Junk refers to any objects or debris which have been dropped into or lost in the hole. Junk can include all manner of things, from downhole tools and bottomhole assembly components, to bit cones, or even hand tools which have been accidentally dropped into the hole. In some cases, it may be clear what the junk is, such as when something has been visibly dropped down the hole. On the other hand, though, it may sometimes be unclear just what is causing the problem. While drilling is taking place, junk can be detected by an irregular torque, or by the drill being unable to move ahead when a new bit has been run. In order to remove any junk from a well, junk removal tools will be used depending on a particular condition of junk and wellbore.
There are three main ways that junk can be dealt with; which method is chosen will depend on the size of the junk itself, and how hard the formation is. The junk can be recovered whole, split into smaller pieces so that these pieces can be recovered or that they are too small to cause any additional issues, or finally pushed into the side of a soft formation or the bottom of a formation with a large enough rathole. If none of these are possible and the junk continues to interfere with well operations, then the well made need to be sidetracked or abandoned.
The junk removal tools are as follows;
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:
- the current depth of the tool
- the type and size of the cable
- the surface tension of the cable just prior to becoming stuck
- the cable-head’s weakpoint rating
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
Between the fracture pressure and the pore pressure of the formation, the hydrostatic pressure of drilling fluid will always be maintained according to conventional drilling practice. In order to control the transport cuttings to the surface as well as the formation fluids, the drilling fluid is held within the wellbore where it circulates. Furthermore, it also keeps the drill bit cool and lubricated as it acts as a stabilizing agent. For effective use, the fluid must be water- or oil-based and this leads to a maximum weight of 19 pounds for each gallon (minimum of 7.8 pounds). As an attempt at imparting fluid loss, density, and rheological properties, it also contains a mixture of liquid and solid products.
Figure 1 – Conventional Drilling
For many years, the conventional drilling has been the safest method when drilling a well but there are also some negatives to using the method. For example, fluid invasion is a common problem because the drilling fluid pressure is naturally above the pressure of the natural formation – this can cause permeability damage. Also, physical blockages and washouts are common as the solids and fluids lodge into the formation. Continue reading
Offshore platforms are used to explore, extract, and process oil and gas retrieved from the seabed. One vital part of these structures is the central processing platform (CPP), where the well head fluid is pumped from the wellhead platforms through the riser for processing. The most important function of the CPP is to separate the oil, gas, and water from this three-phase well head fluid, to produce the final product of the platform.
Most central processing platforms feature the following components:
1. Separation Unit
2. Gas compression and dehydration
3. Produced water conditioning
4. Sea water processing and injection system Continue reading