Patent Application
20160319654
In many hydrocarbon well applications, a wellbore is drilled into a desired hydrocarbon-bearing formation. Well tools are deployed downhole into the wellbore and pressure differentials may be established between internal regions and external regions along certain well tools. Some well tools are constructed with components which operate in a clean fluid, e.g. oil, held within a reservoir of a corresponding housing unit. Such housing units are constructed to maintain a positive pressure in the oil reservoir which drives oil through an elastomeric seal and outwardly into the surrounding environment. For example, the internal oil may be driven outwardly through the seal and into drilling fluid to exclude drilling fluid and particulate contaminants from the inside of the housing unit. The housing units tend to be bulky and expensive units which involve substantial maintenance before running the corresponding well tool downhole. Additionally, the finite supply of clean oil in the reservoir can limit the duration of a given job. The elastomeric seal or seals also are susceptible to failure and can limit the service temperature of the tool.
In general, a system and methodology are provided to facilitate pressure compensation with respect to a tool while limiting detrimental influx of contaminants. In an embodiment, a pressure compensation mechanism comprises a fluid trap chamber which is in fluid communication with a clean fluid chamber via a connector passage. The fluid trap chamber also is in communication with an external pressure region via an inlet passage. The connector passage is located such that a potentially contaminating fluid, e.g. water, entering via the inlet passage is isolated from the clean fluid chamber. The connector passage remains isolated from the potentially contaminating fluid regardless of whether the pressure compensation mechanism is in a vertical operational position or a deviated operational position.
However, many modifications are possible without materially departing from the teachings of this disclosure. Accordingly, such modifications are intended to be included within the scope of this disclosure as defined in the claims.
Certain embodiments of the disclosure will hereafter be described with reference to the accompanying drawings, wherein like reference numerals denote like elements. It should be understood, however, that the accompanying figures illustrate the various implementations described herein and are not meant to limit the scope of various technologies described herein, and:
In the following description, numerous details are set forth to provide an understanding of some embodiments of the present disclosure. However, it will be understood by those of ordinary skill in the art that the system and/or methodology may be practiced without these details and that numerous variations or modifications from the described embodiments may be possible.
With respect to certain embodiments of the present disclosure, a system and methodology are provided to facilitate pressure compensation with respect to a tool while limiting detrimental influx of contaminants. For example, a pressure compensation mechanism may be employed to balance pressure and to prevent detrimental influx of water and/or particulates. In an embodiment, the pressure compensation mechanism comprises a fluid trap chamber which is in fluid communication with a clean fluid chamber via a connector passage. The clean fluid chamber may be in the form of an oil chamber containing a tool mechanism which operates in oil. For example, a variety of actuator mechanisms, bearing elements, or other tool mechanisms may be operated in an oil or other type of clean fluid.
In this example, the fluid trap chamber also is in communication with an external pressure region via an inlet passage. The connector passage is located such that a potentially contaminating fluid, e.g. water, entering via the inlet passage is isolated from the clean fluid chamber. The connector passage remains isolated from the potentially contaminating fluid regardless of whether the pressure compensation mechanism is in a vertical operational position or a deviated, e.g. horizontal, operational position. In many applications, the potentially contaminating fluid is heavier than the oil or other clean fluid. In some well applications, for example, the clean fluid comprises oil and the potentially contaminating fluid comprises water which may enter the wellbore from a surrounding formation or from other sources. The oil floats on water and this characteristic may be used to prevent the water from contaminating the oil chamber in which a given tool mechanism, e.g. bearing element or actuator, is operated.
For a variety of applications, the pressure compensation mechanism presents a simple technique and device for providing pressure compensation within housings containing mechanisms which run in a clean fluid, such as oil. The pressure compensation mechanism enables operation of such tool mechanisms without using conventional, expensive pressure housings and complex positive pressure oil chambers which utilize leaking oil.
Referring generally to
In this example, the tool 28 further comprises a pressure compensation mechanism 32. The pressure compensation mechanism 32 may be formed within a common housing of tool 28 or it may be constructed as a separate component operatively coupled with a main portion of tool 28. In this example, tool 28 comprises a well tool although the pressure compensation mechanism 32 may be used with a variety of other types of tools, including non-well type tools. The pressure compensation mechanism 32 balances pressure differentials between an internal region 34 of tool 28 and an external region 36. In a variety of well applications, the external region 36 may be a region within wellbore 24 but external to tool 28. Without the pressure compensation enabled by pressure compensation mechanism 32, the internal pressure of internal region 34 would remain at a differential with respect to the external pressure of external region 36. As described in greater detail below, the pressure compensation mechanism 32 also prevents contamination of a clean fluid chamber in which tool mechanism 30 operates.
