Abstract: A downhole tool for collecting data from a subsurface formation is disclosed. The tool is provided with a probe for testing and/or sampling an adjacent formation. The tool is also provided with a protector positioned about the probe for engaging and protecting the sidewall of the bore hole surrounding the probe. The protector prevents deterioration of the wellbore during the testing and/or sampling by the probe.

Abstract: A downhole connate water sample drawn from the formation surrounding a well is validated when mud filtrate concentration is acceptably low. A preferred method includes drilling the well with a water-based drilling fluid, or more generally a water-based mud (WBM), containing a water-soluble dye. The dye acts as a tracer to distinguish connate water from WBM filtrate in a downhole sample of formation fluid contaminated by mud filtrate from the water-based mud. Preferably, an optical analyzer in a sampling tool measures light transmitted through the downhole sample to produce optical density data indicative of dye concentration. Preferably, optical density is measured at a first wavelength to obtain a first optical density, and at a second wavelength, close in wavelength to the first wavelength, to obtain a second optical density. First and second optical density data are transmitted to the surface.

Abstract: A system and method for enhancing the reception of electromagnetic (EM) waves in a fixed downhole receiver of an EM telemetry system is provided. In one embodiment, slots are formed in a portion of an outer casing and an EM receiver is positioned within the outer casing so as to be aligned with the slots formed therein. In another embodiment, an inductive coupling arrangement is provided to transfer signals from an EM receiver mounted on the outside surface of an outer casing to a wireline that is attached to the outer surface of an inner casing, which is disposed within the outer casing. In yet another embodiment, an insulated gap is formed in the surface of the outer casing. An EM receiver, mounted on the outer surface of the inner casing, is positioned above the insulated gap of the outer casing. An electrical coupling mechanism is further provided to electrically couple the inner and outer conductors at a point above the EM receiver.

Abstract: The invention concerns a method of sampling the formation fluids in an earth formation surrounding a borehole, the region of the formation immediately surrounding the borehole being at least partially invaded by borehole fluids, and an apparatus for carrying out such a method. According to the invention, a borehole tool is adapted to be lowered into the borehole and is provided with a sampling probe device and means for urging the sampling probe device into contact with the borehole wall, the sampling probe device comprising an inner probe and an outer probe surrounding the inner probe for withdrawing respective fluid samples from the formation, wherein the ratio between the respective flow areas of the inner and outer probes is selected so as to tend to reduce the time taken to obtain via the inner probe a sample of the formation fluids having a given level of contamination by borehole fluids.

Abstract: A method and apparatus for the separation of the water from the oil/gas in the well itself, down-hole, in which gravity is allowed to work on the mixture in a non-vertical section of the well, and then, using separated flow paths, the gravity-separated components pumped to the surface or into a subterranean discharge zone. Detectors are used to control the pumping so as to keep the unsettled/unseparated mixture away from the flow paths. Preferably the discharge zone is chosen to have a formation pressure which is lower than the pressure of the producing zone.

Abstract: A method for determining formation shear slowness of formations surrounding an earth borehole that includes: transmitting sonic energy into the formations from a dipole source in the borehole; measuring signals from orthogonal wave components that have traveled through the formations at each of a plurality of receiver locations in the borehole, spaced at a respective plurality of distances from the transmitter location; transforming the signals to the frequency domain and separating dispersive and non-dispersive portions of the transformed signals; and determining fast and slow shear slowness of the formation from the low frequency asymptotes of the dispersive portions of the transformed signals. Related methods for determining shear directionality and the magnitude of anisotropy of anisotropic formations surrounding an earth borehole and associated apparatus are also described.

Abstract: A method of estimating a petrophysical property of a subsurface area that includes deriving an acoustic calibration relationship correlating acoustic propagation characteristics of a first subsurface area with a petrophysical property of the first subsurface area determined using nuclear spectroscopy measurements; processing acoustic data acquired from a second subsurface area to determine acoustic propagation characteristics associated with a plurality of regions within the second subsurface area; and estimating the petrophysical property of the regions within the second subsurface area using the calibration relationship and the acoustic propagation characteristics associated with the second subsurface area.

