![]() Borehole fluid-density or fluid-capacitance surveysĮach of these tools responds to fluid velocity or fluid type.The logs frequently used for such flow diagnosis and allocation include: Includes tools used to track movement of fluid either inside or immediately outside the casing of a well. Diagnose production problems and allocate production.Effective interpretation of the data from each type of log requires significant education and experience. This approach leads to the five distinct categories listed below that also represent a rough chronological order of tool evolution. An appropriate categorization of production logs is by usage. Production-logging tools find many applications from the time a well is drilled until abandonment and, occasionally, beyond. If the cross sectional area of the spinner at the depth of the spinner blades occupies a significant fraction of the pipe area then the pipe area should be reduced before multiplying it by the spinner velocity and the correction coefficient. Full bore spinners rarely cover more than half the pipe cross section. The prefix "full bore" when applied to a spinner is a marketing name. The calibrated spinner velocity then needs to be converted to an average pipe velocity.The correction coefficient determined by the velocity profile across the pipe cross section can vary from 0.5 for an infinitely small spinner in laminar flow to 1.0 for a spinner that sweeps the entire pipe area. This means that the spinner is typically calibrated downhole by recording the spinner speed at a series of different logging speeds (usually 30, 60,90 ft/min or 10, 20, 30 m/min) and plotting the resultant average spinner speed versus the corresponding average logging speed to determine the slope (gain) and threshold (offset). Unfortunately the gain and offset are not constants but are a complicated function of fluid density, fluid viscosity, spinner pitch, pipe diameter, fluid velocity, etc. This becomes a simple gain and offset transformation from the rotational speed of the spinner. Turbines or Spinners are assumed to rotate at a speed proportional to the average fluid velocity passing through the swept area of the blades with an offset for friction/imperfections. Markers/Tracers such as oxygen activation logs or radioactive iodine tracer logs.This last approach is most commonly used. However it is possible to measure an axial velocity and combine this with an assumed or measured internal diameter to arrive at an axial flow rate. Unfortunately there is not any practical measurement of axial flow rate beyond some special applications of oxygen activation logs. Alternatively we could measure the axial flow rate in a well at a depths above and below the zone of interest and compute the difference and hence the inflow rate. Ideally we would like to measure radial inflow rates using a cheap and accurate sensor. The former is usually easier and more quantitative while the latter is more qualitative. These various tasks can be split between those where the target production is into or out of the well and those where the flow never enters the well, typically flow behind pipe. Production logs are used to allocate production on a zone by zone basis and also to diagnose production problems such as leaks or cross flow. It is usual for cased hole equipment manufacturers to produce a platform of sensors with common power supplies, telemetry (or memory) to cover production logging, saturation logging, and multifinger caliper corrosion logging. This reduced ID means that cased hole toolstrings for live wells are typically sized at 1-11/16" in order to pass through the smallest nipple in a 2-3/8" tubing. Wells with surface pressure typically have a completion tubing of relatively small internal diameter, ID, compared to the casing size across the reservoir. Minimise the grease injection requirements to seal around a wireline cable.Minimise the tool weight needed to overcome the well pressure trying to extrude the cable.With a well that has pressure at surface it is normal to use a small logging cable in order to Services performed in dead, overbalanced, conditions can use relatively simple surface pressure control equipment and are often performed using large open hole style logging cables. ![]() Production Logging is one of a number of cased hole services that includes cement monitoring, corrosion monitoring, monitoring of formation fluid contacts (and saturations), perforating and plug and packer setting. 7.2 Maximum tool length to negotiate bend.7 Planning considerations for production logging.5.3 Answer (anomaly) will jump out from a casual scan of the log.5.1 A production log can be run by anyone.5 Misconceptions about production logging.
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