During the lifespan of an oil reservoir, samples from the reservoir can be collected and analyzed. In order to effectively sample the production fluid from a subsea well, sampling systems are often located subsea, in close proximity to the wellhead. Wellhead sampling presents a challenge due to the potential for dispersed and mist flow from the wellhead containing both liquid and gas phases (multiphase flow). In order to properly sample multiphase flows the liquid phase must be separated from the gas phase. Multiphase flows exhibiting a dispersed or mist flow regime can be difficult to separate into component liquid and gas phase flows, in turn making the collection of liquid-only samples more difficult.
Embodiments of the apparatus and system disclosed can be used for effective and reliable separation of the liquid and gas phase components, even under conditions of high flow rates or high gas fractions where a dispersed or mist flow regime for a multiphase flow exists. Some embodiments relate to a vortex three port separator while others relate to a system for multiphase sampling incorporating a vortex three port container.
The present disclosure teaches a vortex container for separating an inputted multiphase fluid flow including a more dense phase and a less dense phase. The vortex container includes a container with a curved inner surface, an internal volume, and three ports. The three ports include: (1) a multiphase fluid flow inlet port disposed at an angle to the inner surface of the container; (2) a gas outlet port located at the top of the container; and (3) a liquid outlet port located axially below the intersection of the inlet port's central axis with the container's central axis. The angle of the inlet port is configured to cause the inputted multiphase flow to form a vortex such that the more dense phase separates from the less dense phase along the inner surface of the container due to the relative densities of the phases.
In one embodiment of the vortex container, the internal volume of the container is cylindrical.
In one embodiment, the multiphase inlet port may be disposed at an angle relative to the container's central axis. For example, the inlet port may be angled so that the fluid flow is directed tangentially to the container's inner surface. The inlet port may also be angled toward the liquid outlet port or it may be angled approximately perpendicular to the container's central axis. In another embodiment, the gas outlet port may be disposed coaxially with the container's central axis.
The present disclosure also provides for a system of obtaining liquid production samples from an oil reservoir. The system includes an inlet pipe carrying multiphase process fluid and a vortex chamber including a curved inner surface and an internal volume that receives the multiphase fluid flow through an inlet port. The inlet port is angled to the container's inner surface, inducing a vortex such that the more dense phase separates from the less dense phase along the inner surface of the container due to the relative densities of the phases. The separated less dense phase flows through a gas outlet port at the top of the container and then through a gas flow pipe coupled to the outlet port. The separated more dense phase flows through a liquid outlet port disposed axially below the intersection of the inlet port's central axis with the container's central axis and then through a liquid flow pipe coupled to the liquid outlet port.
In one embodiment of the sampling system, the inlet port of the vortex container may be disposed at an angle relative to the container's central axis. The inlet port may also be angled toward the liquid outlet port or it may be angled approximately perpendicular to the container's central axis. In another embodiment, the gas outlet port may be disposed coaxially with the container's central axis. The inlet port may also be angled so that the fluid flow is directed tangentially to the container's inner surface.
In one embodiment of the sampling system, the internal volume of the container is cylindrical.
In one embodiment of the sampling system, the system includes a pressurization device that may comprise a pump.
The sampling system may further comprise a sampling chamber, such as a sampling container, downstream from the liquid outlet port of the vortex container that collects the more dense phase fluid samples. Once the samples have been collected, the sampling chambers may be isolated from the sampling system, retrieved from subsea via an ROV and brought to the surface, allowing the samples to be analyzed, followed by the sampling chambers being returned subsea and reinstalled in the sampling system.
The production well is typically a subsea well but the invention is equally applicable to topside wells.
For a detailed description of the preferred embodiments of the invention, reference will now be made to the accompanying drawings in which:
The following discussion is directed to various embodiments of the invention. The drawing figures are not necessarily to scale. Certain features of the embodiments may be shown exaggerated in scale or in somewhat schematic form and some details of conventional elements may not be shown in the interest of clarity and conciseness. Although one or more of these embodiments may be preferred, the embodiments disclosed should not be interpreted, or otherwise used, as limiting the scope of the disclosure, including the claims. It is to be fully recognized that the different teachings of the embodiments discussed below may be employed separately or in any suitable combination to produce desired results. In addition, one skilled in the art will understand that the following description has broad application, and the discussion of any embodiment is meant only to be exemplary of that embodiment, and not intended to intimate that the scope of the disclosure, including the claims, is limited to that embodiment.
Certain terms are used throughout the following description and claims to refer to particular features or components. As one skilled in the art will appreciate, different persons may refer to the same feature or component by different names. This document does not intend to distinguish between components or features that differ in name but not function. The drawing figures are not necessarily to scale. Certain features and components herein may be shown exaggerated in scale or in somewhat schematic form and some details of conventional elements may not be shown in interest of clarity and conciseness.
In the following discussion and in the claims, the terms “including” and “comprising” are used in an open-ended fashion, and thus should be interpreted to mean “including, but not limited to . . . ” Any use of any form of the terms “connect,” “engage,” “couple,” “attach,” or any other term describing an interaction between elements is not meant to limit the interaction to direct interaction between the elements and may also include indirect interaction between the elements described. The term “fluid” may refer to a liquid or gas and is not solely related to any particular type of fluid such as hydrocarbons. The terms “pipe,” “conduit,” “line” or the like refers to any fluid transmission means. In addition, as used herein, the terms “axial” and “axially” generally mean along or parallel to a central axis (e.g., central axis of a body or a port), while the terms “radial” and “radially” generally mean perpendicular to the central axis. For instance, an axial distance refers to a distance measured along or parallel to the central axis, and a radial distance means a distance measured perpendicular to the central axis. The various characteristics above, as well as other features and characteristics described in more detail below, will be readily apparent to those skilled in the art upon reading the following detailed description of the embodiments, and by referring to the accompanying drawings.
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It should be appreciated that the sampling systems 14 and 18 may be used for oil or gas wells where the multiphase fluid is production fluid from an oil or gas well. The systems 14 and 18 may also be used where the oil or gas well is a subsea well and the system is located subsea. For example, the sampling chamber 15 may store the collected liquid sample for a period of time before the chamber 15 is retrieved, possibly through the use of a ROV, and brought back topside where the liquid sample may be analyzed. Although the present invention has been described with respect to specific details, it is not intended that such details should be regarded as limitations on the scope of the invention, except to the extent that they are included in the accompanying claims.