Drilling mud is a mixture of water and clay , factually it is used to dig deep wells.
the drilled material sometimes has high weight, so water can not be used for this purpose. there should be a viscosity of mud that can easily remove the rocks from the well.
Drilling mud other than raising drilling materials, other works are done at the bottom of the well that we mention to some of them:
Of course, it should be borne in mind that the main task of drilling mud is to maintain the hydro static pressure inside the well.
If the pressure is higher than the pressure of the materials inside the well, then the mud penetrates the builders and causes the flower to drop.
If the flower decreases rapidly, after the pressure is completed or lowered, the well bore erupts. This causes the drilling rig to be destroyed.
In gas or oil builders, this flow is associated with a fire and causes the drill pipe to get into the well. To heal the flowers from different materials such as salt and so on.
The weight and mettle of drilling mud are changed due to well depth and internal pressure and the specific position during operation, which is one of the most important issues of drilling operations.
The following figure shows cleaning the bottom of the well and transferring drilling logs by drilling mud
The base of the drilling mud can be divided into three categories:
Water-base drilling mud consists of bentonite soil with additives such as barium sulfate, calcium carbonate or hematite.
Various condensers are used to impart fluid viscosity, such as gentamicin, guar gum, carboxy methyl cellulose, multi-anionic cellulose and starch.
Some of the benefits of these mud are as follows:
This type of mud is a non-water base mud, often oil-base mud contain 95% to 98% of gas oil, salt, water and other additives.
Oil-base mud is used for drilling in formations where the bottom of the well extends beyond the working temperature range of the Oil-base mud and has advantages over them.
In particular, because of the lack of conductivity of the oil, the thermal stability of additives, the absence of corrosive products and the lack of progression of bacteria in oil-based mud are suitable for corrosion control.
Oil-base mud have the ability to reuse over and over again. They can be stored for long periods of time. Generally, drilling speeds are higher with oily-mud, and more.
This type of mud is used in weak and fractured layers that cannot be drilled with conventional methods and there is a need for air to be used as drilling fluid. This mud is made up of air or nitrogen.
Improving the drilling speed and reducing drilling time, reducing the damage to the layer, better drill performance and increasing drill life, controlling the annoyance of mud and reducing drilling costs are among the benefits of this drilling technique.
In order to prevent the waste of drilling fluid in wells that have many gaps. Sodium bentonite can be used as an inner coating for wells. Bentonite increases the colloidal property and thus the percentage of powder and stone recovery increases.
To prevent drill stuck in high-adhesive rocks.
To increase the percentage of cementing materials
All the common varieties of Gilsonite are substantially in compressible and have a specific gravity sufficiently near to that of water that properly sized granules of the Gilsonite can be readily suspended in aqueous liquid carrier. Thus, Gilsonite is used for this purpose in powder. Particle size (mesh) is variable according to the characteristic of the well bore. Softening point is very important as Gilsonite must soften at a temperature above the temperature of well formation.
In this following figure, you can see the difference between using and not using Gilsonite in drilling mud during drilling:
In the figure , you can see the physical properties drilling mud:
To change pH and alkalize mud.
To increase viscosity
To increase the weight of the flower
To increase the viscosity of the cell (a special type of mud with a higher viscosity, which adds to the well when the well is in place and prevents any wasting).
Raise the difficulty of drilling mud
To enhance viscosity
For penetration inside the pores (at high wasting).
Like the Marsh funnel viscosity (MFV), this is a single-point measurement, which means that it does not show us the abnormal viscosity and, by measuring it, we can only know if the viscosity is acceptable or not.
Due to the mechanical friction resulting from the collision of solids in the mud, the collision of solids with the liquid that surrounds them or the friction resulting from the movement of the liquid layers on one another, but the plastic viscosity is most affected by the concentration of solids in the flower. Therefore, with the addition of the weight of the mud, the viscosity of the plastic increases too.
In liquids that have plastic properties, when pressed to move the pressure fluid, the pressure reaches a point where the liquid begins to move. The yield point is the point of gravity measurement between liquid particles. These forces are positive and negative loads that are located on the surface of the particles, so the tail point depends on the characteristics of the surface of the particle and the concentration of solids in the mud. This benchmark is measurable by the rotating viscosity meter. . The high yield point is a sign of gravity and high viscosity.
The difference between gel strength and the yield point is to measure gel strength measurements of molecular gravity in static or static conditions. In fact, the gel Strength determines the effect of flower molding, while the yield point measurement of the liquid particles in Stream mode.
this animation shows the general method of drilling and the use of drilling mud: