# Pushing a Pipe Down an Oil-Well: Struggling with Moment Vectors

• Bramle
In summary, the conversation discusses the modeling and calculations of the trajectory of an oil-well using vector and plane theory. The use of the "minimum curvature method" is mentioned, as well as assumptions made about the well and pipe. The discussion then shifts to the use of moment vectors and their parameters. The conversation ends with a question about the position vector associated with a moment vector.
Bramle
I am new to the forum... thanks for your help.

I have a moment problem that I am struggling with.

I have an oil-well, that is modeled as a series of joined-up circular arcs. The arcs are not all in one plane, as the well twists and turns. Using vector theory and theory of planes, I have modeled the trajectory of the well from top to bottom. It is a technique known as the "minimum curvature method".

I am pushing a pipe down the well. I assume no fluids in there, and that the pipe is massless and that there is no gravitational field.

I assume a perfect sliding fit between the pipe I am pushing down the well, and the containment diameter of the inside of the well.

I assumed no friction.

The containment diameter compels the pipe to curve in the same arc, and in compelling it to curve, there is a line load along the line of contact. The line of contact for the first arc is along the outer bend of the pipe.

From what bending theory I know...

E*I*d2y/dx2 = -m

...tells me that in order to bend the pipe into a circlular arc, that the line load is not uniform. Effectively I worked back from a circular solution for the curvature, and differentiated it twice to get the moment function... and when expressed as a function of x, it's awful!

I used to think that a uniform line load... lamda, lbf/ft... would give me a circular arc, but I really cannot prove it. I am no longer convinced that I am right in that assumption.

At the top of the topmost arc, the moment there is zero?... because it is a cut surface... but if I apply a uniform line load for the first arc.

Also, is it true to say that if I work out what the disturbing moment is (from a line load along an arc) for the first arc, that I can simply hand that to the top of the second arc as a moment vector, and use that to "kickstart" the moment balance for the second arc?

I can handle 3D force vectors reasonably, but 3D moment vectors are new to me... I really cannot picture them easily. Does a moment vector have to have a position vector associated with it? I know it has to have a direction vector describing the axis about which it is turning?... or is the moment hand-over a "directional" quantity, comprising a modulus and a direction vector about which it turns?

Thanks.

Bramle.

Bramle said:
I can handle 3D force vectors reasonably, but 3D moment vectors are new to me... I really cannot picture them easily. Does a moment vector have to have a position vector associated with it? I know it has to have a direction vector describing the axis about which it is turning?... or is the moment hand-over a "directional" quantity, comprising a modulus and a direction vector about which it turns?

The moment vector is a vector []. It has the same parameters as any other vector - magnitude, direction and orientation. The magnitude describes, of course the magnitude of the moment, the direction states which axis it is 'turning' about, and the orientation (the way the arrow points) states if it's positive or negative, i.e. if it rotates clockwise or counter clockwise. That's the only thing I could help about.

Last edited:

Thanks.

I take it that it does not have a position vector associated with it.

## 1. How does pushing a pipe down an oil-well affect the moment vectors?

The act of pushing a pipe down an oil-well creates a force that can change the direction and magnitude of the moment vectors. This force is dependent on the weight of the pipe, the angle at which it is pushed, and the friction between the pipe and the well walls.

## 2. What is the significance of moment vectors in pushing a pipe down an oil-well?

Moment vectors play a crucial role in the process of pushing a pipe down an oil-well. They indicate the direction and magnitude of the forces acting on the pipe, which helps determine the optimal method for pushing the pipe further into the well.

## 3. How can one overcome the struggle with moment vectors when pushing a pipe down an oil-well?

To overcome the struggle with moment vectors, it is important to carefully consider the weight and angle of the pipe, as well as the friction between the pipe and the well walls. Adjusting these factors can help minimize the resistance and make pushing the pipe easier.

## 4. What are some potential challenges when dealing with moment vectors in pushing a pipe down an oil-well?

Some potential challenges when dealing with moment vectors include issues with pipe stability, uneven well walls, and changes in the weight or angle of the pipe. These factors can affect the direction and magnitude of the moment vectors and make it more difficult to push the pipe down the well.

## 5. How can understanding moment vectors improve the efficiency of pushing a pipe down an oil-well?

By understanding the role of moment vectors in pushing a pipe down an oil-well, one can make more informed decisions about the weight, angle, and friction of the pipe, leading to a more efficient and successful process. This can save time and resources, and ultimately result in a more productive oil-well.

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