Abstract: A formation testing tool and method for providing pressure controlled sampling is provided. A flow line delivers formation fluid to a sample chamber in the testing tool. A first valve controls the flow of formation fluid from the flow line to the sample chamber. A piston is slidably disposed in the sample chamber to define a sample cavity and a actuation cavity having variable volumes determined by movement of the piston. An actuator is also provided to move the piston in a first direction to increase the volume of the sample cavity and a second direction to decrease the volume of the sample cavity whereby formation fluid may be drawn into the sample cavity and pressurized therein using the actuator and the first valve.

Abstract: A method for determining a property of fluids in formations surrounding an earth borehole includes the following steps: producing, from measurements on a multiplicity of fluid samples, a database of stored fluid property training values related to stored fluid measurement training values; deriving, from the database, radial basis function parameters; deriving formation fluid measurement values; and determining, using radial basis function interpolation, the property of formation fluids from values in the database, the parameters, and the derived formation fluid measurement values.

Abstract: The apparatuses and methods herein relate to techniques for extracting fluid from a subsurface formation. A downhole sampling tool is provided with a probe having an internal wall capable of selectively diverting virgin fluids into virgin flow channels for sampling, while diverting contaminated fluids into contaminated flow channels to be discarded. The characteristics of the fluid passing through the channels of the probe may be measured. The data generated during sampling may be sent to a controller capable of generating data, communicating and/or sending command signals. The flow of fluid into the downhole tool may be selectively adjusted to optimize the flow of fluid into the channels by adjusting the internal wall within the probe and/or by adjusting the flow rates through the channels. The configuration of the internal wall and/or the flow rates may be automatically adjusted by the controller and/or manually manipulated to further optimize the fluid flow.

Abstract: A gap collar for an electromagnetic communication unit of a downhole tool positioned in a wellbore is provided. The downhole tool communicates with a surface unit via an electromagnetic field generated by the electromagnetic communication unit. The gap collar includes a first collar having a first end connector and a second collar having a second end connector matingly connectable to the first end connector. The gap collar further includes a non-conductive insulation coating disposed on the first and/or second end connectors, and a non-conductive insulation molding positioned about an inner and/or outer surface of the collars. The insulation molding moldingly conforms to the shape collars. The connectors are provided with mated threads modified to receive the insulation coating. Measurements taken by the downhole tool may be stored in memory, and transmitted to the surface unit via the electromagnetic field.

Abstract: A method and apparatus is provided to determine downhole pressures, such as annular pressure and/or pore pressure, during a drilling operation. A downhole drilling tool includes at least one conduit and a corresponding gauge. The conduit is positioned in the downhole tool and has an opening adapted to receive downhole fluids. The conduit is positionable in fluid communication with one of the wellbore and the formation whereby pressure is equalized therebetween. The gauge is provided for measuring the pressure in the conduit.

Abstract: A method is disclosed for determining viscosity and density of fluid from formations surrounding an earth borehole, including the following steps: (a) suspending a formation testing device in the borehole; (b) drawing formation fluid into the device; (c) causing the fluid to flow in a flow line under a first set of conditions; (d) causing the fluid to flow in the flow line under a second set of conditions; (e) measuring a first fluid pressure differential in the flow line during fluid flow under the first set of conditions, and measuring a second pressure differential in the flow line during fluid flow under the second set of conditions; and (f) determining density and viscosity of the fluid as a function of the first and second measured pressure differentials.

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: The present invention relates to a method and apparatus for detection of hydrogen sulfide in downhole operations. A downhole tool is provided with a coupon adapted to react at varying degrees to exposure to concentrations of hydrogen sulfide. The downhole tool is positioned in the wellbore with the coupon(s) exposed to downhole fluids. A reaction to a change in the coupon, such as coloration, is used to determine the presence and concentration of hydrogen sulfide.

Abstract: A method for refining fluid sample data includes obtaining optical density data for a fluid sample in at least two color channels and at least one fluid component channel and determining a color-absorption function from the optical density data for the fluid sample in the at least two color channels. The method also includes calculating a portion of the optical density caused by color absorptions in each of the at least one fluid component channels, and de-coloring the optical density data in each of the at least one fluid component channels by removing the portion of the optical density data caused by color absorption.

