DSpace Community:http://hdl.handle.net/2440/3042014-09-21T14:07:50Z2014-09-21T14:07:50ZGlacial geomorphological mapping of Coire Mhic Fhearchair, NW Scotland: The contribution of a high-resolution ground based LiDAR surveyMcCormack, D.C.Irving, D.H.B.Brocklehurst, S.H.Rarity, F.http://hdl.handle.net/2440/849722014-09-10T05:01:20Z2007-12-31T13:30:00ZTitle: Glacial geomorphological mapping of Coire Mhic Fhearchair, NW Scotland: The contribution of a high-resolution ground based LiDAR survey
Author: McCormack, D.C.; Irving, D.H.B.; Brocklehurst, S.H.; Rarity, F.
Abstract: Terrestrial Light Detection and Ranging (tLiDAR) surveys are valuable supplements to existing geomorphological mapping techniques, providing information which is of considerable interest to palaeoclimatologists and glaciologists. Fieldwork observations, and the interpretation of aerial photographs and digital elevation models, have been augmented by the study of 3D digital models produced from tLiDAR data, and have led to the production of a detailed geomorphological map at a scale of 1:10,000. A 2 km2 study was carried out in Coire Mhic Fhearchair (NW Scotland), a cirque landform which was covered by an ice-sheet at the Last Glacial Maximum, and experienced localised ice ow during subsequent deglaciation and readvances. The combined map includes glacial (moraines, striae, and depositional lineations) and paraglacial features (debris fans) which have been observed using some or all of the above methods. In addition to this, tLiDAR has been used in conjunction with colour photography to provide a ‘virtual reality’ observational tool at resolutions of up to 50 mm, with great potential for the detailed study of glacial geomorphology on the sub-km scale.2007-12-31T13:30:00ZResources, reserves, and consumption of energyGautier, D.McCabe, P.Ogden, J.Demayo, T.http://hdl.handle.net/2440/849442014-09-04T00:59:35Z2009-12-31T13:30:00ZTitle: Resources, reserves, and consumption of energy
Author: Gautier, D.; McCabe, P.; Ogden, J.; Demayo, T.2009-12-31T13:30:00ZMathematical modelling of formation damage in geothermal wells due to fines migrationYou, Z.Bedrikovetski, P.Hand, M.http://hdl.handle.net/2440/849362014-09-04T00:12:31Z2012-12-31T13:30:00ZTitle: Mathematical modelling of formation damage in geothermal wells due to fines migration
Author: You, Z.; Bedrikovetski, P.; Hand, M.
Abstract: A mathematical model for fines migration during exploitation of geothermal wells is developed. Governing equations in the proposed model describe the flow of water with fines towards the well accounting for particle detachment, migration and straining, which result in permeability decline and well impedance growth. The developed model for well inflow performance has been applied to the field case (geothermal reservoir B, Australia) successfully. The well impedance history obtained from model prediction and from field measurements are in good agreement, which validates the current model. The sensitivity analysis of the flow rate and the temperature reveals that increase of either the flow rate or the temperature worsens the formation damage and well impedance. Geothermal reservoirs are significantly more perceptive for fines migration induced formation damage than traditional oil and gas reservoirs, due to substantial decrease in electrostatic particle-rock attachment at elevated temperature.2012-12-31T13:30:00ZCombining geostatistics with Bayesian updating to continually optimize drilling strategy in shale gas playsWilligers, B.Begg, S.Bratvold, R.http://hdl.handle.net/2440/849032014-09-03T00:45:11Z2012-12-31T13:30:00ZTitle: Combining geostatistics with Bayesian updating to continually optimize drilling strategy in shale gas plays
Author: Willigers, B.; Begg, S.; Bratvold, R.
Abstract: We present a new methodology for improving the economic returns of shale gas plays. The development of an economically efficient drilling programme in such plays is a challenging task, requiring a large number of wells. Even after a relatively large number of wells have been drilled, the average well production and the variation of well performance (economics) remains highly uncertain. The ability to delineate a shale play with the fewest number of wells and to focus drilling in the most productive areas is an important driver of commercial success. The importance of probabilistic modelling in managing uncertainty in shale gas plays has been explicitly emphasised in a number of studies. The objective of this study is to develop a practical valuation methodology that addresses these complexities and is dynamic, in the sense that the optimal drilling strategy can be continually updated as we learn the outcome of each well drilled. Maximizing the returns from a shale gas play is essentially a problem of choosing well locations and numbers to optimize production volumes & rates. Drilling policies have to take account of a large number of already-drilled locations, possible new drilling locations, spatial dependencies between performance at those different (possible) well locations and the extent of uncertainty as to whether or not a well will be economic. These factors cause typical valuation methodologies to be impractical due to the "curse of dimensionality??. In this study an unconventional play is divided into cells. In each cell a fixed number of wells can be drilled. The chance of success (of a well having an NPV greater than zero) in any given cell is itself considered to be an uncertain variable. An initial probability distribution for the chance of success of each cell is derived from analogous plays plus any available information about the specific play. The methodology proceeds as follows. First, as each new well (or group of new wells) is drilled, the outcome is used in combination with the prior probability distribution (using Bayes Theorem) to create an updated probability distribution for the chance of success of the relevant grid cell. Thus, our initial estimate can be continuously updated as we get more and more actual outcomes. Second, the influence of the new chance of success on the surrounding cells, due to spatial correlation, is updated using indicator kriging, a geostatistical technique. The methodology proposed in this study informs the development of drilling policies for shale gas opportunities by using a probabilistic model that accounts for the uncertainty in the chance of success and its spatial dependency. The use of cells to represent a set of wells simplifies the analysis and greatly reduces the computing requirements. The methodology has been applied to a well set from the Barnett Shale, Texas, United States of America.2012-12-31T13:30:00Z