Schlumberger Technology Corporation

International Business Machines Corporation

University of Illinois

Weng C Chew

Robert L Kleinberg

Brian Oliver Clark

Douglas D Griffin, Ii

Barry Jay Rubin

Masafumi Fukuhara

Jason David Morsey

Yuan Liu

David R Mariani

Lijun Jiang

Abdurrahman Sezginer

William E Kenyon

Thomas L Marzetta

Mao-Kin Li

Donald G Dudley

Abdurranhman Sezginer

Peter I Day

Mao-kun Li

Max Lipsicas

A method for performing a signal integrity analysis on an integrated circuit (IC) that includes a plurality of scatterers by dividing the scatterers into subgroups using a nested Huygens' equivalence principle algorithm and solving a set of equations realized thereby with a reduced coupling matrix. The method includes decomposing the IC design into a plurality of small non-overlapping circuit sub-domains, wherein each of the sub-domains is formed as a small, enclosed region. Each sub-domain is analyzed independently of the other sub-domains using only electric fields to represent the interactions of each sub-domains with the other sub-domains as equivalent currents on equivalent surfaces of the plurality of sub-domains. Neighboring equivalent sub-domains are grouped together to form larger sub-domains using equivalent currents on equivalent surfaces to represent the interactions of the sub-domains. The steps of analyzing and grouping the sub-domains are repeated until the grouping approaches a box comprising the entire domain, and that the domain interactions between every sub-domain have been analyzed.

Huygens' box methodology for signal integrity analysis

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 or 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.poi. 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.

Borehole measurement of NMR characteristics of earth formations

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.

Borehole measurement of NMR characteristics of earth formations, and

A well logging apparatus is disclosed which employs slot antennas having a plurality of conductive probes traversing the slot. Also disclosed are a logging apparatus having electrically isolated antenna probes and a logging apparatus with an improved means for generating and applying a reference signal used in phase detection.

Induction well logging apparatus with transformer coupled phase

A method and apparatus investigating a circumferential segment of a borehole with an array of elements, which in effect spatially samples the segment, is described whereby, with a single circumferentially oriented array of spaced-apart elements sufficient overlap can be synthesized so as to reduce artifacts attributable to the spatial sampling. Measurements derived from circumferentially successive elements are combined, such as by summing to establish a desired overlap. In the described embodiment to a single lateral array of small electrodes is used to inject survey currents into the borehole wall and each current is measured. Measurements derived from pairs of successive survey currents are then summed to provide the desired overlap.

Method and apparatus for investigating a borehole using an array of

A wall-engaging apparatus for microinductively investigating a characteristic of earth formations traversed by a borehole includes an antenna set mounted in a longitudinally elongated body adapted for a sliding engagement with the wall of the borehole. The antenna set includes a conductive backplane member mounted in the body parallel to the wall-engaging face of the body and first, second, and third half-loop antenna elements. The half-loop antenna elements are coaxial located symmetrically about the half-loop of the first antenna element, with their respective ends located at the backplane member to couple image currents in the backplane. The locations of the second and third antenna elements are further selected to place the second and third antenna elements in electromagnetic symmetry relative to the first antenna element. A differential coupler is included for coupling the second and third antenna elements.

Apparatus for microinductive investigation of earth formations

A wall-engaging apparatus for microinductively investigating a characteristic of an earth formation traversed by a borehole includes an antenna set mounted in a sensing body adapted for sliding engagement with the wall of the borehole. The antenna set includes first, second and third antenna elements. The second and third elements, being structurally identical but differentially coupled, are positioned in electromagnetic symmetry about the first antenna element. Either the first antenna element or the differentially coupled second and third antenna elements may be energized by suitable circuits, while the other is coupled to circuits for receiving signals indicative of a set characteristic. In another wall-engaging apparatus for microinductively investigating a characteristic of earth formations traversed by a borehole, a transmitter antenna is mounted in a conductive wall-engaging body, within a volume bounded in part by an integral conductive backplane and conductive side wall and opening to the wall-engaging face of the body, for coupling focused electromagnetic energy into a formation. The volume preferably is conformal with the transmitter antenna. Circuits are provided for energizing the transmitter antenna and for detecting a magnetic field from the engaged formation arising from the coupled electromagnetic energy.

A well logging apparatus is disclosed which employs slot antennas having a plurality of conductive probes traversing the slot. Also disclosed are a logging apparatus having electrically isolated antenna probes and a logging apparatus with an improved circuit for generating and applying a reference signal used in phase detection.

Well logging apparatus for determining dip, azimuth, and invaded zone

A wall-engaging apparatus for microinductively investigating a characteristic of an earth formation traversed by a borehole comprises an antenna set mounted in an longitudinally elongated body adapted for a sliding engagement with the wall of the borehole. The antenna set includes a transmitter antenna mounted in the body for coupling electromagnetic energy into a formation; a receiver antenna for sensing a signal indicative of the characteristic; and at least one electroquasistatic shield element mounted coaxially with the magnetic dipole axis of the transmitter antenna. The electroquasistatic shield element comprises a sheet of conductive, non-magnetic material having a conductive center; a first annular band of narrow ray-like conductive segments, each of the conductive segments thereof integrally extending radially from the conductive center and being spaced from adjacent conductive segments by respective narrow radially-extending spaces originating in and traversing the first annular band; and preferably but not necessarily a second annular band of ray-like conductive segments, the conductive segments thereof integrally extending radially in pairs from a respective one of the conductive segment of the first annual band, and being spaced from adjacent pairs of conductive strips of the second annual band by respective longitudinal spaces originating in the first annular band and from one another by a narrow radially-extending space originating in and traversing the second annular band.

Apparatus for microinductive investigation of earth formations with

A wall-engaging apparatus for microinductively investigating a characteristic of earth formation traversed by a borehole includes an antenna set mounted in a longitudinally elongated body adapted for a sliding engagement with the wall of the borehole. The antenna set includes a first antenna element, a second antenna element, and a third antenna element, the respective locations and orientations of the second and third antenna elements being selected to place the second and third antenna elements in electromagnetic symmetry relative to the first antenna element. Differentially coupling the second and third antenna elements. Either the first antenna element or the differentially-coupled second and third antenna elements may be energized by suitable means, while the other is coupled for receiving signals indicative of the characteristic.

Growing community of inventors

Champaign, IL, United States of America

Weng C Chew