Blar i NTNU 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 ... -
Application of a Bingham viscoplastic model to borehole closure: comparison between two numerical approaches
Xie, Xiyang; Fjær, Erling; Detournay, Christine (Chapter, 2019)ABSTRACT: Several field observations by cement bond logs (a technique used to detect substance behind casing) indicate progressive borehole closure in soft rock such as shale. This study considers the problem of progressive ... -
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 ... -
Can heating-induced creep result in shale barriers for P&A applications?
Bauer, Andreas Kurt Marcel; Stenebråten, Jørn; Li, Liming; Fjær, Erling (Chapter, 2017)It has been shown that some shale formations form barriers around a casing of a well due to shale creep that results in closure and sealing of the annulus around the casing. The existence of such shale barriers facilitates ... -
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 (Peer reviewed; Journal article, 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, ... -
Creep and Consolidation in Pierre Shale - Identification of how time-dependent effects are influenced by alteration in pore fluid pH and changes in stress conditions
Lund, Elisabeth; Kleiven, Marta Laukeland (Master thesis, 2016)The Petroleum Safety Authority of Norway (PSA) has now acknowledged the use of shale as an annular barrier for permanent plug and abandonment (PP&A) operations in the oil industry. Shale can exhibit a natural self-sealing ... -
Experimental Measurements of the Capillary Entry Pressure of Outcrop and Field Shale
Sjursen, Thomas Hauknes (Master thesis, 2015)The oil industry often faces borehole stability issues when drilling through shale, especially shale that is water-wet. It is often observed that drilling with oil-based mud yields the best results due to the capillary ... -
Experimental Studies of Stress Dependence,Static vs Dynamic behaviour and Mechanical Anisotropies of Shale
Holt, Rune Martin; Bakk, Audun; Bauer, Andreas; Fjær, Erling; Stenebråten, Jørn (Chapter, 2014)Laboratory data from controlled rock mechanical tests with various shales have been used to understand and quantify stress effects on wave velocities of relevance for 4D seismics, and to quantify the difference between ... -
Frequency-dependent wave velocities in sediments and sedimentary rocks: Laboratory measurements and evidences
Bauer, Andreas; Bhuiyan, Mohammad Hossain; Fjær, Erling; Holt, Rune Martin; Lozovyi, Serhii; Pohl, Mathias; Szewczyk, Dawid (Journal article; Peer reviewed, 2016)The pioneering work of Mike Batzle and his colleagues has provided a fundamental understanding of mechanisms behind dispersion and attenuation of elastic waves in fluid-saturated rocks. It also has made way for a realization ... -
Index Tests and Their Applications - Determining Rock Strength and Strength-anisotropy as a Function of Inclination by use of Index Testing and Mathematical Modelling
Rugland, Tor Andre (Master thesis, 2015)Drilling problems in shale continue to be an expensive problem in the petroleum industry due to lack of information concerning rock mechanical parameters. Conventional laboratory tests are expensive and time consuming, as ... -
Investigation of Creep Characteristics for Stresses close to Failure - Experiments and Anaysis
Olsen, Jørgen Rasmussen (Master thesis, 2015)This study consists of a series of experiments set up to investigate the active processes in creep, with emphasizes on unloading and recovery of strain. The experiments were performed on dry 1x2 inch cylindrical core samples ... -
Long-term creep prediction with a modified power law model
Xie, Xiyang; Fjær, Erling; Pradhan, Srutarshi (Chapter, 2017)Creep in weak rock is a common phenomenon observed in the laboratory. Based on short-term creep, prediction of long-term creep can be a challenge especially at elevated stress levels, since only a small stress increase may ... -
Measurements of the Capillary Entry Pressure in Shale
Augdal, Cerina (Master thesis, 2014)The work in this thesis is based on setting up equipment and establishing a testing procedure for core sample measurements of capillary entry pressure in shale. The industry faces often stability problems regarding drilling ... -
Non-elastic effects in static and dynamic rock stiffness
Lozovyi, Serhii; Sirevaag, Tore Lie; Szewczyk, Dawid; Bauer, Andreas Kurt Marcel; Fjær, Erling (Chapter, 2017)The static stiffness of a rock is generally smaller than its dynamic stiffness, which, for non-dispersive rocks, is due to a difference in strain amplitude in compaction tests (quasi-static) and wave-velocity measurements ... -
Overburden geomechanical effects on 4D seismic response - influences of stiffness contrast, anisotropy, and geometry
Li, Liming; Bauer, Andreas; Holt, Rune Martin; Fjær, Erling; Stenebråten, Jørn; Bakk, Audun (Journal article; Peer reviewed, 2014)Petroleum production and CO2 storage induce effective stress changes and deformations in the reservoir, as well as in the overburden. This may be detected by 4D seismic monitoring due to the stress-sensitivity of the seismic ... -
Relating acoustic wave velocities to formation mechanical properties
Brandås, Linn Tove (Master thesis, 2012)Proper correlation between formation mechanical properties and acoustic data is essential for acquiring field rock mechanical data for analysis, and it has thereby a great significance to oilfield development.This thesis ... -
Relating Static and Dynamic Mechanical Anisotropies of Shale
Holt, Rune Martin; Bauer, Andreas; Fjær, Erling; Stenebråten, Jørn; Szewczyk, Dawid; Horsrud, Per (Chapter, 2015)Experimental studies of shale cores of different orientations have been performed to compare the angular dependence of dynamic moduli acquired at ultrasonic frequencies with static moduli (Young’s moduli and Poisson ratios) ... -
Relations between Static and Dynamic Moduli of Sedimentary Rocks
Fjær, Erling (Journal article; Peer reviewed, 2018)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 ... -
Rock Mechanical Anisotropy, and its Impact on Borehole Stability
Paz, Thomas (Master thesis, 2014)In drilling operations, small margins between wellbore collapse and hydraulicfracturing can become aggravated in anisotropic formations. A stuck piperesulting from borehole failure can give serious economic consequences, ... -
Rock Properties in Synthetic- and Natural Clay Materials - An Experimental Study on Shale Barrier Materials
Oftedal, Ivar Wathne (Master thesis, 2018)Since the late 1960's, thousands of wells have been drilled on the Norwegian Continental Shelf (NCS) - following the discovery of large hydrocarbon reserves on what eventually became Norwegian territory in the North Sea. ...