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: An apparatus and method for determining at least one downhole formation property is disclosed. The apparatus includes a probe and a pretest piston positionable in fluid communication with the formation, and a series of flowlines pressure gauges, and valves configured to selectively draw into the apparatus for measurement of one of formation fluid and mud. The method includes performing a first pretest to determine an estimated formation parameter; using the first pretest to design a second pretest and generate refined formation parameters whereby formation properties may be estimated.

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 viscometer for a down hole tool positionable in a well bore penetrating a subterranean formation is described. The formation contains at least one fluid therein. The down hole tool is adapted to convey at least a portion of the fluid to the viscometer. The viscometer comprises a sensor unit, and at least one magnet. The sensor unit is positionable within the down hole tool and comprises at least two spatially disposed clamps and a wire suspended in tension between the at least two clamps such that the wire is available for interaction with the fluid when the viscometer is positioned within the down hole tool and the down hole tool is positioned within the subterranean formation and receives the fluid from the subterranean formation.

Abstract: A method of sampling fluid from a rock formation penetrated by a borehole includes positioning a downhole tool having a flow line in the borehole, establishing an inlet port through which fluid passes from a first point in the formation into the flow line, establishing an outlet port through which fluid passes from the flow line into a second point in the formation, and passing fluid between the formation and the flow line through the inlet and outlet ports.

Abstract: An apparatus and method for determining at least one downhole formation property is disclosed. The apparatus includes a probe and a pretest piston positionable in fluid communication with the formation, and a series of flowlines pressure gauges, and valves configured to selectively draw into the apparatus for measurement of one of formation fluid and mud. The method includes performing a first pretest to determine an estimated formation parameter; using the first pretest to design a second pretest and generate refined formation parameters whereby formation properties may be estimated.

Abstract: An apparatus and method for determining at least one downhole formation property is disclosed. The apparatus includes a probe and a pretest piston positionable in fluid communication with the formation, and a series of flowlines pressure gauges, and valves configured to selectively draw into the apparatus for measurement of one of formation fluid and mud. The method includes performing a first pretest to determine an estimated formation parameter; using the first pretest to design a second pretest and generate refined formation parameters whereby formation properties may be estimated.

Abstract: Methods and apparatuses for sampling fluid from a subterranean formation penetrated by a wellbore are provided. The subterranean formation has clean formation fluid therein, and the wellbore has a contaminated fluid therein extending into an invaded zone about the wellbore. A shaft is extended from a housing and positioned in a perforation in a sidewall of the wellbore. At least one flowline extends through the shaft and into the housing. The flowline(s) are adapted to receive downhole fluids through the perforation. At least one fluid restrictor, such as a packer, injection fluid or flow inhibitor, may be used to isolate at least a portion of the perforation whereby contaminated fluid is prevented from entering the isolated portion of the perforation. At least one pump selectively draws fluid into the flowline(s).

Abstract: A method for determining properties of a formation fluid including obtaining data related to an optical density at a methane peak and an optical density at an oil peak for a fluid sample at a plurality of times, calculating an apparent gas-oil-ratio of the sample fluid from the optical density of the fluid sample at the methane peak to the optical density of the fluid sample at the oil peak at each of the plurality of times based on the data, selecting a power function of a sampling parameter for a buildup of the apparent gas-oil-ratio, calculating an exponential constant of the power function based on the data, and determining at least one selected from the group consisting of a contamination free gas-oil-ratio and a percent contamination.

Abstract: An apparatus and method for determining at least one downhole formation property is disclosed. The apparatus includes a probe and a pretest piston positionable in fluid communication with the formation, and a series of flowlines pressure gauges, and valves configured to selectively draw into the apparatus for measurement of one of formation fluid and mud; The method includes performing a first pretest to determine an estimated formation parameter; using the first pretest to design a second pretest and generate refined formation parameters whereby formation properties may be estimated.

Abstract: An apparatus and method for determining at least one downhole formation property is disclosed. The apparatus includes a probe and a pretest piston positionable in fluid communication with the formation, and a series of flowlines pressure gauges, and valves configured to selectively draw into the apparatus for measurement of one of formation fluid and mud. The method includes performing a first pretest to determine an estimated formation parameter; using the first pretest to design a second pretest and generate refined formation parameters whereby formation properties may be estimated.

Abstract: A method for determining formation pressure at a depth region of formations surrounding a borehole, including: keeping track of the time since cessation of drilling at the depth region; deriving formation permeability at the depth region; causing wellbore pressure to vary periodically in time and determining, at the depth region, the periodic and non-periodic component of pressure measured in the formations; determining, using the time, the periodic component and the permeability, the formation pressure diffusivity and transmissibility and an estimate of the size of the pressure build-up zone around the wellbore at the depth region; determining, using the time, the formation pressure diffusivity and transmissibility, and the non-periodic component, the leak-off rate of the mudcake at the depth region; determining, using the leak-off rate, the pressure gradient at the depth region; and extrapolating, using the pressure gradient and the size of the build-up zone, to determine the formation pressure.

Abstract: An apparatus and method for determining at least one downhole formation property is disclosed. The apparatus includes a probe and a pretest piston positionable in fluid communication with the formation, and a series of flowlines pressure gauges, and valves configured to selectively draw into the apparatus for measurement of one of formation fluid and mud. The method includes performing a first pretest to determine an estimated formation parameter; using the first pretest to design a second pretest and generate refined formation parameters whereby formation properties may be estimated.

Abstract: An apparatus and method for determining at least one downhole formation property is disclosed. The apparatus includes a probe and a pretest piston positionable in fluid communication with the formation, and a series of flowlines pressure gauges, and valves configured to selectively draw into the apparatus for measurement of one of formation fluid and mud. The method includes performing a first pretest to determine an estimated formation parameter; using the first pretest to design a second pretest and generate refined formation parameters whereby formation properties may be estimated.

Abstract: An apparatus and method for determining at least one downhole formation property is disclosed. The apparatus includes a probe and a pretest piston positionable in fluid communication with the formation, and a series of flowlines pressure gauges, and valves configured to selectively draw into the apparatus for measurement of one of formation fluid and mud. The method includes performing a first pretest to determine an estimated formation parameter; using the first pretest to design a second pretest and generate refined formation parameters whereby formation properties may be estimated.

Abstract: A method for determining properties of a formation fluid including obtaining data related to an optical density at a methane peak and an optical density at an oil peak for a fluid sample at a plurality of times, calculating an apparent gasoilratio of the sample fluid from the optical density of the fluid sample at the methane peak to the optical density of the fluid sample at the oil peak at each of the plurality of times based on the data, selecting a power function of a sampling parameter for a buildup of the apparent gasoilratio, calculating an exponential constant of the power function based on the data, and determining at least one selected from the group consisting of a contamination free gasoilratio and a percent contamination.

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 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: 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: An apparatus and method for determining at least one downhole formation property is disclosed. The apparatus includes a probe and a pretest piston positionable in fluid communication with the formation, and a series of flowlines pressure gauges, and valves configured to selectively draw into the apparatus for measurement of one of formation fluid and mud. The method includes performing a first pretest to determine an estimated formation parameter; using the first pretest to design a second pretest and generate refined formation parameters whereby formation properties may be estimated.