Abstract: A method and apparatus is provided to collect downhole data during a drilling operation via a downhole tool. A differential pressure is created by the difference between internal pressure of fluid passing through the downhole tool and the annular pressure in the wellbore. The apparatus includes a drill collar connectable to the downhole drilling, and has an opening extending into a chamber therein. A piston is positioned in the chamber and has a rod extending into the opening. The piston is movable between a closed position with the rod filling the opening, and an open position with the rod retracted into the chamber to form a cavity for receiving downhole fluid. A sensor is positioned in the rod for collecting data from fluid in the cavity. The apparatus may also be provided with a probe and/or hydraulic circuitry to facilitate the collection of data.

Abstract: The apparatuses and methods herein relate to techniques for extracting fluid from a subsurface formation. A downhole sampling tool is provided with a probe having an internal wall capable of selectively diverting virgin fluids into virgin flow channels for sampling, while diverting contaminated fluids into contaminated flow channels to be discarded. The characteristics of the fluid passing through the channels of the probe may be measured. The data generated during sampling may be sent to a controller capable of generating data, communicating and/or sending command signals. The flow of fluid into the downhole tool may be selectively adjusted to optimize the flow of fluid into the channels by adjusting the internal wall within the probe and/or by adjusting the flow rates through the channels. The configuraton of the internal wall and/or the flow rates may be automatically adjusted by the controller and/or manually manipulated to further optimize the fluid flow.

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: A method for determining virgin formation temperature of earth formations surrounding a borehole is provided. The time duration of drilling fluid circulation and the time after cessation of drilling fluid circulation at the borehole depth regions of interest are tracked. At a particular borehole depth region of interest, fluid flows from the formations into a device in the borehole, and the temperature of the fluid as a function of time with respect to initiation of fluid flow is measured. The thermal history of formations surrounding the particular borehole depth region is modeled for a cooling phase during drilling fluid circulation, a temperature build-up phase after cessation of drilling fluid circulation, and a formation fluid flow phase after initiation of fluid flow. The model and temperature measurements are used to determine a trend of temperature evolution and the virgin formation temperature by extrapolation from the trend.

Abstract: The present invention relates to apparatus for a tool for investigating the wall of a borehole in a geological formation, the apparatus comprising: a non-conductive pad having an inside face and an outside face for pressing against the wall; a set of measurement electrodes mounted on the outside face of the pad and means for measuring the potential difference between two measurement electrodes; and both a source electrode adapted to inject current into the geological formation and a return electrode, the set of measurement electrodes being situated between the source electrode and the return electrode for the current; the apparatus being characterized in that the pad comprises an electrically conductive portion covering the entire measurement electrode zone and electrically insulated from the measurement electrodes.

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: The present invention discloses a method of calculating a static formation temperature in a reservoir penetrated by a wellbore. One embodiment of the present invention comprises estimating the static formation temperature and calculating a formation fluid temperature at the wellbore, the calculation based, in part, on the estimated static formation temperature. The temperature of a sample of formation fluid at the wellbore is measured. The calculated formation fluid temperature at the wellbore is compared with the measured temperature of the sample of formation fluid. The static formation temperature is predicted by altering the estimate of the static formation temperature until an error between the calculated formation fluid temperature at the wellbore and the measured fluid formation temperature is minimized.

Abstract: A method of monitoring a fluid front movement is provided. The method includes: determining at least two techniques for monitoring the fluid front movement; determining a configuration of monitoring sensors, corresponding to the at least two monitoring techniques, from a joint sensitivity study of the at least two techniques; acquiring data with the monitoring sensors; and monitoring the fluid front by joint inverting the data.

Abstract: A method for measuring a downhole formation pressure is disclosed which includes lowering a formation testing tool to a desired measuring position in a well borehole. Then a nozzle in the tool is extended so that the nozzle extends through the mud cake layer on a surface of a formation, forming a seal between the mud cake layer and a sealing surface of the nozzle. In an embodiment of the invention, the nozzle has a porous tip that extends into the invaded zone beyond the mudcake layer and is exposed to the formation pressure. In an alternate embodiment, the nozzle has a retractable tip that retracts into the nozzle. The nozzle and retractable tip are positioned in the mudcake and the retractable tip is retracted into the nozzle. The formation pressure is then communicated through the nozzle to a pressure sensor operatively connected to the nozzle.