In situ hydromechanical responses during well drilling recorded by distributed fiber-optic strain sensing

Abstract

<jats:p>Abstract. Drilling fluid infiltration during well drilling induces pore pressure and strain perturbations in neighboured reservoir formations. In this study, we in situ monitored such small strain changes (~ 20 µε) using fiber-optic distributed strain sensing in two observation wells with different distances (approximately 3 m and 9 m) from a new drilling wellbore in a shallow water aquifer. The results suggest that the drilling induced hydromechanical deformations that occurred at depths of both wells are indicative of the impact zones of fluid invasion and reservoir permeability structure (heterogeneity). A hydraulic diffusion model is used to interpret the strain evolution. The method and data would be useful for understanding reservoir pressure communications, determining the zones for fluid productions or injections (e.g., for CO2 storage), and optimizing reservoir management and utilization. </jats:p>

Toward Retrieving Distributed Aquifer Hydraulic Parameters From Distributed Strain Sensing

“…One concern is that it is unclear whether the measured strain is partially or fully representative of the formation deformation. Some studies have considered the strain transfer problem for unconsolidated formation with loose coupling between formation and cement (Zhang et al., 2020). However, according to Becker et al.…”

“…One concern is that it is unclear whether the measured strain is partially or fully representative of the formation deformation. Some studies have considered the strain transfer problem for unconsolidated formation with loose coupling between formation and cement (Zhang et al, 2020). However, according to Becker et al (2018), for a stiff rock formation with good coupling between formation and cement (without slippage), the strain measurement by DSS represents formation deformation.…”

“…In this study, we focused only on the pumping stage. The fiber optic acquisition was performed using the Neubrescope NBX‐8000 device and the Tunable Wavelength Coherent Optical Time Domain Reflectometry (TW‐COTDR) method (Kishida et al., 2014; Zhang et al., 2020). Continuous and distributed strain data with an accuracy of 0.5 µε, spatial resolution of 5 cm and a time resolution of approximately 1.1 h was obtained during the entire pumping operation.…”

A Type‐Curve Approach for Evaluating Aquifer Properties by Interpreting Shallow Strain Measured During Well Tests

“…Interpretation of strain data during well testing become increasingly important as in‐situ strain measurement becomes more accessible (Cappa et al., 2006; Hua et al., 2017, 2020; Murdoch et al., 2020; Schuite et al., 2017; Sun et al., 2020; Zhang et al., 2020). We envision that simple methods, like the ones described here, could provide initial estimates for more comprehensive analyses of strain data (Barbour & Wyatt, 2014; Murdoch et al., 2019; Schuite et al., 2015, 2017; Vasco et al., 2001).…”

Distributed fiber optic strain sensing of bending deformation of a well mockup in the laboratory

“…First, the cables used in this study are designed to have high robustness so that they will survive the harsh installation process of tubular in deep offshore wellbore. Existing studies on field applications of distributed strain sensing, in contrast, are limited to onshore wells whose construction processes were well-controlled to allow the use of fragile fiber optic cables (Zhang, Lei, Hashimoto, et al 2020;Lei, Xue, and Hashimoto 2019;Sun et al 2020;Sun et al 2021;. Second, the cables in this study were cemented in the annulus of the mockup without directly attaching them to the inner pipe (i.e., casing).…”