Schlumberger Technology Corporation

Elizabeth B Dussan V

Oliver Clinton Mullins

Francois M Auzerais

Xu Wu

Rogerio Tadeu Ramos

Edward Harrigan

Jacques A Jundt

Fadhel Rezgui

David J Rossi

Felix K Chen

Soraya Sofia Betancourt

Douglas W Grant

William E Kenyon

Abderrhamane Ounadjela

William F Murphy

Fikri Kuchuk

Kenneth E Stephenson

Yogesh S Dave

Eric Veignat

T S Ramakrishnan

Barbara I Anderson

Richard W Gaylor

Henning Groenzin

Donald Charles McKeon

Richard D Joyce

Yogeshwar Sharma

James Helwig

Peter Goode

Richard Plumb

Clelia Canuel

Francedillaois Hecquet

Methods are disclosed for processing, in real-time, pressure data acquired with a formation tester during a pretest to quickly establish the quality of the measurement being conducted. The methods can optimize pressure measurement operations by assessing whether it is desirable or not to wait for the formation tester flowline pressure to equilibrate to the sandface pressure. In one embodiment, a determination is made as to whether the pretest succeeded in establishing hydraulic communication between the formation and the flowline by comparing the pressure signal with a simulation of the pressure behavior corresponding to a false buildup during a dry test. In another embodiment, a determination is made as to whether the pretest succeeded in isolating the tool flowline and the formation from the wellbore by using the pressure signal to estimate the sandface pressure during buildup over time, and to compare the estimated sandface pressure signal with the borehole pressure.

Methods for analyzing formation tester pretest data

An apparatus, method and system are provided for characterizing fluid trapped in a subterranean formation using a downhole tool that includes an elongated body and a probe body. The probe body is moveable from and back into the elongated body. The probe body defines a flow line and supports a pressure sensor for measuring fluid pressure in the flow line, a piston and an electrical motor actuator that is adapted to move the piston in order to vary volume of the flow line. The integral electrical motor actuator, piston, pressure sensor and flow line of the probe body can provide for measurement of formation pressure and/or formation mobility.

Apparatus, method and system for measuring formation pressure and mobility

Several optical probes useful in downhole applications are provided. A first probe has a tip in the form of a cubical corner with the diagonal of the cubical corner aligned with the axis of the probe. A second probe has a tip formed in a 45&#xb0; cone. In these designs, light will bounce respectively three times or twice, but still retain the same orientation. To facilitate drainage, the very tip of the probe may be rounded. Both designs also provide a probe with a large numerical aperture and both are useful for detecting reflectance and the holdup of a multiphase fluid. A third probe uses (hemi)spherical or paraboloid probe tip. The third probe tip has a small numerical aperture and is useful for detecting fluorescence and oil velocity. In all three embodiments, the base behind the probe tip may be tapered to facilitate fluid drainage.

Optical probes and probe systems for monitoring fluid flow in a well

Apparatus and methods for measuring oil flow velocity in a well are provided which utilize fluorescence quenching. A marker which quenches the natural fluorescence of crude oil is chosen and injected into the oil flow at a first location. At a second location, the oil flow is subjected to light at a wavelength which will cause oil to naturally fluoresce. The fluorescence signal is detected at the second location by a sensing probe. The time that it takes for the quenching marker to move from the first location to the second location is measured by sensing a decrease in fluorescence due to the quencher. Fluid velocity is determined by dividing the distance between the marker-ejection point and the optical probe position by the time it took the marker to move that distance.

Apparatus and methods for determining velocity of oil in a flow stream

Single point optical probes for measuring three-phase characteristics of fluid flow in a hydrocarbon well and methods of processing signals generated by the probe are disclosed. A single fiber optic probe is coupled to a light source and apparatus for detecting reflectance and fluorescence. Light is delivered to the tip of the probe where it exits the probe and illuminates the liquid ambient the probe tip or is internally reflected in the probe when gas is located at the probe tip. If the fluid at the probe tip is oil, the light exits the probe, illuminates the oil, and causes the oil to fluoresce. According to one signal processing method of the invention, the reflectance signal is binarized at a threshold to provide a gas/liquid quasi-binary signal which changes over time. A time fraction of the signal values is used to calculate the gas holdup. According to other signal processing methods of the invention, the fluorescence indication signal is processed by taking its derivative (and if desired a second derivative) to determine the 'corners' of the fluorescence signal over time. The derivative signal exhibits a positive and a negative peak which are separated by time. The time between the peaks is used to calculate oil holdup and the amplitude of one of the peaks is used to calculate the velocity of the oil drop.

