In-service degradation of a pipe section is monitored in real time with torsional guided waves wh... more In-service degradation of a pipe section is monitored in real time with torsional guided waves which can resolve 5% damage to the internal wall. We use a single permanently installed source–receiver pair as opposed to the current state-of-the-art sensor rings. There is no baseline subtraction requirement as a single reflection coefficient is derived by internal referencing of the time trace. Even with continuously operating pump vibration, there is enough acoustic signal for confident damage localization. Since pipelines wear out gradually in industrial installations, the acoustic footprint is similar to that previously determined in periodically damaged pipes. The reflective method can thus be applied successfully to monitor structural health in industrial pipelines during operation as opposed to the current state-of-the-art guided wave inspection approaches using near-weld reflection techniques along with disassembled and re-assembled sensor rings.
Axial pipeline defects are detectable from torsional guided wave reflections through 90 deg elbow... more Axial pipeline defects are detectable from torsional guided wave reflections through 90 deg elbows. This paper demonstrates that detection of localized damage in carbon steel pipes with a so-called standard long and very long radius elbow is possible using a single permanently installed source–receiver pair. We use dispersion imaging to determine why this is not possible in a short radius elbow pipe. Although the remote damage is detected in a standard short radius bend pipe, there is not enough signal to detect localized damage. Since pipeline bends are normally of at least standard long radius, the acoustical behavior is similar to that previously determined in straight pipes. The reflective method can thus be applied fruitfully to monitor structural health beyond industrial pipeline bends.
Journal of Petroleum Science and Engineering, 2016
A subclass of viscoelastic surfactant fluids are investigated as flow-dependent proppant carrying... more A subclass of viscoelastic surfactant fluids are investigated as flow-dependent proppant carrying fluids. Shear-induced structure networks have the potential to eliminate the need for cross linkers and viscosity breakers associated with traditional fluids because they shear-thicken and shear-thin depending on the fluid pump rates in the fracture. Particle tracking velocimetry is used to visualize proppant settling velocity inside a fracture flow cell. We show that settling velocities in high shear flows are reduced by a factor 20 compared to settling in low shear ones and fluids at rest. Couette cell and oscillatory rheometry are used to investigate the induced viscoelasticity. The critical shear rate required for fluid thickening and the succeeding viscosity contrast ratio determine the extra proppant carrying capacity.
Abstract Fluids displaying flow induced viscoelasticity are tested for proppant placement and flo... more Abstract Fluids displaying flow induced viscoelasticity are tested for proppant placement and flow back. The viscosity is self-regulating and obviates the need for viscosifiers and breakers. The flow induced viscoelasticity degrades at higher flow rates enabling good injectivity. Particle tracking velocimetry is performed to study the influence of flow rate on the particle settling under different flow regimes. These tests show that above a critical flow rate particles are maintained in suspension and settle with a constant velocity giving the fluid an apparent viscosity up to 200 mPa s compared to a zero-shear viscosity of 2 mPa s. During flowback in porous proppant packs the fluid has a low flow resistance with a viscosity comparable to its zero-sheared state. Pack permeability is retained after flowback of the fluid thereby resulting in optimum fracture clean-up.
Olefins are highly nonlinear octane blenders so that standard GC analyses are poor predictors of ... more Olefins are highly nonlinear octane blenders so that standard GC analyses are poor predictors of blend quality. Engine rating is the only way of measuring olefin octane number nonlinearity. It is thus not possible to rapidly assess the quality of the product obtained from an olefin-producing process-stream. An analysis of the kinetics of olefin combustion in terms of mechanisms for depleting active radicals identifies hydrogen abstraction from an allylic carbon as a factor that increases resistance to knock. We can use NMR to find the allylic hydrogen fraction in a sample, and we show that this correlates with mixtures of olefins obtained during processing of the typical gaseous products of a cat-cracked stream. This simple application of NMR has the advantages of quantitatively probing octane number on a sound chemical criterion, as well as the fact that it is fast and requires only small amounts of sample so that process optimization for olefin quality on a small-scale microflow reactor can easily be carried out.
Multi-mode dispersion imaging shows that pure dispersion-free torsional waves are reflected at a ... more Multi-mode dispersion imaging shows that pure dispersion-free torsional waves are reflected at a pipe end and flexural wave modes are suppressed. This effect can be used to locate and assess internal damage. The end reflection coefficient of this single propagating mode decreases with increasing wear. The pipe damage is located from the travel time of the torsional wave component reflected from the damage point.
