Patent Application
20070278009
The drill string 12 preferably includes a plurality of network nodes 30. The nodes 30 are provided at desired intervals along the drill string. Network nodes essentially function as signal repeaters to regenerate data signals and mitigate signal attenuation as data is transmitted up and down the drill string. The nodes 30 may be integrated into an existing section of drill pipe or a downhole tool along the drill string. Sensor package 38 in the bottom hole assembly may also include a network node 30. Connectors 34 represent drill pipe joint connectors, while the connectors 32 connect a node 30 to an upper and lower drill pipe joint.
The nodes 30 comprise a portion of a downhole network 46 used to transmit information along the drill string. A downhole network may thus include multiple nodes based along the drill string. Communication links 48 may be used to connect the nodes to one another, and may comprise cables or other transmission media integrated directly into sections of the drill string. The cable may be routed through the central borehole of the drill string, or routed externally to the drill string, or mounted within a groove, slot or passageway in the drill string. Preferably signals from the plurality of sensors are transmitted to the surface through a wire conductor 48 along the drill string. Communication links may also use wireless connections.
A plurality of packets may be used to transmit information along the nodes. Packets may be used to carry data from tools or sensors located downhole to an uphole mode, or may carry information or data necessary to function the network. Other packets may be used to send control signals from the top node to tools or sensors located at various downhole positions. Further detail with respect to suitable nodes, a network, and data packets are disclosed in U.S. Publication 2005/0284663 A1 hereby incorporated by reference.
Various types of sensors may be employed along the drill string, including axially spaced resistivity, caliper, rock strength (sonic), pressure sensors, temperature sensors, seismic devices, strain gauges, inclinometers, accelerometers, bending, vibration, and rotation sensors, and flow rate sensors. Sensors which measure conditions which would logically experience significant change over time provide particularly valuable information to the drilling operator. For example, the caliper or cross-sectional configuration of a wellbore at a particular depth may change during the drilling operation due to formation stability and fluid washout conditions. The skin of a formation defining the borehole may tend to absorb fluids in the well and may thus also change over time, particularly if the well is overbalanced. By providing a system which allows a sensor to transmit to the surface at a known depth in substantially real time, a particular borehole or formation characteristic, such as the caliper of the well, and by providing another sensor which can provide the same type of information at substantially the same depth with a different sensor as the well is drilled deeper, the operator is able to compare a wellbore caliper profile at a selected depth at time one, and later measure the same caliper at substantially the same depth at time two. This allows the operator to better understand changes in the well that occur over time, and to take action which will mitigate undesirable changes. Other sensors which monitor conditions which are likely to degrade or change over time include sensors that measure wellbore stability, resistivity sensors, equivalent circulating density (ECD) measurements sensors, primary and/or secondary porosity sensors, and temperature sensors.
Other sensors may monitor conditions which are unlikely to substantially change over time, such as borehole inclination, pore pressure sensors, and other sensors measuring petrophysical properties of the formation or of the fluid in the formation. In the latter case, an operator may use the signals from different sensors at different times to make a better determination of the actual condition sensed. For example, the inclination of a wellbore at a particular depth likely will not change. The inclination measurement at time one may thus be averaged with an inclination at the same depth at time two and another inclination measurement at the same depth at time three, so that the average of these three signals at the same depth taken at three times will likely provide a more accurate indication of the actual borehole inclination.
According to the technique of the present invention, an operator at the surface may instruct a particular sensor to take a selected measurement. In most applications, however, a plurality of substantially identical sensors for sensing a particular wellbore formation characteristic will be provided along the drill string, and each of those sensors will output a signal at a selected time interval, e.g., every tenth of a second or every second, such that signals at any depth may be correlated with signals from a similar sensor at another depth. Thus an entire profile of the sensed condition based on a first sensor as a function of depth may be plotted by the computer, and a time lapse plot may be depicted for measurements from a second sensor while at the same depth at a later time. Also, it should be understood that the system may utilize sensors which are able to take reliable readings while the drill string and thus the sensors are rotating in the well, but in another application the rotation of the drill string may be briefly interrupted so that sensed conditions can be obtained from stationary sensors, then drilling resumed. In still other cases, the drill string may slide or rotate slowly in the well while the sensed conditions are monitored, with the majority of the power to the bit being provided by the downhole motor or rotary steerable device.
A significant advantage of the present invention is the ability to analyze information from the sensors when there is time lapse between a particular sensed condition at a particular depth, and the subsequent same sensed condition at the same depth. As disclosed herein, the system provides sensors for sensing characteristics at a selected depth in a well, and a particular depth may be “selected” in that the operator is particularly concerned with signals at that depth, and particularly change and rate of change for certain characteristics. Such change and rate of change (time lapse in the transmitted signals) may be displayed to the operator in real time). Otherwise stated, however, information from a sensor at selected axial locations or after a selected time lapse may be important, and the term “selected” as used herein would include a signal at any known, presumed, or selected depth.
Information from the well site computer 22 may be displayed for the drilling operator on a well site screen 24. Information may also be transmitted from computer 22 to another computer 23, located at a site remote from the well, with this computer 23 allowing an individual in the office remote from the well to review the data output by the sensors 40. Although only five sensors 40 are shown in
Those skilled in the art will appreciate that various forms of markings may be employed to differentiate a first pass from a second pass, and a second pass from a subsequent pass, and that viewing the area difference under the curve of signals from different passes is only one way of determining the desired characteristic of the borehole or formation. Assuming that characteristic #2 is the borehole size, the operator may thus assume that, at a depth shortly above depth D1, the borehole has increased in size, and has again increased in size between the taking of the pass 2 measurements and the pass 3 measurements. For all of the displayed signals, signals may be displayed as a function of plurality of sensors at a single elected location in a borehole, so that a sent signal at a depth of, e.g., 1550 feet, will be compared with a similar signal from a similar sensor subsequently at a depth of 1550 feet.
Although specific embodiments of the invention have been described herein in some detail, this has been done solely for the purposes of explaining the various aspects of the invention, and is not intended to limit the scope of the invention as defined in the claims which follow. Those skilled in the art will understand that the embodiment shown and described is exemplary, and various other substitutions, alterations and modifications, including but not limited to those design alternatives specifically discussed herein, may be made in the practice of the invention without departing from its scope.
Whereas the present invention has been described in particular relation to the drawings attached hereto, it should be understood that other and further modifications apart from those shown or suggested herein, may be made within the scope and spirit of the present invention.
This application is a non-provisional application claiming priority from U.S. provisional application Ser. No. 60/804,015, filed on Jun. 6, 2006—the entire disclosure of which is incorporated by reference herein for all it contains.
| Number | Date | Country | |
|---|---|---|---|
| 60804015 | Jun 2006 | US |
