Patent Application
20120086460
The process of extracting a natural resource from the earth includes many stages including a drilling stage, casing stage and completion stage. During the completion stage, elements such as expansion bridges are placed in the borehole and expanded to define production regions.
Monitoring elements such as gauges are typically permanently or semi-permanently positioned in the production regions of a completed well. The gauges are typically connected in parallel to a single conductor cable that supplies both power to and communication with the gauges. It shall be understood that it is desirable to keep the number of cables traveling from the surface to the production region(s) to a minimum.
According to one embodiment, a system that includes a common line configured to conduct electrical power is provided. The system of this embodiment also includes one or more monitoring devices coupled to the common line and configured to operate when a positive voltage is provided on the common line and a single use device coupled to the common line. The system of this embodiment also includes an activation circuit coupled between the single use device and the common line, the activation circuit only allowing current to flow through the single use device when a negative voltage is provided on the common line.
According to another embodiment, a method comprising coupling one or more monitoring devices coupled to a common line, the one or more monitoring devices configured to operate when a positive voltage is provided on the common line; a first activation circuit to the common line; and coupling a first single use device to the first activation circuit such that a current from the first single use device to the common line when a negative voltage is provided on the common line is disclosed.
Referring now to the drawings wherein like elements are numbered alike in the several Figures:
As discussed above, in some cases it may be preferable to keep the number of the cables that travel from the surface to a production region located below the earth's surface to a minimum. As also discussed above, gauges are typically provided in the production region and include a cable that provides power to them and allows the gauges to communicate to devices located at the surface.
In one embodiment of the present invention, one or more other devices are coupled to the cable in such a manner that they do not interfere with the operation of or communication with the gauges. In one embodiment, the other devices are single use elements. A single use device is a device that after being activated does not need to receive additional power or be communicated with. An example of such a single use element is an expansion bridge plug used in a cased hole. In operation, an expansion bridge plug receives power and is caused to expand within a borehole to seal portions of the borehole from other portions. After the expansion bridge plug has been expanded, there is no longer a need to provide power or other communication with it.
The common line 104 is also coupled to one or more monitoring devices 110. The common line 104 carries power from the surface electronics 106 to the monitoring devices 110. In one embodiment, the common line 104 also allows for communication between the surface electronics 106 and the monitoring devices 110. The communication can be unidirectional from the monitoring devices 110 to the surface electronics 106 or bidirectional between the monitoring devices 110 to the surface electronics 106. In one embodiment, the common line 104 is a tubing encased conductor (TEC). In one embodiment, the monitoring devices 110 are gauges. In particular, the monitoring devices 110 can be any of: a temperature gauge, a pressure gauge, a vibration gauge, a flow rate gauge, or any other type of gauge or monitoring device that can be utilized in a downhole environment.
In one embodiment, the surface electronics 106 include a power supply 112. In general, the power supply 112 provides a positive voltage/current to the one or more monitoring devices 110. To that end, the power supply 112 is illustrated as including a positive power supply portion 114.
In one embodiment, each of the monitoring devices 110 includes a diode 118 having its anode electrically coupled to the common line 104. In this manner, only a positive voltage can provide a current to the monitoring device 110. Stated differently, in the event that a negative voltage was provided on the common line 104, the negative voltage would not affect the monitoring device 110. It shall be understood that the diode 118 could be outside of the monitoring devices in one embodiment.
In one embodiment, an activation circuit 120 is disposed between the common line 104 and the single use devices 102. Examples of activation circuits 120 are described below. In general, the activation circuits 120 are configured such that they only allow current to flow through the single use devices 102 when the common line 104 presents a negative voltage. To that end, the power supply 112 is illustrated as including negative power supply portion 116. Both the negative power supply 116 and the positive power supply 114 are coupled to a supply selector 122. The supply selector 122 couples either the positive power supply 114 or the negative power supply 116 to the common line 104. Of course, the positive power supply 114 and the negative power supply 116 could be the same power supply. In such a case, the supply selector 122 serves to switch the connection of the common line 104 from one configuration to another such that it presents either a positive or negative voltage to elements coupled thereto.
In operation, the common line 104 and some or all of the monitoring devices 110 and the single use devices 102 are lowered into a borehole 130 that penetrates the surface 108 of the earth. When positioned at the desired position, the negative voltage supply 116 is coupled to the common line 104. The negative voltage supply 116 supplies a negative voltage to the common line 104. As discussed above, the monitoring devices 110 each include diodes 118 that only allow current to flow to or from the monitoring devices 110 when a positive voltage is provided thereto. Thus, at this stage, the monitoring devices 110 are not powered.
In contrast, application of a negative voltage to the common line 104 causes current to flow through the single use devices 102 in the direction shown by arrow A. This current causes the single use devices 102 to actuate. For example, in one embodiment, single use devices 102 are expansion bridge plugs. Supplying about 400 ma to them causes them to actuate and expand and seal the borehole 130. The activation circuit 120 blocks current from flowing in the opposite direction of arrow A. As such, when a positive voltage is provided to the common line 104, the single use devices 102 are electrically isolated from other devices coupled to the common line 104. Of course, in some cases, it may be beneficial to completely remove or increase the electrical isolation of the single use device 102 from the common line 104 after they have been used.
As discussed above, it may be beneficial to electrically isolate the single use device 102 from the common line 104 after the single use device 102 has been actuated. To that end, and as shown in
The different activation circuits 120 include, for example, different numbers of zener diodes coupled in series between the common line 104 and the single use devices 102. For example, as illustrated in
While preferred embodiments have been shown and described, modifications and substitutions may be made thereto without departing from the spirit and scope of the invention. Accordingly, it is to be understood that the present invention has been described by way of illustrations and not limitation. For example, the monitoring device 110 could be operable by the application of a negative voltage, and the activation circuit 120 could be operable by the application of a positive voltage.
