Communications: directive radio wave systems and devices (e.g. – Determining distance – Material level within container
Reexamination Certificate
2001-09-14
2003-11-18
Lobo, Ian J. (Department: 3662)
Communications: directive radio wave systems and devices (e.g.,
Determining distance
Material level within container
C367S099000, C073S29000R, C073S29000R, C073S152290, C073S152310, C073S152320
Reexamination Certificate
active
06650280
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates generally to fluid measurements and, more specifically, to a fluid measurement system that may be utilized for making mass measurements during fluid flow. The present invention also has application in reduced and zero gravity environments and for finding discontinuities in an otherwise homogeneous material.
2. Background of the Invention
It is well known that when drilling wells for hydrocarbons, a standard drilling practice involves circulating drilling fluid from the surface downwardly through the drilling string. The drilling fluid emerges at the drill bit and returns to the surface through the annulus in the wellbore on the outside of the drilling string. The drilling fluid performs many functions, some of which are discussed herein. The drilling fluid cools and reduces friction of rotating the drilling string. The drilling fluid removes excavated material from the wellbore in the circulation stream flowing to the surface. The drilling fluid is preferably weighted so that a downhole hydrostatic force is created adjacent to hydrocarbon bearing formations, which is greater than the internal pressure within the hydrocarbon bearing if formations. Thus, by adjusting the weight of the drilling fluid with suitable weighting material, blowouts are prevented during the drilling process.
However, due to various conditions downhole, problems may occur with the circulation. For instance, drilling may occur into a lost circulation zone whereby the lost circulation zone, such as a downhole cavern, absorbs a portion of the drilling fluid, thereby reducing the hydrostatic pressure and increasing the potential for a blowout. As another example, drilling may occur into an unanticipated high pressure zone whereby gas bubbles begin to push the drilling fluid out of the wellbore at a higher rate than fluid is pumped into the wellbore thereby reducing the hydrostatic pressure and increasing the potential for a blowout. Surface blowout preventors can be activated to prevent blowouts, but it is highly desirable to have some early warning of impending circulation problems so that suitable pressure control steps can be taken before a blowout actually occurs. It would also be desirable to monitor the drilling fluid density and/or flow rates and/or instantaneous mass in real time with very high accuracy for use in adjusting drilling weights, evaluating formation cuttings, determining changes in drilling such as entry into new formation layers, evaluating drill bit performance in terms of excavated material, and the like, as well as providing early warnings of impending circulation problems.
The following patents listed herein disclose various attempts by previous inventors to solve problems which may be related to the above:
U.S. Pat. No. 4,268,282, issued May 19, 1981, to Cribbs et al., discloses a microwave radar system which employs heterodyned swept frequency at approximately two millisecond sweep intervals. The power source is a reliable solid state, low power device such as a Gunn diode. The heterodyned difference frequency signals are converted to digital form, transformed into the frequency domain by means of a Fourier power transform, and then averaged by computer processing. Performing the Fourier power transform before averaging enables the processing of quasi-incoherent data whereby signal-to-noise ratio improvement is a function of the square root of the average number of samples taken. High-speed processing is used to offset the loss of statistical averaging of phase-coherent data which cannot be preserved because of target motion. Thus, the sequence of the power transform allows phase-less averaging over the entire collection period. Complementary elements including signal isolation and stability, through interdependent design features of the antenna and circulator, permit the use of low-power CW radar which minimizes danger to ecology and human safety. Thus, the invention has particular applicability to the analysis of clouds, the extraction of range and thickness data of clouds, and the presence and velocity of rainfall. The invention can be used for point targets as well. Algorithms are built into the computer to compensate for various factors such as wind, temperature, and the nature of scattering nuclei.
U.S. Pat. No. 4,732,035, issued Mar. 22, 1988, to Lagergren et al., discloses a method and apparatus for substantially eliminating measuring inaccuracies in a storage tank leak detection system caused by temperature-induced volumetric changes in the stored fluid product. In a preferred embodiment of the method, a limp bladder is connected to an end of a pressure tube having an inlet and a substantially hollow core. The pressure tube and the bladder are filled with a medium having a temperature coefficient substantially lower than the temperature coefficient of the fluid product. The pressure tube and the bladder are then supported in a substantially vertical manner in the storage tank such that a first portion of the medium is supported in the bladder in static equilibrium with respect to a second portion of the medium supported in the pressure tube. The large disparity between the temperature coefficients of the medium and the fluid product insures that temperature-induced volumetric changes in the fluid product do not vary the level of the medium in the pressure tube. Accordingly, variations in the medium level in the tube represent a true indication of leakage of the fluid product out of the storage tank or leakage of a foreign product into the storage tank.
U.S. Pat. No. 4,847,623, issued Jul. 11, 1989, to Jean et al., discloses a sweep frequency, continuous wave radar tank gauge providing measurement of the level of tank contents or ullage, having greatly improved accuracy through improved methods of processing calibrate and return signals directed toward the surface of tank contents. Use of sweep synchronous measurement of time domain calibrate/return difference signals and time domain of a virtual “carrier” fundamental in the frequency domain, provide highly accurate measure of tank signal return times. The entire range of return signals is made available for processing and analysis, including distinguishable tank bottom reflections.
U.S. Pat. No. 4,991,124, issued Feb. 5, 1991, to Bruce R. Kline, discloses a method and system that determines the density of a liquid, such as aircraft fuel, by measuring the amplitude of the reflections of ultrasonic pulses from the faces of the walls of a reference material. A transducer is used to transmit an ultrasonic interrogation pulse through a liquid to the reference material. The density of the reference material is known, and its boundaries are well defined. The interrogation pulse is reflected from the faces of the reference material boundaries to provide first, second and third return pulses that can be used to determine the density of the liquid. The density determination is accomplished by determining characteristic impedances, reflection coefficients and transmission coefficients as a function of the returned pulse amplitudes.
U.S. Pat. No. 5,198,989, issued Mar. 30, 1993, to Alan M. Petroff, discloses a sewer flow monitoring system wherein the volume of flow is determined from the depth of fluid in a pipe together with the average velocity of flow through the pipe as determined by detecting the peak velocity from particles flowing in sewage at different velocities and then determining average velocity to be approximately 90% of the peak velocity.
U.S. Pat. No. 5,233,352, issued Aug. 3, 1993, to Thomas C. Cournane, discloses a generation of a first and second identical pseudo-random binary sequences. The second sequence is delayed in a variable delay arrangement, and a reflected first sequence is compared with a delayed second sequence. The second sequence is delayed until the reflected sequence and the delayed sequence are coincident. The delay of the adjustable delay is equal to the travel time of the first sequence.
U.S. Pat. No. 5,315,880,
Arndt G. Dickey
Byerly Kent A.
Carl James R.
Ngo Phong H.
Lobo Ian J.
Ro Theodore U.
The United States of America as represented by the Administrator
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