System and method for sensing parameters in a wellbore

A system and method is provided for sensing parameters within a wellbore. At least one sensor sub is coupled between stage components of an electric submersible pumping system. A plurality of sensor subs can be disposed between adjacent pairs of stage components to obtain sensor data along the electric submersible pump string. Each sensor sub contains a sensor element or elements designed to sense parameters internal and/or external to the electric submersible pumping system.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention generally relates to a system and methodology for sensing parameters in a wellbore. The parameters can be sensed internally and/or externally of an electric submersible pumping system deployed within the wellbore.

2. Description of Related Art

An electric submersible pumping system generally is formed as an electric submersible pump string having at least three main component sections. The sections comprise three-phase motor stages, pump stages, and motor protector stages generally located between the motor stages and the pump stages. In a typical arrangement, the motor stages are located below the pump stages within the wellbore. Historically, measurement of parameters within the well was constrained to sensors located below the motor stages and above the pump stages. For example, certain existing electric submersible pump string sensor systems utilize a sensing unit connected at the bottom of the submersible motor.

Attempts have been made to collect data from locations along the electric submersible pump string on various parameters. For example, a complete transducer has been attached to the side of the pump string by clamps or gauge carriers. In other attempts, a pressure line has been routed from a location along the pump string to a pressure sensor in a unit mounted below the motor. Also, sensors have been attached to the outside of the pump string and coupled to a dedicated electrical or fiber optic line run from a surface location. However, none of these approaches has succeeded in providing a rugged system of sensors for integration into an electric submersible pump string.

BRIEF SUMMARY OF THE INVENTION

In general, the present invention provides a system and methodology for sensing various parameters within a wellbore. The system utilizes one or more sensor subs designed for integrated coupling between stages of an electric submersible pumping system. Each sensor sub is coupled in line with the electric submersible pump string and is connected to ends of the adjacent pump string stages. Each sensor sub can be used to sense parameters internal and/or external to the electric submersible pump string.

DETAILED DESCRIPTION OF THE INVENTION

In the following description, numerous details are set forth to provide an understanding of the present invention. However, it will be understood by those of ordinary skill in the art that the present invention may be practiced without these details and that numerous variations or modifications from the described embodiments may be possible.

The present invention generally relates to a system and methodology for sensing well-related parameters. The parameters sensed can be parameters internal to the electric submersible pumping system, on the shaft/coupling, and/or parameters external to the pumping system. Furthermore, the present invention generally provides a system and methodology that facilitates positioning of sensing elements by incorporating small sensor subs between different component stages of an electric submersible pumping string. The sensor subs have integrated electronics and sensing element or elements that can be arranged to have access to external and/or internal portions of the electric submersible pumping system.

As explained more fully below, each sensor sub uses the standard profile and flange connections of the electric submersible pumping system component stages. This enables measurements of desired parameters to be acquired between any set of stages. For example, parameters may be sensed between two submersible motor stages, between submersible motor and motor protector stages, between two motor protector stages, between motor protector and pump intake stages, between pump intake and submersible pump stages, between two submersible pump stages, between submersible pump and discharge head stages, or between other types of component stages that may be used in the pump string.

The ability to install sensor subs between component stages enables the installation of a plurality of sensors at multiple longitudinal locations along the length of a given electric submersible pump string. The multiple sensor subs can be used to obtain a distributed set of measurements, e.g. temperature, vibration, or pressure measurements, along the pump string. The distributed set of measurements enables the monitoring of performance along the different stages of the electric submersible pumping system.

Although the sensor subs can be installed into a variety of electric submersible pumping systems, a single embodiment is illustrated inFIG. 1to provide an example and to further an understanding of the many systems and methodologies that can benefit from the use of the sensor subs. Accordingly, the reader should recognize that the sensor subs can be installed in electric submersible pump strings having, for example, a variety of additional component stages, fewer component stages, different component stages, and different arrangements of component stages. Referring generally toFIG. 1, an electric submersible pumping system20is illustrated as deployed for use in a well22having a wellbore24lined with a wellbore casing26. Wellbore24is formed in a formation28that may contain, for example, desirable fluids, such as oil or gas. Electric submersible pumping system20is located within the interior of casing26and is deployed on a tubing30, such as production tubing or coiled tubing. In some embodiments, tubing30is used as a conduit for carrying produced fluids, e.g. oil, from electric submersible pumping system20to a desired collection location.

In the embodiment illustrated, electric submersible pumping system20comprises a variety of component stages. Examples of the component stages comprise a submersible motor32operatively coupled to submersible pumps34and36. Between submersible motor32and submersible pumps34,36are a pair of motor protectors38and40. Additionally, a pump intake42is positioned between motor protector40and submersible pump34. Pump intake42enables electric submersible pumping system20to draw in well fluid, e.g. oil, from formation28, through a plurality of perforations44formed in wellbore casing26. The fluid is pulled into wellbore24and subsequently into submersible pumps34and36for production through tubing30.

