Abstract: A cutting tool for cutting a wireline, slickline, coiled tubing, or other well access line stuck downhole in a well. The tool includes a host of features including a propulsion mechanism to aid in delivering the tool to a predetermined cut location of the line. In this manner, the risk of unintended uphole cutting of the line may be minimized.

Abstract: The present invention provides methods and apparatus for separating and/or analyzing fluids of interest. According to principles of the present invention, fluid analysis is accomplished with microfluidic devices and may be reported in real-time or near real-time in a subterranean environment. In addition or alternative to oilfield applications, the principles of the present invention contemplate separation in a laboratory or other environment for biological sample separation and analytical chemistry applications. The present invention is capable of separating liquid-liquid mixtures or emulsions in a microfluidic device without fouling.

Abstract: Resistivity measurements at different radial depths of investigation obtained from time lapse resistivity data gained from multiple passes of a resistivity tool through a borehole are analyzed together to obtain indications of at least one of fractional flow, residual oil and water saturations, oil saturation, and water saturation in a formation. For each of the logging passes having resistivity measurements with multiple radial depths of investigation, filtrate loss into the formation is also obtained through joint inversion.

Abstract: A well bore treatment fluid and methods for selectively reducing the outflow of water during recovery of hydrocarbons from a hydrocarbon reservoir in a formation are described, wherein fluid contains 5 to 40 weight per cent of a dissolved compound based on ?-branched carboxylic acid, derivatives or co-polymers thereof, and capable of forming a precipitate that is substantially soluble in hydrocarbons and substantially insoluble in water.

Abstract: A method of acquiring seismic data that includes deploying a first array of seismic receivers and a second array of seismic receivers, and simultaneously receiving drill noise seismic energy produced as a wellbore is drilled relatively near the first and second arrays of seismic receivers using the first and second array of seismic receivers, wherein the first array of seismic receivers is closer to the source of the drill noise seismic energy than the second array of seismic receivers. A related method for processing seismic data and computer useable media are also described. Also a method of acquiring seismic data that includes deploying a first array of seismic receivers within a borehole, receiving seismic energy produced as a wellbore is drilled relatively near first array using said seismic receivers, and recording seismic data associated with the received seismic energy. A related method for acquiring and processing seismic data is also described.

Abstract: Methods and apparatus facilitating radial profiling of shear slowness or shear modulus c66 in the cross-sectional plane of a borehole in an anisotropic formation with the vertical X3-axis are disclosed. According to some aspects of the invention, sonic tool bias is accounted for and removed from radial profiles. According to some aspects, sonic tool bias is accounted for by modeling the sonic tool as a heavy-fluid.

Abstract: A method of determining formation density in a cased hole environment using a logging tool having a gamma ray source, a long spacing detector, and a short spacing detector that includes developing one or more cased hole calibration relationships that utilize differences between scattered gamma rays observed by short spacing detectors and scattered gamma rays observed by long spacing detectors to determine corrected formation density values, and using the cased hole calibration relationships and scattered gamma ray measurements obtained by the long spacing detector and the short spacing detector to determine the formation density. An associated article of manufacture and computerized well logging system are also described.

Abstract: A method of making a fiber optic accelerometer includes (a) drawing an optical fiber through a resin; (b) winding the resin coated fiber onto a disc mounted on an assembly having a central shaft; and (c) curing the resin-coated fiber. The optical fiber may be drawn through a resin by providing a container filled with a resin having an orifice therethrough and drawing the fiber through the orifice. The resin may be cured such that the fiber is bonded to the disc by curing the resin to the fiber and the disc at the same time.

Abstract: A method of characterizing a borehole traversing an earth formation including (a) obtaining an array of data from a formation characterization tool, wherein the data describes a section of the borehole; (b) computing at least one spatial characteristic describing the relative position of pairs of data; (c) assigning said pairs of data to bins based on the spatial characteristic, wherein the size of the bins are selected based on the tool; (d) transforming the data to petrophysical properties of the borehole; (e) calculating the variance of each bin; (f) developing a model of the variances; (g) determining at least one geostatistical parameter using the model; and (h) upscaling the geostatistical parameters to characterize a region of said earth formation. The method may further include generating a heterogeneity index log using the geostatistical model parameters. The method may be implemented using a computer program product for processing and interpreting borehole data.

Abstract: A method and apparatus for electrically interfacing between two or more distinct environments. The method and apparatus are directed to an electrical feedthru with one or more electrical transmission lines coated with one or more thin dielectric layers of material to insulate the transmission lines from a feedthru body. The dielectric layers may include a diamond-like carbon coating, which electrically insulates, but also thermally conducts. The use of thin dielectric layers facilitates smaller, more efficient electrical feedthrus. Therefore, the electrical feedthru may be used, for example, with MEMS devices. The electrical feedthru is not limited to any particular geometry, it may be adapted to fit between any two environments.

Abstract: Methods and apparatus for investigating a hydrocarbon bearing geological formation traversed by a borehole are disclosed. A borehole tool is used to acquire a sample of fluid in the formation. Compositional analysis of the fluid sample is conducted to provide a determination of the composition of the sample. The sample composition is then related to a model of the thermodynamic behavior of the fluid; i.e., the mass fractions of the fluid components are used as inputs to an equation of state (EOS) to predict the phase behavior of the fluid.

