Methods employing distributed temperature sensing and distributed acoustic sensing for geothermal well planning and development
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Solution Overview
Problem
Conventional geothermal well planning and development methods are time-consuming and disruptive, requiring multiple shallow temperature wells for temperature logging, which can disturb the formation temperature and risk tool loss, and often necessitate additional seismic monitoring wells for microseismicity monitoring.
Innovation Solution
Employ a Distributed Temperature Sensing (DTS) optical fiber system in shallow wells to measure temperature profiles, followed by selecting and configuring Distributed Acoustic Sensing (DAS) interrogators in selected shallow wells for acoustic monitoring, eliminating the need for special-purpose seismic monitoring wells.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If conventional temperature logging methods are used in shallow wells, then temperature profiles can be measured, but the formation temperature is disturbed and tools may be lost requiring well re-entry
Solution Approach 1:
The patent replaces conventional mechanical temperature logging tools with an optical fiber-based Distributed Temperature Sensing (DTS) system. The optical fiber is installed in the shallow well during drilling and remains stationary, eliminating the need for repeated tool insertions and extractions. This substitution of mechanical measurement systems with optical sensing technology provides continuous temperature monitoring without disturbing the formation, thereby resolving the contradiction between measurement capability and formation stability.
2Measurement precision
If multiple shallow temperature wells are drilled for temperature logging, then temperature profiles can be obtained, but time is lost and formation is disturbed
Solution Approach 1:
The patent implements preliminary action by installing the optical fiber cable in the shallow well during the drilling process itself, before any temperature logging operations are needed. This advance preparation eliminates the need for subsequent well re-entries and tool insertions, allowing temperature profiles to be measured continuously and immediately when required. The time-consuming repeated access operations are eliminated while maintaining full temperature measurement capability.
3Measurement precision
If special-purpose seismic monitoring wells are drilled for microseismicity monitoring, then microseismic events can be detected, but device complexity and cost increase
Solution Approach 1:
The patent applies multi-functionality by enabling the optical fiber installed in shallow wells to serve dual purposes: temperature sensing via DTS and acoustic/microseismic monitoring via Distributed Acoustic Sensing (DAS). The same optical fiber infrastructure that measures temperature profiles also detects microseismic events associated with geothermal stimulation activities. This eliminates the need for separate dedicated seismic monitoring wells and reduces overall system complexity while maintaining comprehensive monitoring capabilities.
4Measurement precision
If conventional well logging tools are used repeatedly, then temperature data can be collected, but the risk of tool loss increases
Solution Approach 1:
The patent replaces mechanical well logging tools that must be repeatedly inserted and extracted with a stationary optical fiber sensing system. The optical fiber is permanently installed in the well during drilling and remains in place for the lifetime of the well, eliminating the mechanical operations that carry tool loss risk. Temperature data collection continues with high precision through the stationary optical fiber without any risk of tool retrieval issues.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
Efficiently determines geothermal reservoir location and monitors microseismic events without well re-entry, reducing time and risk, and optimizing geothermal well placement.
Implementation Method 1
Employ a Distributed Temperature Sensing (DTS) optical fiber system in shallow wells to measure temperature profiles
Implementation Method 2
selecting and configuring Distributed Acoustic Sensing (DAS) interrogators in selected shallow wells for acoustic monitoring
Data Source
AI summary
Methods for geothermal well planning and development are provided. This includes: installing fiber optic cables that extend within a plurality of shallow wells, wherein the fiber optic cables support both DTS measurements and DAS measurements; connecting DTS interrogators to the fiber optic cables and configuring the DTS interrogators to measure temperature profiles in the plurality of shallow wells over time; determining planned location of one or more geothermal wells that access a geothermal reservoir from the measured temperature profiles; selecting at least one shallow well to be used for DAS measurements; at each selected shallow well, disconnecting the DTS interrogator from the fiber optic cable at the shallow well and connecting a DAS interrogator to the fiber optic cable at the shallow well; and configuring the DAS interrogator at each selected shallow well to measure an acoustic profile in the selected shallow well over time.