Downhole Tractor Switch State Machines for Reliable Perforation Control
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Solution Overview
Problem
Current systems for perforating guns in oil and gas wells face challenges such as unreliable firing sequences, limited capacity for simultaneous gun firing, and protection against unwanted power, which can lead to safety issues and inefficiencies in well completion operations.
Innovation Solution
A command and response system utilizing state machines for bidirectional communication and power management, allowing for fast and reliable communication with downhole tractors and safety subs, enabling selective firing of multiple guns while preventing unwanted power from reaching sensitive tools, through a combination of electrical switches and safety subs.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If percussion switches are used to selectively fire guns, then the firing sequence can be controlled, but the system is unreliable because a single switch failure stops the entire operation
Solution Approach 1:
The patent replaces mechanical percussion switches with electronic switching devices that have no moving parts. The electronic switches use electrical signals and solid-state components to control firing sequences, eliminating mechanical wear and failure points while maintaining sequential control capability.
Solution Approach 2:
The patent introduces an electronic control system that acts as an intermediary between the power source and the guns. This control system uses electrical signals to selectively activate guns in sequence, providing reliable control without direct mechanical connection between switches and guns.
2Quantity of substance
If electronic switches with bidirectional communication are used, then more guns can be fired selectively, but the firing speed decreases due to long communication sequences
Solution Approach 1:
The patent implements preliminary addressing where each electronic switch is pre-configured with a unique address code during system setup. This eliminates the need for lengthy bidirectional communication sequences during actual firing operations, as the control system can directly address and activate specific guns by their pre-assigned addresses, significantly reducing communication time while maintaining the ability to control large numbers of guns.
3Use of energy by moving object
If high voltage power is transmitted through the tractor to power tools, then the tools can be powered, but unwanted voltage can accidentally fire guns or damage electronics
Solution Approach 1:
The patent introduces electronic switching devices as intermediaries between the high voltage power source and the tools/guns. These switches use controlled electrical signaling to manage power distribution, allowing legitimate power transmission to tools while preventing accidental voltage transmission to guns through proper control logic and isolation mechanisms.
Solution Approach 2:
The patent implements feedback control where the electronic switching system continuously monitors the state of connected devices and adjusts power transmission accordingly. This feedback mechanism ensures that power is only transmitted when appropriate and prevents unwanted voltage effects by detecting and responding to system conditions in real-time.
Data Source
AI summary
Apparatus and methods for controlling and communicating with one or more tools in a downhole tool string including a tractor, an auxiliary tractor tool, a logging tool, a safety sub, a release mechanism, a unit containing sensors for monitoring downhole conditions, a setting tool, and a perforating gun. Control and communication are accomplished by sending signals from the surface to control switches in the control units on the tool, with redundant switches for safety, to state machines in the respective control units, each state machine returning a signal verifying switch status to the surface. The state machine need not return a signal including a unique identifier.