Abstract: A receptacle (10) for use in collecting samples down a well bore (14) is provided, the receptacle comprising a plurality of interconnecting modules (22, 24, 26, 30, 32, 34). A main chamber (22) is capable of holding a sample, and sensors (58, 60, 62, 64) within the chamber detect physical and chemical characteristics of the sample. Valves (50, 52) in a chamber wall seal the chamber (22) after a fluid sample has been collected. A communication means is placed in communication with the chamber (22) so as to provide an externally accessible port which communicates with the inside of the chamber (22) and allows detection and analysis of sample characteristics without removing the sample from the sealed chamber (22). The chamber (22) includes a piston (82) which is adjustable to keep pressure constant in the chamber and a heating element (58) to keep temperature constant. A method for sampling downhole fluids is also provided.

Abstract: A method is provided for estimating the position of a movable device in a borehole. The method comprises the steps of: (a) providing a prior location probability distribution associated with a first position of the device in the borehole, (b) providing a measurement of a putative distance moved by the device and/or a measurement of a characteristic of the surroundings of the device, the or each measurement being associated with movement of the device to a subsequent position in the borehole, and (c) calculating a posterior location probability distribution associated with the subsequent position, the posterior location probability distribution being conditional on the prior location probability distribution, and the or each measurement.

Abstract: A method of seismic surveying comprising the steps of actuating the or each vibrator in a first vibrator group at time T0, and subsequently actuating the or each vibrator in a second vibrator group at time T1 that satisfies T0<T1<T0+S1+L where S1 is the sweep time of the first vibrator group and L is the listening time. At least one of the first vibrator group and the second vibrator group comprises at least two vibrators. The first group and the second group of vibrators may be the same group, or they may be different groups. This method enables the time required to complete a seismic survey to be reduced compared to the prior art “simultaneous shooting” and “slip-sweep shooting” techniques.

Abstract: A method for determining the maximum and minimum horizontal stresses of formations surrounding a borehole includes the following steps: suspending a logging device in the borehole; transmitting sonic energy from the logging device to establish flexural waves in the formations; receiving, at the logging device, sonic energy from the flexural waves, and producing, from the received sonic energy, measurement signals at a number of frequencies; determining, at the number of frequencies, the fast and slow flexural wave velocities in the formations, to obtain fast and slow flexural velocity dispersions; establishing a model of formation stresses in which stresses of a loaded state are represented by the sum of an omnidirectional hydrostatically loaded mean reference stress, a vertical stress perturbation, and maximum and minimum horizontal stress perturbations; establishing an inversion model that includes inputs from the fast and slow flexural velocity dispersions and also includes unknown horizontal perturbations

Abstract: The invention concerns an aqueous viscoelastic fluid for use in the recovery of hydrocarbons. According to the invention this fluid comprises a first viscoelastic surfactant and a second surfactant able to decompose under downhole conditions to release a compound itself able to reduce the viscosity of the aqueous viscoelastic fluid.

Abstract: A method for tuning a nuclear magnetic resonance (NMR) tool having an operating frequency and equipped with an antenna, is disclosed comprising: (a) transmitting a rf magnetic field to a sample under investigation; (b) receiving an NMR signal from the sample within a detection window; (c) determining mistuning of said antenna relative to said operating frequency; (d) analyzing the received echo signal to determine mistuning of the received signal from the operating frequency. The mistuning of the received signals from the operating frequency may be determined by analyzing any changes in phase of the echo along the echo signal. The antenna tuning process may be automated by measuring calibrated signal amplitudes at more than one frequency and identifying a maximum amplitude. The system tuning may be maintained by repeating (a) through-(d) while operating the tool and implementing a feedback loop.

Abstract: A method and materials for stabilizing a wellbore against excess fluid pressure is described. It comprises forming or placing a flexible and essentially impermeable lining on or in the wellbore wall. The flexibility of the lining ensures that it remains in compression as the pressure in the wellbore is increased above the fluid pressure in the surrounding rock and it therefore does not need high tensile strength. The lining may be a preformed elastomer sleeve or formed in situ by the use of a reactive drilling fluid. Appropriate reactive formulations are described for the situation where the rock contains significant quantities of clay.

Abstract: The effects of storage on the interpretation of data obtained at observation probes of a borehole tool are eliminated by controlling the storage volumes relative to the observation probes. For a homogeneous medium, the effect of storage on the interpretation of data is eliminated by causing the flow line volumes connected to each observation probe to be equal to each other. For a heterogeneous medium, the effect of storage on the interpretation of data is eliminated by causing the flow line volumes to vary in proportion to the relative permeabilities of the strata of the heterogeneous medium adjacent the probes. The borehole tool is provided with mechanisms for conducting flow line volume adjustment.

Abstract: A method and apparatus detects dew precipitation and determines dew precipitation onset pressure in a sample of formation fluid located downhole in an oilfield reservoir. In a preferred embodiment, the method includes (a) isolating a sample of formation fluid downhole; (b) illuminating the sample downhole with fluorescence excitation light; (c) measuring at least one characteristic of fluorescence short from the sample; (d) reducing pressure on the sample; (e) repeating steps (b) to (d); (f) detecting dew precipitation when a change is detected in a parameter that is a function of the at least one characteristic of fluorescence emission; and (g) setting dew precipitation onset pressure equal to pressure on the sample when the change in the parameter is detected. The parameter preferably is a function of fluorescence intensity and fluorescence red shift, and the change is an increase in fluorescence intensity and detection of fluorescence red shift.