Patent Application
20180038515
This disclosure relates generally to the field of subsea pipelines for oil or gas, and in particular to the initial pre-commissioning of such subsea pipelines prior to their use to convey oil or gas.
Offshore efforts to produce oil and gas typically require subsea pipelines for transport of oil and gas from wellheads to gathering structures, hub facilities and to onshore processing refineries. Newly constructed subsea pipelines must undergo a series of pre-commissioning steps which generally may include flooding, cleaning and gauging, hydrotesting, dewatering and drying before any oil or gas product can be introduced into the pipeline. The initial flooding operations typically include pushing, or pumping, a preinstalled pig, or pigs, through the pipeline with seawater, which may be chemically treated and filtered. The pipeline may be flooded between a pair of valved closures such as pipeline end terminations. The pig, or pigs, passing through the pipeline in conjunction with flooding may clean the pipeline of millscale and other debris, as well as assess dents, buckles and other out of round defects in the pipeline. Typically, an electric or hydraulic pump associated with or on a subsea vehicle, or Remote Operated Vehicle (“ROV”), is used to push, or pump, the pig in the initial flooding operations.
The following presents a simplified summary of the disclosed subject matter in order to provide a basic understanding of some aspects of the subject matter disclosed herein. This summary is not an exhaustive overview of the technology disclosed herein. It is not intended to identify key or critical elements of the invention or to delineate the scope of the invention. Its sole purpose is to present some concepts in a simplified form as a prelude to the more detailed description that is discussed later.
In one illustrative embodiment, a system for flooding a subsea pipeline with seawater may include: a high pressure/low flow pump; a jet pump having a jet pump housing, a nozzle within the jet pump housing having a nozzle inlet in fluid communication with the high pressure/low flow pump and a nozzle outlet, a fluid inlet in the jet pump housing in fluid communication with the nozzle outlet, a diffuser in the jet pump housing in fluid communication with the nozzle outlet and the fluid inlet and a diffuser outlet adapted to be in fluid communication with the subsea pipeline.
In another illustrative embodiment, a method for flooding a subsea pipeline with seawater may include: disposing a high pressure/low flow pump in fluid communication with a nozzle inlet of a nozzle disposed within a jet pump housing of a jet pump; pumping sea water with the high pressure/low flow pump into the nozzle inlet of the jet pump and out of a nozzle outlet into the jet pump housing sucking in seawater into the jet pump housing through a fluid inlet in the jet pump housing; pumping the seawater from the nozzle outlet and the seawater from the fluid inlet through into a diffuser in the jet pump housing; and pumping seawater from the diffuser into the subsea pipeline.
In another illustrative embodiment, a subsea pipeline may include: at least one subsea pipe section disposed between first and second pipeline end terminations; a high pressure/low flow pump; a jet pump having a jet pump housing, a nozzle within the jet pump housing having a nozzle inlet in fluid communication with the high pressure/low flow pump and a nozzle outlet, a fluid inlet in the jet pump housing in fluid communication with the nozzle outlet, a diffuser in the jet pump housing in fluid communication with the nozzle outlet and the fluid inlet, and a diffuser outlet adapted to be in fluid communication with the first pipeline end termination of the at least one subsea pipe section; and at least one pig disposed in the at least one subsea pipe section.
The present system and method may be understood by reference to the following description taken in conjunction with the accompanying drawing, in which:
While certain embodiments of the present system and method will be described in connection with the present illustrative embodiments shown herein, it will be understood that it is not intended to limit the invention to those embodiments. On the contrary, it is intended to cover all alternatives, modifications, and equivalents, as may be included within the spirit and scope of the invention as defined by the appended claims. In the drawing figures, which are not to scale, the same reference numerals are used throughout the description and in the drawing figures for components and elements having the same structure, and primed reference numerals may be used for components and elements having a similar function and construction to those components and elements having the same unprimed reference numerals.
It should be understood that, although an illustrative implementation of one or more embodiments are provided below, the various specific embodiments may be implemented using any number of techniques known by persons of ordinary skill in the art. The disclosure should in no way be limited to the illustrative embodiments, drawings, and/or techniques illustrated below, including the exemplary designs and implementations illustrated and described herein. Furthermore, the disclosure may be modified within the scope of the appended claims along with their full scope of equivalents.
With reference to
To initially flood the pipeline 40, at least one pig 41 may be loaded into the pipeline 40 using any suitable technique. For example, the pig 41 may be launched from the support vessel 10 using available techniques and systems connecting to the pipeline 40. Alternatively, as shown in
As seen in
Pump, or pumps, 60 may be a test pump 61 which are sometimes found on support ships or vessels, 10 in connection with offshore operations. Pump 60 is preferably capable of pumping a fluid, such as seawater, at a pressure range of from 50 to 690 bar, at a flow rate in the range of 6 to 120 M3/hr for each pump. Seawater to be pumped by pump 60 may be obtained from the sea 23 in any conventional manner, such as by use of a suction line (not shown) placed within the ocean 23 and in fluid communication between the ocean 23 and the inlet, or suction side, of pump 60. A downline 65 extends downwardly from pump 60 to a jet pump 80, as will hereinafter be described in greater detail. A downline is a conduit between a vessel, or ship, on the ocean surface and a subsea pipeline connection. Downline 65 may be coiled tubing or a hose, 66 of any suitable construction having the requisite strength characteristics to be used in an offshore environment to pump a fluid, such as seawater, at a high pressure and low flow rate from pump 60 to jet pump 80. Jet pump may be associated with, and rest upon, a subsea skid frame (not shown) which rests upon the ocean floor 21.
