{"id":1475,"date":"2011-03-10T09:50:19","date_gmt":"2011-03-10T09:50:19","guid":{"rendered":"http:\/\/www.joswassink.nl\/insight\/?p=1475"},"modified":"2011-03-10T09:50:19","modified_gmt":"2011-03-10T09:50:19","slug":"the-sounds-of-stones","status":"publish","type":"post","link":"https:\/\/www.joswassink.nl\/insight\/?p=1475","title":{"rendered":"The sounds of stones"},"content":{"rendered":"<p><strong><\/p>\n<div id=\"attachment_1476\" style=\"width: 177px\" class=\"wp-caption alignright\"><\/strong><strong><a rel=\"attachment wp-att-1476\" href=\"http:\/\/www.joswassink.nl\/insight\/?attachment_id=1476\"><img loading=\"lazy\" decoding=\"async\" aria-describedby=\"caption-attachment-1476\" class=\"size-full wp-image-1476  \" title=\"science02_copy3\" src=\"http:\/\/www.joswassink.nl\/insight\/wp-content\/uploads\/2011\/03\/science02_copy3.jpg\" alt=\"\" width=\"167\" height=\"252\" \/><\/a><\/strong><p id=\"caption-attachment-1476\" class=\"wp-caption-text\">Karel van Dalen reads the waves - Photo: Tomas van Dijk<\/p><\/div>\n<p>There is more information in seismic waves than is generally used, says  Dr Karel van Dalen. His new wave processing method could benefit oil and  gas explorations.<\/p>\n<p>\u201cIt was one of my finest moments,\u201d recalls Karel van Dalen (PhD  student at Civil Engineering and Geosciences). \u201cI had calculated the  propagation of sound waves through porous stone and had predicted the  waveforms at its surface. When I did the experiment some time later in  the laboratory of the university in Leuven, the exact same waveforms  appeared on the screen.\u201d It confirmed to him that he was on the right  track, and that he&#8217;d finally mastered the complex mathematics of how  sound waves travel along the surface of and through porous material.<!--more--><\/p>\n<p>The  practical applications of such knowledge lie in oil and gas  exploration, but also in detecting groundwater or the examining of  bones. Typically the damping or propagation speed is measured to assess  certain material properties.\u00a0 However, if one not only wants to find out  how much gas is contained in the stone (the porosity) but also how  mobile it is (the permeability), one must analyse the full waveform  instead of just its speed and damping. Once Van Dalen had figured out  how sound waves propagate, he could start on the inverse problem: given a  particular waveform, what are the material properties causing it? He  approached this by calculating the difference between measurement and  model, and subsequently minimising the result.<\/p>\n<p>The trouble was:  this gave him not a single solution but rather a range of possible  values for the gas content and mobility that fit the bill. Repeating the  analysis for another type of wave (shear instead of compression),  produced another range of solutions. However, the overlap of the two  pretty precisely pinned down the values for porosity and permeability.<\/p>\n<p>Until  now, most of this work has been lab-based and computer-calculated. But  in a bore hole the same technique could be used to map the permeability  of the geological surroundings up to distance of 40 metres.<br \/>\nVan Dalen  has recently published his findings in Geophysical Research Letters and  will soon inform the Dutch Petrophysical Society of his findings.<\/p>\n<p><em>K.N.  van Dalen, &#8216;Multi-component acoustic characterization of porous media&#8217;,  7 March 2011, PhD supervisors Professor Kees Wapenaar, Professor David  Smeulders and Dr Guy Drijkoningen.<\/em><\/p>\n","protected":false},"excerpt":{"rendered":"<p>There is more information in seismic waves than is generally used, says Dr Karel van Dalen. His new wave processing method could benefit oil and gas explorations.<\/p>\n","protected":false},"author":1,"featured_media":0,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[3,6],"tags":[196,319,379],"class_list":["post-1475","post","type-post","status-publish","format-standard","hentry","category-articles","category-delta","tag-geology","tag-oil-and-gas-explorations","tag-seismology"],"_links":{"self":[{"href":"https:\/\/www.joswassink.nl\/insight\/index.php?rest_route=\/wp\/v2\/posts\/1475","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/www.joswassink.nl\/insight\/index.php?rest_route=\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/www.joswassink.nl\/insight\/index.php?rest_route=\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/www.joswassink.nl\/insight\/index.php?rest_route=\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"https:\/\/www.joswassink.nl\/insight\/index.php?rest_route=%2Fwp%2Fv2%2Fcomments&post=1475"}],"version-history":[{"count":0,"href":"https:\/\/www.joswassink.nl\/insight\/index.php?rest_route=\/wp\/v2\/posts\/1475\/revisions"}],"wp:attachment":[{"href":"https:\/\/www.joswassink.nl\/insight\/index.php?rest_route=%2Fwp%2Fv2%2Fmedia&parent=1475"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/www.joswassink.nl\/insight\/index.php?rest_route=%2Fwp%2Fv2%2Fcategories&post=1475"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/www.joswassink.nl\/insight\/index.php?rest_route=%2Fwp%2Fv2%2Ftags&post=1475"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}