RU2091285C1 - Method of construction and filling of underground storages of liquefied gas in permafrost rocks - Google Patents

Abstract

FIELD: construction of underground vessels in permafrost rocks applicable for storage of liquid hydrocarbons at subzero temperatures. SUBSTANCE: the offered method includes formation of underground working by well sinking and metal vessel is installed in the working with gap filled with frozen solution; and well above metal vessel is filled with wetted sand. In this case, well depth exceeds the total height of metal vessel and functional layer by 1-3 m. Injection of low-temperature liquefied gas is effected in the period of subzero temperature of ambient air after freezing of solution and wetted sand for 3-20 days. EFFECT: higher efficiency. 4 cl, 1 dwg

Description

 The invention relates to methods for the construction of underground tanks in frozen rocks for storage of liquid hydrocarbons at a negative temperature.

It is known to store gas with a low critical temperature, in which gas storage tanks are placed in underground workings and immersed in material having a slightly higher critical temperature. This material is cooled to a temperature below the critical temperature of the gas and maintained during operation [1]
The disadvantages of this method are the high costs of creating and operating the storage, which is associated with the need to construct waterproofing of the mine and maintaining the set temperature.

A known method of constructing compressed gas storages is that wells are drilled, metal containers are installed in them, made of pipe sections with a bottom and shut-off devices at the upper end, partially or completely fill the wells with concrete mixture, compressed gas is pumped into metal containers from the compressor [2]
A disadvantage of the known method is that the construction of storages in this way in permafrost soils does not ensure the reliability of the design and operation, does not provide for the supply of chilled gas.

A known method of constructing an underground storage of liquid hydrocarbons at a negative temperature, adopted as the closest analogue, including the drilling of wells, the formation of underground workings, the creation of its shell and filling with liquefied gas having a negative temperature [3]
The disadvantage of this method is the complexity and complexity of the operations for the formation of production at great depths, economically feasible in the construction of large storage facilities.

 The objective of the method is to simplify and accelerate the operations of construction in permafrost soils of underground liquefied gas storages.

 The essence of the method is to use the properties of permafrost when accelerated and reliable construction at a shallow depth of small volume storage for low-temperature storage of liquefied gas. This is achieved by the fact that they pass the well, form a hole and build its insulating shell. At the same time, according to the method, the production is formed by the sinking of the well, the shell is created by installing a gap of a sealed metal tank, the gap between the wall of the well and the wall of the metal tank is filled with a freezing solution, and the space of the well between the tank and the boundary of the active layer with moistened sand. At the same time, the well passes through a depth exceeding the total height of the metal container and the active layer, and the solution and sand are frozen for 3 to 20 days before the injection of low-temperature liquefied gas. The depth of the well exceeds the total height of the metal tank and active layer by 1 3 m. As a freezing solution, lime or ground mortar is used. The injection of low-temperature liquefied gas is carried out during the period of negative air temperatures.

The method is illustrated in the drawing, which shows the layout of the underground storage, where 1 active layer of permafrost soil, 2 metal tank, 3 well, 4 clearance between the walls of the well and metal tank, 5 pipe for injection and gas extraction, 6 pipe with valve for relieving excess pressure , H _{with the} height (power) of the active layer, H _{E the} height of the metal container.

 The method is as follows.

 The diameter and depth of the well 3 are determined based on the required storage volume. When determining the depth of the well, it is taken into account that the thickness (height) of the active layer 1 depends on the intensity and duration of heating of the surface and in the same area it is not the same in different years. In addition, to ensure the effect of natural thermostating of the stored liquefied gas (which ensures constant pressure5 inside the metal tank) and to effectively freeze the metal tank 2 in permafrost soil (which ensures its removal and retention), it should be installed in the well 3 below the level of the active layer 1 , and the space around the metal container should be filled with a freezing material. To do this, pass a well 3 with a diameter larger than the diameter of the metal container, for example, with a screw-screw installation, with a depth exceeding the total height of the container 2 and the active layer 1 by 1 3 m. A metal container 2 is installed in the well 3 with a gap 4. The container 2 can be standard, factory-made , or made of a pipe whose metal is designed for operation at low temperatures. The metal tank 3 is provided with a pipe 5 brought to the surface for filling and sampling gas with stop valves and a pipe 6 with a valve for relieving excess pressure. In the gap between the walls of the well and the metal tank, a solution is injected, for example, lime, or based on drilled slag. Above capacity 2, well 3 is filled with moistened sand. Due to the fact that the metal tank 3 is installed at a sufficient depth below the boundary of the active layer 1, the injected solution and moistened sand freeze with the creation of a monolith around the metal tank, reinforcing and holding it at a set level and, together with the surrounding permafrost, creating without additional costs low temperature natural temperature control of the stored gas.

 In practice, it has been established that a complete freezing of a metal container occurs within 3 to 20 days and depends on the time of year, the properties of the solution used and the volume of solution and sand placed in the well. The most effective period for the construction of storage facilities for the injection of liquefied gas is the period of negative ambient temperatures.

 The application of the proposed method will allow you to quickly and inexpensively build underground storage using available means and materials, while due to the low-temperature state of the stored gas and the formed monolith, it becomes possible to use thin-walled metal containers, which reduces the metal consumption of the structure.

Claims (4)

 1. A method of constructing and filling underground liquefied gas storages in permafrost, including sinking a well, forming a well below the boundary of the active layer, creating a casing, installing shut-off valves and injecting low-temperature liquefied gas, characterized in that the production is formed by well sinking, the shell is created by installing a sealed metal container in the well with a gap, the gap being filled with a freezing solution, and I fill the space of the well above the metal container tons of moistened sand and freezing moistened sand and solution for 3 to 20 days prior to the injection of low-temperature liquefied gas, while the well pass a depth exceeding the total height of the metal tank and active layer.  2. The method according to claim 1, characterized in that the well pass through a depth exceeding the total height of the metal tank and active layer by 1 3 m  3. The method according to claim 1 or 2, characterized in that as a freezing solution using lime or ground mortar.  4. The method according to any one of claims 1 to 3, characterized in that the injection of low-temperature liquefied gas is carried out in the period of negative air temperatures.