gas hydrate - CCOP

Figures 15 and 16 plot the water production rate and cumulative water produced with time.
It can be seen that:
1) The start time for water produced lags behind than that for the gas. This is because less
free water exists in the experimental vessel after hydrate formation;
2) The water production rate oscillates around the water injection rate;
3) The cumulative water produced is lower than the cumulative water injected. The
difference is due to the water from hydrate dissociation.
Wat er rat e( ml / mi n )
16
14
12
10
8
6
4
Water injection rate
2
Wat er pr oduct i on r at e
0
0 50 100 150 200
Ti me( mi n)
Cumulative water( ml )
2000
1800
1600
1400
1200
1000
800
600
400
200
0
Cumul at i ve
water injected
Cumul at i ve
wat er produced
0 50 100 150 200
Ti me( mi n)
Figure 15. Water injected and produced rate.
Figure 16. Total water injected and produced.
Figures 17 and 18 give the thermal efficiency and energy ratio for hot water injection. It can
be found that with the increasing hot water injection rate, the thermal efficiency and energy
ratio increase and a peak can be observed at an injection rate of 8ml/min. This is because with
the increasing hot water injection rate, the heat front moves faster, which reduces the thermal
loss. However, further increasing the hot water injection rate is un-favorable for the flood of
free gas and dissociated gas, resulting in more bounded gas in the reservoir.
8. 0
1. 5
Ther mal ef f i ci ency
7. 5
7. 0
6. 5
6. 0
5. 5
5. 0
2 4 6 8 10 12
Wat er i nj ect ed r at e( ml/min
Ener gy ratio
1. 3
1. 1
0. 9
0. 7
2 4 6 8 10 12
Wat er i nj ect ed r at e
ml/min
Figure 17. Heat efficiency curve.
Figure 18. Utilize rate of heat.
74
New Energy Resources in the CCOP Region - Gas Hydrates and Coalbed Methane