In-service degradation of a pipe section is monitored in real time with torsional guided waves wh... more In-service degradation of a pipe section is monitored in real time with torsional guided waves which can resolve 5% damage to the internal wall. We use a single permanently installed source–receiver pair as opposed to the current state-of-the-art sensor rings. There is no baseline subtraction requirement as a single reflection coefficient is derived by internal referencing of the time trace. Even with continuously operating pump vibration, there is enough acoustic signal for confident damage localization. Since pipelines wear out gradually in industrial installations, the acoustic footprint is similar to that previously determined in periodically damaged pipes. The reflective method can thus be applied successfully to monitor structural health in industrial pipelines during operation as opposed to the current state-of-the-art guided wave inspection approaches using near-weld reflection techniques along with disassembled and re-assembled sensor rings.
Axial pipeline defects are detectable from torsional guided wave reflections through 90 deg elbow... more Axial pipeline defects are detectable from torsional guided wave reflections through 90 deg elbows. This paper demonstrates that detection of localized damage in carbon steel pipes with a so-called standard long and very long radius elbow is possible using a single permanently installed source–receiver pair. We use dispersion imaging to determine why this is not possible in a short radius elbow pipe. Although the remote damage is detected in a standard short radius bend pipe, there is not enough signal to detect localized damage. Since pipeline bends are normally of at least standard long radius, the acoustical behavior is similar to that previously determined in straight pipes. The reflective method can thus be applied fruitfully to monitor structural health beyond industrial pipeline bends.
Journal of Petroleum Science and Engineering, 2016
A subclass of viscoelastic surfactant fluids are investigated as flow-dependent proppant carrying... more A subclass of viscoelastic surfactant fluids are investigated as flow-dependent proppant carrying fluids. Shear-induced structure networks have the potential to eliminate the need for cross linkers and viscosity breakers associated with traditional fluids because they shear-thicken and shear-thin depending on the fluid pump rates in the fracture. Particle tracking velocimetry is used to visualize proppant settling velocity inside a fracture flow cell. We show that settling velocities in high shear flows are reduced by a factor 20 compared to settling in low shear ones and fluids at rest. Couette cell and oscillatory rheometry are used to investigate the induced viscoelasticity. The critical shear rate required for fluid thickening and the succeeding viscosity contrast ratio determine the extra proppant carrying capacity.
Abstract Fluids displaying flow induced viscoelasticity are tested for proppant placement and flo... more Abstract Fluids displaying flow induced viscoelasticity are tested for proppant placement and flow back. The viscosity is self-regulating and obviates the need for viscosifiers and breakers. The flow induced viscoelasticity degrades at higher flow rates enabling good injectivity. Particle tracking velocimetry is performed to study the influence of flow rate on the particle settling under different flow regimes. These tests show that above a critical flow rate particles are maintained in suspension and settle with a constant velocity giving the fluid an apparent viscosity up to 200 mPa s compared to a zero-shear viscosity of 2 mPa s. During flowback in porous proppant packs the fluid has a low flow resistance with a viscosity comparable to its zero-sheared state. Pack permeability is retained after flowback of the fluid thereby resulting in optimum fracture clean-up.
Olefins are highly nonlinear octane blenders so that standard GC analyses are poor predictors of ... more Olefins are highly nonlinear octane blenders so that standard GC analyses are poor predictors of blend quality. Engine rating is the only way of measuring olefin octane number nonlinearity. It is thus not possible to rapidly assess the quality of the product obtained from an olefin-producing process-stream. An analysis of the kinetics of olefin combustion in terms of mechanisms for depleting active radicals identifies hydrogen abstraction from an allylic carbon as a factor that increases resistance to knock. We can use NMR to find the allylic hydrogen fraction in a sample, and we show that this correlates with mixtures of olefins obtained during processing of the typical gaseous products of a cat-cracked stream. This simple application of NMR has the advantages of quantitatively probing octane number on a sound chemical criterion, as well as the fact that it is fast and requires only small amounts of sample so that process optimization for olefin quality on a small-scale microflow reactor can easily be carried out.
Multi-mode dispersion imaging shows that pure dispersion-free torsional waves are reflected at a ... more Multi-mode dispersion imaging shows that pure dispersion-free torsional waves are reflected at a pipe end and flexural wave modes are suppressed. This effect can be used to locate and assess internal damage. The end reflection coefficient of this single propagating mode decreases with increasing wear. The pipe damage is located from the travel time of the torsional wave component reflected from the damage point.
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Papers by Michael Golombok