Boring or penetrating the earth – With signaling – indicating – testing or measuring – Ray energy detection or measuring
Reexamination Certificate
2001-10-26
2003-11-18
Bagnell, David (Department: 3672)
Boring or penetrating the earth
With signaling, indicating, testing or measuring
Ray energy detection or measuring
C250S254000, C250S269400, C073S152040
Reexamination Certificate
active
06648083
ABSTRACT:
BACKGROUND OF INVENTION
1. Field of the Invention
The invention relates generally to exploration and production, and more particularly, to a method and apparatus for monitoring the properties of the borehole fluid.
2. Description of Related Art
The characteristics of geological formations are of significant interest in the exploration for and production of subsurface mineral deposits, such as oil and gas. Many characteristics, such as the hydrocarbon volume, porosity, lithology, and permeability of a formation, may be deduced from certain measurable quantities. Among these quantities are the density, neutron porosity, photoelectric factor, hydrogen index, salinity, and thermal neutron capture cross section (sigma). The quantities are typically measured by logging-while-drilling (“LWD”) and wireline tools. The tool carries one or more sources that radiate energy into the formation and detectors that sense the result of the radiation. These detectors either transmit the data back uphole or temporarily store it downhole. Typically, once uphole, the data is input to one or more formation evaluation models, which are typically software programs used to evaluate the geological formation from which the data was gathered.
In addition to the formation, the fluids in the borehole are also of interest, both intrinsically and for their effect on the measurements directed at formation evaluation. Currently, the borehole fluid (“drilling mud” or “mud”) is typically characterized at the surface and its properties are extrapolated to conditions downhole. Factors such as temperature, pressure, and mud composition can vary in both space and time along the borehole. In addition, new mud formulations are continually evolving in the industry.
U.S. Pat. No. 3,688,115, issued to Antkiw, discloses a fluid density measuring device for use in producing oil wells. Density is determined by forcing the well fluid to pass through a chamber in the device. The fluid attenuates a beam of gamma radiation that traverses the chamber, the relative changes in the beam intensity providing a measure of the density in question.
U.S. Pat. No. 4,412,130, issued to Winters, discloses an apparatus for use within a well for indicating the difference in densities between two well fluids. The apparatus, for use with measurement-while-drilling (MWD) systems, is formed within a drill collar with a source of radiation removably disposed in a wall of the drill collar. At least two radiation detectors are located equidistant from the source of radiation with one detector adjacent an interior central bore through the drill collar and a second detector is adjacent the exterior of the drill collar. Two fluid sample chambers are spaced between the source of radiation and the detectors, respectively; one chamber for diverting fluid from the bore and the other chamber for diverting fluid from the annular space between the drill bore and the drill collar. Suitable circuitry is connected to the detectors for producing a differential signal substantially proportional to the difference in radiation received at the two detectors. The difference in the density between fluid passing through the drill collar and returning through the annular space is detected and indicated by the apparatus for early detection and prevention of blowouts.
U.S. Pat. No. 4,492,865, issued to Murphy et al., discloses a system for detecting changes in drilling fluid density downhole during a drilling operation that includes a radiation source and detector which are arranged in the outer wall of a drill string sub to measure the density of drilling fluids passing between the source and detector. Radiation counts detected downhole are transmitted to the surface by telemetry methods or recorded downhole, where such counts are analyzed to determine the occurrence of fluid influx into the drilling fluid from earth formations. Changes in the density of the mud downhole may indicate the influx of formation fluids into the borehole. Such changes in influx are determinative of formation parameters including surpressures which may lead to the encountering of gas kicks in the borehole. Gas kicks may potentially result in blowouts, which of course are to be avoided if possible. Hydrocarbon shows may also be indicative of producible formation fluids. The radiation source and detector in one embodiment of the system are arranged in the wall of the drill string sub to provide a direct in-line transmission of gamma rays through the drilling fluid.
U.S. Pat. No. 4,698,501, issued to Paske et al., discloses a system for logging subterranean formations for the determination of formation density by using gamma radiation. Gamma ray source and detection means are disposed within a housing adapted for positioning within a borehole for the emission and detection of gamma rays propagating through earth formations and borehole drilling fluid. The gamma ray detection means comprises first and second gamma radiation sensors geometrically disposed within the housing the same longitudinal distance from the gamma ray source and diametrically opposed in a common plane. A formation matrix density output signal is produced in proportion to the output signal from each of the gamma ray sensors and in conjunction with certain constants established by the geometrical configuration of the sensors relative to the gamma ray source and the borehole diameter. Formation density is determined without regard to the radial position of the logging probe within the borehole in a measuring while drilling mode.
U.S. Pat. No. 5,144,126, issued to Perry et al., discloses an apparatus for nuclear logging. Nuclear detectors and electronic components are all mounted in chambers within the sub wall with covers being removably attached to the chambers. A single bus for delivering both power and signals extends through the sub wall between either end of the tool. This bus terminates at a modular ring connector positioned on each tool end. This tool construction (including sub wall mounted sensors and electronics, single power and signal bus, and ring connectors) is also well suited for other formation evaluation tools used in measurement-while-drilling applications.
U.S. Pat. No. 5,469,736, issued to Moake., discloses a caliper apparatus and a method for measuring the diameter of a borehole, and the standoff of a drilling tool from the walls of a borehole during a drilling operation. The apparatus includes three or more sensors, such as acoustic transducers arranged circumferentially around a downhole tool or drill collar. The transducers transmit ultrasonic signals to the borehole wall through the drilling fluid surrounding the drillstring and receive reflected signals back from the wall. Travel times for these signals are used to calculate standoff data for each transducer. The standoff measurements may be used to calculate the diameter of the borehole, the eccentricity of the tool in the borehole, and the angle of eccentricity with respect to the transducer position. The eccentricity and angle computations may be used to detect unusual movements of the drillstring in the borehole, such as sticking, banging, and whirling.
U.S. Pat. No. 5,473,158, issued to Holenka et al., discloses a method and apparatus for measuring formation characteristics as a function of angular distance sectors about the borehole. The measurement apparatus includes a logging while drilling tool which turns in the borehole while drilling. Such characteristics as bulk density, photoelectric effect (PEF), neutron porosity and ultrasonic standoff are all measured as a function of such angular distance sectors where one of such sectors is defined to include that portion of a “down” or earth's gravity vector which is in a radial cross sectional plane of the tool. The measurement is accomplished with either a generally cylindrical tool which generally touches a down or bottom portion of the borehole while the tool rotates in an inclined borehole or with a tool centered by stabilizer blades in the borehole.
U.S. Pat. No. 6,032,102, issued to Wijeyes
Adolph Robert A
Evans Michael
Radtke Richard J
Sloan W Robert
Bagnell David
Jeffery Brigitte L.
Ryberg John
Schlumberger Technology Corporation
Segura Victor H.
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