Data Home | Math Topics | Environment Topics | Topics Matrix | Master List | Help

Download the Data

PDF

Excel File

Text File

Minitab File

Data Set #065

About the Data
View the Data
Help with Using Data
Play with the data on StatCrunch
 

  Go to Top  

About the Data

About natural gas storage:

    Natural gas is an important fuel source in the United States, produced by wells drilled into rocks in the Gulf Coast states, in California, and along the continental shelf (among other locales). Natural gas consumption is currently running about 20 trillion cubic feet annually and is expected to increase another 10 Tcf over the next few decades as consumers switch from oil and electric heat to natural gas, and as new demands for natural gas crop up (see below).

    Demand for natural gas for heating increases during the US winter, however it's not possible to increase production from gas wells to match the increasing demand; production remains more-or-less constant. Therefore, gas produced during the low demand summer months must be stored until needed, which presents a big challenge to the gas industry; natural gas, even condensed into LNG, takes up a lot of volume. Above ground storage tanks are useful and convenient on a small scale, but most natural gas is stored underground. Underground reservoirs for gas include oil fields that have been depleted of their petroleum (the extraction wells can be easily reversed and turned into injection wells) and abandoned salt mines (common in the Gulf Coast states where natural gas is produced from nearby formations). The current US underground storage capacity is over 3 trillion cubic feet.

    The data show the variation in natural gas storage in the US (almost all underground) with time (on a weekly basis) from April 1997 to March 2000, covering three gas years. The data are quite cyclical, as expected. Stored gas increases throughout the summer months at a fairly constant rate until about September, when the storage rate begins to decline. Volume stored reaches a peak around New Years Day, when wellhead production can no longer meet demand, and net extraction from reservoirs begins to dominate.

    The student can model the cyclical nature of gas storage using a sinusoidal function, and will discover that the data are not symmetric about the Y-axis. The student can calculate the residuals from the model, and speculate on the origin of this asymmetric behavior.

    Gas storage underground has traditionally been used to attenuate the yearly demand cycle, however natural gas is changing as a commodity in many ways. For example, gas fired turbines that generate electricity are becoming more common, and some of that electric demand will occur in the summer, to drive cooling systems. Cooling demand for gas-fired electricity will run counter cyclical to the heating demand.

Source: American Gas Association's report, The Evolution of Underground Natural Gas Storage: Changes in Utilization Patterns, prepared by International Gas Consulting, Inc. (whose website contains a condensed version of this report).

     
  Go to Top  
View the Data

US underground natural gas storage, April 1997-March 2000
Source: International Gas Consulting Inc.
volume of ng given in billions of cubic feet (Gcf)
   
week Gcf
1 859
2 834
3 832
4 862
5 906
6 986
7 1033
8 1111
9 1199
10 1301
11 1395
12 1500
13 1561
14 1660
15 1746
16 1798
17 1862
18 1928
19 1986
20 2058
21 2127
22 2215
23 2309
24 2395
25 2467
26 2563
27 2643
28 2718
29 2781
30 2809
31 2812
32 2817
33 2754
34 2660
35 2599
36 2525
37 2403
38 2260
39 2177
40 2047
41 1978
42 1840
43 1691
44 1605
45 1522
46 1442
47 1351
48 1309
49 1238
50 1116
51 1053
52 1009
53 1070
54 1070
55 1133
56 1192
57 1274
58 1380
59 1459
60 1553
61 1650
62 1734
63 1831
64 1927
65 1995
66 2063
67 2155
68 2227
69 2310
70 2368
71 2436
72 2518
73 2575
74 2647
75 2688
76 2741
77 2800
78 2836
79 2866
80 2908
81 2975
82 3014
83 3055
84 3096
85 3051
86 3037
87 3037
88 3063
89 3018
90 2928
91 2751
92 2613
93 2394
94 2196
95 2093
96 2025
97 1930
98 1878
99 1790
100 1655
101 1600
102 1445
103 1374
104 1334
105 1343
106 1374
107 1380
108 1380
109 1423
110 1489
111 1563
112 1640
113 1700
114 1791
115 1866
116 1943
117 2029
118 2089
119 2163
120 2257
121 2309
122 2320
123 2371
124 2414
125 2463
126 2529
127 2589
128 2671
129 2743
130 2826
131 2886
132 2914
133 2971
134 2986
135 2986
136 3010
137 3015
138 2995
139 3000
140 2929
141 2857
142 2780
143 2586
144 2437
145 2314
146 2214
147 2029
148 1780
149 1560
150 1409
151 1277
152 1197
153 1171
154 1120
155 1080
156 1034
Go to Top