Abstract: Method and apparatus are provided for adjusting electromagnetic well logging data for effects of frequency dispersion. In exemplary embodiments, a model is provided for estimating an electrical property of an earth formation as a function of frequency. The model is derived, for each particular volume of interest, based on measured data obtained by employing a plurality of interrogation frequencies. Measured data may include electrical properties of the volume of interest such as conductivity and dielectric constant. The model predicts the measurements expected to be obtained by a tool employing a selected interrogation frequency, including frequencies for which no measured data are available. In one embodiment, the model may be used to adjust measured data for effects of frequency dispersion to correspond to a selected interrogation frequency, allowing the adjusted data to be more effectively correlated to logging data obtained by a different type of tool employing a different interrogation frequency.

Abstract: Various apparatus and methods of supplying regulated battery power to an electrical device, such as a downhole tool, are provided. In one aspect, a method of providing power to an electrical device is provided that includes providing a plurality of batteries and providing a plurality of controllable regulators for regulating the power output of the plurality of batteries. The plurality of controllable regulators is set so that power is drawn from a minimum number of the plurality of batteries necessary to satisfy demand from the electrical device. The electrical device is enabled to periodically draw power from and thereby depassivate each of the plurality of batteries.

Abstract: A method for determining rotational offset between first and second gravity measurement devices deployed on a downhole tool is disclosed. The method includes positioning the tool in a previously surveyed section of a borehole that provides a historical survey including at least three previously surveyed azimuthal reference points and utilizing the gravity measurement devices to determine local azimuths at three or more sites in the previously surveyed section of the borehole. The method further includes comparing local azimuths with the historical survey and determining a rotational offset between the measurement devices that gives a best fit between local azimuths and the historical survey. A system adapted to execute the disclosed method and a computer system including computer-readable logic configured to instruct a processor to execute the disclosed method are also provided.

Abstract: A method for determining the location of a target subterranean structure from within an adjacent borehole is disclosed which uses first and second gravity measurement devices disposed at corresponding first and second positions in the adjacent borehole and a magnetic field measurement device disposed one of the first and second positions. The method includes processing a total local magnetic field, a reference magnetic field, and a local azimuth determined using the gravity measurement devices to determine a portion of the total magnetic field attributable to the subterranean structure multiple points in the adjacent borehole. The location of the subterranean structure is determined using the portion of the total magnetic field attributable thereto. A system adapted to execute the disclosed method and a computer system including computer-readable logic configured to instruct a processor to execute the disclosed method are also provided.

Abstract: A downhole tool for use in a well bore is provided. The tool includes a tool body and at least one elongated sprung member deployed on an outer surface thereof. The sprung member is configured to lie in a rest position substantially parallel to the outer surface and further includes at least one movable end that is movable with respect to the tool body. The tool further includes an actuation module deployed on the tool body. The actuation module is operably engaged with the sprung member, and disposed, upon actuation, to deflect said movable end thereof away from the rest position. Displacement of the movable end of the sprung member causes elastic spring biasing of the sprung member via bending thereof. The biasing urges the sprung member to return to the rest position upon de-actuation of the actuation module.

Abstract: Methods and systems for enabling estimations of porosity that are less sensitive to standoff and borehole size effects, and less reliant on corrective techniques for such effects. In one embodiment, a method is provided for estimating porosity of a formation using a downhole neutron tool. The method includes obtaining a near count rate in water, obtaining a far count rate in water, obtaining a near count rate in the formation and a corresponding far count rate in the formation, subtracting the near count rate in water from the near count rate in the formation to form an adjusted near count rate, subtracting the far count rate in water from the far count rate in the formation to form an adjusted far count rate, and estimating a formation porosity value as a function of the adjusted near count rate and the adjusted far count rate.

Abstract: A downhole tool for use in a well bore is provided. The tool includes a tool body and at least one elongated sprung member deployed on an outer surface thereof. The sprung member is configured to lie in a rest position substantially parallel to the outer surface and further includes at least one movable end that is movable with respect to the tool body. The tool further includes an actuation module deployed on the tool body. The actuation module is operably engaged with the sprung member, and disposed, upon actuation, to deflect said movable end thereof away from the rest position. Displacement of the movable end of the sprung member causes elastic spring biasing of the sprung member via bending thereof. The biasing urges the sprung member to return to the rest position upon de-actuation of the actuation module.

Abstract: A method for surveying a borehole is disclosed which uses first and second gravity measurement devices disposed at corresponding first and second positions in the borehole and a supplemental reference measurement device disposed at the first position. Exemplary supplemental reference measurement devices include magnetometers and gyroscopes. The method includes determining a reference borehole azimuth at the first position using the supplemental reference measurement device, determining a change in borehole azimuth between the first and second positions using the first and second gravity measurement devices and determining the borehole azimuth at the second position by applying the change in borehole azimuth the reference azimuth. A system adapted to execute the disclosed method and a computer system including computer-readable logic configured to instruct a processor to execute the disclosed method are also provided.

Abstract: Briefly, a method of estimating electrical parameters of an earth formation employs a simplified model of a measurement tool or device in transforming or normalizing data measured by the measurement tool. Electrical parameters of the earth formation, such as conductivity or dielectric constant, for example, may be estimated based on the normalized data.

Abstract: Techniques are provided to transform attenuation and phase measurements taken in conjunction with a drilling operation into independent electrical parameters such as electrical resistivity and dielectric values. The electrical parameters are correlated with background values such that resulting estimates of the electrical parameters are independent of each other. It is shown an attenuation measurement is sensitive to the resistivity in essentially the same volume of an earth formation as the corresponding phase measurement is sensitive to the dielectric constant. Further, the attenuation measurement is shown to be sensitive to the dielectric constant in essentially the same volume that the corresponding phase measurement is sensitive to the resistivity. Techniques are employed to define systems of simultaneous equations that produce more accurate measurements of the resistivity and/or the dielectric constant within the earth formation than are available from currently practiced techniques.