Enhanced Gas Production from Hydrate Reservoirs with Underlying Water Layer

Abstract

The recovery of natural gas from a marine hydrate reservoir is a complicated geological process, involving heat and mass transfer inside hydrate-bearing sediments as well between the overburden and underlying layers. Yet, most attention has been paid merely to the evolution of the hydrate reservoir itself. The idea has been proposed to consider as a whole the hydrate layer together with the overburden and underlying layers. In this work, the enhanced gas production behavior from the hydrate reservoir with an underlying water layer was specifically studied. It is found that the initial pressure propagation from the hydrate layer to the free water layer was very difficult; this thereby dominated the early stage of hydrate dissociation. The following dissociation of hydrate was majorly controlled by the heat supply from the sensible heat of the water layer and the resulting temperature distribution. A stepwise depressurization could significantly help enable a stable production rate, and the accumulative water yield depended strongly on the overall pressure drop, regardless of the process of depressurizing. Injecting heat was limited by the low efficiency of horizontal heat transfer resulting from the long distance and low thermal conductivity. The results are helpful in terms of providing guidance to field tests where there is commonly an underlying water layer and water production is frequently encountered.

Recent Advances in Methods of Gas Recovery from Hydrate-Bearing Sediments: A Review

“…The DP can also be applied to Class 3 sediments with high permeability and a strong capacity for heat transfer. When it used for Class 2 sediments or HBS with high water saturation, it is indispensable to isolate the hydrate–water interface through well completion and to manage the high WGR or liquid loading so that the depressurizing difficulty, ,, the high load of the gas–water separation device, , the NGH deposition and blockage in the well , could be alleviated. However, benefiting from the DP via the extraction of underlying water in Class 2 sediments, one constant-rate production, rather than constant-pressure production used in Class 3 sediments, might be what is expected …”

Progress on Laboratory-Scale Reactors for Simulating Gas Production from Hydrate Reservoir

“…In the process of depressurization, a higher gradient of depressurization may cause icing inside the reservoir . Reducing the pressure drop gradient will decrease gas production efficiency.…”

“…In the process of depressurization, a higher gradient of depressurization may cause icing inside the reservoir. 120 Reducing the pressure drop gradient will decrease gas production efficiency. Some researchers have combined pressure reduction and heat injection to speed up the efficiency of gas production.…”

Virtual Special Issue of Recent Research Advances in China: Unconventional Gas

“…There are six reviews covering a wide range of aspects related to methane hydrates targeting resource potential, production methods (depressurization and CH 4 /CO 2 exchange), exploration activities, sand management, and hydrate properties . The original research articles pertaining to the topic of hydrates cover a wide spectrum of areas, from numerical modeling, ,,, hydrate properties and characterization, ,,,, hydrate equipment ,,, to fluid production analysis, ,− ,, etc.…”