In the illustrated example, electric submersible pumping system20also comprises a discharge head46, through which fluid is discharged from submersible pump36into tubing30. The system also may comprise a base unit48connected below the submersible motor32. Base unit48can be used to communicate information from the wellbore to the surface. In one embodiment, base unit48uses a power cable50as the communication line for transferring data to the surface. Power cable50is electrically connected to the submersible motor or motors, e.g. submersible motor32, to power the motor and thereby power the electric submersible pumping system20.

At least one sensor sub and often a plurality of sensor subs are connected into electric submersible pumping system20between ends of adjacent component stages. In the embodiment ofFIG. 1, three sensor subs52,54, and56are illustrated for purposes of explanation. In this example, sensor sub52is connected between pump intake42and submersible pump34; sensor sub54is connected between submersible pump34and submersible pump36; and sensor sub56is connected between submersible pump36and discharge head46. However, other numbers of sensor subs may be used, and the sensor subs can be located between different component stages of the electric submersible pumping system depending on the application in which the sensor subs are employed. In the system illustrated, sensor subs52,54, and56are deployed at selected locations58,60, and62along the pump string to provide a distributed set of measurements. For example, the sensor subs can be spaced along the submersible pumps to enable an operator to obtain a distributed set of measurements related to pump system performance along the different pump stages.

The sensor subs can be designed to utilize various methods for communicating data related to sensed parameters to desired collection locations, such as a surface control system. For example, the sensor subs can be coupled to base unit48by dedicated communication lines64that are used to carry power and communication data. Physical communication lines64also can be replaced with wireless communication lines. If a wireless system is utilized, the sensor subs can be powered by, for example, an internal battery or by incorporating a small generator powered by the rotating shaft of the electric submersible pumping system. As discussed above, the power cable50can be utilized by base unit48to transmit signals received from the sensor subs to a surface location. Depending on a variety of factors, such as the potential baud rate for communicating data along the power cable, the base unit48may transmit sensor data immediately upon receipt or it may acquire several measurements from each sensor sub before transmitting the sensor data to the surface or other data collection location. The actual methodology for transferring data can be selected according to the application, environment, and components available/utilized for a given project.

As illustrated, sensor subs52,54, and56are coupled in longitudinal, e.g. axial, alignment with the component stages of the electric submersible pumping system20. The sensor subs are disposed between ends66,68of sequential component stages, as further illustrated inFIG. 2. In this embodiment, sensor sub54is used as an example, but the explanation also applies to sensor subs52and56, as well as other sensor subs that may be used between other component stages.

In this embodiment, each sensor sub utilizes a standard profile and flange connection of the electric submersible pumping system component stages. As illustrated, the sensor sub, e.g. sensor sub54, has a pair of opposed standard sealing faces70and72designed for engagement with component stage ends66and68, respectively. The sensor sub54is captured between component stage ends66and68by a plurality of threaded fasteners74, such as threaded studs or bolts, that extend longitudinally through the sensor sub. Alternatively, threaded fasteners74may be integral with sensor sub54. In many applications, the sensor sub can be mounted between adjacent component stages by simply using longer bolts or longer threaded studs to replace those that conventionally connect electric submersible pumping system stage components. An extended coupling76is used to drivingly couple sequential shaft sections78and80of sequential component stages connected to opposed ends of the sensor sub. Extended coupling76rotates within a generally central opening82disposed longitudinally through the sensor sub54.

Each sensor sub further comprises a sensor or sensors84designed to sense one or more well-related parameters. For example, sensors84may have sensing elements designed to detect and/or measure a variety of parameters internal to the electric submersible pumping system20and/or a variety of parameters external to the electric submersible pumping system20. The sensors designed to measure internal parameters can be designed to measure, for example, internal pressure, internal temperature, vibration, torque through coupling76, rotational speed, and/or stress on system components. In some applications, sensing elements can be placed on coupling76to facilitate the measurement of certain internal parameters, such as torque and rotational speed. A variety of parameters external to the electric submersible pumping system20can also be sensed by appropriate sensors84. Examples of these external parameters include external pressure and temperature, and chemical measurements, such as for scale and hydrogen sulfide detection. The positioning of multiple sensor subs can be used to obtain distributed sets of measurements for a variety of these parameters, including internal/external temperature and pressure.

The data collected by sensors84is processed by appropriate electronics86, the design of which depends on the specific types of sensors utilized, as well as the parameters to be sensed. The electronics86output data collected by sensors84to, for example, base unit48for further transfer to a desired surface or other location. In the sample illustrated inFIG. 2, data is output through a cable88coupled to the sensor sub by a cable head90. It should be noted, however, component90also may be designed as a transponder for outputting data wirelessly to the base unit48or to other data collection devices.

Accordingly, sensor subs, such as sensor subs52,54, and56, can be integrated into a variety of electric submersible pump strings directly in line with the system component stages. The sensor subs are readily coupled between multiple types and arrangements of stages to facilitate the gathering of data at many locations along the pump string. The ability to securely and integrally incorporate sensor subs at multiple desired locations along the pump string further enables the electric submersible pumping system designer to design systems for obtaining distributed sets of measurements of one or more parameters of interest, whether those parameters be internal to the system or external to the system.

Although, only a few embodiments of the present invention 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 invention. Accordingly, such modifications are intended to be included within the scope of this invention as defined in the claims.