Abstract: A method for determining properties of a transverse isotropic region of earth formations traversed by a wellbore having substantially vertical and deviated sections therethrough, including measuring sonic velocity properties in formations surrounding the substantially vertical section of the wellbore; measuring sonic velocity properties in formations surrounding the deviated section of the wellbore; and determining, from the measured velocities, all of the transverse isotropic elastic constants of the region.

Abstract: A method for determining an earth formation property from nuclear magnetic resonance measurements includes applying suppression functions to spin echoes in at least one burst measurement set to produce a modified burst data set, the suppression functions to suppress contribution of spin echoes having non-negligible polarization correction; inverting the modified burst data set and at least one standard spin echo measurement set to produce a nuclear magnetic resonance parameter distribution, the at least one standard spin echo measurement set and the at least one burst measurement set being acquired on an earth formation sample; and computing the earth formation property from the nuclear magnetic resonance parameter distribution. The nuclear magnetic resonance parameter includes at least one selected from longitudinal relaxation time, transverse relaxation time, a ratio of longitudinal relaxation time to transverse relaxation time, and diffusion constant.

Abstract: A method and system is described for estimating stress characteristics from seismic data. The method includes receiving seismic data acquired over a region, receiving properties of rock at a location within the region, and estimating one or more stress characteristics for a sub-region by combining the seismic data and the rock properties using a relationship between the stress characteristics in the sub-region and elastic stiffness and/or sonic velocity in the sub-region. The relationship is based on a non-linear elasticity theory.

Abstract: The present invention provides methods and apparatus for determining flow velocity within a formation utilizing nuclear magnetic resonance (NMR) techniques in which the shape of the resonance region is restricted so that sensitivity to radial flow or vertical flow is obtained (or both when more than one NMR tool is used). Flow velocity using these NMR tools is determined using decay amplitude, frequency displacement or stimulated echoes (where the spins are stored along the magnetic field instead of the transverse plane to exploit echo decays and frequency displacements) based on the application of adiabatic pulses. Based on the described NMR measurement of flow velocity, additional wellbore parameters may be obtained such as a direct measurement of permeability, an assessment of drilling damage to the wellbore, formation pressure, invasion rate of the mud filtrate or the migration of fine mud particles during sampling operations.

Abstract: A method for obtaining quantitative characteristics of an area of investigation includes measuring characteristics of the area of investigation in a first dimension, coordinating the measured characteristics with an index of a second dimension, the coordinating enabling an identification of a trend of the measured characteristics, and extrapolating using the trend in the second dimension to obtain quantitative characteristics of the area of investigation. An apparatus configured for use in a drill hole environment includes a clock configured to receive data from the depth meter and a processor configured to correlate clock data and depth data to provide a time after bit measure associated with a plurality of measurements of the measurements taken by the tool whereby the measurements taken at different depths are useful as compared to measurements taken independent of the time after bit measurements.

Abstract: A wireline well-logging data acquisition system and method with corrected depth index. The system having a winch for reeling-in a wireline cable connected to a well-logging tool. A depth index device and a cable tension meter are connected to the wireline cable. A computer system adjusts the depth index as a function of wireline tension measured by the cable tension meter. The computer system executes a method that includes a control loop for adjusting the depth index as function of the wireline tension.

Abstract: In a method for a well logging data presentation, data sets are identified from well logging data. Each data set is assigned a unique identifier. A presentation template, which defines a presentation for the well logging data, is configured. The presentation for the logging data may be in the form of a display and/or a hard copy. The presentation template includes definitions of a number of component presentations. Each component presentation includes a corresponding component template. Each component template includes a pointer pointing to a source for one of the data sets and defines a structure for the component's presentation. A graphical presentation program generates the presentation, responsive to reading the presentation template, component templates and data sets. The presentation can be viewed and changed while data is still being acquired.

