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Abstract Production logging denotes that area of well logging concerned with two general goals:problem well diagnosis, and
reservoir surveillance.
problem well diagnosis, and (2) reservoir surveillance. The purpose of logging is to track fluid movement within or behind pipe or to monitor the movement of reservoir fluid contacts. The logs have been, traditionally, tools of the workover or subsurface engineer and the reservoir engineer. However, with the increasing hazards of drilling, the logs are becoming of vital importance to the drilling engineer. In many areas of the world, a suite of production logs are obtained before a particular well is even perforated for production. This is especially perforated for production. This is especially important for wells drilled within or near producing fields. Successful completions through strata producing fields. Successful completions through strata with unequal pressures are difficult.
Because of the increasing importance of production logs, a survey of the subject is appropriate. production logs, a survey of the subject is appropriate. In this paper, we review how the various logging tools work, what they measure, and how these measurements are related to flow. By example logs, we wish to illustrate three important points. First, production logs should be run in suites of production logs should be run in suites of complementing devices. Seldom does one log alone give satisfactory answers to a particular problem. Second, the subtle features, rather than the obvious anomalies, of a particular log often contain the desired information. Finally, production logging evolution has only recently turned in a direction of attempting to deal with multiphase flow of gases and liquids at low rates. As a result, the technology in this area is still insufficient.
Introduction Historically, the term "production log" was used to designate a well log run after a well had been placed on production. However, in modern usage, the term has come to mean any borehole survey used as an aid to either eliminating or assisting production. Traditionally, it has been the need to eliminate an unwanted flow that has spurred the growth of production logging. For a well being drilled, this flow is usually the result of premature entry into the wellbore of oil, gas, or water due to either mud pressure loss from fracturing and flow into a weak formation or to abnormally high fluid pressure within the pore space of a formation. With drill pipe in the hole, the logging device must be capable of detecting flow in the annular space between the pipe and the wellbore. For wells on production, the unwanted flow is most likely to be a water flow accompanying the hydrocarbon. This water may originate in the completed interval or it may channel behind pipe into the perforations from another formation or it may enter the wellbore through holes in the casing. The logging sonde should therefore respond to flow either within or behind pipe. Finally, for injection wells, the unwanted flow would be that part of the injection which is lost by leaks to zones other than the designated injection zones. Again, the unwanted flow can be within or behind pipe.
By the early 1940s, downhole recording thermometers were in use to track the type of flows described above. During the 1940s, downhole recording pressure gauges and flow meters were added to thermometers as production logging devices. The disadvantage of not knowing the survey results until the device was retrieved from the well became quickly apparent. The late 1940s and early 1950s saw the development of surface indicating thermometers, flow meters, and pressure gauges. Production logging subsequently became a part of the repertoire of service companies part of the repertoire of service companies established in the field of open hole logging. Because of the difficulty and hazard of running an electric logging cable into a well against pressure, the downhole recording devices run on small, solid wire lines - remained in wide- spread use. The introduction of grease injection control heads in the early 1960s resolved most of the pressure difficulties. We shall therefore discuss only those logging devices that are surface recording.
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