Stuck Pipe Logs

Stuck pipe is an expensive drilling problem because it usually baits all operations until the pipe is released. Common causes for stuck pipe are as follows:

  • sand cave-in
  • mechanical sticking, such as stuck packers or crooked pipe
  • keyseating
  • hole sloughing
  • hole heaving
  • undergauged hole
  • differential sticking
  • blowouts
  • lost circulation

Unfortunately, several of these causes for pipe sticking have similar characteristics and, as such, are often diagnosed improperly.

The pipe must be released before drilling can resume. Logs most commonly used to assist in this process are the free-point indicator, Ihe string shot backoff tool, and the pipe recovery log. Proper application of these logs and tools can assist in an accurate diagnosis of the drilling problem. Various pipe release techniques are then used. Typical is the string shot backoff and chemical cutter tools.

Free-Point Indicator. The free-point indicator measures the shallowest top of the stuck section, it is possible that free pipe exists below the upper stuck section. The recovery log, described in a following section, can be used to identify all free and stuck sections.

The tool, shown in Fig. 17-8, usually consists of two electromagnets connected with a telescopic joint. It is designed to measure stretch and torque movement in a string of stuck pipe. Upward pull, or tension, and rotary torque are applied to (he pipe. Since the applied tension and torque are not transmitted through the stuck section, the free section of the pipe is identified by the measured stretch and torque. Thus, the shallowest stuck pipe point is located.

String Shot Backoff. The string shot backoff tool uses a precisely calculated quantity of explosive detonating cord (Prima Cord) to produce a vibratory shock wave for loosening or unscrewing a predetermined joint of pipe (Fig, !7-9). It is detonated by an electrical blasting cap. The backoff is accomplished by applying left-hand torque in the string when the shot is exploded. The torque is applied at the neutral weight, with the pipe in neither compression nor tension at the shot point. The explosion produces the same effect as a hammer blow and is designed to cause the joint to unscrew at the proper point.

Pipe Recovery Log. The pipe recovery log gives a complete record of all stuck intervals and possible trouble areas in a string of stuck pipe. It indicates the length of each interval, the severity of stuck conditions at each interval, and

Back Off Tool String

Fig. 17-9 String shot back-off tool (Courtesy NL McCullough)

Fig, 17-8 Free point indicator tool (Courtesy NL McCullough)

Fig. 17-9 String shot back-off tool (Courtesy NL McCullough)

Gamma Ray Collar Log Pipe Recovery Log

Gamma Ray Collar Log Pipe Recovery Log

Casing Collar Log And Gamma Ray Log
Fig. 17-10 Pipe recovery log run in conjunction with a gamma ray log (Courtesy NL McCullough)

the amount that each interval contributes to the total stuck condition (Fig. 17-10).

The tool is calibrated in known free pipe, normally near the bottom of the surface pipe or the last casing string. A signal attenuation scale is placed on the log. The scale, expressed in percentages, indicates the severity of the stuck condition at each interval.

The recovery log is best run in conjunction with a gamma ray log if no other lithology log on the well is available. The gamma ray log shows the type of formation causing the stuck pipe. This information is beneficial in identifying the type of problem and in helping select the most practical remedy.

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Responses

  • quartilla
    How often drill pipe stuck?
    9 years ago
  • isto
    What tool is used to measure stuck drill pipe?
    7 years ago

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