Abstract: A downhole signal transmission system provides electric radiofrequency signals that are coupled to electrically conductive or non-conductive fluids through electrical insulators. A plurality of signal repeaters are tuned to the frequencies of the radiofrequency signals, and a plurality of transmission lines terminated by resonance circuits are also provided such that the terminating resonance circuits resonate on the frequencies of the electric radiofrequency signals. The plurality of signal repeaters and plurality of transmission elements are arranged to be redundant such that a failure of one or more of the signal repeaters or a failure of one or more of the transmission elements does not substantially affect the operation of the data transmission system. The signal repeaters and transmission elements also are arranged such that a failure of any of the signal repeaters or a failure of any of the transmission elements is communicated to the surface.

Abstract: A high-frequency data and/or power transmission system suitable for down-hole use including signal/power couplers, transmission line segments and signal repeaters. Signals and power are/is transmitted between couplers and/or between couplers and repeaters by means of electromagnetic resonance coupling. In at least a portion of the system, the transmission line segments form parallel data paths and the repeaters provide crossover capability between the data/power paths, thereby significantly improving reliability. The invention also includes methods of transmitting data and/or distributing high-frequency power through a downhole transmission system including multiple data/power paths and multiple crossovers wherein a fault location in one data/power path is bypassed by routing data and/or power to a parallel data/power path by means of electromagnetic resonance coupling.

Abstract: A nuclear magnetic resonance well logging tool, where some embodiments comprise two, oppositely oriented magnets separated by a pole piece to guide static magnetic flux into a sensitive volume, and another pole piece serving as a core for several antennas For some embodiments, the antennas are solenoids Two of the antennas serve as transmit and receive antennas, where they are driven to generate an elliptically polarized magnetic field, and their antenna responses are combined so that the combined response is sensitive to elliptically polarized magnetic fields, but with zero gradient in the z-direction A third antenna is a receive antenna sensitive to magnetic field vectors having a sinusoidal spatial venation in the z-direction of period equal to the length of the third antenna A fourth antenna serves as a receive antenna sensitive to sinusoidal magnetic field vectors with the same spatial-frequency as the third antenna, phase shifted by 90 degrees.

Abstract: An NMR logging tool for conducting NMR measurements in a plurality of sensitive volumes ranging up to a meter from the tool. The tool comprises a magnetic assembly using one or more permanent magnets and at least one pole piece for extending a magnet pole and shaping the magnetic field to simulate a magnetic monopole in a sensitive volume within the formation. Different embodiments of a segmented antenna enable directional NMR logging. The tool embodiments and methods of their use are suitable for wireline or LWD logging, and can be used for directional drilling.

Abstract: A downhole signal transmission system provides electric radiofrequency signals that are coupled to electrically conductive or non-conductive fluids through electrical insulators. A plurality of signal repeaters are tuned to the frequencies of the radiofrequency signals, and a plurality of transmission lines terminated by resonance circuits are also provided such that the terminating resonance circuits resonate on the frequencies of the electric radiofrequency signals. The plurality of signal repeaters and plurality of transmission elements are arranged to be redundant such that a failure of one or more of the signal repeaters or a failure of one or more of the transmission elements does not substantially affect the operation of the data transmission system. The signal repeaters and transmission elements also are arranged such that a failure of any of the signal repeaters or a failure of any of the transmission elements is communicated to the surface.

Abstract: An NMR logging tool for conducting NMR measurements in a plurality of sensitive volumes ranging up to a meter from the tool. The tool comprises a magnetic assembly using one or more permanent magnets and at least one pole piece for extending a magnet pole and shaping the magnetic field to simulate a magnetic monopole in a sensitive volume within the formation. Different embodiments of a segmented antenna enable directional NMR logging. The tool embodiments and methods of their use are suitable for wireline or LWD logging, and can be used for directional drilling.

Abstract: An NMR logging tool for conducting NMR measurements in a plurality of sensitive volumes ranging up to a meter from the tool. The tool comprises a magnetic assembly using one or more permanent magnets and at least one pole piece for extending a magnet pole and shaping the magnetic field to simulate a magnetic monopole in a sensitive volume within the formation. Different embodiments of a segmented antenna enable directional NMR logging. The tool embodiments and methods of their use are suitable for wireline or LWD logging, and can be used for directional drilling.

