公开(公告)号：US4933638A

公开(公告)日：1990-06-12

申请号：US368916

申请日：1989-06-19

申请人： Robert L. Kleinberg ,  Douglas D. Griffin ,  Masafumi Fukuhara ,  Abdurranhman Sezginer ,  Weng C. Chew ,  William E. Kenyon ,  Peter I. Day ,  Max Lipsicas

发明人： Robert L. Kleinberg ,  Douglas D. Griffin ,  Masafumi Fukuhara ,  Abdurranhman Sezginer ,  Weng C. Chew ,  William E. Kenyon ,  Peter I. Day ,  Max Lipsicas

IPC分类号： G01R33/34 ,  G01R33/38 ,  G01R33/44 ,  G01V3/18 ,  G01V3/32

CPC分类号： G01R33/341 ,  G01N24/081 ,  G01R33/3671 ,  G01R33/3808 ,  G01V3/32

摘要： Borehole NMR logging apparatus and methods, and methods for the interpretation thereof. A logging tool is provided which produces a strong, static and homogeneous magnetic field B.sub.0 in a Volume of an adjacent formation on one side of the tool to measure nuclear magnetic resonance characteristics thereof. In the preferred embodiment, the tool has an RF antenna mounted on the outside of the metal body of the tool, directing focussed oscillating magnetic fields B.sub.1 at said Volume to polarize or tip the magnetic moments of hydrogen nuclei of fluids within rock pores. The same antenna can be used to receive signals of proton precession in the Volume of interest immediately after transmission of the RF polarizing field B.sub.1. Extremely rapid damping of the antenna between the transmitting and receiving modes of operation is accomplished by a Q-switch disclosed herein. The invention provides for the direct measurement of NMR decay having transverse relaxation time T.sub.2 behavior, and further provides for the fast repetition of pulsed measurements from within a borehole. An additional magnet array may be mounted offset from the first magnet configuration to prepolarize a formation before it is measured in order to pre-align a larger number of protons than the single magnet configuration could do by itself. Additional features of the invention are disclosed which increase the Signal/Noise ratio of the measured data, and improve the quality and quantity of borehole NMR measurements, per unit of time spent. Disclosed interpretation methods determine fluid flow permeability and longitudinal relaxation time T.sub.1 -type parameters by directly comparing the measured decay signals (such as T.sub.2 and T.sub.2 * type decay) to a representation which responds to both the decay time t.sub.dec and the imposed polarization period prior to such decay, t.sub.pol. The parameters of amplitude and T.sub.1 are determined and combined with certain preferred methods to generate robust values of formation characteristics such as fluid flow permeability. Other related methods are disclosed.

公开(公告)号：US5142472A

公开(公告)日：1992-08-25

申请号：US401006

申请日：1989-08-31

申请人： Peter I. Day

发明人： Peter I. Day

IPC分类号： E21B47/026 ,  G01V3/28

CPC分类号： G01V3/28 ,  E21B47/026

摘要： A method used for determining true in-situ resistivity of a thin layer within a formation from dual induction log data. The method calculates true resistivity without the existing need: 1) for an accurate estimate of the layer thickness, or 2) to extrapolate correction factors for thin layers. The method first corrects resistivity data read from the dual induction log. A representative shoulder bed resistivity is first determined from average deep resistivity data near the shoulder bed. A paired estimate of layer resistivity and thickness is then computed based upon the determined shoulder bed resistivity, dip angle, and both deep and medium resistivity data related to the thin bed. The method does not require thickness data to be input, and in fact outputs this infomation, if needed.

摘要翻译： 一种用于从双归纳测井数据确定地层内薄层真实原位电阻率的方法。 该方法在没有现有需要的情况下计算真实电阻率：1）准确估计层厚度，或2）推断薄层校正因子。 该方法首先校正从双感应测井读取的电阻率数据。 首先根据肩床附近的平均深电阻率数据确定代表性的床层电阻率。 然后基于确定的肩层电阻率，倾角以及与薄床相关的深和中电阻率数据来计算层电阻率和厚度的配对估计。 该方法不需要输入厚度数据，实际上如果需要输出该信息。