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AI-GEOSTATS:

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  • murray lark (SRI)
    Dear Colleagues, Below is information on a post-doctoral position which may be of interest to members of the list. Please pass this on to anyone who might be
    Message 1 of 34 , Mar 17, 2003
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      Dear Colleagues,

      Below is information on a post-doctoral position which may be of interest to members of the list. Please pass this on to anyone who might be interested.

      best regards

      Murray Lark


      Post-Doctoral position in Environmetrics.

      Silsoe Research Institute in Bedfordshire, England, is to initiate a new research programme in Environmetrics starting in 2003. This research will be focussed on mathematical and statistical problems which arise in the analysis of data on complex environmental variables and processes. We are likely to take a particular interest in the problems which arise from non-stationarity or from contaminating point processes and the implications of these for sampling, mapping and temporal monitoring.

      We are looking for a post-doctoral worker to develop this area under the direction of Murray Lark in the Biomathematics group, and in collaboration with the Institute's Soil Physics group. A suitable candidate will have a strong background in mathematics or statistics, and knowledge of the current array of methods used in spatial analysis (geostatistics, wavelet transforms, spatial point processes etc). The ideal candidate will have experience of applying these methods in an environmental physical science (soil science, hydrology, geochemistry). We would hope that someone could start in this post as soon as possible after 1st April 2003.

      More information on the Institute can be found at http://www.sri.bbsrc.ac.uk/ and more information on our activities in spatial analysis see http://www.sri.bbsrc.ac.uk/science/mdsg/personal/murraylark.htm.

      For more information contact Murray Lark in the first instance at murray.lark@...



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    • sebastiano trevisani
      Thank you for your help What make me think in this problem is this (having to perform groundwater flow modeling): If for example I have two lithological
      Message 34 of 34 , Nov 21, 2003
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        Thank you for your help

        What make me think in this problem is this (having to perform groundwater
        flow modeling):
        If for example I have two lithological categories with very different
        spatial structures ( different anisotropy, different variogram ecc..) but
        with the same Hydrogeologic parameters, does grouping these two lithologic
        categories together make sense?(for me not too much!)

        But, and I'm sorry for my English, what I was asking in my mail was not in
        which way I can find the "right" categories. But in which way, once I have
        my categories along the boreholes, I can geometrically discretize the
        boreholes in data to use in simulation or estimation.
        For example I divided a borehole of 10m in punctual values spaced every
        25cm....but probably it is not the best approach.

        Sincerely
        Sebastiano Trevisani

        ---------------------------------------------------------------------------------------------------
        past mails (in geological order!!!!)

        Sebastiano

        The way we do it is to 'composite' samples with the
        same lithology, to a reasonably consistent length.
        Then we do semi-variogram analysis either on each
        lithology separately or at least not pairing samples
        between lithologies. This is an excellent way of
        finding out whether your lithologies have different
        continuity of values or not. Sometimes you can then
        group similar units together.

        Depending on how that stage goes, you can then krige
        within lithologies or in proper 3d.

        Isobel
        http://geoecosse.bizland.com/BYOGeostats.htm

        ________________________________________________________________________
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        -------------------------------------------------------------------------------------------------------------------------

        Sebastiano,

        This is a much debated, classic problem reservoir engineers have in the oil
        industry. To deal with it, I would recommend you first focus on what you
        want your model to do for you. If you plan to build a flow simulation model,
        you need to decide how the different rock types affect flow and how they can
        be grouped to capture different depletion schemes. Rock types generally can
        be grouped together if they have similar properties like porosity,
        permeability, and residual saturations. Another way to identify flow units
        is to plot (by well) cum well permeability vs. depth or cum well
        permeability vs. cum porosity (also called a Lorenz plot), where changes in
        the slope of the plot identify breaks between flow units. If these breaks
        can be correlated across the reservoir, they make nice boundaries for
        geostatistical data points.

        Regards,

        Paul Taylor
        Sr. Reservoir Engineer
        BP

        ----- Original Message -----
        From: "sebastiano trevisani" <sebastiano.trevisani@...>
        To: <ai-geostats@...>
        Sent: Thursday, November 20, 2003 3:21 PM
        Subject: AI-GEOSTATS:

        ---------------------------------------------------------------------------------------------------------------------
        > Hi list members!!!
        > Another question for you!
        >
        > I have to perform geostatistical geological modeling using some boreholes.
        > The litology in these boreholes is described according to geotechnical
        > classification. My question essentially is this: which is the best way to
        > transform boreholes in data to use in geostatical modeling? The
        litological
        > vertical variability is very high, for example I can have layers
        > with thickness of only 10cm. If I discretize the boreholes with a coarse
        > grid (say a step of 50cm) I lose these details (that in the case of a clay
        > layer could be very important from the hydraulic point of view) and if I
        > use a too dense grid I have too many data. For example I tried to
        > discretize borehole data with a grid, along the borehole, of 10 cm,
        > obtaining about 9.000 data. I'm wondering if it could be an idea try to
        > discretize in an "intelligent way", for example trying to adapt the step
        of
        > the grid in relation to the thickness of the level (and why not to the
        > category?) encountered. Or if there is another approach...
        > I have read some books in geostatistical reservoir modeling...but they
        > don't deal with this problem.
        > If some has some idea where to look thank you for your help!
        >
        > Sebastiano Trevisani
        >
        >
        >
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