Study on the generation law of hydrates in oil and gas pipelines under undulating terrain
In response to the problem of natural gas hydrates will be generated in the mixed transportation of oil,gas and water,the flow model of a climbing oil-gas-water mixed pipeline is established by using OLGA,and the production changes in the early,middle and later stages of development are considered to study the formation law of hydrates.The results show that with the increase of natural gas flow rate,the peak volume fraction of gas hydrate in the pipeline decreases.In the block of Changqing Oilfield,the production is relatively large in the early stage,and hydrate unblocking facilities should be mainly installed at the pipeline outlet position.After the production declines in the later stage of development,attention should be paid to setting up hydrate unblocking facilities near the high and the low-lying place.As the gas-liquid ratio increases,the hydrate volume fraction in the pipeline increases significantly.When the gas-liquid ratio is 140∶1,the volume fraction of hydrates reach the maximum peak of 17%at the pipeline mileage of 5 812 m.At this time,attention should be paid to the low-lying part of the pipeline for the problem of hydrate accumulation,and measures such as heating should be taken in advance to prevent production accidents caused by hydrates blockage.
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