Referring generally to
The connector passage 44 may be located along a central axis 48 which intersects a center of the fluid trap chamber 32. In some embodiments, for example, the fluid trap chamber 42 is in the shape of a cylinder and the central axis 48 forms the main axis of the cylindrical shape of fluid trap chamber 42. Depending on the application, the pressure compensation mechanism 32 may comprise other features, such as a particle filter 50. Particle filter 50 is positioned to block flow of particles through the inlet passage 46.
As illustrated in
In the embodiment illustrated in
As illustrated in
In a variety of well applications, e.g. vertical wellbore drilling applications, the tool 28 remains in a vertical operational position in which fluid trap chamber 42 is below clean fluid/oil chamber 40, as illustrated in
However, the tool 28 also may be used in a deviated operational position in which the pressure compensation mechanism 32 is turned to a deviated, e.g. horizontal, operational position as illustrated in
The configuration of fluid trap chamber 42 effectively traps the incoming external fluid 56 at a position separated from connector passage 44. Thus, the potentially contaminating fluid 56 is again prevented from entering the clean fluid/oil chamber 40 containing tool mechanism 30. It should be noted that in some applications, operation of the tool 28 may promote a mixing of the fluids and formation of some form of emulsion. However, the structure of fluid trap chamber 42 and connector passage 44 is still able to provide effective protection of clean fluid chamber 40.
The fluid trap chamber 42 may comprise a variety of shapes, however one useful shape is a cylindrical shape which facilitates collection and settling of incoming fluid 56 in a pool against an outer wall forming fluid trap chamber 42. The collection of incoming fluid 56 along an outer wall of fluid trap chamber 42 occurs regardless of the rotational orientation of pressure compensation mechanism 32 about axis 48. The cylindrical shape of the fluid trap chamber 42 also facilitates movement of the pool of fluid 56 along the outer wall surface of chamber 42 as the tool 28 and thus pressure compensation mechanism 32 rotate about axis 48. This configuration of fluid trap chamber 42 also minimizes mixing of external fluid 56 with clean fluid/oil 52. Because of the location of connection passage 44 (which may be in the form of a fine bore tube or other suitable form) there is no direct path by which the contaminant fluid 56 gains access to clean fluid chamber 40. Formation of connection passage 44 as a small diameter tube or other suitable, small passage further ensures limited space (or no space) for mixing of fluids in a manner which would allow the external fluid 56 access to clean fluid chamber 40.
Referring generally to
In some applications, the baffle 62 may be constructed to provide the central region 58 with a conical shape. The potentially contaminating external fluid 56 may be trapped in the outer annular region 60, at least when the pressure compensation mechanism 32 is in a deviated, e.g. horizontal, operational position as illustrated in
Depending on the application, the pressure compensation mechanism 32 can be used to equilibrate pressure and to guard against contamination in a variety of tools. In well applications, for example, the pressure compensation mechanism 32 may be employed to protect bearings, actuators, and/or other tool mechanisms in many types of downhole well tools. Similarly, the pressure compensation mechanism 32 may be used in drilling operations, production operations, injection operations, and/or other well related operations. However, the pressure compensation mechanism 32 also may be utilized in various non-well related applications with tools other than well tools.
The size and configuration of the pressure compensation mechanism 32 may be adjusted to accommodate the parameters of a given application. For example, the size and shape of the clean fluid chamber and the fluid trap chamber may be adjusted. Depending on the type of tool mechanism, e.g. bearing element or actuator, disposed in the clean fluid chamber, the shape and configuration of the interior wall surfaces defining the clean fluid chamber may be constructed accordingly. Similarly, the fluid trap chamber may have single regions or plural regions with cylindrical constructions, conical constructions, or other suitable constructions or combinations of differently shaped constructions. The clean fluid may comprise a variety of oils or other liquids suitable to downhole environments or other environments in which the pressure compensation mechanism is operated. Similarly, the diameter, length, and configuration of the connector passage and the inlet passage may be selected according to the parameters and goals of a given application.
Although a few embodiments of the disclosure have been described in detail above, those of ordinary skill in the art will readily appreciate that many modifications are possible without materially departing from the teachings of this disclosure. Accordingly, such modifications are intended to be included within the scope of this disclosure as defined in the claims.
