Abstract: A methodology improves sampling and characterization of heterogeneous, unconventional hydrocarbon-bearing regions. The methodology is designed to integrate consistently across measurements and scales. Additionally, the methodology involves characterizing various scales, such as regional-scale heterogeneity, wellbore-scale heterogeneity, core-scale heterogeneity, sample-scale, and pore-scale heterogeneity. The results are integrated across the multiple scales based on results obtained from the characterization of the scales. The methodology further comprises determining data propagation across the multiple scales in a hydrocarbon-bearing region.

Abstract: A method to determine one or more borehole corrected formation properties using measurements made using a logging tool disposed in a borehole penetrating an earth formation is disclosed. The measurements are used to determine an apparent conductivity tensor for the formation and, for a set of parameters, a parameter value for each parameter in a subset of the set of parameters. A parameter value for each parameter in the set of parameters not in the subset is provided and a borehole-inclusive modeled conductivity tensor is computed. The apparent conductivity tensor and the borehole-inclusive modeled conductivity tensor are iteratively used to optimize the parameter values, and the optimized parameter values are used to compute an optimized conductivity tensor. A borehole corrected conductivity tensor is computed using the optimized conductivity tensor, and the borehole corrected formation properties are determined using the borehole corrected conductivity tensor and/or the optimized parameter values.

Abstract: A computer-based method of generating a survey of a wellbore section is provided. The method includes analyzing a plurality of surveys of the wellbore section to identify survey measurements that do not comprise gross errors, generating an initial weighted average survey, and calculating an initial set of measurement differences between the identified survey measurements and the initial weighted average survey. The method further includes calculating a plurality of error term estimates for the plurality of surveys and using the plurality of error term estimates to correct the identified survey measurements. The method further includes generating an updated weighted average survey and calculating an updated set of measurement differences between the identified survey measurements and the updated weighted average survey.

Abstract: A method of passive surveying comprises generating one or more detected signals by passively detecting a signal generated within a subsurface earth formation due to a seismoelectric response or an electroseismic response in at least one porous subsurface earth formation containing at least one fluid, and processing the one or more detected signals to determine at least one property of the subsurface earth formation.

Abstract: A method of passive surveying comprises generating one or more detected signals by passively detecting a signal generated within a subsurface earth formation due to a seismoelectric response or an electroseismic response in at least one porous subsurface earth formation containing at least one fluid, and processing the one or more detected signals to determine at least one property of the subsurface earth formation.

Abstract: A gas trap with a gas analyzer for continuous gas analysis can include a sample chamber, means for agitating and creating a vortex, gas capturing chamber for receiving liberated gas, gas analyzer for providing real-time gas speciation of the liberated gas. A suction pump can pull the liberated fluid, a filtration means can condition the liberated fluid, and an exhaust port can exhaust analyzed fluid. An exhaust line can flow non-analyzed fluid to a drilling fluid storage chamber, drilling fluid stream, or both.

Abstract: A method to monitor a status from a secondary location of a plurality of equipment on a drilling site, while simultaneously enabling preventive maintenance for the plurality of equipment is described herein. A user can view at least one cycle, at least one control state, and at least one pressure. The user can also view equipment information, equipment repair history, and other information necessary to ensure that a piece of equipment has minimal down time.

Abstract: A computer assisted method to monitor a status from a secondary location of a plurality of equipment on a drilling site, while simultaneously enabling preventive maintenance is described herein. A user can view at least one cycle, at least one control state, and at least one pressure. The user can also view equipment information, equipment repair history, and other information necessary to ensure that a piece of equipment has minimal down time.

Abstract: A system to monitor a status from a secondary location of a plurality of equipment on a drilling site, while simultaneously enabling preventive maintenance is described herein. A user can view at least one cycle, at least one control state, and at least one pressure. The user can also view equipment information, equipment repair history, and other information necessary to ensure that a piece of equipment has minimal down time.

