How did the underground gas storage develop?

The earliest natural gas storage in the United States started operation in Buffalo, new york on 19 16. Zoar gas field is a depleted gas reservoir, which is still in use. With the great development of natural gas pipeline network after World War II, in order to meet the demand for natural gas in cold season, people's demand for new natural gas storage is also increasing. By 1965, the natural gas industry had developed water-bearing gas storage in the midwest of the United States and built deep depleted gas storage in West Virginia, Ohio and Pennsylvania.

196 1 year built the first salt gas storage in Michigan, 1970 built the first salt cavern gas storage in Mississippi, USA. The natural gas provided by the gas storage replaced the production interrupted by the hurricane in the Gulf of Mexico.

In the 1960s and 1970s, most natural gas storage plans were terminated due to the federal decree on interstate natural gas prices. These laws prohibit the use of natural gas reserves that have been put into storage in summer. In the late 1970s, the new federal law changed the price of natural gas, and a large number of wells led to an oversupply of natural gas in the early 1980s. Finally, the ban on the use of reserved natural gas was lifted.

Selection of natural gas reserves

Most natural gas is stored underground. Depleted natural gas storage is the most commonly used gas storage. Natural gas is "injected" into the ground through the previous natural gas well, and then extracted when necessary. The pressure in natural gas storage will increase when injecting natural gas, but will decrease when extracting or producing natural gas.

There must be a certain amount of "cushion gas" (residual gas that cannot be recovered in the underground gas storage) in order to use the reserved natural gas. Generally speaking, although the natural gas industry has been seeking to replace it with nitrogen or other gases, this "cushion gas" has always used natural gas. This cushion gas provides enough pressure for the gas storage, so that natural gas can flow into the borehole from the gas storage. In the normal operation of gas storage, this cushion gas cannot be extracted. On the contrary, when necessary, the "useful" gas can be extracted and delivered to users. This is a changing process of gas injection and extraction in a normal gas storage cycle.

Aquifer is a porous and highly permeable aquifer. When the exhausted reservoir can't be used, the aquifer provides conditions for storing natural gas. In the midwest of the United States, several water-bearing gas storages have been put into use. However, gas storage with water requires a high proportion of cushion gas (up to 80% of the total gas volume), which limits its use. Moreover, there is no natural gas drilling and production facilities in the location of this gas storage, just like those exhausted gas storage, the aquifer must be tested before development.

Gas storage holes are underground holes, which may be formed by mining coal or other minerals or by leaching (holes after groundwater is drained). These caves include salt mounds (which can be layered salt-bearing strata or salt mounds) and rock caves (such as tunnels in coal mines). Because the cave is a pressure vessel and an ideal gas storage that can be recycled, the buffer volume required for gas storage in the cave is low (about 1/3 of the total gas volume). However, it is very expensive to develop leaching caves, because the process of leaching will pump out a lot of groundwater and prevent the circulation of groundwater.

Generally speaking, the output capacity of gas storage decreases with time. With the increase of service life of natural gas wells, some wells have been damaged. Modern natural gas research has developed many methods to prevent gas flow from decreasing and strengthen the treatment of reformed wells. These methods are effective.

Different from underground gas storage, natural gas distribution companies work in ground factories, and the gas storage tanks store liquefied natural gas (LNG) or liquefied petroleum gas (LPG). The gas storage capacity of these gasholders is generally much lower than that of underground gas storage (5× 108 ~ 20× 108 FT3 or10×106 ~ 60×106m3). The above-ground gas storage can provide enough natural gas in a limited time, which generally refers to the peak period of natural gas demand (5 ~ 15 days). The operation of LNG and LPG storage tanks will be discussed in Chapter 6 "Natural Gas Distribution System".

Figure 5.2 Examples of several underground gas storages used in the United States.

Service objectives of natural gas storage

There are two kinds of service objects for underground gas storage: basic supply and peak supply. The basic supply can store enough natural gas to supply large users with insufficient long-distance pipelines. Peak gas supply is to supply gas at the peak time when a large amount of natural gas is needed for only a few hours or days. Peak shaving gas storage can supply a large amount of gas in a limited time, but it also needs to be replenished quickly, which cannot meet the requirement of maintaining this gas supply state for many years. Some exhausted underground gas storage can be used as such gas storage, but the current trend is to develop caves as gas storage for peak gas supply.

Traditionally, underground gas storage is generally controlled by pipeline companies, but in recent years, natural gas distribution companies have also controlled more gas storage. Generally speaking, these companies use reserves to ensure supply and meet the demand of peak gas consumption. Some natural gas market businessmen have also invested in the construction of gas storage to protect their users, which can also ensure the requirements of the contract.

In the 1990s, with the increase of natural gas demand, the demand for new natural gas reserves also increased greatly, and the scale of gas storage continued to expand. Different from the previous situation that there is only one gas supply peak in a year due to seasonal changes, there will be many short-term gas supply peaks in a year. In addition, the legal changes of the federal government also make it impossible for many pipeline companies to continue their traditional service methods. Many natural gas distribution companies and large users pay more and more attention to their natural gas supply pipelines, and many companies no longer sign long-term contracts.

The types of natural gas reserves have also changed, in order to adapt to the change from long-term demand (150 days) to short-term demand, which has increased the flexibility of services. Therefore, some new gas storage schemes have emerged in the past five years. By 2000, more than 80 new gas storage schemes had been completed. Among these schemes, 40 schemes have effectively improved the gas supply capacity and made them have higher gas transmission capacity. Increasing natural gas reserves by nearly 4000×108ft3 (/kloc-0 ×108m3) can increase gas supply capacity by150×108ft3 (4.25×108m3).

With the continuous increase of peak demand for natural gas, the reserve gas volume should be increased more flexibly. Due to the heating demand of residents, the peak demand increases, so it is necessary to reserve 5 ~ 20 days of peak supply gas storage to replace those seasonal gas storage. Recently, the natural gas industry has developed many technologies to increase the capacity of old gas storage in order to supply a large amount of gas in short-term service. These new technologies mainly focus on the diagnostic software used to check the characteristics of gas storage and analyze the operating elements of gas storage.

refer to

Albrecht, "Underground gas storage: improvement process. Enhancing resources ",Natural Gas Research Institute Abstract 2 1, Xia Xia 1998 (No.2), pp. 12- 15. Beckman, Kenneth L. and Determeyer, Peggy L., "Natural gas storage: historical development and expected evolution", GasTIP, Spring 1997 (No.2) pp 13-22. Ewing, Tezah, "High-dose Winter Peak Natural Gas Price Reverses Recent Losses", Wall Street Journal, 1 1 6th, 1998, p. C 17.