Method for measuring hydrate blockage risks at wellheads of salt-cave underground gas storages
A method of determination, a technique for hydrates, used in forecasting, instrumentation, data processing applications, etc.
Active Publication Date: 2017-08-18
BC P INC CHINA NAT PETROLEUM CORP +1
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For the calculation of the probability of hydrate blockage at the wellhead of underground gas storage, there are no relevant reports at home and abroad
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[0043] The present invention will be further described in detail below in conjunction with specific embodiments, which are explanations of the present invention rather than limitations.
[0044] A method for measuring the risk of hydrate blockage at the wellhead of a salt cavern underground gas storage according to the present invention, in order to solve the two key problems of the existence time of the hydrate formation condition and the critical condition for the formation of blockage, the following assumptions are made:
[0045] (1) The formation of hydrates with a length of 1 meter will cause blockage of the facility;
[0046] (2) The additional gas cooling occurs in the wellbore due to the cooling of the wellhead and the upper half of the wellbore by the ambient temperature;
[0047] (3) Assume that the produced gas is saturated with water and no free water is produced with the natural gas;
[0048] (4) The probability of hydrate blockage is equal to the quotient of the...
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The invention discloses a method for measuring hydrate blockage risks at wellheads of salt-cave underground gas storages. The method comprises the following steps of: 1, determining a cooling degree required by hydrate generation in a gas production process of a salt-save gas storage; 2, determining a time of duration when the environment change temperature is equal to the cooling degree, namely, a time for existence of a hydrate generation condition; 3, calculating a maximum mass of hydrate generated by natural gas and water generated every day; 4, calculating the mass of hydrate forming 1-meter long hydrate blockage at a wellbore or a wellhead according to the sectional area of the wellbore or wellhead; 5, calculating a number of days capable of forming the 1-meter long hydrate blockage according to results of the steps 3 and 4; 6, calculating a hydrate blockage probability at the wellhead of the salt-cave underground gas storage according to the time for the existence of the hydrate and the time for forming the 1-meter long hydrate; and 7, taking the hydrate blockage probability at the wellhead of the salt-cave underground gas storage as an index, and if the probability is greater, considering that the hydrate blockage risk at the wellhead of the salt-cave underground gas storage is higher.
Description
technical field [0001] The invention relates to risk control of salt-cavern underground gas storage, in particular to a method for measuring the risk of wellhead hydrate blockage of salt-cavern underground gas storage. Background technique [0002] Hydrate formation is one of the harmful factors that affect the safe and stable operation of the gas storage and cause the risk of the decline in the injection and production capacity of the gas storage. Hydrates are ice crystal-like solid substances formed by combining components in natural gas and liquid water. As the gas is extracted from the gas storage, the temperature and pressure of the gas flowing up the wellbore will drop due to the expansion of the gas. This Joule-Thomson cooling effect will create favorable conditions for gas wells to generate hydrates. Usually, by comparing the wellhead pressure and temperature with the pressure and temperature curves in the hydrate stable area, it is judged whether hydrates are form...
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IPC IPC(8): G06Q10/04G06Q10/06G06Q50/02
CPCG06Q10/04G06Q10/0635G06Q50/02
Inventor 李丽锋罗金恒赵新伟任国琪张皓
Owner BC P INC CHINA NAT PETROLEUM CORP