Abstract: A method for determining compositional data for fluids within a geological formation having a borehole therein may include collecting first and second dataset snapshots of the geological formation based upon measurements from the borehole at respective different first and second times, and with the borehole subject to fluid injection between the first and second times to displace fluids in the geological formation adjacent the borehole. The method may further include generating a differential dataset based upon the first and second dataset snapshots, normalizing the differential dataset to generate a normalized differential dataset, determining vertices defining a geometric shape and corresponding to respective different displaced fluid signatures based upon the normalized differential dataset, and determining displaced compositional data with respect to the different displaced fluid signatures based upon a position of a datapoint from the normalized differential dataset on the geometric shape.

Abstract: Methods and apparatus to process measurements associated with drilling operations are described. An example method of modifying processing results during a subterranean formation drilling operation includes identifying a plurality of parameters and processing measurements associated with the subterranean formation obtained while drilling and the plurality of parameters to generate first results. Additionally, the example method includes processing measurements associated with the subterranean formation obtained while drilling is temporarily suspended and the plurality of parameters to generate second results and comparing the first and second results. Further, the example method includes, in response to the comparison of the first and second results, modifying the first results based on the second results to improve a quality of the first results.

Abstract: A method for making downhole whirl measurements in a drill string includes rotating a sensor set in a borehole. The sensor set is deployed in the drill string and includes at least one cross-axial accelerometer and at least one cross-axial magnetometer. Sensor measurements, including a plurality of accelerometer measurements and a plurality of magnetometer measurements made at predetermined measurement intervals, may be obtained while drilling and used to compute a whirl magnitude.

Abstract: According to some embodiments of the present disclosure, a method of determining a critical depth of cut of a drill bit comprises selecting a radial swath associated with an area of a bit face of a drill bit. The method further comprises identifying a plurality of cutting elements disposed on the bit face that each include at least a portion located within the radial swath. The method also comprises identifying a depth of cut controller (DOCC) disposed on the bit face and configured to control a depth of cut of the portions of the plurality of cutting elements located within the radial swath. The method additionally comprises calculating a critical depth of cut associated with the radial swath and DOCC based on a depth of cut associated with each portion of the plurality of cutting elements located within the radial swath and controlled by the DOCC.

Abstract: In one aspect, a method of determining the presence of whirl for a rotating tool is disclosed that in one embodiment includes obtaining measurements (ax) of a parameter relating to the whirl of the tool along a first axis and measurements (ay) of the parameter along a second axis of the tool, determining a first whirl in a time domain for the tool using ax and ay measurements, determining a second whirl rate for the tool in a frequency domain from ax and ay measurements and determining the presence of the whirl from the first whirl rate and second whirl rate. The method further quantifies the whirl of the tool from the first and second whirl rates.

Abstract: According to some embodiments of the present disclosure, a method of determining a critical depth of cut of a drill bit comprises selecting a radial swath associated with an area of a bit face of a drill bit. The method further comprises identifying a plurality of cutting elements disposed on the bit face that each include at least a portion located within the radial swath. The method also comprises identifying a depth of cut controller (DOCC) disposed on the bit face and configured to control a depth of cut of the portions of the plurality of cutting elements located within the radial swath. The method additionally comprises calculating a critical depth of cut associated with the radial swath and DOCC based on a depth of cut associated with each portion of the plurality of cutting elements located within the radial swath and controlled by the DOCC.

Abstract: Apparatus and methods for guiding a drilling operation are disclosed. The apparatus includes a drilling apparatus, a receiving apparatus, and a display apparatus. The drill apparatus includes a bit with a steerable motor having a toolface and a rotary drive adapted to steer the bit during the drilling operation. The receiving apparatus is adapted to receive electronic data on a recurring basis, wherein the electronic data comprises quill position data, at least one of actual gravity-based toolface orientation data and actual magnetic-based toolface orientation data, and recommended toolface orientation data. The display apparatus is adapted to display the electronic data on a user-viewable display in a historical format depicting data resulting from a recent measurement and a plurality of immediately prior measurements.

Abstract: Systems and methods which provide accurate formation information regardless of formation and borehole geometry, including those associated with high angle and horizontal wells, are shown. In providing processing of logging or image data, such as may be provided by a density tool or other tool, according to embodiments, formation attributes or features (e.g., density and dip angle) are estimated using raw data provided by a the tool. The foregoing estimations may thereafter be iteratively refined using effective volume of interest (EVOI) information. According to embodiments, depth boundaries of formation information provided by the tool are shifted as a function of azimuth for correct spatial positioning of formation features using EVOI information. Processing of formation attribute or feature data provided by embodiments may be used with respect to various tool configurations, including configurations with and without borehole standoff.

