Method for relieving annular belt pressure of natural gas and gas storage well

Abstract

The invention discloses a method for relieving annular belt pressure of natural gas and a gas storage well. The method comprises the following steps that according to the sizes of a production casing and an oil pipe, the size of an annular clearance, the well depth and the formation pressure, by predicting the change values of the temperature and pressure of the natural gas during production, the amount of expansion or contraction, caused by the temperature and pressure effects, of protection liquid, the production casing, the oil pipe and the like is calculated; according to a calculated result, inert gas (such as nitrogen) with a certain length and pressure is injected into a wellhead portion in an annular space between the production casing and the oil pipe; when the temperature and pressure of the natural gas in the oil pipe rise or drop, the production casing and the oil pipe expand or contract, and meanwhile expansion or contraction of the protection liquid in the annular space can also be caused; the change causes compression or expansion of the inert gas (such as nitrogen), but the pressure at an annular wellhead does not change obviously, so that wellhead equipment, the production casing, the oil pipe, a sliding sleeve, a packer and the like are protected.

Description

technical field [0001] The invention relates to a method for alleviating pressure in the annulus of natural gas and gas storage wells, belonging to the technical field of natural gas development and storage. Background technique [0002] In the process of natural gas development and storage, in order to balance the upper and lower pressures of the production packer and slow down the corrosion of the tubing and production casing annulus, the conventional practice is to fill the tubing and production casing annulus with a certain density of pressure balance protection fluid. This method has the following problems: 1) When natural gas is produced and stored, the pressure and temperature in the tubing rise sharply. The leakage of the separator is caused by the pressure and temperature effect; 2) The sharp rise of the annular pressure of the oil jacket may cause the sealing failure of the production casing. The site had to take measures such as frequent pressure release and annu...

AI Technical Summary

Problems solved by technology

This method has the following problems: 1) When natural gas is produced and stored, the pressure and temperature in the tubing rise sharply. Whether it is caused by the leakage of the separator or the effect of pressure and temperature; 2) The sharp rise of the annular pressure of the oil jacket may cause the sealing failure of the production casing

The site had to take measures such as frequent pressure release and annular protection fluid replenishment, which resulted in increased workload and increased management costs on site; 3) The sharp rise in the annular pressure of the oil casing may lead to the failure of the packer and the protection Liquid leakage to the production area; 4) Due to changes in operating procedures, such as well killing and workover operations, the pressure and temperature in the tubing will decrease, and the tubing and annulus protection fluid will occur under the influence of temperature and pressure effects Volume shrinkage leads to a decrease in the pressure of the annular wellhead. If the wellhead cannot replenish the protective fluid in time, a vacuum section may be formed, which may even cause seal failure and leakage of the wellhead equipment, wellhead tubing, and production casing, which may easily cause the wellhead Corrosion of section tubing and production casing annulus

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