Abstract: A method is disclosed for operating a well logging tool having a controllable radiation source operatively coupled to a power source. The method includes monitoring at least one condition in a wellbore, and operatively disconnecting the power source from the radiation source when the at least one condition changes. Also disclosed is a downhole measurement assembly, which includes a radiation source, a power source, and at least one interlock operatively connected between the power source and the radiation source, where the at least one interlock is adapted to selectively arm and disarm the radiation source.

Abstract: A method is disclosed for measuring neutron interaction properties of an earth formation. The method includes irradiating the formation with bursts of high energy neutrons. The bursts have a duration selected to enable detection of short duration burst related phenomena. After at least one of the bursts, short duration burst related phenomena are measured. After a selected number of the bursts, long duration neutron burst-related phenomena are detected. In some embodiments, the short duration burst related phenomena include at least one of inelastic gamma ray related phenomena, neutron slowing down related phenomena and short capture cross section related phenomena.

Abstract: This invention provides a method and an apparatus for fiber optic tomographic analysis and imaging of fluids. This invention includes a method for providing information on downhole fluid flowing in a hydrocarbon well, utilizing at least one downhole tomograph chamber (10). Light is introduced into the tomograph chamber (10) by an optical fiber bundle (24), and portions of the light are collected in other optical fiber bundles (32, 34). The collected portions of light are conveyed through the optical fiber bundles (32, 34) to a surface system (14), where the light is detected to produce signals proportional to the portions of light to provide information on optical properties of downhole fluid flowing in the well. This invention allows the generation of two or three dimensional images of multiple phase flow in the wellbore and allows determination of production parameters of multiple zones on an individual zone basis.

Abstract: A method and apparatus is provided for determining a quality of downhole fluid. A series of measurements are taken of at least one parameter of borehole fluid that is indicative of OBM filtrate contamination. By curve-fitting, the series of the measured parameter values are used to create an asymptotic curve indicative of the quality of the downhole fluid. One embodiment determines OBM filtrate fraction in a borehole fluid sample. One embodiment is used when there is significant difference between the coloration of formation fluid and the coloration of OBM filtrate. Another is used when there is little or no difference between the coloration of formation fluid and the coloration of OBM filtrate. Another determines GOR of formation fluid corrected for OBM filtrate contamination. Another determines OD of formation fluid corrected for OBM filtrate contamination. Another determines conditions that would render optical density measurements invalid and sample capture premature.

Abstract: A sealed tube neutron generator (&agr;-STNG) incorporates an internal associated-&agr; detector for well logging. The &agr;-STNG comprises a gas-tight envelope, a Penning ion source, a gas supply, an accelerating electrode and a target as those in conventional STNG; and further comprises a special target chamber, an ion leading out and focusing assembly, an annular associated -&agr; particle detector mounted in the target chamber, a gas absorber, and a collimator for &agr;-particles. The &agr;-STNG can be employed within a nuclear Carbon/Oxygen Well Logging Apparatus which adopts the Associated Particle and Time of Flight Approach for collecting data to satisfy the special requirements of well logging, to expel the adverse effect resulted from cased hole materials and thermal neutrons capture for increasing the precision of carbon/oxygen ratio logged. When the carbon window is 3.17 to 4.65 Mev and the oxygen window is 4.68 to 6.

Abstract: A system for measuring the size of a borehole penetrating an earth formation is disclosed. The system uses a neutron source and a least one neutron detector. The neutron detector responds primarily to the composite hydrogen content of material within the borehole and formation upon irradiation by the neutron source. A partition response function is used to delineate the portion of the detector response resulting from borehole and from the formation. Since the detector response from the borehole can be isolated using the partition function and the hydrogen content of the borehole fluid is generally known, the size of the borehole can be determined from borehole response portion of the composite detector response if combined with a neutron porosity measurement of the formation. The neutron porosity measurement can be obtained independently, or by combining the neutron detector response with the response of a second neutron detector at a different axial spacing from the neutron source.

Abstract: A method and apparatus is provided for determining OBM filtrate fraction in a downhole fluid sample. One embodiment of the method is used when there is significant difference between the coloration of formation fluid and the coloration of OBM filtrate. Another is used when there is little or no difference between the coloration of formation fluid and the coloration of OBM filtrate. Another determines GOR of formation fluid corrected for OBM filtrate contamination. Another determines OD of formation fluid corrected for OBM filtrate contamination. Another determines conditions that would render optical density measurements invalid and sample capture premature. Another predicts the reduction of filtrate fraction for a specific extended pumping time. Another initiates sample capture when computed contamination fraction exhibits stable asymptotic convergence.

Abstract: Methods and apparatuses for investigating formations surrounding a borehole involve acquiring a fluorescent signal over a portion of the borehole and analyzing the signal to detect the presence of crude oil. Analyzing the signal to detect the presence of crude oil may involve distinguishing mineral fluorescence from oil fluorescence. The signal may be analyzed further to distinguish characteristics of the crude oil, such as its grade (light, medium or heavy), and to indicate a physical property correlated with the fluorescence, such as the presence of laminations or formation permeability. In some embodiments, fluorescence signals from illuminating the portion of the borehole with at least two different wavelengths of light are analyzed.

Abstract: The invention relates to a flow section for measurements concerning oil well effluent, the section comprising a pipe in parallel with a pipe connected to the well head. The flow section includes elements of material having low attenuation for gamma rays fixed in recesses formed in the wall of the pipe on its inside, and protection members disposed in housings connecting said recesses respectively to the outside, said housings being suitable for receiving gamma ray attenuation measuring means after the protection members have been removed.