Mechanical Sticking (cause of stuck pipe)

Mechanical Sticking (cause of stuck pipe)

Mechanical sticking occurs as a result of one or more of the following 8 conditions:

1. inadequate hole cleaning

2. formation instability

3. key seating (not often a problem but has happened…

Fishing Tools: Drilling/ Fishing Jars,Accelerators, Bumper Subs

This article describes force multiplying fishing tools: Jars, Accelerators, Bumper Subs.

Drilling/ Fishing Jars

If a fishing specialist contractor is used, the contractor should be consulted on a case…

Fishing in slim hole wells

 With improved equipment and operating practices, downhole failures have decreased in all drilling operations. The cost and time to sidetrack round a fish has been substantially reduced due to…

Fishing with Overshots

The following guidelines should be considered when fishing with overshots:

  • A pack-off should be installed if circulation through the fish is required before POOH.
  • If the hole size is larger than the…

Milling Guidelines

To effectively remove the cuttings while milling stuck pipe, it shall be ensured that:

- the yield point of the mud is increased as high as possible prior to commencing milling, taking advice from the…

Spotting Fluids to Free Stuck Pipe

If the pipe becomes stuck, and pulling and working the string has failed to free the pipe, spotting fluids should be used around the stuck part of the string, in an attempt to eliminate the root cause …

Fishing Assemblies and tools

Fishing Assemblies and tools

Fishing Assemblies and tools.Fishing is the general term used to describe the special techniques that are employed to recover items or equipment from downhole. Details of tools, equipment, and…

Jarring Stuck Pipe

The pipe shall be immediately worked and jarred in the opposite direction to that when it became stuck. That is, if stuck when POOH jar down, if stuck when drilling or RIH jar up.

Notes:  Pipe…

Pulling Stuck Pipe

Prior to pulling stuck drill pipe or stuck casing, carry out the following preparations:

1. Ensure that all surface pulling equipment is in good working condition. Do not exceed the maximum allowable…

Differential Sticking (Cause of Stuck Pipe)

Differential Sticking (Cause of Stuck Pipe)

In normal overbalanced drilling conditions, a pressure differential exists between the mud column and the formation pressure. In situations where the formation pressure is significantly lower than…

Stuck Pipe - Free Point Determination

Stuck Pipe - Free Point Determination

Detection of the stuck point to locate the lowest possible back-off point can be established by stretching the string and using the stretch charts for drillpipe. This method gives only an approximate…

When to Give Up Attempts to Free the Pipe

After effort has been put into freeing the pipe the decision has to be made whether to back off or continue. There are two options to consider: 

1. Back off above the free point and run in with a…

Use of Drag charts for hole cleaning - WellPlan

Softwares are used to produce Drag charts on which is shown the measured and predicted weights vs. depth. The purpose is to provide the crew with the expected torque and drag during the drilling of…

Fishing with Spears

Recommendations to be used when fishing with a spear:

  • Spears shall be dressed with a pack-off rubber to circulate when required. A stop ring or stop sub shall be used to prevent the spear from…

Backing-off procedure with top drive

A. Backing off stuck pipe - Preliminary remarks:

a. The neutral weight is calculated as the weight in air of the string above the stuck point.

b. In order to avoid unintentional b/o (back-off), the…

Back-Off Procedures

The conditions for a successful back-off are described below:

a) The string shot strength should be sufficient to back-off the pipe without causing damage to the pipe or the connection. The size of…

Taper Mills

Taper mills can be used for reaming out collapsed or stuck pipe such as casing and liners. They can also be used to clean up permanent whipstock windows, to mill through jagged or split guide shoes…

Effective Pull On Stuck Pipe

The first actions taken when the drillstring becomes stuck have a great influence on the chance of success. The information detailed belowl give guidance to the correct early response when the pipe…

Stuck Pipe Prevention

Good drilling practices, particularly with regard to circulating and tripping activities, can greatly reduce the occurrence of stuck pip.

Stuck Pipe Procedures

Drilling Contractor personnel must be…

Freeing Differentially Stuck Pipe

The pipe shall immediately be pulled to the maximum safe pull specified for the assembly and jarring shall commence.

