In one aspect, a resistivity logging tool for a fluid-producing formation if provided. The resistivity logging tool includes at least one transmitter device connected to at least one excitation electrode, multiple receiver devices respectively connected to monitoring electrodes, and a controller. The transmitter can inject an excitation current into the formation via the excitation electrode. Each receiver device can determine a respective voltage level induced by the excitation current. The controller can determine whether a voltage level measured by at least one receiver device is within a specified range. Based on the measured voltage level, the controller can select a global amplitude adjustment algorithm for modifying excitation currents or a localized amplitude adjustment algorithm for modifying one or more gains of one or more receiver devices. The controller can modify the excitation current or gains by executing the selected algorithm.

A method, computer program product, and computing system for receiving downhole logging data for a porous media. A pore size distribution index may be estimated based upon, at least in part, nuclear magnetic resonance data (NMR) from the downhole logging data of the porous media. A relative permeability and capillary pressure curve may be generated with a feasible region of solutions based upon, at least in part, the pore size distribution index.

A method, computer program product, and computing system for receiving downhole logging data for a porous media. A pore size distribution index may be estimated based upon, at least in part, nuclear magnetic resonance data (NMR) from the downhole logging data of the porous media. A relative permeability and capillary pressure curve may be generated with a feasible region of solutions based upon, at least in part, the pore size distribution index.

Various implementations directed to a system and method for using a magnetometer in a gyro-while-drilling (GWD) survey tool are provided. In one implementation, a method may include acquiring gyroscopic data using gyroscopic sensors of a GWD survey tool while the tool is disposed at a first position within a wellbore. The method may also include acquiring first magnetic data using a magnetometer of the GWD survey tool while the tool is disposed at the first position. The method may further include determining an offset value for the magnetometer based on the gyroscopic data and the first magnetic data. The method may additionally include acquiring second magnetic data using the magnetometer while the tool is disposed at second positions within the wellbore. The method may also include determining magnetic azimuth values for the tool disposed at the second positions based on the second magnetic data and the offset value.

Various implementations directed to a system and method for using a magnetometer in a gyro-while-drilling (GWD) survey tool are provided. In one implementation, a method may include acquiring gyroscopic data using gyroscopic sensors of a GWD survey tool while the tool is disposed at a first position within a wellbore. The method may also include acquiring first magnetic data using a magnetometer of the GWD survey tool while the tool is disposed at the first position. The method may further include determining an offset value for the magnetometer based on the gyroscopic data and the first magnetic data. The method may additionally include acquiring second magnetic data using the magnetometer while the tool is disposed at second positions within the wellbore. The method may also include determining magnetic azimuth values for the tool disposed at the second positions based on the second magnetic data and the offset value.

Provided are apparatus and methods for generating a representation of a physical environment, comprising: a mobile sensor platform (MSP) including sensors that output sensor signals relating to parameters such as range, gravity, direction of the Earth's magnetic field, and angular velocity. The MSP is adapted to be moved through the environment. The sensor signals are processed and observations of axes in the environment are generated for a sequence of time steps, the orientation of the MSP is estimated for each of the time steps, observed axes are identified at each orientation, and similar axes are associated. The orientations, the axes in the environment, and the directions of gravity and the Earth's magnetic field are linked such that each observation is predicted based on the estimates of the orientations. An estimate of the orientations is optimized and an output of the representation of the physical environment is generated based on the optimized orientation estimates. The output may be an axis map, a visual representation, and/or a data set. In one embodiment the output device may produce an output comprising a stereonet.

Provided are apparatus and methods for generating a representation of a physical environment, comprising: a mobile sensor platform (MSP) including sensors that output sensor signals relating to parameters such as range, gravity, direction of the Earth's magnetic field, and angular velocity. The MSP is adapted to be moved through the environment. The sensor signals are processed and observations of axes in the environment are generated for a sequence of time steps, the orientation of the MSP is estimated for each of the time steps, observed axes are identified at each orientation, and similar axes are associated. The orientations, the axes in the environment, and the directions of gravity and the Earth's magnetic field are linked such that each observation is predicted based on the estimates of the orientations. An estimate of the orientations is optimized and an output of the representation of the physical environment is generated based on the optimized orientation estimates. The output may be an axis map, a visual representation, and/or a data set. In one embodiment the output device may produce an output comprising a stereonet.

Various implementations described herein are directed to a method for surveying a wellbore. A statistical estimation process that combines magnetic survey measurement data and gyroscopic survey measurement data to form error estimates in a magnetic survey system is applied. The error estimates are used to correct magnetic survey data provided by the magnetic survey system. Magnetic only survey data is used when convergence of the error estimates has occurred. Information that facilitates drilling the wellbore is provided.

Various implementations described herein are directed to a method for surveying a wellbore. A statistical estimation process that combines magnetic survey measurement data and gyroscopic survey measurement data to form error estimates in a magnetic survey system is applied. The error estimates are used to correct magnetic survey data provided by the magnetic survey system. Magnetic only survey data is used when convergence of the error estimates has occurred. Information that facilitates drilling the wellbore is provided.

A system includes at least one sensing unit, the sensing unit including a sensing element. The system includes at least one spatial Lorentz filter coupled to the sensing element. The spatial Lorentz filter (SLF) includes an input coupled to the sensing element and an analog to digital converter (ADC) providing a filtered output signal. The sensing unit is connected to a processor configured for determining velocity or position with respect to a magnetic field and/or a geographic position by processing SLF output signals.