Abstract: Apparatus and methods to remove impurities at a sensor in a downhole tool are disclosed. During the testing and/or sampling of formation fluid in a borehole, the downhole tool creates a transient high rate of fluid flow of the formation fluid to remove impurities at the sensor.

Abstract: A fluid sampling system retrieves a formation fluid sample from a formation surrounding a wellbore extending along a wellbore axis, wherein the formation has a virgin fluid and a contaminated fluid therein. The system includes a sample inlet, a first guard inlet positioned adjacent to the sample inlet and spaced from the sample inlet in a first direction along the wellbore axis, and a second guard inlet positioned adjacent to the sample inlet and spaced from the sample inlet in a second, opposite direction along the wellbore axis. At least one cleanup flowline is fluidly connected to the first and second guard inlets for passing contaminated fluid, and an evaluation flowline is fluidly connected to the sample inlet for collecting virgin fluid.

Abstract: A downhole tool is provided including apparatus for unsticking the tool from the wall or a borehole. The tool may include a housing defining a longitudinal axis and a sleeve coupled to the housing and mounted for rotation relative to the housing, the sleeve having an exterior surface including at least one projection extending radially outwardly with respect to the longitudinal axis. A transmission mechanism may be coupled to and adapted to rotate the sleeve, and a motor may be coupled to the transmission mechanism. A method for unsticking the downhole tool by rotating a sleeve is also disclosed.

Abstract: Methods for performing downhole fluid compatibility tests include obtaining an downhole fluid sample, mixing it with a test fluid, and detecting a reaction between the fluids. Tools for performing downhole fluid compatibility tests include a plurality of fluid chambers, a reversible pump and one or more sensors capable of detecting a reaction between the fluids.

Abstract: A system for testing an underground formation penetrated by a well includes a downhole tool that is configured to be coupled to a work string and that includes an outer surface, a connection for coupling a stabilizing sub to the downhole tool, and at least one portion configured to receive a frame. The system further includes a plurality of stabilizing subs that are configured to be coupled to the downhole tool, a plurality of frames configured to be detachably mounted on the at least one portion of the downhole tool, and at least one measuring device configured to be secured in at least one of the plurality of frames.

Abstract: A downhole formation fluid pumping and a sampling apparatus are disclosed that may form part of a formation evaluation while drilling tool or part of a tool pipe string. The operation of the pump is optimized based upon parameters generated from formation pressure test data as well as tool system data thereby ensuring optimum performance of the pump at higher speeds and with greater dependability. New pump designs for fluid sampling apparatuses for use in MWD systems are also disclosed.

Abstract: A method for acquiring a sample of a virgin fluid from a subsurface formation penetrated by a wellbore surrounded by a layer of contaminated fluid includes abutting a first packer against a wall of the wellbore, and extending at least a portion of a second packer beyond the first packer, wherein the second packer is at least partially disposed in the first packer. An inlet to a first flowline is at least partially defined by the first packer, and an inlet to a second flowline is defined by the second packer. The method further includes drawing one of virgin fluid, contaminated fluid and combinations thereof into the first flowline; and drawing virgin fluid into the second flowline.

Abstract: Methods and apparatus to characterize stock-tank oil during fluid composition analysis are disclosed. A disclosed example method to characterize a fluid associated with an underground geological formation comprises obtaining a sample of the fluid associated with the underground geological formation, determining, in a borehole associated with the underground geological formation, a stock-tank oil type for the sample of the fluid associated with the underground geological formation, and determining a property of the fluid associated with the underground geological formation based on the stock-tank oil type.

Abstract: A system for testing a subterranean formation penetrated by a well includes a downhole tool configured to be coupled to a work string that includes a tool body having a longitudinal bore for circulating a fluid and at least one aperture configured to receive at least one module. The system further includes a plurality of modules that are each configured to engage the at least one aperture and at least one cavity configured for receiving a probe, and a plurality of probes that each include at least one orifice configured for testing the formation, wherein a first of the plurality of probes has a first configuration and a second of the plurality of probes has a second configuration.

