Abstract: Methods and systems for thermal compensation of pressure measurements by a pressure gauge. Errors in pressure values are reduced by utilizing a predetermined correlation between the error in pressure measurements, due to temperature gradient in a pressure gauge, and the temperature gradient caused by temperature at a surface of the pressure gauge and temperature at an inner portion of the pressure gauge. Thermally corrected pressure values are derived based on the correlation between the pressure errors and the temperature gradients in conditions such as due to fast and large pressure variations in oil wells.

Abstract: A method of determining the sonic slowness of a formation traversed by a borehole comprising generating tracks from sonic waveform peaks received at a plurality of depths wherein the peaks that are not classified prior to tracking is set forth. A method for generating a slowness versus depth log is generated for waveform arrivals by classifying long tracks, classifying small tracks; classifying tracks that overlap; filling in gaps; and creating a final log is disclosed. In further improvements, non-classified tracks and interpolation are used to fill in gaps.

Abstract: A formation logging tool having a substantially continuous central mandrel with regularly spaced mass blocks disposed thereon, at least some of the mass blocks carrying sensors such as receivers. By adopting this structure, the tool can be made to behave as a mass-spring structure and its flexural and extensional behaviour controlled such that its dispersion curve does not extend into the dispersion curve of the formation to be logged. The structure can be applied to the whole of the logging tool or just to the receiver section and/or any spacer section between the receiver and the transmitter section.

Abstract: An acoustic logging tool sleeve with a preferably discontinuous, alternating structure that is acoustically opaque in some zones, and acoustically transparent in others. The sleeve may be modular, with several stages connected together. The multiple stages provide a sleeve that may be useful with a variety of borehole logging tools to reduce or eliminate the transmission of noise to the receiving elements.

Abstract: A downhole fluid analysis system comprises an input light signal that is directed through a fluid sample housed in a sample cell. The input light signal may originate from a plurality of light sources. A light signal output from the sample cell is then routed to two or more spectrometers for measurement of the represented wavelengths in the output light signal. The output of the spectrometers is then compared to known values for hydrocarbons typically encountered downhole. This provides insight into the composition of the sample fluid. Additionally, the input light can be routed directly to the two or more spectrometers to be used in calibration of the system in the high temperature and noise environment downhole.

Abstract: A borehole seismic acquisition tool configured for release from a stuck position within a borehole having a tool body with at least one sensor package, an anchoring arm, and anchoring arm linkage adapted to connect the anchoring arm to the tool body. The anchoring arm linkage includes a weakpoint mechanism adapted to break in response to a minimum threshold amount of breaking force being applied upon the weakpoint mechanism. The anchoring arm includes a first end adapted for contacting a borehole wall surface and a second end pivotally attached to the anchoring arm linkage. The anchoring arm also includes a movable cam removably secured to the first end via a first connector pin. The cam being at least partially rotatable about the first connector pin and configured and arranged to rotate against the borehole wall by a pulling force at a top portion of the borehole seismic acquisition tool.

Abstract: A radiation detector operating at high temperatures is shown comprising a LuAP scintillating material for producing light when excited by incident radiation, a photocathode, and an electron multiplier. The photocathode is deposited directly onto the surface of the scintillating material that is oriented toward the electron multiplier. In a preferred embodiment, a metal flange is hermetically sealed to the scintillating material and this is fusion welded to the electron multiplier to create a vacuum envelope. This invention is particularly useful in high temperature noisy environments such as downhole operations to detect radiation within a well hole.

Abstract: A method for distributed processing in a subsurface environment includes running a local program on a local computation unit, wherein the local program is configured to call a remote procedure to be executed by a remote computation unit, wherein the local computation unit and the remote computation unit are disposed in a subsurface environment; initiating a remote procedure call; executing the remote procedure on the remote computation unit, while the local computation unit performs another operation; and returning a result from the executing the remote procedure to the local computation unit.

Abstract: Methods and systems are provided for downhole analysis of formation fluids by deriving fluid properties and associated uncertainty in the predicted fluid properties based on downhole data, and generating answer products of interest based on differences in the fluid properties. Measured data are used to compute levels of contamination in downhole fluids using an oil-base mud contamination monitoring (OCM) algorithm. Fluid properties are predicted for the fluids and uncertainties in predicted fluid properties are derived. A statistical framework is provided for comparing the fluids to generate, in real-time, robust answer products relating to the formation fluids and reservoirs thereof. Systematic errors in measured data are reduced or eliminated by preferred sampling procedures.

Abstract: A borehole tool positioning and measuring apparatus and its methods of use are provided. The apparatus and method can be used to centralize a logging tool in a wellbore, or position a logging tool at a desired relative alignment relative to the wellbore perimeter surface. The method and apparatuses can be used to determine useful information regarding borehole size and configuration. Various embodiments are useful for centralizing, eccentralizing, and otherwise positioning a borehole tool in a wellbore. Methods of determining borehole size and configuration measurements using a positioning apparatus are also provided.

