Drilling mud is a mixture of water and clay and is in fact a special group of drilling fluids that are used to dig deep wells.
So that the drilled material is brought to the bottom of the well, since the drilled material is sometimes of high weight, water can not be used for this purpose.
Of course, there should be a viscosity of flower that can easily remove the rocks from the well.
Once the material is brought to the surface by drilling mud, the material is separated and reused by special sieves.
Drilling mud other than raising drilling materials, other works are done at the bottom of the well that we mention to some of them:
- Cooling and reducing the friction and wear of drill with the ground;
- Lubricate drill and drill pipes
- Laying and protecting the well wall and preventing the fall of the floors (the drill bit puts pressure on the well wall and prevents it from falling);
- Establishing a balance between fluid and fluid in the well;
- Transfer underground gas or oil to the surface and measuring devices such as a gas detection device or a gas-type device.
- Underground pressure control
- Hydraulic transfer of pumps to drill
Of course, it should be borne in mind that the main task of drilling mud is to maintain the hydrostatic 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 wellbore 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 base of the drilling mud can be divided into three categories:
- Water-based mud
Water-based 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 muds are as follows:
- High viscosity
- Lack of solids
- Fluid Waste Management
- Stable wells
- Help prevent wasting muds
- Oil-based mud:
This type of mud is a non-water base mud, often oil-based mud contain 95% to 98% of gas oil, salt, water and other additives.
Oil-based mud is used for drilling in formations where the bottom of the well extends beyond the working temperature range of the Oil-based muds 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-based 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.
- Gas-base mud:
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.
Minerals used in drilling:
This mineral is a unique combination of Gilsonite grade to provide optimum and optimal operation in drilling mud to stabilize shale (oil well walls). This material reduces slurry weight.
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.
Whenever the drill and its axle stuck at the time of drilling, this material is used and when removed, the barrier is removed from the well.
To control specific gravity.
to control specific gravity.
- Lime and dolomite
To reduce specific gravity and alkaline control.
To prevent carbonate contamination and also to clay minerals.
To increase the percentage of cementing materials.
At the time of drilling, in order to control the diameter of the well and also to control the scattering of the clay.
- Carbonate and sodium bicarbonate
In order to control the solutions and prevent the risk of contamination.
- Perlite and volcanic ash
Used as cement
- In conventional drilling operation a drilling mud based on bentonite or other materials mentioned are commonly used, but The solid organic materials used are difficult to keep suspended in the drilling fluid, being of a higher specific gravity than the fluid, while materials such as expanded perlite, though easily to suspend, become compressed to a specific gravity higher than that of the fluid under the bore hole. Furthermore, the commonly used materials lack adhesive power and are insoluble, and they have been known to become lodged in the wall of the bore hole so as to obstruct or seal off a producing oil or gas zone, thus causing a costly or even a complete loss of production.
All the common varieties of Gilsonite are substantially incompressible 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
- By adding some minerals or chemicals to the drilling mud, some of its properties are reduced or increased. In this section, we will examine the materials and the effect on drilling mud:
To change pH and alkalize muds.
To increase viscosity
To increase the weight of the flower
- CMC Hv:
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
- Additives like walnut skin, chocolate mica skin and. . . .
For penetration inside the pores (at high wasting).
- The mechanical properties of muds that should be determined in the laboratory are:
- Apparent Viscosity (AV):
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.
- Plastic viscosity(PV)
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.
- Yield point(YP)
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.
- Gel Strength(GS)
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.
- An animation follows the general method of drilling and the use of drilling mud: