%0 Journal Article
%T NMR logging probing the internal magnetic field gradients of rocks<br>核磁共振测井探测岩石内部磁场梯度的方法
%A XIE Ran-Hong
%A XIAO Li-Zhi
%A <br>谢然红
%J 地球物理学报
%D 2009
%I 
%X The internal field gradients in rocks has a big effect on nuclear magnetic resonance (NMR) transverse relaxation T2 distribution. A two-dimensional NMR method of probing the internal magnetic field gradients of rocks and its inversion algorithms are developed using CPMG pulse sequence. Internal field gradient distributions of water-saturated sandstones and shaly sandstones with paramagnetic impurities are obtained. The results show that internal field gradients of rocks increase with the increasing of content of paramagnetic impurities. The internal field gradients of sandstones with uniform grain show unimodal distributions. The T2 distributions of water-saturated shaly sandstones with chlorite show bimodal feature with obvious irreducible water peak. The small pores with short T2 have higher internal field gradients than that of the big pore with long T2. When the content of chlorite is less than 15%, the short T2 components corresponding to irreducible water peak increase with increasing the content of chlorite, T2 distribution becomes wider. However, when the content of chlorite is more than 15%, the higher internal field gradients result in short relaxation component decaying quickly, the short T2 components decrease, T2 distribution becomes narrower with increasing the content of chlorite.
%K Nuclear Magnetic Resonance (NMR)
%K Logging
%K Internal field gradients
%K 2D NMR
%K T2 distribution<br>核磁共振
%K 测井
%K 岩石内部磁场梯度
%K 二维核磁共振
%K 横向弛豫T2分布
%U http://www.alljournals.cn/get_abstract_url.aspx?pcid=E62459D214FD64A3C8082E4ED1ABABED5711027BBBDDD35B&cid=1E44AE713D8A6DE0&jid=14DC41C59CBF6770055A7D610D53AE46&aid=D1DCE811BFE45C6284729EFDEC199825&yid=DE12191FBD62783C&vid=286FB2D22CF8D013&iid=94C357A881DFC066&sid=2AF38D6ACB828704&eid=AFB21040E5F48417&journal_id=0001-5733&journal_name=地球物理学报&referenced_num=1&reference_num=25