Prevention and Monitoring for Pipes

Prevention and monitoring

• Cleaning the Hole

• Torque and drag

• Hints of pipe glue – clippings and landslides

• Drilling Parameters

* Hole Cleaning

In high-angle wells, 80% of pipe-glue events are due to hole cleaning

Achieving good cleaning of the hole is the key to preventing non-productive times (NPT) and associated cost (red money) caused by the pipe sticking in the well

Piping Stress Analysis Services

• Vertical Wells Vs. Directional Wells

-Used hole cleaning techniques are effective depending mainly on the angle of the well section.

-The cleaning parameters in the vertical sections are different from those used in the horizontal sections.

-The cleaning of the hole becomes more critical in the sections with angles between 30 and 60 degrees of inclination.

Piping Stress Analysis Services

During drilling, the velocity of the fluid must be strong enough to counteract the effects of gravity, which will make the clippings fall to the bottom of the well. Usually this speed is reached efficiently in the vertical wells, fulfilling well the task of cleaning the hole. 

However, in Direcccionales wells present this problem with greater difficulty. Under the influence of gravity, the clippings will try, but because of the inclination of the well, they do not have to fall far to reach the lower part of the well wall. In this situation, the velocity of the drilling fluid should be higher even in order to keep the clippings going up to the surface.

For a certain inclination of the well will occur a rapid settlement of individual particles in a bed of clippings already existing in the lower part of the well

Once the critical mass has accumulated the particles can slide down the annular very quickly

Conveyer Bar Concept

• Proper use of mud pills can improve hole cleaning in vertical and directional wells.

• High viscosity (preferably heavy) pills are often effective in holes greater than 8 ½ "while low viscosity pills are effective in smaller holes.

• Pumping low viscosity pills followed by a high viscosity (heavy) pill ensures proper hole cleaning in large diameter wells in vertical well sections.

• Combining pills with string rotation improves hole cleaning

• The specific volume of the pills should be determined based on the diameter of the hole and the calculation of the hydrostatic column.

• Pumped pills have to be carefully monitored and the returns of clippings need to be assessed

String rotation

The rotation of the string:

Increases flow velocity in hole walls

Keeps cuts off the walls (speed and mechanical strength effects)

contributes more as the angle of the well increases

* TORQUE and drag

Increases in Torque and drag trends are indicators of hole problems, such as:

Increase in hole clippings

Hole stability Problems

Tight hole conditions

Tortuosity in the Hole

Drilling equipment problems

Widened hole by erosion ("washouts")

Why monitor Torque and drag variations?

• Evaluate hole deterioration and problems related to well stability

• Check the cleaning efficiency of the hole by circulating in each connection, circulating overhead, bump pumping, calibration trips, etc.

• Detect the formation of clipping beds (combined with DEC, removal of clippings in vibrating nets, etc.)

• Identify torque problems and equipment limitation.

• Finding mud-lubricating capacity failures plus the effects of sludge weight and changes in their properties.

• Define the friction factors for each well and build a data base of friction factors for multiple wells, both for open holes and for coated holes.

• Understand the effects of training.

• Identify changes in angles of inclination and direction – through construction sequences, spinning, laying down, maintaining angles in certain portions of the well.

• Anticipate well problems that affect the run of the liner.

When to monitor?

• On each connection

• While traveling down and out of the hole, especially in open sections.

• After considerable changes in inclination and direction.

• Before, during and after calibration trips.

• Before and after circulating backgrounds and pumping potholes.

• With the auger inside the liner, before drilling out/back into the open hole.

• After an increase/decrease in the weight of the sludge, change of type of sludge or considerable changes in the rheology of the same.

• At full depth after the hole has been cleaned.

• Before and after adding torque reducers such as non-rotating lubricants and pipe protectors etc.

* Hints of pipe glue

Surface Condition and parameter analysis

* Analysis of cuts and landslides

Landslides:

They are fragments of rock caused by the instability of the hole that are transported to the surface by the drilling fluid

Typically landslides are 1 to 2 centimeters long, but their dimensions may vary from millimeters to 10 centimeters or more.

Utility for the analysis of landslides

are an alarm signal about the instability of the hole

They allow to deduce which formations are unstable

Its geometry is an indicator of the fault mechanism

Allow you to define a remedial action