The truck carries the downhole measurement in The main winch contains up to 30, ft of seven-conductor logging cable; the optional small winch at the rear contains 24, ft of slim monoconductor cable for servicing producing wells under pressure. Data acquisition and computer equipment are inside the logging cab.
For offshore-remote locations, the cab and winch assemblies are mounted on a skid. The downhole measurement instruments are usually composed of two components. One component contains the sensors used in making the measurement, called the sonde. The type of sensor depends, of course, upon the nature of the measurement. Resistivity sensors use electrodes or coils; acoustic sensors use transducers; radioactivity sensors use detectors sensitive to radioactivity; etc.
The other component of the downhole tool is the cartridge. The cartridge contains the electronics that power the sensors, process the resulting measurement signals, and transmit the signals up the cable to the truck. The cartridge may be a separate component screwed to the sonde to form the total tool, or it may be combined with the sensors into a single tool. That depends, of course, upon how much space the sensors and electronics require and the sensor requirements. The cartridge housing is usually made of steel. Today, most logging tools are readily combinable.
In other words, the sondes and cartridges of several tools can be connected to form one tool and thereby make many measurements and logs on a single descent into and ascent from the borehole. The downhole tool or tools is attached to an electrical cable that is used to lower the tool into and remove from the well. Most cable used in openhole logging today con New cable developments include a fiber optics conductor in the center of six copper conductors. The cable is wrapped with a steel armor to give it the strength to support the tool weight and provide some strength to pull on the tool in case it becomes stuck in the borehole.
The cable and tools are run in and out of the borehole by means of a unit-mounted winch. Well depths are measured with a calibratedmeasuring wheel system. Logs are normally recorded during the ascent from the well to assure a taunt cable and better depth control. Signal transmission over the cable may be in analog or digital form; modern trends favor digital.
The cable is also used, of course, to transmit the electrical power from the surface to the downhole tools. The surface instrumentation Fig. The desired signals are output to magnetic tape in digital form and to a cathoderay tube and photographic film in analytical form.
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The photographic film is processed on the unit, and paper prints are made from the film. This continuous recording of the downhole measurement signals is referred to as the log. Table 1 Data rate transmission tools. M-The CSU is a computer-based integrated data acquisition and processing system. The main elements areRight: a video data display and optical film units to record data. Wireline-logging technology is being changed by the rapid advancements in digital electronics and data-handling methods. These new concepts have changed our thinking about existing logging techniques and remolded our ideas about the direction of future developments.
Affected are the sensors, the downhole electronics, the cable, the cable telemetry, and the signal processing at the surface. Basic logging measurements may contain large amounts of information. In the past, some of this data was not recorded because of the lack of high data-rate sensors and electronics downhole, the inability to transmit the data up the cable, and inability to record it in the logging unit. Similarly, those limitations have prevented or delayed the introduction of some new logging measurements and tools.
With digital telemefry, there has been a tremendous increase in the data rate that can be handled by the logging cable.
Digital recording techniques within the logging unit provide a substantial increase in recording capability. The use of digitized signals also facilitates the transmission of log signals by radio, satellite, or telephone line to computing centers or base offices. In Table l-1 the data rate for one of the older tool systems, the induction-sonic combination, is contrasted with the data-rate transmission requirements for some of the newer tools.
It illustrates the tremendous increase in. Signal processing can be performed at at least three levels: downhole in the tool, uphole in the truck, and at a central computing center. Where the processing is done depends on where the desired results can most efficiently be produced, where the extracted information is first needed, where the background expertise exists, or where technological considerations dictate. Where it seems desirable, the logging tool is designed so that the data are processed downhole and the processed signal is transmitted to the surface. This is the case when little future use is envisioned for the raw data or when the amount of raw data precludes its transmission.
In most cases, however, it is desirable to bring measured raw data to the surface for recording and processing. The original data are thus available for any further processing or display purposes and are permanently preserved for future use. The system provides the capability to handle large amounts of data. It overcomes many of the past limitations of combination logging systems the stacking or combination of many measurement sensors into a single logging tool string.
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It also ex Tool calibration is performed much more quickly and accurately, and tool operation is more efficiently and effectively controlled. The CSU system provides the obvious potential for wellsite processing of data.
Processing of sonic waveforms for compressional and shear velocities is already being done, as is the processing of nuclear energy spectra for elemental composition and, then, chemical composition. More sophisticated deconvolution and signal filtering schemes are practical with the CSU system. Nearly all the common log interpretation models and equations are executable on the CSU unit. Although not quite as sophisticated as the log interpretation programs available in computing centers, the wellsite interpretation programs significantly exceed what can be done manually.
Wellsite programs exist to determine porosity and saturations in simple and complex lithology, to identify lithology, to calculate formation dip, to calculate permeablity, and to determine many more petrophysical parameters. In addition, data whether recorded, processed, or computed can be reformatted in the form most appropriate for the user. The demand for wellsite formation evaluation processing will undoubtedly increase and programs will become more sophisticated.
The computing center offers a more powerful computer, expert log analysts, more time, and the integration of more data. Schlumberger computing centers are located in major oil centers throughout the world. They provide more sophisticated signal processing and formation analysis than the wellsite CSU system. Statistical techniques can be employed more extensively, both in the selection of parameters and in the actual computations. Log processing seems to be moving more and more toward integrated treatment of all log measurements simultaneously. Programs are being designed to recognize that the log parameters of a given volume of rock are interrelated in predictable ways, and these relationships are given attention during processing.
New programs can now use data from more sources, such as cores, pressure and production testing, and reservoir modeling. The CSU system is able to transmit logs with a suitable communication link. The receiving station can be another CSU system, a transmission terminal, or a central computing center.
Data can be edited or reformatted before transmission to reduce the transmission time or to tailor the data to the recipient. Built-in checks on the transmission quality ensure the reliability of the transmitted information. This service is available in the continental U. Virtually any telephone is a possible receiving station. Since the system is two way, offset logs or computed logs can be trammitted back to the wellsite.
The system also provides normal two-way voice communication.2018.ugmek.ru/includes/ma-zithromax-azithromycin.php
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There are several receiving station options: A standard digital FAX machine will receive log graphic data directly at the office. Since this station is automatic, it can receive data unattended. A complete library of environmental corrections as well as the entire range of Schlunberger advanced answer products are available with this new workstation. All data are encrypted to provide security while transmitting over the airways.
In some instances, transmission from the wellsite is possible. In others, transmission must originate from a more permanent communication station. With some preplanning, it is possible to transmit log data from nearly any point in the world to another. Schlumberger, C. Doll, E. Stratton, E. DeChambrier, P. April 18, No. Allaud, L. Pontecorvo, B. Tittle, C.
April 16, No. Russell, J. April Bush, R. Russell, W. Wyllie, M. April 17, No. Allen, L. Alger, R.
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