With reference to
Housing 81 also includes a fluid inlet 85 which may be an annular pipe section 86, which includes an annular flange 87 at its upper end 88. The jet pump housing 81 includes a diffuser 95 which has a diffuser inlet 96 and a diffused outlet 97 as shown in
The nozzle inlet 91 of nozzle 90 is in fluid communication with the high pressure/low flow pump 60 via downline 65 and the fluid, or seawater, being pumped by the pump 60 enters the nozzle inlet 91 and exits nozzle outlet 92. The fluid being pumped through downline 65 would have a flow rate and pressure commensurate with the water depth, pipeline diameter, and the desired speed for the pig 41 in pipeline 40. As an example, the flow rate may be approximately 45 M3/hr and at a pressure of approximately 400 bar. Nozzle 90 is a tapering tube 93 having a circular cross-sectional configuration, whereby the diameter of tube 93 at the nozzle inlet 91 decreases as tube 93 tapers to nozzle outlet 92. As the fluid, or seawater, being pumped by pump 60 enters nozzle inlet 91, the high pressure seawater which initially enters nozzle outlet 91 at a low flow rate is compressed as it passes through nozzle 90 toward nozzle outlet 92. The seawater exiting the nozzle outlet 92 is then moving at a much higher velocity, or speed, but is at a much lower pressure. The increase in the velocity of the seawater fluid exiting nozzle 90 and the lowering of the pressure of the seawater exiting fluid outlet 92 results from the Bernoulli's Principle.
As seen in
The seawater exiting the diffuser outlet may have a flow rate in the range of from 100 M3/hr to 1000 M3/hr and a pressure in the range of from 1 bar to 40 bar above the subsea pressure where pipeline 40 is located. As an example, the flow rate may be approximately 200 M3/hr at a pressure of approximately 214 bar.
Preferably, and optionally, the fluid inlet 85 may be provided with a filter 100 which has an annular flange fitting 101 which permits filter 100 to be connected to the annular flange 87 of fluid inlet 85. Thus, as seawater is sucked into fluid inlet 85, it first passes through filter 100 which filters, or screens, undesired materials, such as seaweed, and other similar undesired materials, from entering jet pump 80.
With reference to
Although pump 80 resting upon a subsea skid frame on the ocean floor 21 adjacent subsea pipeline 40 is described in connection with
If desired, the seawater being pumped by the high pressure/low flow pump 60 of vessel 10 could be chemically treated before it is pumped to jet pump 80 via downline 65 to add at least one chemical to the seawater pumped from pump 60 and ultimately into the pipe section 44 of subsea pipeline 40. If desired, seawater exiting diffuser 95 may pass through a flowmeter and/or by a pressure transducer to provide the operator of the jet pump 80 with information as to the operation of the jet pump 80.
At least one embodiment is disclosed and variations, combinations, and/or modifications of the embodiment(s) and/or features of the embodiment(s) made by a person having ordinary skill in the art are within the scope of the disclosure. Alternative embodiments that result from combining, integrating, and/or omitting features of the embodiment(s) are also within the scope of the disclosure. When numerical ranges or limitations are expressly stated, such express ranges or limitations may be understood to include iterative ranges or limitations of like magnitude falling within the expressly stated ranges or limitations (e.g., from about 1 to about 10 includes, 2, 3, 4, etc.; greater than 0.10 includes 0.11, 0.12, 0.13, etc.). The use of the term “about” means ±10% of the subsequent number, unless otherwise stated.
Use of the term “optionally” with respect to any element of a claim means that the element is required, or alternatively, the element is not required, both alternatives being within the scope of the claim. Use of broader terms such as comprises, includes, and having may be understood to provide support for narrower terms such as consisting of, consisting essentially of, and comprised substantially of. Accordingly, the scope of protection is not limited by the description set out above, but is defined by the claims that follow, that scope including all equivalents of the subject matter of the claims. Each and every claim is incorporated as further disclosure into the specification and the claims are embodiment(s) of the present disclosure.
While several embodiments have been provided in the present disclosure, it may be understood that the disclosed embodiments might be embodied in many other specific forms without departing from the spirit or scope of the present disclosure and the appended claims. The present examples are to be considered as illustrative and not restrictive, and the intention is not to be limited to the details given herein. For example, the various elements or components may be combined or integrated in another system or certain features may be omitted, or not implemented.
In addition, the various embodiments described and illustrated in the various embodiments as discrete or separate may be combined or integrated with other systems, modules, techniques, or methods without departing from the scope of the present disclosure. Other items shown or discussed as coupled or directly coupled or communicating with each other may be indirectly coupled or communicating through some interface, device, or intermediate component whether electrically, mechanically, or otherwise. Other examples of changes, substitutions, and alterations are ascertainable by one skilled in the art and may be made without departing from the spirit and scope disclosed herein.
