PROCESS FOR PREVENTING THE FORMATION OF HYDRATES IN FLUIDS CONTAINING GAS OR GAS CONDENSATE

Abstract

Process for preventing the formation of hydrates in fluids containing gas or gas condensate, which comprises subjecting said fluids to electromagnetic waves operating in the visible and infrared spectrum region, comprised in the ? band from equal to greater than 500 nm to less than 1 mm (from greater than 300 GHz to less than or equal to 600 THz), reducing or preventing the formation of hydrates.

Claims

1. A process for preventing the formation of hydrates in a fluid comprising a gas or a gas condensate, the process comprising subjecting a fluid comprising a gas or a gas condensate to electromagnetic waves, thereby preventing the formation of crystalline bonds responsible for the formation of hydrates, wherein the electromagnetic waves operate within the visible and infrared spectrum region included in the ? band from 500 nm or higher to lower than 1 mm.

2. The process according to claim 1, wherein the electromagnetic waves are within the ? band from 700 nm to 0.1 mm.

3. The process according to claim 1, wherein the electromagnetic waves are within the ? band from 700 nm to 6 ?m.

4. The process according to claim 1, wherein the fluid comprising a gas or a gas condensate further comprises a chemical hydrate-inhibitor additive.

5. The process according to claim 4, wherein the chemical hydrate-inhibitor additive is a thermodynamic and/or kinetic inhibitor and/or an anti-agglomerant agent.

6. The process according to claim 1, wherein the electromagnetic waves are emitted by one or more irradiation stations which comprise an electromagnetic source electrically fed by an umbilical system.

7. The process according to claim 6, wherein the one or more irradiation stations are positioned: along a pipeline transporting and/or treating the fluid comprising a gas or a gas condensate; in a sealine or a riser of an off-shore plant used for transporting gases/gas condensates; upstream and downstream of a choke valve; in any point of a liquefaction or compression plant of methane for storage; in any point of offloading and/or transportation plant of gas coming from liquefied and/or compressed methane carriers, tanks or geological structures.

8. The process according to claim 6, wherein the one or more irradiation stations further comprise one or more light sources situated inside a pipeline or any part of a plant for gas storage in a reservoir or a ship for transporting liquefied or compressed gas, in a gas loading or unloading phase from the reservoir or ship, through which the electromagnetic waves will interact with the stream transported.

9. The process according to claim 1, wherein the gas or gas condensate in the fluid is a hydrocarbon.

10. A system for preventing the formation of hydrates in pipelines for fluids containing gases or gas condensates comprising one or more irradiation stations positioned along the pipeline, at a suitable distance from each other, wherein each irradiation station contains an electromagnetic source electrically fed by an umbilical system or by one or more light sources through which luminous radiation will interact with the fluid transported inside the pipeline.

11. A process for dissolving hydrates formed in a fluid comprising a gas or a gas condensate, the process comprising subjecting a fluid comprising a gas or a gas condensate to electromagnetic waves, wherein the electromagnetic waves operate within the visible and infrared spectrum region included in the ? band from 500 nm or higher to lower than 1 mm.

Description

[0033] Descriptions of embodiments of the invention are provided hereunder, using FIGS. 1-4, which should not be considered as being limited to the same or by the same.

[0034] An embodiment of the system consists of a series of electromagnetic irradiation stations positioned along the pipeline, risers or flowlines suitably spaced from each other. Each station interacts with the flow transported, disassociating any possible formation of hydrate already present in the fluid and inducing a reordering of the molecular structure of the water with the effect of inhibiting the formation of hydrates for a certain period of time.

[0035] Each irradiation station, of which an example is provided in FIG. 1, consists of an electromagnetic source (EM) electrically powered by means of an umbilical system (U) and by various light sources through which the light radiation interacts with the stream transported in the pipeline/sea-line (P). In determining the number of irradiation stations, Wt should be considered that this depends on: [0036] The thermodynamic conditions present during the transportation of the fluid. Considering the risers, for example, i.e. the means for transporting the hydrocarbons from the marine wells up to the surface, only a section of the riser will be involved in the phenomenon of the formation of hydrates, typically the central sections, as high pressures and low temperature are present in these sections. Under these conditions, the stations can be localized only in the sections involved in the formation phenomenon. [0037] The type of fluid transported, with particular reference to the amount of water. The higher the presence of water, the higher the probability will be of the formation of hydrates. [0038] The type of flow established inside the transportation means. This depends on various factors, such as flow-rate, fluid density, viscosity, diameter of the pipeline, inclination, etc. Non-stratified flows require greater attention as they increase the interaction surface between gas and water.

[0039] FIGS. 2 and 3 show examples of the arrangement of the ht sources (I) for irradiating the flow in a certain section, in relation to the characteristics of the gas flow (G)/transported liquid (L) (FIG. 2 laminar flow; FIG. 3 turbulent flow).

[0040] The electromagnetic source interacts, by means of the light sources positioned along the walls of the pipeline, flowline or riser, with the fluid being transported, inhibiting the formation of hydrates. In the design phase of the light sources, it particularly important to know the type of fluid and flow conditions in order to maximize the illumination on the surface of the water. Considering the operative band of the infrared previously described, the irradiation diagram of the light sources is usually a few degrees in the far infrared or hundredths of degrees in the far infrared, as in the case of lasers. In all cases, it is indispensable to use diverging lenses, which allow the beam to be enlarged, maximizing the irradiated area with the double advantage of reducing the number of light sources necessary for the complete illumination of the fluid.

[0041] Another application field relates to local prevention in specific areas with a high probability of the formation of hydrates.

[0042] FIG. 4 shows an example of the arrangement of the light sources for irradiating the flow in a critical point, such as that close to a bend.

[0043] The valves are considered as being critical areas, such as for example, but not only, the choke valves in which the Joule-Thomson effect is manifested, branches off, curves, etc. cannot be excluded, i.e. all situations in which there is a decrease in the section useful for the flow, which causes an acceleration in the fluids, and consequently a variation in the pressure and temperature. In this case, generally occurs a decrease in the temperature and pressure and it is probable that favourable thermodynamic conditions for the formation of hydrates will be formed. In this case, an irradiation focused upstream and/or downstream of the valve, helps to prevent and maintain the correct functioning of the system without complicating or altering the rest of the plant.