Abstract: Conventional formation evaluation with dual inflatable packers includes the steps of pressurizing the packers so as to isolate an annular portion of the borehole wall, collecting one or more samples of formation fluid via the isolated portion of the borehole wall, and depressurizing the packers so as to permit movement of the mandrel within the borehole. A sampling method and apparatus that utilize one or more of the following to advantage is provided: restricting deformation of the packers during inflation using an annular bracing assembly; actively retracting the packers using ambient borehole pressure; and substantially centralizing the mandrel intermediate the packers so as to resist buckling of the mandrel.

Abstract: A formation evaluation tool positionable in a wellbore penetrating a subterranean formation is provided. The formation evaluation tool includes a cooling system adapted to pass a cooling fluid through electronics in the formation evaluation tool whereby heat is dissipated therefrom, the electronics has at least one gauge, a fluid communication device having an inlet adapted to receive the formation fluid and a flowline operatively connected to the fluid communication device and the gauge for placing the formation fluid in fluid communication therewith whereby properties of the formation fluid are determined.

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: A downhole drilling tool positionable in a wellbore penetrating a subterranean formation is provided. The tool includes a formation evaluation tool having fixed and retrievable portions. The fixed portion is operatively connected to a drill collar of the downhole tool. The fixed portion is for establishing fluid communication with a subterranean formation. The retrievable portion is fluidly connected to the fixed portion and retrievable therefrom to a surface location. The retrievable portion is for receiving a formation fluid from the subterranean formation.

Abstract: Methods and apparatus for investigating a hydrocarbon bearing geological formation traversed by a borehole are disclosed. An example method to characterize a fluid associated with an underground geological formation obtains a sample of the fluid associated with the underground geological formation. The example method measures, in a borehole associated with the underground geological formation, a chemical composition and a thermophysical property of the sample of the fluid. The example method selects a mathematical model to represent the sample of the fluid based on at least one of the chemical composition or the thermophysical property and adjusts a parameter of the mathematical model based on at least one of the chemical composition or the thermophysical property to generate an adjusted mathematical model. The example method then determines a property of the fluid associated with the underground geological formation based on the adjusted mathematical model.

Abstract: A method for controlling fluid flow through a passageway includes slidably disposing a piston having a conduit that reduces the flow area through the passageway in the passageway and selectively closing the conduit of the piston by moving at least one of the piston and a plug.

Abstract: An electromagnetic logging that includes a support; and at least one four-coil array disposed on the support, wherein the at least one four-coil array comprises: a transmitter, a bucking coil, a receiver, and a trim coil. A method for balancing an induction array includes applying an alternating current to a transmitter of the induction array that comprises the transmitter, a bucking coil and a receiver; measuring a mutual coupling between the transmitter and the receiver; and adding an extra bucking coil, if the mutual coupling exceeds a selected criterion.

Abstract: A method of evaluating a fluid from a subterranean formation drawn into a downhole tool positioned in a wellbore penetrating the subterranean formation is provided. The method involves drawing fluid from a formation into an evaluation flowline, drawing fluid from a formation into a cleanup flowline, measuring a property of the fluid in the evaluation flowline and detecting stabilization of the property of the fluid in the evaluation flowline. Fluid properties in a combined flowline may be generated from the evaluation and cleanup flowlines. The fluid properties of the combined flowline may be used to project future evaluation flowline fluid properties. Contamination levels for a given fluid property of a given flowline may also be determined.

Abstract: A method for determining a property of earth formations surrounding a borehole includes the following steps: deriving a fluid sample downhole in the borehole, subjecting the sample while downhole to a magnetic field; measuring a magneto-optical shift of a beam of electromagnetic radiation passed through the sample, and determining the property from the measured magneto-optical shift.

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 fluid analysis assembly for analyzing a fluid the fluid analysis assembly includes a chamber, a fluid movement device, a pressurization assembly and at least one sensor. The chamber defines an evaluation cavity for receiving the fluid. The fluid movement device has a force medium applying force to the fluid to cause the fluid to move within the cavity. The pressurization assembly changes the pressure of the fluid in a continuous manner. The at least one sensor communicates with the fluid for sensing at least one parameter of the fluid while the pressure of the fluid is changing in the continuous manner.