Abstract: In some embodiments, an apparatus and a system, as well as a method and an article, may operate to acquire input data to determine properties of a formation, using a combination of down hole transmitters and receivers, to select a portion of the input data using a formation model chosen from a plurality of down hole tool response models in a formation model database, based on a valid sensitive range for the bed boundary distance and a greatest signal-to-noise ratio (SNR), and to solve for at least resistivity formation parameters in the properties using the chosen formation model and the selected portion of the input data. The database may be updated with boundary distance and the resistivity formation parameters. Additional apparatus, systems, and methods are disclosed.

Abstract: Methods and systems for processing acoustic measurements related to subterranean formations. The methods and systems provide receiving acoustic waveforms with a plurality of receivers, deriving slowness of the formation based on the acoustic waveforms, and modeling dominant waveforms in the acoustic waveforms based on the formation slowness, wherein deriving the formation slowness comprises parametric inversion for complex and frequency dependent slowness and the derived complex slowness has real and imaginary parts.

Abstract: An apparatus for providing a downhole measurement-while-drilling (MWD) tool with diagnostic capability by including one or more printed circuit boards to the tool with firmware processors that internally record significant system diagnostic events that can be time correlated with known tool operational problems. The concept includes firmware protocol to enable transfer all of the recorded data to an external software analysis program after the MWD tool is removed from a drilling run.

Abstract: Method, system, and apparatus for evaluating drilling accuracy performance in drilling a wellbore that can include: (1) monitoring an actual toolface orientation of a tool, e.g., a downhole steerable motor, by monitoring a drilling operation parameter indicative of a difference between the actual toolface orientation and a toolface advisory; (2) recording the difference between the actual toolface orientation and the toolface advisory; and (3) scoring the difference between the actual toolface orientation and the toolface advisory.

Abstract: Variable volume systems and methods of use thereof described herein are capable of making calibrated determinations of fluid properties and phase behavior of a fluid sample. The determinations can be calibrated based on one or more calibration functions, such as system volume corrected for pressure and temperature variations. Cross-checking the results of measurements can be used to determine accuracy of the calibration or monitor for leaks or other anomalies of the variable volume systems. The variable volume systems can be implemented in a well logging tool and are capable of being calibrated downhole.

Abstract: A system and a method analyze fatigue damage of a bottom hole assembly (“BHA”), and more specifically, use a multi-scale approach for fatigue analysis of a BHA. Three length scales may be used in modeling of a BHA, namely the BHA scale, the component scale and the feature scale. Loading conditions for each collar/tool of the BHA may be determined, such as by use of a beam model, and may be applied to the finite element models for the collar/tool to determine the fatigue damage of each fatigue susceptible feature of each collar/tool. A cumulative fatigue damage of each critical feature may be determined, and the weakest component of the BHA may be identified. Prognostic and diagnostic implementation with well survey and drilling data may monitor fatigue damage of critical components of the BHA.

Abstract: A method to obtain gain-corrected measurements. A measurement tool having one or more arrays is provided, wherein the arrays include two co-located triaxial transmitters and two co-located triaxial receivers. Measurements are obtained using the transmitters and the receivers. Impedance matrices are formed from the obtained measurements and the impedance matrices are combined to provide gain-corrected measurements. The apparatus may alternatively be a while-drilling logging tool having one or more arrays, wherein each array comprises a transmitter, a receiver, and a buck, and wherein the signal received by the receiver is subtracted from the signal received by the buck or vice versa. A slotted shield may be incorporated into either embodiment of the tool. The slots may form one or more island elements. A material is disposed in the slots. The islands and shield body have complementary tapered sides that confine the islands within the shield body.

Abstract: A method of passive surveying comprises generating one or more detected signals by passively detecting a signal generated within a subsurface earth formation due to a seismoelectric response or an electroseismic response in at least one porous subsurface earth formation containing at least one fluid, and processing the one or more detected signals to determine at least one property of the subsurface earth formation.