Methods and apparatus utilizing a derivative of a fluorescene signal for

A method for producing, in a hydrocarbon well, a signal indicative of a local flow parameter of a multiphase fluid, includes the steps of placing at least one local sensor in the fluid and producing a signal whose level is characteristic of the phase in which the sensor is immersed, the signal being generated at a spike whose radius of curvature is less than 100 microns. The method is applicable to determining hold-ups of different phases of the fluid.

Method and apparatus for locally measuring flow parameters of a

Characteristics of invasion profiles exhibiting effects of gravity, and particularly their manifestations on resistivity logs of a plurality of different radial depths of investigation, are used to determine formation characteristics, including vertical permeability. One embodiment includes the following steps: suspending a logging tool in the borehole; producing a plurality of resistivity measurements, having respectively different radial depths of investigation, as the logging device is moved through the borehole, to obtain a plurality of resistivity logs; determining the presence of a buoyancy marker in the resistivity logs in a formation bed invaded with filtrate from the drilling mud, and the extent of the buoyancy marker; and determining permeability of the formations as a function of the extent of the buoyancy marker.

Method and apparatus for determining permeability of subsurface

A borehole tool having adjacently located fluid injection/withdrawal apparatus and an electromagnetic measurement apparatus is provided. The electromagnetic measurement apparatus can be an imaging apparatus for helping set the tool in desired locations for permeability testing via fluid injection or withdrawal. In a second mode, during fluid injection or withdrawal, and if desired, before and/or after injection or withdrawal, a plurality of electromagnetic measurements (images) are made. Based on the electromagnetic and hydraulic measurements, and a model which interrelates the measurements, determinations are made as to various characteristics of the formation, including effective permeabilities. Related methods for utilizing the tool and for treating the data in an integrated fashion are also set forth.

Integrated permeability measurement and resistivity imaging tool

Apparatus for obtaining horizontal and/or vertical permeability measurements through a probe having an elongate aperture. The invention uses the elongate aperture in the probe to orient fluid flow in an earth formation horizontally or vertically. The elongate aperture is approximated through the use of a single elongate opening or through the use of a group of aligned openings of varying shapes. Measurements can be taken at different orientations by including additional probe openings along more than one axis.

Apparatus for determining horizontal and/or vertical permeability of an

Fluid flow measurements are made in situ using a repeat formation tester with a modified probe aperture, or on rock samples using a mini-permeameter with a modified probe aperture. The modified probe aperture has an elongate cross-section, such as elliptic or rectangular. A first flow measurement is made with the longer dimension of the probe aperture in a first orientation (e.g., horizontal or vertical) with respect to the formation bedding planes. A second flow measurement is made with the probe aperture orthogonal to the first orientation, or with a probe aperture of non-elongate (e.g., circular) cross-section. Simultaneous equations relating values of known and measured quantities are solved to obtain estimates of local horizontal and/or vertical formation permeability.

Determining horizontal and/or vertical permeability of an earth formation

Pressure and flow measurements made during extraction of fluid samples from a subsurface earth formation using a borehole logging tool having a single extraction probe are analyzed to derive separate values for both horizontal and vertical formation permeability. Build-up measurements are used to derive the slope of variation of formation pressure with respect to a spherical time function, and this value is incorporated in an expression for a dimensionless variable relating pressure, flowrate, porosity, compressibility and probe radius. The resulting value of the dimensionless constant provides an index into a look-up table obtained by a new analysis of the fluid dynamics in the immediate vicinity of the probe for an anisotropic formation. The table gives values for two or more dimensionless variables from which the permeability values are derived.

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Ridgefield, CT, United States of America

Elizabeth B Dussan V