Apparatus and method for communicating information between a wellbore and surface

1. Field of the Disclosure

This disclosure relates to apparatus and methods that provide data communication between a surface location and downhole tools during drilling of the wellbore

2. Description of the Related Art

Wellbores or boreholes are drilled in the earth\'s subsurface formations for the production of hydrocarbons (such as oil and gas) utilizing a rig (land or offshore) and a drill string that includes a tubing (jointed pipe or a coiled tubing) and a drilling assembly (also referred to as a bottom hole assembly or “BHA”). The drilling assembly carries a drill bit that is rotated by a motor at the surface and/or a drilling motor (also referred to as mud motor) carried by the drilling assembly. The drilling assembly typically carries a variety of downhole tools, usually referred to as the measurement-while-drilling (“MWD”) tools. Drilling fluid or mud is pumped by mud pumps at the surface into the drill string. After discharging at the drill bit bottom, the drilling fluid returns to the surface via an annulus between the drill string and the wellbore walls. The MWD tools may include a resistivity sensor, acoustic sensor, nuclear-magnetic-resonance sensor, nuclear sensors, formation testing tools, etc. for providing information about various properties of the formation surrounding the wellbore. The drilling assembly may also include tools and sensors that are useful in drilling the wellbore along a desired trajectory. Additional sensors, such as pressure sensors, temperature sensors and flow rate sensors are used to determine pressure, temperature and fluid flow rates in the wellbore.

The MWD tools and sensors are capable of providing a large amount of data that is useful for drilling the wellbore along a desired trajectory and for estimating the properties of the formations surrounding the wellbore. It is therefore desirable to send large amounts of data to the surface during drilling of the wellbore. Also, it is desirable to send data from the surface to the downhole MWD tools to cause the tools to perform in a desired manner. Wired-pipe and mud pulse telemetry have been used to transmit data between the downhole tools and the surface. Wired-pipes provide wide band data communication, while mud pulse telemetry sends a few bits per second.

The present disclosure provides an improved apparatus and methods for communicating data between the downhole tools and the surface using both the wired-pipe and the mud pulse telemetry.

The present disclosure, in one aspect, provides a method for communicating data between a wellbore and the surface. The method includes the features of (i) transmitting data from tools in the wellbore to the surface at a first data rate via a communication link that is carried by a tubing that supplies fluid under pressure to the wellbore; (ii) detecting a fault condition relating to the data communication link; and (iii) switching transmission of least some of the tool data from the data communication link to a mud pulse telemetry unit that sends data by generating pressure pulses in the fluid in the tubing at a second data rate.

In another aspect, a wellbore telemetry system is provided that includes a dill pipe or tubing that carries a conductor along the length of the pipe or the conductor. A data transmission device transmits data received from the tools in the drilling assembly to the surface via the data conductor at a first data rate. A downhole controller switches sending at least some of the data from the tools to a mud pulse telemetry unit when a fault is detected with the conductor. The mud pulse telemetry unit sends the data to the surface by generating pressure pulses in the fluid in the wired pipe or tubing at a second data rate that is lower than the first data rate. A control circuit in the drilling assembly activates a pulser that generates the pressure pulses. The control circuit, in one aspect, may send commands to the tools in the drilling assembly to cause them to send data at a data rate that is compatible with the transmission of the data by the pulser.

In another aspect, a drilling assembly is provided that includes a control circuit that is configured to transmit downhole tool data via wired-pipe or tubing at a wide band data rate during normal drilling operations and to automatically switch the data transmission to a mud pulse telemetry unit when the data communication link fails or exhibits data transmission that is below a selected standard.

Examples of the more important features of the invention have been summarized (albeit rather broadly) in order that the detailed description thereof that follows may be better understood and in order that the contributions they represent to the art may be appreciated. There are, of course, additional features of the invention that will be described hereinafter and which will form the subject of the claims appended hereto.