Abstract: Various techniques for generating a polar display include a method, which involves receiving information identifying a formation property of an anomaly within a geologic formation from a measurement-while-drilling (MWD) tool that includes several sensors. The formation property is identified by at least one magnitude and at least one distance. The formation property is also identified relative to a corresponding property of the geologic formation. The method also involves receiving information identifying an azimuthal angle from the MWD tool, where the azimuthal angle relates a position of the anomalous formation to a position of a first sensor. The method then generates a graphic, based upon the at least one magnitude and the at least one distance and the azimuthal angle, and displays the graphic on a polar display, in which a center of the polar display corresponds to a location of the borehole in which the MWD tool is located.

Abstract: A method of passive surveying comprises generating one or more detected signals by passively detecting a signal generated within a subsurface earth formation due to a seismoelectric response or an electroseismic response in at least one porous subsurface earth formation containing at least one fluid, and processing the one or more detected signals to determine at least one property of the subsurface earth formation.

Abstract: An acoustic emissions testing device includes a test cutter including a first surface, an acoustic sensor, an indenter coupled to the first surface, and a load. The load is exerted on the indenter, which transfers the load to the first surface. The acoustic sensor is communicably coupled to the test cutter and detects one or more acoustic events occurring therein. An acoustic emissions testing system includes a data recorder coupled to the testing device. The data recorder records the data from testing device. Based upon the data received, the toughness of the test cutter is objectively determined and can be ranked comparatively to the toughness of other test cutters. The load is ramped up to a peak load, held for a period of time, and then ramped down. Cutters from the same cutter type as the test cutters have similar toughness.

Abstract: A hydrocarbon exploration method is disclosed for generating anisotropic resistivity models of a subsurface reservoir from seismic and well data using a rock physics model. In one embodiment, the method comprises: selecting wells within a region of interest (101); obtaining a plurality of rock properties (102) and adjusting selected rock parameters (103) in the calibration of the rock physics model at the well locations; inverting porosity and shale content from seismic data (107); propagating the calibrated rock physics model to the region of interest (109) and calculating effective resistivity for the entire region of interest (109). The inventive method also provides for analyzing the uncertainty associated with the prediction of the resistivity volume.

Abstract: A steerable, magnetic dipole antenna for Measurement-While-Drilling (MWD) or Logging-While-Drilling (LWD) applications. The antenna elements use a hole arrangement in addition to grooves in a steel tool body, which is typically a drill collar. This antenna embodiment is extremely robust, meaning that does not significantly reduce the structural integrity of the tool body in which it is disposed. The antenna embodiment is also relatively wear resistant. The resultant magnetic dipole generated by this antenna is also electrically steerable in inclination angle from a common origin. A variable dipole moment inclination angle combined with independently measured tool rotation orientation during normal drilling allows the antenna to generate a magnetic dipole moment that may be directed at any three dimensional angle and from a common origin point at the centroid of the antenna. The antenna can also be embodied to be more sensitive to resitivity in a particular azimuthal direction.

Abstract: A directional resistivity tool includes a pair of transmitters deployed between at least one pair of receivers. Each of the transmitters and receivers preferably includes collocated z-mode and x-mode antennae. Exemplary embodiments may further include additional receivers, for example, additional pairs of receivers deployed axially about the transmitters or one or more deep reading receivers deployed on one axial end of the transmitters. Tools in accordance with the invention enable directional resistivity measurements to be acquired at multiple depths of investigation using fewer transmitter firings than conventional tools.

Abstract: A method of generating a directional response of a drill bit based on one or more drilling parameters includes performing actual or simulated tests with a drill bit in a test material having a strength under different experimental drilling parameters and recording the results of the plurality of tests. A representation of an expected directional response of the drill bit is formed based on the results. Current drilling parameters are receiving current drilling parameters at a computing device and the directional response is generated based on the current drilling parameters by utilizing the representation.

Abstract: A method for making dynamic borehole azimuth measurements while drilling includes processing cross-axial magnetic field measurements in combination with accelerometer measurements to compute the dynamic borehole azimuth. In one or more embodiments, the cross-axial magnetic field measurements and the accelerometer measurements may be used to compute the magnitude of a cross-axial magnetic field component, a toolface offset, and a borehole inclination, which may in turn be used to compute the dynamic borehole azimuth. The disclosed methods may utilize near-bit sensor measurements obtained while drilling, thereby enabling a near-bit dynamic borehole azimuth to be computed while drilling.