If pulling and jarring are not immediately successful, the pipe shall be slugged…

Fishing with Washover Strings

Washover strings can be used when:

  • the formation has bridged off and stuck the string.
  • the string has become cemented in the hole.
  • dressing the top of the fish for latching on with an overshot.
  • milling…

Overpulls/ Stuck Pipe In Surface Hole

If any tight hole is experienced when drilling with water the followint actions should be taken to prevent stuck pipe:

- With kelly: Immediately pull the string back to above the tight spot (after…

Backing off Procedures

The string shot size shall be determined by the Logging Engineer so that it will be large enough to back-off the joint to be released without splitting the pipe. If the pipe does not back-off after…

Chemical Cutters for Stuck Tubing or Drillpipe

The chemical cutter is a tool designed to cut and allow retrieval of stuck tubing or drillpipe in a well. The primary advantages of this tool over explosive methods are its ability to sever tubing…

Fishing Planning and Preparation

Fishing Planning and Preparation

When equipment has been lost or is stuck in the hole, the following points shall be considered in deciding the optimum course of action:

  • The type of equipment in the hole to be fished (drillpipe,…

Pipe Sticking

In many drilling operations, the drill string is stuck while pulling out after first having experienced tight hole, swabbing and overpulls.

This indicates the following shortcomings:

  • Pulling out has…

Lost Sidewall Sample Bullets

In case of lost Sidewall Sample Bullets, the following guidelines should be considered ...

  • If bullets are lost in the hole, run in with a rockbit (without nozzles) and junk sub, and rotate and…

Jarring precautions

Heavy pulling and jarring shall be carried out using the top drive/ kelly on the string. On those rare occasions where this is not possible, the elevator latch shall be secured by means of a rope or…

Formation Instability

When dealing with areas of formation instability it is necessary to:

- trip cautiously through swelling formations

- pick up and ream midway through each stand (if hole conditions are severe, more…

Pilot Mill

Pilot Mill

Pilot mills are used for milling the following equipment/ material: adapters, liners, casing, swaged casing, stuck drillpipe, wash pipe.

The procedure for milling with a pilot mill is as follows:

Miscellaneous Fishing Tools

This article describes the following fishing tools: Magnets,  Lead Impression Blocks, Rope Spears, Taper Taps and Die Collars.

Magnets

The following guidelines should be used when using magnets:…

Responsibilities during Fishing Operations

Responsibilities of the Company Drilling Supervisor, Specialist Contractor Engineer, Drilling Contractor Toolpusher, during fishing operations.

Company Drilling Supervisor:

  • The overall responsibility…

Preventing Differential Sticking

The Drilling Programme shall indicate any permeable formations which may lead to differential sticking, particularly if the risk of differential sticking is considered to be high.

Data Acquisition

An…

Changing a Bottom Hole Assembly

To avoid problems with under gauge hole and BHA changes it is important to ensure the following to reduce the riskof stuck pipe:

  • bits and stabilisers shall always be gauged after each trip
  • if the bit…

Stretch graph for 3.5" and 5" Drilll Pipe

Stretch graph for 3.5

Stretch graph for 3.5" and 5" Drilll Pipe are presented below:

Stretch graph for 3.5" Drilll Pipe

Stretch graph for 5" Drilll Pipe

Junk Mill

When milling loose junk, spudding shall be periodically carried out to pound junk down to the bottom of the hole where it can be effectively milled. The following procedure shall be considerd:

Loose…

Fishing with Junk Subs

Junk subs are constructed with rib guides which are welded to the main body. These guides assist in preventing the cup from becoming crushed and guide the tool. Junk subs are available in various…

Fishing tools selection

The table below presents the types of fishing tools and their applications

Type of Fishing Job

Type of Fishing Tool

Names of Tools

Recovery of Tubular Fish

Connecting Tools

-External…

Fishing Guidelines

The following best practices should be considered for fishing operations:

  • All fishing tool details shall be recorded on a drawing prior to running the tool. In particular, the safe working load for…

Hole Cleaning

The following are possible indicators of hole cleaning problems:

- excessive overpull on connections and trips

- reduced overpull when pumping

- excessive fill after trips

- erratic and increasing…

Fishing with Junk Retrievers

The following 2 types of Junk retrievers are discussed in this article: Coring Type Basket and Reverse Circulation Junk Basket or Jet Retriever.

Coring Type Basket

The coring type basket cuts a short…