Method for predicting natural gas hydrate generation area in submarine gas pipeline

Abstract

The invention discloses a method for predicting a natural gas hydrate generation area in a submarine gas pipeline. The method comprises the following steps: (1) acquiring submarine natural gas pipeline transportation basic parameters and initial conditions according to submarine gas pipeline process design and marine environment parameters; (2) performing space node division; (3) establishing an on-way temperature distribution calculation model and a pressure distribution calculation model of the submarine gas pipeline; (4) calculating the fluid temperature Tm (i + 1) and the pipeline pressurePm (i + 1) at the next node i + 1 according to the fluid temperature Tm (i) and the pipeline pressure Pm (i) at the node i in the gas pipeline, and judging whether hydrate is generated at the node i+ 1 or not according to a natural gas hydrate phase balance model; and (5) iteratively calculating from a pipeline conveying starting point to an end point to obtain temperature distribution and pressure distribution in the seabed gas conveying pipeline, and judging a natural gas hydrate generation area in the seabed gas conveying pipeline. The invention can provide an effective method for predicting the generation area of the natural gas hydrate in the submarine gas pipeline, and can provide an important guarantee for flowing safety of the submarine gas pipeline.

Description

technical field [0001] The invention belongs to the technical field of storage and transportation of oil and natural gas, and in particular relates to the safe transportation technology of oil and natural gas pipelines, in particular to a method for predicting natural gas hydrate formation areas in submarine gas pipelines. Background technique [0002] Natural gas hydrate is a crystalline clathrate complex formed by water molecules and light hydrocarbon molecules such as methane under low temperature and high pressure conditions, also known as "combustible ice". Since the discovery of natural gas hydrates in the natural gas pipelines of the former Soviet Union in the 1930s, the formation and blockage of natural gas hydrates in gas pipelines has attracted widespread attention, especially in gas pipelines under low-temperature submarine environments. . Hydrates appear in pipelines, ranging from increased operating costs, damage to equipment along the line, or blockage of pipe...

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Problems solved by technology

Patent CN201510891515.X discloses a device and method for research on natural gas hydrate prevention and control technology in oil and gas transmission pipelines. It preliminarily divides the clogging stages of hydrates in pipelines and proposes a method for unblocking them, but does not prevent hydrates from clogging pipelines. However, the research on prediction cannot effectively prevent the formation of hydrate blockage in pipelines.

Patent CN201610735694.2 discloses a gas hydrate blockage monitoring device in deep-water gas well testing, which can calculate the hydrate blockage time in the test string, but the monitoring device and method are only limited to deep-water gas well testing, and cannot detect hydrate Generate regions for prediction

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