to be the most economically viable production method for gas hydrates because there is no extra heat introduced into the system. This method is applied by decreasing reservoir pressure within hydrate stability zone, causing hydrate to decompose and release gas and water that will migrate towards the wellbore. Although there is no additional heat input cost of depressurization method, its disadvantages are low gas production rates, high amounts of water production, the risk of hydrate reformation due to fast depressurization, and the risk of reservoir subsidence (Konno et al., 2010; Chong et al., 2015; Xu and Li, 2015). By increasing the temperature of hydrate deposits, reservoir con- ditions are shifted the outside of hydrate equilibrium conditions. Below hydrate equilibrium line, hydrate starts to dissociate after * Corresponding author. E-mail address: merey@metu.edu.tr (S. Merey). Contents lists available at ScienceDirect Journal of Natural Gas Science and Engineering journal homepage: www.elsevier.com/locate/jngse http://dx.doi.org/10.1016/j.jngse.2016.04.030 1875-5100/© 2016 Elsevier B.V. All rights reserved. Journal of Natural Gas Science and Engineering 33 (2016) 162e185