Fault detection and tolerance in downhole tool string assemblies

Patent metadata

Field	Value
Publication number	US-10007260-B2
Application number	US-201514755323-A
Country	US
Kind code	B2
Filing date	Jun 30, 2015
Priority date	Jun 30, 2015
Publication date	Jun 26, 2018
Grant date	Jun 26, 2018

Abstract

Systems, methods, and devices for fault detection and tolerance in a downhole tool string are provided. If a fault is detected in an electrical path between tools of downhole tool string, one or more switches of a fault detection and tolerance circuit may be kept open to isolate the fault in an electrical path between tools of downhole tool string. If a fault is not detected, one or more switches of a fault detection and tolerance circuit may be closed to enable the transmission of signals on the electrical path. In some embodiments of fault detection and tolerance circuits, an additional one or more switches may be kept open to isolate the fault in electronics of the tool.

First claim

What is claimed is:

1. A method, comprising:
providing a first signal and a second signal from a signal source to a first tool of a plurality of tools in a tool string, the plurality of tools configured to obtain measurements in a wellbore of a well, wherein the signal source is located downhole from the first tool, and the first signal comprises power, and the second signal comprises a communication to at least one of the tools of the plurality of tools;
determining whether a fault having a resistance exists in an electrical path between the first tool and a second tool of the plurality of tools; and
maintaining an uphole switch in an open position and switching a downhole switch to a closed position if the fault exists and the resistance comprises a first resistance; and
maintaining the uphole switch in an open position and maintaining the downhole switch in an open position if the fault exists and the resistance comprises a second resistance higher than the first resistance.

2. The method of claim 1 , wherein maintaining an uphole switch in an open position and a downhole switch in a closed position prevents the first signal and the second signal from transmitting to the second tool.

3. The method of claim 1 , wherein maintaining the uphole switch in an open position and the downhole switch in an open position prevents the first signal from transmitting to the second tool and enables the second signal to transmit to the second tool.

4. The method of claim 3 , wherein the second tool comprises an internal power source, wherein the internal power source is configured to provide power to the second tool when the first signal is prevented from transmitting to the second tool.

5. The method of claim 1 , wherein the fault is a first fault, the method comprising determining whether a second fault exists in an electrical component of the first tool.

6. The method of claim 5 , further comprising maintaining the uphole switch in an open position and the downhole switch in an open position if the second fault exists, wherein maintaining the uphole switch in an open position and the downhole switch in an open position prevents the first signal from transmitting to the second tool and enables the second signal to transmit to the second tool.

7. The method of claim 1 , wherein determining whether a fault having a resistance exists in an electrical path between the first tool and a second tool of the plurality of tools comprises measuring the resistance in the electrical path using a sense resistor, wherein the sense resistor is coupled to a first portion of the electrical path on a first side of the uphole switch and on a second portion of the electrical path on a second side of the downhole switch.

8. The method of claim 1 , wherein the first signal is transmitted using direct current and the second signal is transmitted using alternating current.

Assignees

• Schlumberger Technology Corp

Inventors

• Hoefel Albert
• Harms Kent David
• Villareal Steven G

Classifications

• E21B44/005

  Below-ground automatic control systems · CPC title

• G05B23/0218 Primary

  characterised by the fault detection method dealing with either existing or incipient faults · CPC title

• G05B23/0291 Primary

  Switching into safety or degraded mode, e.g. protection and supervision after failure · CPC title