Blar i SINTEF Open på forfatter "Fjær, Erling"

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    • Acid treatment as a way to reduce shale rock mechanical strength and to create a material prone to the formation of permanent well barrier 

      Gawel, Kamila; Lozovyi, Maksym; Bhuiyan, Mohammad Hossain; Bjørge, Ruben; Fjær, Erling (Peer reviewed; Journal article, 2021)
      Utilization of natural shale formations for the creation of annular barriers in oil and gas wells is currently discussed as a mean of simplifying cumbersome plugging and abandonment procedures. Shales that are likely to ...

    • Can Heating Induce Borehole Closure? 

      Xie, Xiyang; Bauer, Andreas; Stenebråten, Jørn; Bakheim, Sigurd; Lavrov, Alexandre; Fjær, Erling; Kristiansen, Tron Golder (Peer reviewed; Journal article, 2020)
      The current study shows that heating a cased borehole in low-permeability shale rock can induce plastic deformation, leading to the closure of the casing annulus and decreasing annulus connectivity. The thermally induced ...

    • Characteristic features of shale barrier materials 

      Fjær, Erling; Stenebråten, Jørn; Bakheim, Sigurd; Larsen, Idar (Peer reviewed; Journal article, 2023)
      Deep wells in soft formations are completed with a steel tube (“casing”) that isolates the well from the surrounding rock. The annulus between the casing and the rock is usually left open in long sections of the well, thus ...

    • Comparing mechanical and ultrasonic behaviour of a brittle and a ductile shale: Relevance to prediction of borehole stability and verification of shale barriers 

      Holt, Rune Martin; Larsen, Idar; Fjær, Erling; Stenebråten, Jørn (Journal article; Peer reviewed, 2019)
      Borehole collapse during drilling operations in shale formations is a well-known and costly problem within the petroleum industry. Recently it has become evident that shales may also form sealing barriers around the casing, ...

    • Relations between Static and Dynamic Moduli of Sedimentary Rocks 

      Fjær, Erling (Peer reviewed; Journal article, 2019)
      Static moduli of rocks are usually different from the corresponding dynamic moduli. The ratio between them is generally complex and depends on several conditions, including stress state and stress history. Different drainage ...

    • Time-dependent closure of a borehole in a viscoplastic rock 

      Xie, Xiyang; Fjær, Erling; Detournay, Emmanuel (Peer reviewed; Journal article, 2019)
      The paper describes a model to predict and analyze the time-dependent closure of a borehole drilled in a soft rock subjected to an initial isotropic stress, and the build-up of stress on a rigid casing after contact with ...