Abstract: A downhole optical apparatus includes an LED source, reflectance and fluorescence detectors, a plurality of fibers, a dichroic mirror (DM), a beam splitter/coupler, a probe, a short-pass filter (SP), a dichroic long-pass filter (LP), and a lens. Source light filtered by the SP is fed to the DM which deflects light of desired wavelengths only. The deflected light is focused by the lens onto a fiber and is ultimately injected into an oil flow by the probe. Light reflected by oil or fluorescing therefrom is received by the probe, and split by the splitter. A small portion is received by the reflectance detector. A large portion is received by the lens and directed to the DM which deflects reflected light and passes light at longer fluorescing wavelengths. Passed light is further filtered by the DM and LP to eliminate remnants of the reflected light, and provided to the fluorescence detector.

Abstract: A method for detecting hydrocarbon-bearing zones in a formation penetrated by a wellbore includes acquiring at least two nuclear magnetic resonance measurements, each of the at least two nuclear magnetic resonance measurements acquired from a volume of investigation at a different radial depth from the wellbore; and determining whether the formation bears hydrocarbons by comparing the at least two nuclear magnetic resonance measurements. A method for detecting fines invasion in a formation surrounding a wellbore includes acquiring at least two nuclear magnetic resonance measurements, each of the at least two nuclear magnetic resonance measurements acquired from a volume of investigation at a different radial depth from the wellbore; and determining whether the fines invasion has occurred by comparing the at least two nuclear magnetic resonance measurements.

Abstract: A method is disclosed for measuring neutron interaction properties of an earth formation. The method includes irradiating the formation with bursts of high energy neutrons. The bursts have a duration selected to enable detection of short duration burst related phenomena. After at least one of the bursts, short duration burst related phenomena are measured. After a selected number of the bursts, long duration neutron burst-related phenomena are detected. In some embodiments, the short duration burst related phenomena include at least one of inelastic gamma ray related phenomena, neutron slowing down related phenomena and short capture cross section related phenomena.

Abstract: A method for tool path identification in formation evaluation includes obtaining measurements of formation properties in azimuthal sectors for each of a plurality of depth levels; calculating quality factors from the measurements; identifying a centroid or maximum of the quality factors among the measurements in each of the azimuthal sectors for each depth level; and associating the centroid or maximum of the quality factors at each depth level along a borehole to form the tool path. Calculating the quality factors may include parameterizing the measurements according to at least one factor selected from a spine factor, a rib factor, and a volumetric photoelectric factor. A method for determining corrected measurements for formation properties includes identifying a tool path from measurements taken in azimuthal sectors at each depth level along a borehole; and calculating a corrected measurement at the each depth level by averaging measurements in the azimuthal sectors adjacent the tool path.

Abstract: An apparatus and a method for controlling oilfield production to improve efficiency includes a remote sensing unit that is placed within a subsurface formation, an antenna structure for communicating with the remote sensing unit, a casing joint having nonconductive “windows” for allowing a internally located antenna to communicate with the remote sensing unit, and a system for obtaining subsurface formation data and for producing the formation data to a central location for subsequent analysis. The remote sensing unit is placed sufficiently far from the wellbore to reduce or eliminate effects that the wellbore might have on formation data samples taken by the remote sensing unit. The remote sensing unit is an active device with the capability of responding to control commands by determining certain subsurface formation characteristics such as pressure or temperature, and transmitting corresponding data values to a wellbore tool.

Abstract: Methods and apparatus for making subsurface measurements with reduced or eliminated borehole effects. Antenna and electrode configurations address the undesired axial electric currents that are induced along the borehole when antennas with tilted or transverse axes are used to make electromagnetic measurements. Current and measure electrodes are used in combination with antennas to limit the flow of undesired axial borehole currents. Embodiments use passive, active, or semi-active electrodes to limit the undesired current flow.