Abstract: A method for obtaining high-quality well logging data acquired during a drilling operation includes acquiring well logging data during a pump-off period when a mud pump is turned off; and extracting a subset of data from the acquired well logging data, wherein the subset of data corresponds to a quiet period within the pump-off period, wherein the quiet period is substantially free of interference from turning the mud pump on or off.

Abstract: Various techniques are described which may be used to facilitate and improve seismic exploration activities. For example, one aspect of the present invention is directed to a technique for enabling in-situ measurement of geophone response parameters. Another aspect of the present invention is directed to a technique for improving geophone calibration and for improving the accuracy of measurement of geophone response parameters. Yet another aspect of the present invention is directed to a technique for compensating geophone response output data in order to improve the accuracy of such data.

Abstract: Apparatus and methods for acoustically isolating logging tool receiver and transmitter sections. One or more modular isolators is arranged between the receiver and transmitter sections. The modular isolators comprise a high tensile strength while also providing for a high wave attenuation level. The modular isolators are mechanical mass-spring systems capable of absorbing acoustic waves propagating along the logging tool. The mass is a swinging sleeve, and the spring includes a Belleville spring stack. The use of the strong modular isolators provides acoustic isolation between the transmitters and receivers for the complete sonic frequency band at multiple modes.

Abstract: Methods and apparatus facilitating logging-while-drilling (LWD) using a multi-pole acoustic transmitter source. The multi-pole transmitter source enables measurement of formation velocities, including shear wave velocities through formations that are slower than velocities through local fluids. The methods and apparatus may be utilized for LWD and wireline seismic surveys in which both the seismic or acoustic source and receivers are both deployed in a borehole, but may also be used for VSPs (vertical seismic profiling).

Abstract: A method and apparatus for communicating between downhole tools without the necessity of routing the communication through a surface module. Communications sent by downhole tools are examined and extracted downhole. If the communications are intended for other downhole tools, the communications are copied to a downlink and send to a specific intended tool, a group of tools, or all the tools. This is all done downhole, significantly reducing the latency between command and response.

Abstract: The present invention provides an apparatus and method for sensing subsurface data. One embodiment of the invention comprises a shuttle attached to a conveyance where the conveyance and shuttle are adapted to be spooled downhole into a borehole for sensing seismic data. The shuttle contains a sensor package that is preferably acoustically isolated in the shuttle. The sensor package includes a sensor array and a magnet clamp. A sensor section can contain several shuttles, each shuttle containing at least one sensor. In one embodiment, the sensor can be a fiber optic sensor. The magnet clamp is operable to controllably clamp and acoustically couple together the sensor package, the shuttle, and the adjacent structure which is typically the borehole casing. The magnet clamp is likewise operable to unclamp and uncouple the shuttle from the adjacent structure so as to be retracted uphole for subsequent use.

Abstract: The present invention provides methods and apparatus for measuring subterranean strain. The methods and apparatus use fluid expansion principles to compensate for temperature variations and increase the accuracy of the strain measurements. The methods and apparatus contemplate the use of multiple fluid chambers according to some embodiments in order to remove temperature dependence from stress or strain measurements.

Abstract: The present invention is directed to methods and systems for taking measurements relating to subterranean formations. The methods and systems effectively compress data and thus facilitate more efficient data transmission. The methods and systems are capable of automatically varying data compression rates during a measurement operation. The variable data compression capability facilitates reliable collection of measurement data at faster and/or constant logging speeds. The data compression methods and systems may be applied to any measurement operation relating to subterranean formations, including, but not limited to: acoustic wireline logging measurements, acoustic logging-while-drilling measurements, electromagnetic measurements, nuclear magnetic resonance measurements, and resistivity measurements.

Abstract: A vibration transducer such as a geophone, comprising a central pole piece (110) with a magnet (112) and coil (118) concentrically arranged around it. The position of the magnet (112) is fixed relative to the pole piece (110) and the coil (118) is movable relative to the magnet (112). A method of manufacturing a vibration transducer is characterised in that a bobbin carrying the coils is formed from a substantially tubular body which is positioned on a mandrel and at least one coil is wound around its outer surface, the mandrel being removed from the bobbin when the coil is complete. Another method is characterised in that the coil is formed separately and the bobbin is formed from a substantially tubular body which is positioned inside the coil and expanded to contact the coil when in position.

Abstract: A method and system for calibrating acoustic receivers (112). The method and system facilitate calibrating the acoustic receivers (112) while they are mounted to a downhole acoustic tool (102). Calibrating the acoustic receivers (112) in situ provides more accurate results than previously available. The method and system provide separate compensation factors for the acoustic receivers (112) at different frequencies and for different transmission sources. The separate compensation factors facilitate more accurate signal acquisition over a wider range of conditions.