Abstract: Methods and apparatus for evaluating an earth formation intersected by a borehole. Methods include using at least one transmitter to generate electromagnetic (EM) waves propagating through the formation; generating measurement signals at at least one receiver responsive to the propagating EM waves; taking a plurality of propagation measurements from the measurement signals representative of the propagating EM waves, where each propagation measurement of the plurality comprises at least one of: i) a relative phase shift between a first wave of the plurality of propagating EM waves and a second wave of the plurality of propagating EM waves; and ii) a relative attenuation between a first wave of the plurality of propagating EM waves and a second wave of the plurality of propagating EM waves; and performing a single inversion which uses the plurality of propagation measurements as input and generates at least one petrophysical parameter as output.

Abstract: A method for transforming an earth formation and/or production equipment based on correcting nuclear magnetic resonance (NMR) data to account for partially water-saturated rock includes: receiving NMR logging data having echo-trains for an earth formation; inverting the echo-trains to provide transverse relaxation time constant (T2) distributions for various components of fluid in the earth formation; substituting a T2 distribution for mobile water of fully water-saturated rock for a T2 distribution for mobile water of partially water-saturated rock based on values of the mobile water T2 distribution of partially water-saturated rock and a total porosity constraint; summing the T2 distribution for mobile water of fully water-saturated rock and a T2 distribution for an immobile water component of the fluid to provide a T2, distribution for fully water-saturated rock; and transforming the earth formation and/or the production equipment based on a parameter derived from the T2 distribution for fully water-satura

Abstract: Examples of techniques for generating a high-resolution lithology model for subsurface formation evaluation are disclosed. In one example implementation according to aspects of the present disclosure, a computer-implemented method includes determining, by a processing device, a low-resolution lithology volumetric model. The method further includes comparing, by the processing device, the low-resolution lithology volumetric model to a high-resolution imaging log. The method further includes calculating, by the processing device, a dynamic boundary curve for each of a plurality of moving windows. The method further includes generating, by the processing device, the high-resolution lithology model based at least in part on the calculated dynamic boundary curve for each of the plurality of moving windows. The method further includes controlling a drilling operation based at least in part on the high-resolution lithology model.

Abstract: Methods and apparatus for evaluating a volume of an earth formation carried out using complex dielectric measurements. Methods include making measurements of complex permittivity at a plurality of frequencies; identifying an optimal frequency by: identifying candidate frequencies having a corresponding measurement with a respective sensitivity to at least one of i) salinity and ii) water-filled porosity, by determining that each respective sensitivity is substantially independent of rock texture; selecting a maximum of the candidate frequencies as the optimal frequency; using a table search method based on a forward model to generate an initial estimate of at least two parameters of the volume; and using the initial estimate as an initial condition for an inversion of other measurements at frequencies other than the optimal frequency to generate a final solution comprising final estimates for formation properties. The at least two parameters may comprise water salinity and water filled porosity.

Abstract: A method for transforming an earth formation and/or production equipment based on correcting nuclear magnetic resonance (NMR) data to account for partially water-saturated rock includes: receiving NMR logging data having echo-trains for an earth formation; inverting the echo-trains to provide transverse relaxation time constant (T2) distributions for various components of fluid in the earth formation; substituting a T2 distribution for mobile water of fully water-saturated rock for a T2 distribution for mobile water of partially water-saturated rock based on values of the mobile water T2 distribution of partially water-saturated rock and a total porosity constraint; summing the T2 distribution for mobile water of fully water-saturated rock and a T2 distribution for an immobile water component of the fluid to provide a T, distribution for fully water-saturated rock; and transforming the earth formation and/or the production equipment based on a parameter derived from the T2 distribution for fully water-saturat

Abstract: Examples of techniques for generating a high-resolution lithology model for subsurface formation evaluation are disclosed. In one example implementation according to aspects of the present disclosure, a computer-implemented method includes determining, by a processing device, a low-resolution lithology volumetric model. The method further includes comparing, by the processing device, the low-resolution lithology volumetric model to a high-resolution imaging log. The method further includes calculating, by the processing device, a dynamic boundary curve for each of a plurality of moving windows. The method further includes generating, by the processing device, the high-resolution lithology model based at least in part on the calculated dynamic boundary curve for each of the plurality of moving windows. The method further includes controlling a drilling operation based at least in part on the high-resolution lithology model.

Abstract: Methods and apparatus for evaluating a volume of an earth formation carried out using complex dielectric measurements. Methods include making measurements of complex permittivity at a plurality of frequencies; identifying an optimal frequency by: identifying candidate frequencies having a corresponding measurement with a respective sensitivity to at least one of i) salinity and ii) water-filled porosity, by determining that each respective sensitivity is substantially independent of rock texture; selecting a maximum of the candidate frequencies as the optimal frequency; using a table search method based on a forward model to generate an initial estimate of at least two parameters of the volume; and using the initial estimate as an initial condition for an inversion of other measurements at frequencies other than the optimal frequency to generate a final solution comprising final estimates for formation properties. The at least two parameters may comprise water salinity and water filled porosity.

Abstract: Methods and apparatus for evaluating an earth formation intersected by a borehole. Methods include using at least one transmitter to generate electromagnetic (EM) waves propagating through the formation; generating measurement signals at at least one receiver responsive to the propagating EM waves; taking a plurality of propagation measurements from the measurement signals representative of the propagating EM waves, where each propagation measurement of the plurality comprises at least one of: i) a relative phase shift between a first wave of the plurality of propagating EM waves and a second wave of the plurality of propagating EM waves; and ii) a relative attenuation between a first wave of the plurality of propagating EM waves and a second wave of the plurality of propagating EM waves; and performing a single inversion which uses the plurality of propagation measurements as input and generates at least one petrophysical parameter as output.

Abstract: An agitator for agitating drilling fluid or other slurries or mixtures in a tank includes a pressurized and fluid-free compartment within the tank. The motor driving the agitator is housed in the fluid-free compartment. Control apparatus senses fluid levels and, in conjunction with a compressed gas source, maintains the compartment fluid-free. Additionally, when the fluid level in the enclosure drops to a predetermined minimum, the speed of the agitator may be slowed.

Abstract: High Definition Induction Logging (HDIL) tools can provide reliable information about the vertical and radial variations of resistivity structure in isotropic media. The focusing technique provides quantitative information about the resistivity variation and qualitative information about invasion at the well site. This type of logging tool utilizes transmitter-receiver arrays coaxial with the borehole and thus cannot provide information about anisotropy in vertical wells. This greatly limits the application of array induction tools in the characterization of reservoirs with finely laminated sand/shale sequences. A multi-component induction tool, 3DEX™, has been developed by Baker Atlas and Royal Dutch Shell. It provides the much needed ability to detect anisotropy for sand-shale laminated reservoirs. Data from such a logging tool are inverted to give an estimate of vertical and horizontal resistivity in a vertical borehole.

Abstract: High Definition Induction Logging (HDIL) tools provide reliable information about the vertical and radial variations of resistivity structure in isotropic media. Focusing techniques provide quantitative information about resistivity variation and qualitative information about invasion at the well site. Coaxial alignment of transmitter-receiver arrays with the borehole prevents obtaining information about anisotropy in vertical wells, thereby greatly limiting the application of array induction tools in the characterization of reservoirs with finely laminated sand/shale sequences. A multi-component induction tool, 3DEX™, enables the detection of anisotropy in laminated reservoirs. Multi-component data are invert to give an estimate of vertical and horizontal resistivity in a vertical borehole. 3DEX™ may encounter difficulties in looking through an invaded zone and detecting the anisotropy in the formations.