oil-recovery-core-15.html
DTU Olie og Gas
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day ? to the industry being able to recover more
oil
. ??e aim is to visualize what is actu- ally happening inside the
core
sample
when we study a recovery process,? says amalia yunita halim, a postdoc at dhrtc. ?o?en when you use an eor method on a
core
sample
in the laboratory, you can actually see that
oil
is being produced. however, you don?t actually know how the
oil
moves inside the
core
sample
, and where in the
core
sample
oil
remains. ?anks to the improved image analysis provided by ct scans of the dense chalk
core
sample
s, it is possible to see whether the
oil
actually moves, and where it is trapped, and use this knowledge quan- titatively without having to dope one of the fluids with contrast agent.? work in the laboratory conducting the experiments with
core
sample
s takes three to four months. these are parallel, comparable experiments, with some of them being ct-scanned along the way. during the scanning, the following happens: ? all dry
core
sample
s are ct-scanned to establish their 3d porosity ? saturation with brine which matches that found in the specific
oil
reservoir which the
core
sample
comes from ? saturation with
oil
, so the
core
sample
now contains both
oil
and brine ? the eor process in the
core
sample
is scanned several times during the process the ct scans must be corrected, as the x-ray tube in the scanner be- comes hot and moves during the scanning. this changes the image values. to correct this, a pressure tank is used in which the
core
sam- ple is placed as a reference material. the materials have a known ct value, and when their ct value deviates from the expected value, the entire image can be corrected according to the right value. the bore
sample
s are placed in a rubber sleeve in the pressure tank. they can therefore move slightly between the scans as the liquid is injected. within medical image analysis, it is a well-known problem that images taken at different times or using different scanners have to be combined so they match as precisely as pos- sible?so-called co-registration. these methods have been adapted so they can be used on bore
sample
s. the raw images from the scanner have a noise texture which makes it impossible to obtain quantitative information by deduct- ing them directly from each other. the images are smoothed out instead using a gaussian filter. ?e
core
sample
s are cut out of the drill
core
s, which have been removed from the rock in connection with the drilling of the wells. ?ey measure 4 cm in diameter and are about 9 cm long. photo: mirhossein taheriotaghsara, dhrtc 16 dhrtc 2016
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