Abstract: A method for making dynamic gravity toolface measurements while rotating a downhole measurement tool in a borehole is disclosed. The method includes processing magnetic field measurements and accelerometer measurements to compute a toolface offset and further processing the toolface offset in combination with a magnetic toolface to obtain the dynamic gravity toolface. Methods for correcting dynamic and static navigational sensor measurements to remove sensor biases, for example, are also disclosed.

Abstract: A system for geosteering during directional drilling of a wellbore including a processor, a data storage, and client devices in communication with the processor through a network. The processor can receive data from directional drilling equipment and can present that data to users in an executive dashboard. Users can send data and/or commands to the directional drilling equipment. The executive dashboard can present: a portion of interest in a stratigraphic cross section for user identification of: the drill bit in the stratigraphic cross section, formations in the stratigraphic cross section, and other formation data. The system can be used to: identify a projected path for the drill bit, import data, compute wellbore profiles and stratigraphic cross sections, plot actual drilling paths, overlay the actual drilling path onto the projected path, and present control buttons to the user.

Abstract: A method for geosteering during directional drilling of a wellbore including a processor, a data storage, and client devices in communication with the processor through a network. The processor can receive data from directional drilling equipment and can present that data to users in an executive dashboard. Users can send data and/or commands to the directional drilling equipment. The executive dashboard can present a portion of interest in a stratigraphic cross section for user identification of the drill bit in the stratigraphic cross section, formations in the stratigraphic cross section, and other formation data. The method can be used to identify a projected path for the drill bit, import data, compute wellbore profiles and stratigraphic cross sections, plot actual drilling paths, overlay the actual drilling path onto the projected path, and present control buttons to the user.

Abstract: An apparatus is provided for assessing the location of a drill bit underground. The apparatus includes an acoustic sound generator that is driven by the drilling mud supplied to the drill bit. The sound generator a characteristic string of pulses, which may be termed a signature or key. The key is repeated over and over. Monitors (i.e., sensors) at the surface listen for this key. The key is distorted by the inconstant angular velocity of the drill bit. Thus the observed data do not precisely match the key. On the basis of numerical algorithms, a digitally revised reference signal or key, is identified to map the known reference key onto the best fitting observed data. The correction factors are then applied to map the modified reference key onto the data observed at other sensors of an array of sensors mounted on the surface.

Abstract: A real-time drilling monitor (RTDM) workstation provides real-time information at a well-site. The workstation may include a display and a processor coupled to the display. The processor receives sensor signals from a plurality of sensors and generates a single graphical user interface (GUI) populated with dynamically generated parameters based on the sensor signals, as well as static information and dynamically updated uncertainty assessments.

Abstract: A method and system for producing look-ahead profiles measurements includes positioning an energy transmitter, such as a transmitting antenna, proximate to a borehole assembly tool. One or more energy receivers, such as receiving antennas, are positioned along a length of the borehole assembly. Next, energy is transmitted to produce look-ahead scans relative to the borehole assembly tool. Look-ahead graph data with an x-axis being a function of a time relative to the position of the borehole assembly tool is generated. The look-ahead graph is produced and displayed on a display device. The look-ahead graph may track estimated formation values based on earth models. The estimated formation values are displayed below a tool position history line that is part of the look-ahead graph. The estimated formation values in the look-ahead graph may be based on inversions of resistivity data from the look-ahead scans.

Abstract: Various embodiments include apparatus and methods of operation with respect to well logging. Apparatus and methods include a tool having an arrangement of transmitters and receivers that are operated at different positions downhole and a processing unit to process collected signals such that the arrangement of transmitters and receivers provides measurements that mimic operation of a different arrangement of transmitters and receivers. Additional apparatus, systems, and methods are disclosed.

Abstract: A system and method for monitoring underground drilling in which vibration is monitored by creating a model of the drill string using finite element techniques or finite difference techniques and (i) predicting vibration by inputting real time values of operating parameters into the model, and then adjusting the model to agree with measured vibration data, (ii) predicting the weight on bit and drill string and mud motor speeds at which resonance will occur, as well as when stick-slip will occur, so that the operator can avoid operating regimes that will result in high vibration, (iii) determining vibration and torque levels along the length of the drill string based on the measured vibration and torque at one or more locations, (iv) determining the remaining life of critical components of the drill string based on the history of the vibration to which the components have been subjected, and (v) determining the optimum drilling parameters that will avoid excessive vibration of the drill string.

