Peer Review of Interim Report on Computational Fluid Dynamics Model for Predicting Wellhead Oil-Burning Efficiency at Bench and Intermediate Scales (2021) / Chapter Skim
Currently Skimming:
2 The Committee's Responses to the Charge Questions
2 The Committee's Responses to the Charge Questions
Pages 5-14
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From page 5... ...
Were the assumptions regarding wellhead conditions and two-phase wellbore flow (including film thickness and instability, liquid entrainment, and droplet diameter and its influence on wellhead ejection behavior) adequately characterized?
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From page 6... ...
The choice of modeling methods will affect outputs from the Hilcorp WCD model, which were used as input conditions for the NRL model. Perhaps it is possible for BSEE to provide input ranges used for the WCD model for the particular reservoir of interest in the NRL study so there is some control on the input, initial, and boundary conditions used with the NRL model.
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From page 7... ...
Nonetheless, the subprocess models were taken off the shelf with little further development, and the NRL interim report contains sufficient information to show that further development is needed based on the droplet dynamics and combustion data. Given the complexity of the overall problem, subprocess models must work in tandem, and it would have been preferable to provide sensitivity and uncertainty quantification of model assumptions, constants, and boundary and initial conditions as they relate to the ultimate objective of predicting burn efficiency.
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From page 8... ...
Additionally, representing crude oil using a single-component heptane is unsuitable because the heptane is too light and has specific associated sooting propensity due to its chemical structure; hence the sooting potential and characteristics will be different from those of crude oil. Does the droplet injection model adequately simulate realistic diameters and velocities of two-phase, high-speed flows that would occur during a wellhead blowout event?
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From page 9... ...
Were the phase Doppler anemometry imaging diagnostic methods for the droplet behavior measurements appropriately designed, clearly described, and adequate to capture droplet behavior for the Gas Phase and Two-Phase Spray Flame? There was agreement on phase Doppler anemometry (PDA)
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From page 10... ...
Were the diagnostic methods (3-Color High-Speed Pyrometry) for the temperature measurements appropriately designed, clearly described, and adequate to capture temperature for the Gas Phase and Two-Phase Spray Flame?
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From page 11... ...
More explicitly, in this instance, because the Hilcorp WCD model is proprietary, no details are provided. Information on pipe flow and wellbore model details and types are also missing, as is the application of key expertise in wellbore pipe flow and WCD modeling and experimental research.
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From page 12... ...
The committee reached agreement that this research product does not adequately address how the wellbore flow would influence the behavior of the ejected spray plume. The initial experiments are foundational, but need to be expanded based on the current limited observations and limited conditions considered.
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From page 13... ...
between the simpler surrogate fuels used for the NRL study and the actual crude properties will likely influence the predicted burn efficiency. Particulate mass generation should include all relevant crude oil combustion particles (e.g., liquid-phase coking, ash, sand, rock)
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From page 14... ...
At the core, there are concerns about the omission of certain information in the model -- e.g., buoyancy, droplet size and velocity distributions, spray falling to the ground, and the potential for a fire whirl -- that would have been relevant to the resulting burn efficiency. Additionally, even in the CFD model, a great deal of uncertainty in the submodels was not characterized.
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