Abstract: Apparatus and method for providing in-situ data of formation fluids at true reservoir conditions. The apparatus has NMR chamber of the flow-through type, so it is no longer necessary to divert a sample for the basic NMR analysis or transfer it uphole for laboratory analysis. The apparatus is preferably modular and is compatible with wireline tools configurable for a variety of sampling, testing and monitoring purposes. Fluid properties such as viscosity can be derived from diffusivities and relaxation times, as measured by NMR. Additional accuracy is provided in the downhole sampling process, and in the interpretation of NMR logs in real time at true reservoir conditions.

Abstract: A downhole telemetry system employing code division multiple access (CDMA) is disclosed. In one embodiment, the downhole telemetry system comprises one or more downhole transmitters and an uphole receiver. Each of the downhole transmitters transmits a corresponding uplink signal which is generated using amplitude modulation of corresponding code word signals. The code word signals are orthogonal to each other, and the transmitters may be configured to adjust the timing to assure synchronous arrival of the various uplink signals at the receiver. Each of the transmitters may be allocated a different number of code words when it is desired to allow for unequal bandwidth requirements. Such allocation is preferably dynamic. Additional modulation techniques may be employed with CDMA, including frequency division multiplexing, time division multiplexing, and frequency re-use.

Abstract: A logging while drilling (LWD) and measuring while drilling (MWD) method is disclosed for analyzing the porosity of geologic formations containing carbonate-formations. The method is based on a combination of T1 and T2 measurements that enables detection of diffusivity coupling and permits more accurate determination of pore size distribution, formation permeability and irreducible water saturation.

Abstract: A system and method for calculating the lateral velocity of a rotating drilling tool within a borehole, the system comprising: a pair of accelerometers placed oppositely across the drilling tool axis of rotation and two magnetometers. The method comprises: reading tool radial acceleration signals ar1, ar2, and tangential acceleration signals, at1 and at3, obtained with a quadrature accelerometer detection system; reading Bx and By, the tool's magnetic phase data, from two orthogonally placed magnetometers; determining the rotational phase angle of the drilling tool relative to the earth's gravity field by first determining the tool's magnetic phase, and the phase shift between the tool's magnetic phase and gravity phase; and processing the foregoing data to yield a lateral tool velocity which optionally compensates for the effect of gravity on the accelerometers, or converts the lateral tool velocity from the tool reference frame to the borehole reference frame, or does both.

Abstract: A magnet assembly and a magnetic field configuration are disclosed for the generation of a magnetic field in a defined volume, with the field being homogeneous over a pre-determined portion of the volume and not homogeneous over the rest. The disclosed magnetic assembly has a plurality of spaced-apart magnets arranged in pairs. The magnets of each pair are be positioned diametrically opposite each other with respect to an enclosed volume. In different embodiments magnets may all be arranged such that their magnetization directions are substantially aligned, or could alternatively be arranged to have magnetizations pointing in different directions. The angular spacing between the magnets is selected in the range of approximately 13°-17° and could be as large as the size of the magnets. The assembly generates a homogeneous magnetic field within an inner portion of the defined volume, and a second magnetic field, substantially different from the homogeneous magnetic field throughout the remainder, i.e.

Abstract: An method and system are disclosed for NMR echo-train data acquisition and processing for enhanced vertical resolution for a given signal to noise ratio. In one aspect, the method is based on providing an estimate of non-formation signal components and removing the estimate from the NMR signals. Computation of the estimate is done from the data itself or using a direct measurement of non-formation signals. In another aspect, the functions of reducing coherent noise components is separated from the function of reducing the random noise components, to enhance the resolution of the NMR pulse echo data for a given signal to noise ratio (SNR) of the data. Combination processing is disclosed, which enables efficient filtering of the input NMR data for both relatively high and relatively low SNR of the formation data.

Abstract: A system and method for calculating the lateral velocity of a rotating drilling tool within a borehole, the system comprising: a pair of accelerometers placed oppositely across the drilling tool axis of rotation and two magnetometers. The method comprises: reading tool radial acceleration signals ar1, ar2, and tangential acceleration signals, at1 and at3, obtained with a quadrature accelerometer detection system; reading Bx and By, the tool's magnetic phase data, from two orthogonally placed magnetometers; determining the rotational phase angle of the drilling tool relative to the earth's gravity field by first determining the tool's magnetic phase, and the phase shift between the tool's magnetic phase and gravity phase; and processing the foregoing data to yield a lateral tool velocity which optionally compensates for the effect of gravity on the accelerometers, or converts the lateral tool velocity from the tool reference frame to the borehole reference frame, or does both.

