Physio-Chemical and Mineralogical Characteristics of Gas Hydrate-Bearing Sediments of the Kerala-Konkan, Krishna-Godavari, and Mahanadi Basins

Anupama Kumari,Sina Rezaei Gomari,Gaurav Dixit,Amit Arora,Chandrajit Balomajumder

doi:10.3390/jmse9080808

Anupama Kumari, Sina Rezaei Gomari + Show 3 more

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https://doi.org/10.3390/jmse9080808

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Abstract

The characteristics of the hydrate-bearing sediments affect the formation and dissociation of gas hydrate in sediments. The mineral composition, their dispersion, and chemical composition of hydrate-bearing sediment samples plays a dominant role in the hydrate stability condition and its economic development. In this paper, the physical properties of hydrate-bearing sediment of India are compared with each other. The sediment samples are taken from the Krishan-Godavari basin (Depth—127.5 and 203.2 mbsf), Mahanadi basin (Depth—217.4 mbsf), and Kerala-Konkan basin (Depth—217.4 mbsf). The saturation of the gas hydrate observed at these sites is between 3 and 50%. Particle size is an important parameter of the sediments because it provides information on the transportation and deposition of sediment and the deposition history. In the present study, we investigated the mineralogy of hydrate-bearing sediments by chemical analysis and X-ray Diffraction. XRD, FTIR, and Raman Spectroscopy distinguished the mineralogical behavior of sediments. Quartz is the main mineral (66.8% approx.) observed in the gas hydrate-bearing sediments. The specific surface area was higher for the sediment sample from the Mahanadi basin, representing the sediments’ dissipation degree. This characterization will give important information for the possible recovery of gas from Indian hydrate reservoirs by controlling the behavior of host sediment. SEM analysis shows the morphology of the sediments, which can affect the mechanical properties of the hydrate-bearing sediments. These properties can become the main parameters to consider for the design of suitable and economic dissociation techniques for gas hydrates formed in sediments.

Highlights

Gas hydrates are formed when the guest molecules of suitable size and shape are captured through van der Waals forces in the well-defined cages of host molecules [1].The molecules of water and gas chemically interact to construct an ice-like crystalline structure [2], which is stable at an absolute pressure and temperature range [3]
After performing the X-ray Diffraction (XRD) analysis of the dried and wet hydrate-bearing sediment samples, we observed that approximately 64% the halite was present in dissolved form and 36% of the halite was in mineral form in all sediment samples
Sediment samples were taken from the Mahanadi basin (Depth—217.4 mbsf, Hydrate Saturation—>50%, Sea Floor Temperature—2.4 ◦ C), Kerala-Konkan basin (Depth—246.8 mbsf, Hydrate Saturation—15%), and Krishna-Godavari basin

Summary

Introduction

Gas hydrates are formed when the guest molecules of suitable size and shape are captured through van der Waals forces in the well-defined cages of host molecules [1].The molecules of water and gas chemically interact to construct an ice-like crystalline structure [2], which is stable at an absolute pressure and temperature range [3]. The bottom of the stability area of hydrate structures is designated with the Bottom-Simulating Reflectors (BSR), which are parallel to the seafloor at a sub-bottom depth of a specific hundred meters [4,5]. These BSRs are formed by a sharp elastic contrast between the methane hydrates bearing and the underlying sediments, which are either brine or gas saturated [6]. The amount of energy in methane hydrate is significantly more considerable than the hydrocarbon deposits on earth [7]. The various hydrate dissociation techniques are thermal stimulation, depressurization, chemical injection, and CO2 sequestration [10,11]

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