Abstract: Various methods are disclosed, comprising obtaining a plurality of raw depth measurements for a wellbore; obtaining survey data about a bottom hole assembly; obtaining depth compensation information; calculating a plurality of compensated depth measurements from the raw depth measurements and the depth compensation information and one or more additional corrections for residual pipe compliance, tide, and rig heave; calculating sag angle and correcting the survey data with the sag angle; determining a high fidelity wellbore trajectory from the compensated depth measurements and the survey data; and then employing the high fidelity wellbore trajectory in various drilling, formation evaluation, and production and reservoir analysis applications. Depth compensation information may comprise at least one of weight on bit, a friction factor, temperature profile, borehole profile, drill string mechanical properties, hookload, and drilling fluid property. The surveys may include both static and continuous surveys.

Abstract: A system and a method for determining stretch or compression of a drill string is disclosed. Sensors are positioned along the drill string for collecting data for determining the stretch or compression. The stretch or the compression of the drill string may be used to calculate depths at which measurements are obtained by tools associated with the drill string.

Abstract: A method for correcting errors in LWD depths includes performing torque and drag model analysis using drillstring weight, downhole friction, weight on bit, thermal expansion, rig heave and tide to produce a corrected time-depth file, wherein the torque and drag model is automatically calibrated using effective block weight, drillpipe wear, and sliding friction; and correcting time-based LWD data using the corrected time-depth file to produce depth-corrected LWD data. A system for correcting errors in LWD depths includes a processor and a memory that stores a program having instructions for: performing torque and drag model analysis using drillstring weight, downhole friction, weight on bit, thermal expansion, rig heave and tide to produce a corrected time-depth file, wherein the torque and drag model is automatically calibrated using effective block weight, drillpipe wear, and sliding friction; and correcting time-based LWD data using the corrected time-depth file to produce depth-corrected LWD data.

Abstract: A system and a method for determining stretch or compression of a drill string is disclosed. Sensors are positioned along the drill string for collecting data for determining the stretch or compression. The stretch or the compression of the drill string may be used to calculate depths at which measurements are obtained by tools associated with the drill string.

Abstract: Various methods are disclosed, comprising obtaining a plurality of raw depth measurements for a wellbore; obtaining survey data about a bottom hole assembly; obtaining depth compensation information; calculating a plurality of compensated depth measurements from the raw depth measurements and the depth compensation information and one or more additional corrections for residual pipe compliance, tide, and rig heave; calculating sag angle and correcting the survey data with the sag angle; determining a high fidelity wellbore trajectory from the compensated depth measurements and the survey data; and then employing the high fidelity wellbore trajectory in various drilling, formation evaluation, and production and reservoir analysis applications. Depth compensation information may comprise at least one of weight on bit, a friction factor, temperature profile, borehole profile, drill string mechanical properties, hookload, and drilling fluid property. The surveys may include both static and continuous surveys.

Abstract: A method for estimating hydrocarbon volume in a layered subsurface formation includes determining a vertical resistivity and a horizontal resistivity in the formation. A bound water saturation and a total porosity of individual layers of the formation are determined. Values of horizontal resistivity and vertical resistivity of the formation are calculated based on the bound water saturation and the total porosity for each layer and on an estimated irreducible bulk volume of water in each layer. The estimated values are compared to the determined horizontal resistivity and vertical resistivity. The estimated irreducible water saturation in each layer is adjusted and estimating the values is repeated until differences between the estimated values and the determined vertical and horizontal resistivity values fall below a selected threshold. The hydrocarbon volume is estimated from the adjusted irreducible water saturation for each layer.

Abstract: A method for correcting errors in LWD depths includes performing torque and drag model analysis using drillstring weight, downhole friction, weight on bit, thermal expansion, rig heave and tide to produce a corrected time-depth file, wherein the torque and drag model is automatically calibrated using effective block weight, drillpipe wear, and sliding friction; and correcting time-based LWD data using the corrected time-depth file to produce depth-corrected LWD data. A system for correcting errors in LWD depths includes a processor and a memory that stores a program having instructions for: performing torque and drag model analysis using drillstring weight, downhole friction, weight on bit, thermal expansion, rig heave and tide to produce a corrected time-depth file, wherein the torque and drag model is automatically calibrated using effective block weight, drillpipe wear, and sliding friction; and correcting time-based LWD data using the corrected time-depth file to produce depth-corrected LWD data.

Abstract: A method for identifying a nature of formation contrasts that cause changes in seismic or sonic wave properties in a low-frequency range includes obtaining a selected property of a formation surrounding a borehole, wherein the selected property is at least one selected from the group consisting of a permeability and a fracture density; decomposing seismic signals into a set of instant amplitudes and frequency fields; calculating a plurality of low-frequency attributes characterizing the low-frequency range of the seismic signals; and establishing a correlation between at least one of the plurality of the low-frequency attributes and the selected property of the formation.

Abstract: A method for estimating hydrocarbon volume in a layered subsurface formation includes determining a vertical resistivity and a horizontal resistivity in the formation. A bound water saturation and a total porosity of individual layers of the formation are determined. Values of horizontal resistivity and vertical resistivity of the formation are calculated based on the bound water saturation and the total porosity for each layer and on an estimated irreducible bulk volume of water in each layer. The estimated values are compared to the determined horizontal resistivity and vertical resistivity. The estimated irreducible water saturation in each layer is adjusted and estimating the values is repeated until differences between the estimated values and the determined vertical and horizontal resistivity values fall below a selected threshold. The hydrocarbon volume is estimated from the adjusted irreducible water saturation for each layer.