Wireline Tool Recovery In Case of Wireline Tool Stuck

Wireline tool such as logging tool, slick line tool can be stuck in the hole therefore we need to understand about wireline recovery tool. This article demonstrate typical wireline fishing / recovery tool.  Common wireline tool issues center around the cable being tangled or wadded in the hole, as well as the fact that attempts at fishing can pull the wireline out of the rope socket or part, further complicating tool retrieval.

Stuck Cable or Tools

As soon as a wireline assembly becomes stuck, the operator will need to determine whether the problem is in the cable or the tool. Usually, one would apply normal logging tension on the cable and allow it to sit for a few minutes. During this time, four things should be recorded:

  1. the current depth of the tool
  2. the type and size of the cable
  3. the surface tension of the cable just prior to becoming stuck
  4. the cable-head’s weakpoint rating

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What is Fishing Operation?

In technical terms, a fish can be any object which has been lost or stuck in a borehole, and has a serious negative impact on well operations. Fishes can be anything, whether that is a drill string that has come away, a bit cone, or even a hand tool that has been inadvertently dropped into the well. To solve this issue, fishing involves the use of special tools and procedures to recover the fish and allow drilling to continue. While this article will deal solely with regular fishing, there is also an alternative method, which involves using through-tubing processes that make use of tools on a wireline or coiled tubing.

Virtually any object that is dropped into a well, or even run into it, may need to be fished out at some point. Furthermore, the need for fishing may arise at any given point during operations, and there are therefore a wide range of different tools and methods. There are three main technologies that these solutions are built around, though: pulling, milling, or cutting the pipe itself, and other downhole parts.

A fishing job is one option, but this will depend on the cost and likelihood of success. Other options include:

  • Leaving the fish where it is, and sidetracking or redrilling the well to follow an alternative path
  • Leaving the fish where it is, and completing the well in a shallower zone
  • Abandoning the well altogether

Preferably, the fish should be completely avoided in the first place, thanks to the right planning and proper drilling practices. However, it is important that a contingency plan is in place should the situation arise. Continue reading

What are Turbine Drilling Motors?

Turbine Motors work by harnessing the energy of a continuous flow of steam which passes through them. More specifically, drilling fluid travelling down the drillstem is deflected by the blades of a stator which is connected to the housing. This deflected fluid then flows over the blades of a rotor, which causes the drive shaft itself to rotate. The blades of both the rotor and stator are configured in the same way as a standard ventilation fan, but with the blades positioned in reverse. This is because a fan is designed to propel air outwards with a motor, whereas a turbine requires an input of air or liquid to turn its motor.

Mud or drilling fluid is pumped down the drillstring from the surface, until it enters the power section of the turbine. It then comes into contact with the stator blades, which cannot move since they are fixed to the turbine housing. The fluid’s momentum is therefore redirected to the rotor blades. This then moves the drive shaft to the drill bit, causing it to rotate. When the rotor blades perform their exit turns, the liquid is then directed into the next rotor/stator stage. Each turbine may include up to 400 of these stages, although a more typical figure is 100-250. Every stage will transmit the same amount of torque to the drive shaft, and uses up an equal amount of the total energy.

Figure 1 - Turbine Motors, (oilandgasproductnews.com, 2015)

Figure 1 – Components of Turbine Motors, (oilandgasproductnews.com, 2015)

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What are Positive Displacement Mud Motors in Drilling for Oil and Gas?

Positive-Displacement Motors (PDM) make use of a power generation section which is made up of a rotor/stator combination. In order to move a rotor part,  a PDM requires hydraulic power from drilling fluid flowing through the power generation part. With a PDM, the stator and rotor work in tandem in the same way that gears do. The stator acts as the outer gear, and is made from a moulded elastomer featuring at least two lobes. The OD of the elastomer is protected by a secure metal casing. The rotor is positioned within the stator, and acts as an internal gear. This rotor is made of metal, and will have one less gear or lobe than the stator. Because of this difference, a cavity is created which is filled with drilling fluid when the PDM is downhole. This cavity acts as a wedge when it is put under pressure, and because the drilling fluid itself can’t be compressed, the force applied to the top of the wedge causes the rotor to move.

Mud Motor

Figure 1 – Mud Motor

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What are Hole Openers for Drilling?

Hole openers are used to increase size of well bore and there are two broad categories of hole openers: fixed diameter hole openers, and under-reamers.

Fixed diameter hole openers are usually made up of three “cutters” arranged around a mandrel, and mounted on “saddles” by strong retaining pins. Cutters may be milled tooth, PDC, or TC inserts, which will vary depending on the formation to be cut.

Fixed Diameter Hole Opener

Fixed Diameter Hole Opener (Getech Equipments International, 2018)

Under-reamers, on the other hand, are hydraulically actuated hole openers that possess two or three arms. They are primarily used when a hole needs to be opened to a diameter larger than the casing which has already been set. Both of these forms typically feature a series of fluid passages, or “jets”, which are arranged to keep the cutters lubricated and help with the removal of cuttings. These need to be set up properly before use, to ensure a balanced mud flow both through and out of the hole opener.

Crew sets up the under reamer to enlarge the hole,

Crew sets up the under reamer to enlarge the hole, (tamu.edu, 2003)

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