Analysis of Strain Responses in Vertical Monitoring Wells for Low-Frequency Distributed Acoustic Sensing

Srinivasan, Aishwarya; Liu, Yongzan; Wu, Kan; Jin, Ge; Moridis, George J.

doi:10.56952/arma-2022-0263

Cited by 2 publications

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Geomechanical Modeling of Fracture-Induced Vertical Strain Measured by Distributed Fiber-Optic Strain Sensing

Srinivasan

Liu

et al. 2023

SPE Production &Amp; Operations

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Summary Distributed acoustic sensing (DAS) has recently gained importance in monitoring hydraulic fracturing treatments in the oil and gas industry. DAS data contain critical information about the fracture geometry as linearly relatable induced strain variations during the stimulation. The low-frequency components of the DAS (LF-DAS) data are known for their complexity as they exhibit various characteristic signals—caused by several mechanisms—that complicate their interpretation. LF-DAS data from horizontal monitoring wells (HMWs) have been used to detect fracture hits and characterize fracture geometry. However, the LF-DAS data from vertical monitoring wells (VMWs) have not been studied extensively as a means to infer fracture geometry. The major limitation of VMWs is the number of monitored stages, but the data contain more information about fracture height compared with LF-DAS measurements from HMWs. Hence, it is necessary to have a physical rock deformation model to simulate the strain rate responses in offset VMWs during fracture propagation to understand and interpret the various patterns that are observed in the field data sets. The objective of this study is to simulate strain rate signals in VMWs during hydraulic fracturing and to analyze the measurements to obtain information on the fracture geometry, especially the fracture height. The fracture boundary can be directly related to the strain rate signals. In this study, we propose a workflow to determine fracture height at different fiber-to-fracture (dff) distances for fracture heights ranging from 20 m to 300 m. We conduct a detailed sensitivity analysis to understand the impacts of the dff, the perforation location, the fracture passing time, and the well inclinations on the measured strain rate signals. The analysis helps interpret the various patterns observed in field data and the underlying mechanisms. Interpretation of field data from the Hydraulic Fracture Testing Site 2 (HFTS-2) using the results from our forward physical model provides valuable information on the fracture characteristics that can be captured by the physical model. The results of this study are expected to provide better interpretations of LF-DAS signals from VMWs.

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Geomechanical Modeling of Fracture-Induced Vertical Strain Measured by Distributed Fiber-Optic Strain Sensing

Srinivasan

Liu

et al. 2023

SPE Production &Amp; Operations

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Optimization of Enhanced Geothermal System Operations Using Distributed Fiber Optic Sensing and Offset Pressure Monitoring

Titov,

Dadi,

Galban

et al. 2024

Day 2 Wed, February 07, 2024

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Enhanced Geothermal Systems (EGS) have emerged as a promising method to generate electricity from geothermal resources in areas that lack natural fractures and/or faults needed to connect injector/production well sets, virtually eliminating dry hole risk. EGS leverages much of the learnings from the past two decades of unconventional developments, connecting horizontal wells with multi-stage stimulations to create connectivity to flow water between wells to mine heat from the subsurface. This paper presents a case study in measuring EGS fracture geometry, utilizing measurements from vertical and horizontal permanent fiber optic cables and offset pressure monitoring. The Devon Quantification of Interference (DQI) analysis is also applied to multi-stage stimulated geothermal wells, integrated with fracture and reservoir simulation. Fervo Energy, a first mover in EGS, is leading the way in developing this technology. Devon, an industry leader in unconventional oil and gas development, leverages their learnings in this field to optimize EGS operations. Optimal well spacing and completions design, much like in oil and gas, are critical to optimizing for a successful EGS development. Analysis of strain rate in offset well and multi-well microseismic recorded with fiber optic cables during stimulation and well testing allowed to characterize stimulated reservoir volume created by hydraulic stimulation and optimize well placement. The DQI analysis examined the well-to-well connectivity of the multi-stage stimulation between the two wells in the case study, providing insight into the conductive fracture geometry. The paper also discusses the execution of well preparation, stimulation, and high-level well performance. This study provides valuable insights into the development of EGS using vertical and horizontal permanent fiber optic cables and offset pressure monitoring. The findings suggest that this approach can be effective in optimizing EGS operations. Fervo Energy’s expertise in EGS development, combined with Devon’s expertise in unconventional oil and gas development, can be leveraged to further advance EGS technology at scale and generate electricity from geothermal resources. This paper serves as a valuable resource for operators looking to optimize EGS operations.

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Analysis of Strain Responses in Vertical Monitoring Wells for Low-Frequency Distributed Acoustic Sensing

Cited by 2 publications

References 0 publications

Geomechanical Modeling of Fracture-Induced Vertical Strain Measured by Distributed Fiber-Optic Strain Sensing

Geomechanical Modeling of Fracture-Induced Vertical Strain Measured by Distributed Fiber-Optic Strain Sensing

Optimization of Enhanced Geothermal System Operations Using Distributed Fiber Optic Sensing and Offset Pressure Monitoring

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