Abstract:
The present disclosure relates to methods and apparatuses for calibrating a sensor, particularly a gravimeter, which involves positioning the sensor in at least three different orientations and calibrating the sensor using a linear model and the sensor outputs from the at least three different orientations. The method may include applying an external force to the sensor. The apparatus includes a processor and storage subsystem with a program that, when executed, implements the method.
Abstract:
NMR measurements are made with a MWD tool having azimuthal sensitivity. The permanent magnet may be a U-shaped magnet or may have an opposed pair of magnets with axial orientation. The tool is designed for pulsing with short sequences for estimating BVI and CBW and minimizes the effect of tool motion.
Abstract:
A method and apparatus for estimating a flow rate of a phase of a multiphase fluid is disclosed. In the first method, nuclei in the fluid are polarized over two distances and a measured magnetization gives the relative fraction of two components of the fluid for a selected velocity. In the second method, nuclei in the fluid are polarized over a specified distance and measurements of the decay of spin echo signals is used to give the relative fraction of two components of the fluid for the selected velocity.
Abstract:
An apparatus and method for estimating a parameter of interest using a force responsive element comprising, at least in part, a balanced material. The balanced material is temperature insensitive over a specified range of temperatures such that the force responsive element may estimate the parameter of interest by responding to a desired force with relatively little interference due to temperature changes within the specified range of temperatures.
Abstract:
The quality factor of a NMR-antenna depends upon mud conductivity, formation resistivity and the borehole size. The Q of the antenna is measured. From measurement of one of formation conductivity or borehole size, the other can be determined.
Abstract:
The invention is an objective oriented NMR logging method and apparatus. Based on an objective, a combination of multiple building blocks that form a comprehensive logging program achieves a defined set of logging objectives. An example of a building block is a trainlet sequence 413 with a short interval between trainlets. Another example of a building block is a CPMG sequence 403 or a modified CPMG sequence having a refocusing angle between 90 and 180 degrees.
Abstract:
The present disclosure relates to methods and apparatuses for acquiring multi-component gravity information for an earth formation. More particularly, the present disclosure relates to estimating the movement of fluid in an earth formation using at least one gravimeter configured to generate multi-component gravity information. The method may include estimating density changes in the earth formation. The method may include estimating a position of the at least one gravimeter. The apparatus may include a multi- component gravimeter configured to estimate gravity vectors for each vector component.
Abstract:
An instrument for measuring gravitational acceleration, the instrument including: a plurality of accelerometers disposed about a three-dimensional structure, the plurality of accelerometers providing output used for measuring the gravitational acceleration; wherein each accelerometer in the plurality is implemented by at least one of a micro-electromechanical system (MEMS) and a nano-electromechanical system (NEMS).
Abstract:
A method to correct for a systematic error of a sensor having a plurality of accelerometers configured to measure gravitational acceleration, the method including: rotating the plurality of accelerometers about a first axis; obtaining a first set of calibration measurements from the plurality of accelerometers from the rotation about the first axis; determining a first systematic error for each accelerometer in the plurality using the first set of calibration measurements; and removing the first systematic error from sensor measurements to correct for the systematic error.
Abstract:
A magnet assembly for measuring properties of a formation from a borehole, the magnet assembly including a first device and a second device, each device adapted for insertion into the borehole, the first device producing a first magnetic field, the second device producing a second magnetic field; wherein the second magnetic field is configurable for one of reinforcing and reducing the first magnetic field; and wherein the first device comprises a permanent magnet and the second device comprises at least one of one of a switchable magnet and switching windings.