Time filter

Source Type


Lee C.,Ashima Research | Lawson W.G.,Point Carbon | Richardson M.I.,Ashima Research | Anderson J.L.,IMaGE | And 3 more authors.
Journal of Geophysical Research E: Planets

We describe a global atmospheric data assimilation scheme that has been adapted for use with a Martian General Circulation Model (GCM), with the ultimate goal of creating globally and temporally interpolated "reanalysis" data sets from planetary atmospheric observations. The system uses the Data Assimilation Research Testbed (DART) software to apply an Ensemble Kalman Filter (EnKF) to the MarsWRF GCM. Specific application to Mars also required the development of a radiance forward model for near-nadir Thermal Emission Spectrometer (TES) observations. Preliminary results from an assimilation of 40 sols of TES radiance data, taken around Ls = 150 (August 1999, Mars Year 24), are provided. 1.3 million TES observations are ingested and used to improve the state prediction by the GCM, with bias and error reductions obtained throughout the state vector. Results from the assimilation suggest steepening of the latitudinal and vertical thermal gradients with concurrent strengthening of the mid-latitude zonal jets, and a slower recession of the southern polar ice edge than predicted by the unaided GCM. Limitations of the prescribed dust model are highlighted by the presence of an atmospheric radiance bias. Preliminary results suggest the prescribed dust vertical profile might not be suitable for all seasons, in accordance with more recent observations of the vertical distribution of dust by the Mars Climate Sounder. The tools developed using this DA system are available at http://www.marsclimatecenter.com. A tutorial and example TES radiance assimilation are also provided. Copyright 2011 by the American Geophysical Union. Source

Maxwell S.C.,Itasca Calgary Inc. | Lee B.,IMaGE | Mack M.,IMaGE
6th EAGE Workshop on Passive Seismic: From Data to Decision

A coupled hydraulic-geomechanical simulation is used to model hydraulic fracture growth and predict the corresponding microseismicity. Using a case study from the Horn River Basin, a quantitative match between the modeled and observed microseismic deformation is used to calibrate a reconstruction of the hydraulic fracture network that reconciles the geological and geomechanical earth model with the fracture engineering. The calibrated fracture model includes an estimate of the propped portion of the fracture network and can then be used to investigate alternate designs to optimize the well, completion and injection to maximize the conductive fracture and thereby reservoir drainage. © 2016, European Association of Geoscientists and Engineers, EAGE. All rights reserved. Source

Zhang F.,IMaGE | Lee B.T.,IMaGE | Mack M.,IMaGE
49th US Rock Mechanics / Geomechanics Symposium 2015

A grain-based rock model was developed and applied to study wellbore stability. The rock is represented as an assembly of tetrahedral blocks with bonded contacts. Material heterogeneity is modeled by varying the tensile strength at the block contacts. This grain-based rock model differs from previous disk/sphere particle-based rock models (e.g., Potyondy and Cundall, [1]) in its ability to represent a zero (or very low) initial porosity condition, as well as highly interlocked irregular block shapes that provide resistance to movement even after contact breakage. As a result, this model can reach higher uniaxial compressive strength to tensile strength ratios and larger friction coefficients than the disk/sphere particle-based rock model. The model was first used to match the properties of typical rocks (such as sandstone) by simulating the direct tension test and uniaxial compression test. The calibrated model was then applied to study wellbore breakout and the thick-walled cylinder (TWC) test. The model captured the fragmentation process near the wellbore due to buckling and spalling. Thin fragments of rock similar to onion skins were produced, as observed in laboratory breakout experiments (e.g., Haimson, [2]). The resuhs suggest that this approach may be well-suited to study the rock disaggregation process and other geomechanical problems in the oil and gas industry. Copyright 2015 ARMA, American Rock Mechanics Association. Source

Maxwell S.C.,IMaGE | Mack M.,IMaGE | Zhang F.,IMaGE | Chorney D.,IMaGE | And 2 more authors.
Society of Petroleum Engineers - Unconventional Resources Technology Conference, URTeC 2015

Microseismicity induced by hydraulic fracturing can be caused by a variety of pressure and mechanical effects, resulting in both 'wet' microseismic events directly associated with the hydraulic fracture network and potentially remote 'dry' events. Understanding the cause of the specific microseismic events is critical to standard interpretation of fracture geometry, to avoid overestimation of the fracture geometry by including dry events. Furthermore, differentiation of the event types is also important for source characterization interpretations of the fracture deformation. In this study, a geomechanical model is used to understand the conditions for generation of different types of events. Predictions of synthetic microseismicity from geomechanical modeling is also used to identify event types based on the hydraulic and stress conditions. The event classification is then used to study various microseismic attributes and test their practical application to differentiate events based on spatial/temporal microseismic characteristics, speed of growth away from the fracture initiation points, source mechanism and frequency-magnitude relationships. Copyright 2015, Unconventional Resources Technology Conference. Source

Discover hidden collaborations