公开(公告)号：US06714014B2

公开(公告)日：2004-03-30

申请号：US09836980

申请日：2001-04-18

申请人： Martin Townley Evans ,  Andrew Richard Burt ,  Albert Alexy

发明人： Martin Townley Evans ,  Andrew Richard Burt ,  Albert Alexy

IPC分类号： G01V320

CPC分类号： G01V3/28 ,  E21B47/026 ,  G01V3/24

摘要： An apparatus for obtaining resistivity images of a borehole includes an array of measure electrodes separated from a pad or the body of the instrument by a focusing electrode. The focusing electrode is maintained at a slightly higher potential than the measure electrodes. The apparatus is primarily intended for use with conducting fluids but may also be used with non-conducting fluids. A modulated electrical current with a carrier frequency of 1 MHz is injected into the formation. When used with a non-conducting fluid, capacitive coupling between the electrode and the conductive formation is provided by the dielectric of fluid. When used with a conducting borehole fluid, an additional capacitor may be incorporated into the circuit. The current in the measure electrode is indicative of the conductivity of the formation. To avoid cross-talk between conductors in an isolator section between the current source and the measure electrode, signals indicative of the measure currents are demodulated to a frequency of 1.1 kHz. This makes it possible to use the configuration of prior art devices designed for conductive coupling between the logging tool and the formation.

摘要翻译： 用于获得钻孔电阻率图像的装置包括通过聚焦电极与仪器的垫或仪器主体分离的测量电极阵列。 聚焦电极保持在比测量电极略高的电位。 该装置主要用于导电流体，但也可用于非导电流体。 将载波频率为1 MHz的调制电流注入地层。 当与非导电流体一起使用时，电极和导电层之间的电容耦合由流体的电介质提供。 当与导电钻孔流体一起使用时，可以将另外的电容器并入电路中。 测量电极中的电流表示地层的电导率。 为了避免电流源和测量电极之间的隔离器部分中的导体之间的串扰，指示测量电流的信号被解调为1.1kHz的频率。 这使得可以使用设计用于测井工具和地层之间的导电耦合的现有技术装置的构造。

公开(公告)号：US06348796B2

公开(公告)日：2002-02-19

申请号：US09754431

申请日：2001-01-04

申请人： Martin Townley Evans ,  Andrew Richard Burt

发明人： Martin Townley Evans ,  Andrew Richard Burt

IPC分类号： G01V320

CPC分类号： G01V3/20

摘要： An apparatus for obtaining resistivity images of a borehole includes an array of measure electrodes separated from a pad or the body of the instrument by a guard electrode. The guard electrode is maintained at a slightly lower potential than the pad and the measure electrode is at an intermediate potential thereto. With this arrangement, the current from the guard electrode defocuses the measure current from the measure electrode as it enters the formation, and at greater distances, the current from the measure electrode is refocused by the effect of the current from the pad. This defocusing and refocusing defines a region of investigation away from the borehole wall that is relatively insensitive to borehole rugosity. Circumferential and vertical overlap may be obtained either by the arrangement of the measure electrodes, or by relying on the broadening of the measure beam as it enters the formation.

摘要翻译： 用于获得钻孔电阻率图像的装置包括通过保护电极与仪器的垫或仪器主体分离的测量电极阵列。 保护电极保持在比焊盘稍低的电位，并且测量电极处于中间电位。 通过这种布置，来自保护电极的电流在测量电极进入地层时使测量电流离散，并且在更大的距离处，来自测量电极的电流被来自焊盘的电流的影响重新聚焦。 这种散焦和重新聚焦定义了一个远离井壁的调查区域，对钻孔粗糙度相对不敏感。 可以通过测量电极的布置或者通过依靠测量梁进入地层时的扩宽来获得圆周和垂直重叠。