Abstract: An illustrative embodiment of a method is disclosed for assessing image quality of a down hole formation image, the method comprising collecting acquisition system data from a plurality of sensors down hole; applying a set of rules to the acquisition system data to obtain an acquisition quality indicator; and presenting the acquisition quality indicator at a surface location. A system is disclosed for performing the method.

Abstract: A method for drilling a well, the method including: identifying another well proximate to the well being drilled; collecting spatial information for at least a portion of the another well and the well being drilled; estimating a trajectory for at least a portion of the well being drilled and the another well; estimating an uncertainty in spatial information for each trajectory; estimating a probability of a collision with the another well during the drilling of the well by integrating a probability density function using the uncertainties and the trajectories; and performing the drilling in a manner that limits the probability of collision. A system and another method are provided.

Abstract: A system for determining at least one of a lithology of a formation traversed by a borehole and an operational condition of a component of a drill string disposed in the borehole is disclosed. The system includes a drill string with a high speed wired pipe telemetry system for transmitting downhole measurements made by a sensor to a computer processing system in real time. The computer processing system is external to the drill string and includes a model that models operation of the drill string and/or a formation that is being drilled. The model receives the downhole measurements and surface measurements of a drilling parameter and provides as output detection of the lithology of the formation and/or the operational condition of the component.

Abstract: A method for determining a status of a drill string in a wellbore. The method can include obtaining pressure data and hook load data for the drill string. The pressure data can be filtered to obtain pressure sections. A low pressure threshold can be determined based upon the pressure sections. The hook load data can be filtered to obtain hook load sections. Hook load baselines can be determined based upon the hook load sections. Dynamic thresholds can be determined based upon the hook load baselines. An in-slips status of the drill string can be determined based upon the low pressure threshold, the dynamic thresholds, or both.

Abstract: A method for making downhole dynamics measurements using rotating navigational sensors includes rotating navigational accelerometers in a subterranean borehole to obtain a string of accelerometer measurements while rotating. The measurements are differentiated to obtain a string of differentiated accelerometer measurements and may then be further processed to obtain a drill string vibration parameter. Substantially simultaneous magnetometer measurements may be obtained and utilized to compute a corrected vibration parameter in which at least one of a gravitational acceleration component, a tangential acceleration component, and a centripetal acceleration component is removed from the vibration parameter.

Abstract: The present disclosure relates to a method to determine a characteristic of a subsurface formation using a downhole logging tool. A downhole logging tool having the ability to make substantially concurrent disparate measurements on the subsurface formation is provided and substantially concurrent disparate measurements on the formation using the downhole logging tool are made. Those measurements are used to solve a system of equations simultaneously and the solution to the system of equations is used to determine the characteristic of the subsurface formation.

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: Method for estimating porosity and water saturation or other geological parameters of a subsurface region when the lithology of the region is unknown, requiring only geophysical data from remote surveys. The geophysical data are inverted (14-18) treating lithology as a third, and discrete, unknown model parameter (12) to be solved for in the inversion. A technique for solving mixed integer non-linear programs may be used. Suitable rock physics relationships (13) are used to relate the desired geological parameters to the geophysical model parameters required for simulating the geophysical data in the inversion process.

Abstract: An apparatus and method for measuring depth, velocity, or both depth and velocity of instrumentation within a wellbore is provided. The apparatus includes a downhole portion movable within the wellbore in a direction generally parallel to the wellbore. The apparatus further includes a first acceleration sensor mounted at a first position within the downhole portion. The first acceleration sensor generates a first signal indicative of a first acceleration in a first direction generally parallel to the wellbore at the first position. The apparatus further includes a second acceleration sensor mounted at a second position within the downhole portion. The second acceleration sensor generates a second signal indicative of a second acceleration in a second direction generally parallel to the wellbore at the second position. The apparatus further includes a bend sensor generating a third signal indicative of an amount of bend of at least a portion of the downhole portion.