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: 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: 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: 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: 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.

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 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 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: Proposed is a new method and system to obtain enhanced-resolution NMR data by merging, in the time domain, different NMR pulse echo trains into a single echo train. The input echo trains can be acquired with different inter-echo spacing, wait time, and signal-to-noise ratio parameters that are optimized to correspond to both fast and slow portions of the T2 spectrum. The merged echo trains are inverted into complete T2 spectra in a single step thereby overcoming ambiguities and other limitations of prior art methods. In a preferred embodiment the merging process does not require a priori information about T1, and the merged echo trains are optimized in with respect to T2 resolution. The method of this invention is preferably practiced with the latest generation of multi-volume NMR logging tools, that allow simultaneous recordation of NMR data with different inter-echo spacing Te, wait time Tw, and signal-to-noise ratio (SNR) parameters.

Abstract: An 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 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 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: An 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: A well logging system and method are disclosed for detecting the presence and estimating the quantity of gaseous and liquid hydrocarbons in the near wellbore zone. The system uses a gradient-based, multiple-frequency NMR logging tool to extract signal components characteristic for each type of hydrocarbons. To this end, a new data acquisition method is proposed in which measurements at different frequencies are interleaved to obtain, in a single logging pass, multiple data streams corresponding to different recovery times and/or diffusivity for the same spot in the formation. The resultant data streams are processed to determine mineralogy-independent water and hydrocarbon saturations and porosity estimates. Gas and oil saturations are used to obtain accurate estimates of the water content, permeability and other parameters of interest.

Abstract: Novel pulse sequence and data acquisition method are disclosed which eliminate the effects of spurious NMR signals caused by mechanical resonances within the measurement apparatus. The proposed method alleviates interference problems typically arising from strong “excitation” pulses in a sequence, and enables the use of the corresponding data points to increase the resolution of the measurement. The method is based on changing the measurement frequency between pulse sequences and averaging out data points obtained from the different sequences in a way that effectuates cancellation of the spurious signals. The novel cycle of ulse sequences and a data acquisition method can be used, or example, with any existing NMR logging instruments.

Abstract: A method and apparatus for processing nuclear magnetic resonance (NMR) information to differentiate between oil based mud filtrate (OBM), and connate oils, during subsurface exploration. An NMR experiment is performed on a sample of formation fluid, and the resulting data is then processed to differentiate between the relaxation time parameters characteristic of OBMs and those characteristic of connate oils. A simple arithmetic difference between relaxation times calculated for successive samples may be followed by a distributional analysis performed in either the time domain or relaxation spectrum domain. The process is repeated for other fluid samples and the data for successive fluid samples is compared so that the user may determine when the formation fluid consists almost entirely of connate oil.

Abstract: An NMR pulse sequence and signal processing method is disclosed for measurement of fast decay response signals from materials containing a fluid state. The proposed pulse sequence and processing method are applicable in borehole NMR logging as well as measurements of attributes of man-made or natural materials. The disclosed pulse sequence comprises a series of short NMR pulse trains separated by intervals which are shorter than the time required for polarization of nuclear magnetization in bulk fluids of the fluid state. By stacking response signals to increase the signal to noise ratio, time domain data is obtained that generally corresponds to transverse decay components as short as about 0.5 ms. Various attributes of the materials being investigated can be derived in a single measurement.