Communications: electrical – Wellbore telemetering or control – Using a specific transmission medium
Reexamination Certificate
1999-04-06
2001-12-25
Horabik, Michael (Department: 2735)
Communications: electrical
Wellbore telemetering or control
Using a specific transmission medium
C340S870030, C340S572700, C340S539230, C166S254200, C166S255100, C705S065000, C342S042000
Reexamination Certificate
active
06333699
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates generally to devices for detecting intermediate points within wells, gas and oil pipelines, and the like, and more specifically to a system using radio frequency resonant devices installed at various points in the well or pipe. A detector is inserted into the pipe, and detects the resonant devices where installed to transmit location or depth and other information back to a station at the surface or along the pipe. The present invention may provide for the storage of the information gathered for downloading upon retrieval of the device from the well or pipe.
2. Description of the Related Art
The need for accurate measurement of the depth of a drilled well is critical, as oftentimes the stratum of interest in the well, resides within a relatively narrow band. Wells are typically cased after drilling, with cement being poured between the casing and the wall of the drilled hole in order to seal and stabilize the hole. The casing and cement are perforated at the desired depth in order to access the stratum of interest (oil bearing deposits, gas, water, etc.), with the casing and cement serving to prevent the flow and mixing of undesired fluids with the fluid of interest from the well (e.g., water with oil, etc.).
In view of the above, it is critical that the well be perforated at precisely the proper depth in order to avoid drawing an undesirable fluid into the well, and/or missing the desired stratum of interest in the well. As wells typically extend from a few to several thousand feet below the surface in the case of oil and gas wells, the precise measurement of the depth of the well to within a few feet, poses a difficult problem. U.S. Pat. No. 5,279,366 provides an excellent and detailed discussion of the problem in the Background of the Invention, columns 1 through 4, for further background.
Accordingly, numerous devices and systems have been developed in the past for logging or measuring the precise depth of the well, for perforating the well or for other purposes as required. Such principles as MRI (magnetic resonance imaging), gamma ray detection, and others, have been utilized in order to enable a detector lowered into the well casing to determine its position or depth within the hole. However, none of the systems or principles utilized in the past, provide the needed accuracy to enable an operator to determine precisely the depth of the tool within the hole. It is very easy for the well to be logged incorrectly, or for the tool to detect the wrong joint or point in the casing, and thus throw off all calculations and measurements accordingly. As the conventional well casing pipe has a length of some thirty feet, it will be seen that an error in the detection of one joint location, could cause a perforating gun or other tool to miss the stratum of interest completely.
Those skilled in the art are aware that the limitations of the prior art extend to other types of pipelines and the like, and are not limited only to generally vertical well bores. For example, the standard procedure for examining a cross-country oil, gas, or other pipeline, is to “pig” the line, i.e., send a mechanical device (called a “pig”) through the line, generally by pneumatic means. The “pig” may sense various information relating to the condition of the line, or other factors, which information may be stored within the device until it is recovered at some point in the line. However, any flaws or other problems in the line must be identified as to location, and the mechanical “pigs” used for such operations have no means of determining their position in the line. Rather, their location must be detected externally, by a worker stationed along the pipe or line as the “pig” travels through the line, and who logs the passage of the “pig” at various points along the line, relative to time. By knowing the time that any information was gathered in the pipe, and the time of passage of the “pig” at various points, the location of any anomalies may be indirectly determined.
However, it will be seen that it can be difficult to determine the precise location of various anomalies or other points of interest in such a pipeline, as the detection of the passage of the “pig” through the line, is determined at only a relatively few widely separated points along the line. Thus, when the record of the recovered “pig” is examined, it may not be possible to narrow the location of some point of interest in the line, to an area smaller than perhaps a few hundred feet of pipeline, or perhaps more.
Accordingly, a need will be seen for a system which positively identifies the location or depth of a well tool at various points within the well. The system comprises a plurality of passive or active radio frequency resonant devices, which are installed at several, or all, of the joints in the well casing. Each of the devices is preferably constructed or tuned to provide a unique individual signal. A well tool is provided which transmits a low power and/or directional signal on an appropriate frequency for reception by the devices, which then resonate to provide a responding signal to the well tool. The responding signal passes up the wire line to the well operator at the surface, who is able to determine precisely the location or depth of the well tool in the well. Alternatively, the information may be stored within the downhole tool, for downloading into a computer or other suitable reading device at the surface, after recovery of the tool.
A further need will be seen for a system which is capable of positively identifying the location of a tool which is passed through a pipeline or the like, and recording the location corresponding to the tool at various points in time as the tool passes through the pipeline. The system may utilize active or passive radio frequency resonant devices, with information being stored within the pipeline tool for later recovery when the tool is recovered from the line.
A discussion of the related art of which the present inventor is aware, and its differences and distinctions from the present invention, is provided below.
U.S. Pat. No. 4,572,293 issued on Feb. 25, 1986 to James G. Wilson et al., titled “Method Of Placing Magnetic Markers On Collarless Cased Wellbores,” describes the magnetic polarizing of well casing by positioning one or more electromagnets within the casing, and activating the electromagnets to impart a permanent magnetic field at the location of the electromagnet(s) within the casing or pipe. The magnetically polarized area may be detected using a conventional magnetic reading casing collar locator. The Wilson et al. method does not provide any means of differentiating between magnetically marked spots, nor of precisely positioning the magnetically polarized areas at predetermined points in the casing. Moreover, Wilson et al. do not disclose any means of logging or determining the position of a device in a cross country or other fluid pipeline, as provided by the present method and apparatus.
U.S. Pat. No. 4,630,044 issued on Dec. 16, 1986 to Rudolf Polzer, titled “Programmable Inductively Coupled Transponder,” describes a passive radio identification device (PRID) including a memory for modulating the response signal when triggered by an appropriate transmitter. Polzer describes the placement of the resonating transponder on a moving object, e.g., a railroad car, with the triggering transmitter having a stationary mounting. This configuration is precisely the opposite of the present invention, with its stationary responding devices and triggering transmitter being mounted within a moving well hole or pipeline “pigging” tool. Moreover, Polzer makes no suggestion of using his invention for determining depth or other characteristics in a well casing or other fluid pipeline, as provided by the present invention.
U.S. Pat. No. 4,808,925 issued on Feb. 28, 1989 to Gary K. Baird, titled “Three Magnet Casing Collar Locator,” describes a magnetic device for detecting pipe or casing joints in a well. The dev
Ebel Jack E.
Horabik Michael
Marathon Oil Company
Wong Albert K.
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