Abstract: A method for manufacturing NMR measurement-while-drilling tool having the mechanical strength and measurement sensitivity to perform NMR measurements of an earth formation while drilling a borehole, and a method and apparatus for monitoring the motion of the measuring tool in order to take this motion into account when processing NMR signals from the borehole. The tool has a permanent magnet with a magnetic field direction substantially perpendicular to the axis of the borehole, a steel collar of a non-magnetic material surrounding the magnet, antenna positioned outside the collar, and a soft magnetic material positioned in a predetermined relationship with the collar and the magnet that helps to shape the magnetic field of the tool. Due to the non-magnetic collar, the tool can withstand the extreme conditions in the borehole environment while the borehole is being drilled.

Abstract: An apparatus is disclosed for generating a magnetic field of high field strength, spatial uniformity and minimal drift of magnetic field intensity over a temperature range of about 0° C. to 175° C. This apparatus may be used in a standard modular logging tool for direct downhole NMR measurements of various parameters of fluid samples of geologic formations near the walls of a borehole. In one embodiment, the apparatus is composed of two tubular permanent magnets made of different magnetic materials with different magnetic temperature coefficients to provide temperature compensation. The apparatus preferably also utilizes a pressure barrel that surrounds the magnets and provides a return path for magnetic flux lines, thereby increasing flux density within the measurement volume.

Abstract: The present invention is a system and method capable of providing continuous measurements of resistivity-through-casing (RTC) of a geological formation traversed by a boreholeby eliminating measurement of the casing resistance. To this end, a real-time feedback control substantially eliminates current flow along the casing in the vicinity of an injection point for injecting a measuring current into the formation. This allows direct estimation of the measuring current injected into the formation along with the casing voltage used to drive the current into the formation. As a result, there is no need for “nulling” or calibration cycle that requires two step measurements with the RTC tool held stationary. The preferred feedback is by the proportional integral derivative procedure (PID) with a digital signal processor that controls bi-directional steerable current sources supplying one or more current to the casing at various points.

Abstract: A method for manufacturing NMR measurement-while-drilling tool having the mechanical strength and measurement sensitivity to perform NMR measurements of an earth formation while drilling a borehole, and a method and apparatus for monitoring the motion of the measuring tool in order to take this motion into account when processing NMR signals from the borehole. The tool has a permanent magnet with a magnetic field direction substantially perpendicular to the axis of the borehole, a steel collar of a non-magnetic material surrounding the magnet, antenna positioned outside the collar, and a soft magnetic material positioned in a predetermined relationship with the collar and the magnet that helps to shape the magnetic field of the tool. Due to the non-magnetic collar, the tool can withstand the extreme conditions in the borehole environment while the borehole is being drilled.

Abstract: Apparatus and method for providing in-situ data of formation fluids at true reservoir conditions. The apparatus has NMR chamber of the flow-through type, so it is no longer necessary to divert a sample for the basic NMR analysis or transfer it uphole for laboratory analysis. The apparatus is preferably modular and is compatible with wireline tools configurable for a variety of sampling, testing and monitoring purposes. Fluid properties such as viscosity can be derived from diffusivities and relaxation times, as measured by NMR. Additional accuracy is provided in the downhole sampling process, and in the interpretation of NMR logs in real time at true reservoir conditions.

Abstract: A downhole telemetry system employing code division multiple access (CDMA) is disclosed. In one embodiment, the downhole telemetry system comprises one or more downhole transmitters and an uphole receiver. Each of the downhole transmitters transmits a corresponding uplink signal which is generated using amplitude modulation of corresponding code word signals. The code word signals are orthogonal to each other, and the transmitters may be configured to adjust the timing to assure synchronous arrival of the various uplink signals at the receiver. Each of the transmitters may be allocated a different number of code words when it is desired to allow for unequal bandwidth requirements. Such allocation is preferably dynamic. Additional modulation techniques may be employed with CDMA, including frequency division multiplexing, time division multiplexing, and frequency re-use.