Why is it important to measure the amount of filtrate in the drilling mud?
The filtration and wall building characteristics of a drilling mud are important for providing a relative measure of the amount of mud filtrate invasion into a porous and permeable formation and the amount of filter cake that will be deposited on the wall of the well bore wherever filtration occurs.
What are the two components of drilling mud?
A typical water-based drilling mud contains a clay, usually bentonite, to give it enough viscosity to carry cutting chips to the surface, as well as a mineral such as barite (barium sulfate) to increase the weight of the column enough to stabilize the borehole.
What are the components of drilling mud?
The Components of Drilling Fluids/Mud
Water-based drilling mud most commonly consists of Bentonite clay (gel) with additives such as Barium sulfate (Barite), Calcium carbonate (chalk) or Hematite. Various thickeners are used to influence the viscosity of the fluid, e.g. xanthan gum, guar gum, glycol, or starch.
What is filtration loss?
3.8 Fluid Loss (Filtration) Control. Fluid loss refers to the volume of filtrate lost to the permeable material due to the process of filtration.
How are the mud mud filtrate and Mudcake resistivities usually determined?
There are two methods of determining the resistivity of mud filtrate and mud cake, one being direct measurement at surface temperature and the other the conversion of mud resistivity (R/sub m/) measured at surface temperature into resistivity of mud filtrate and mud cake using appropriate charts.
How do you control fluid loss?
Fluid loss control additives are employed for maintaining a constant water/solid ratio in cement slurries downhole by controlling the rate of water loss to adjacent permeable zones through suitable viscosification; otherwise the cement slurries would lose water by filtration into these zones.
What is drilling mud called?
Drilling mud, also called drilling fluid, aids in the process of drilling a borehole into the earth. Such holes are drilled for oil and gas extraction, core sampling, and other purposes.
What are drilling mud additives?
1. n. [Drilling Fluids] A material added to a drilling fluid to perform one or more specific functions, such as a weighting agent, viscosifier or lubricant.
What are types of mud?
|Mud Type||Principal Components|
|Spud mud||Bentonite, water|
|Saltwater||Seawater, brine or saturated saltwater; saltwater clay, starch, cellulosic polymer|
How is filtration control?
Filtration control mechanisms include physical blocking of pore spaces, inhibition, thickening (viscosity), and deflocculation. Bentonite (gel) provides a basic level of filtration control; however, many times lower fluid loss is required for deeper sections of the well.
How Mudcake is formed?
Mud cake (also mudcake) is the layer of particulates from drill mud coating (caking) the inside of a borehole after the suspension medium has seeped through a porous geological formation. Similar to filter cake.
What is mud resistivity?
Therefore , the drilling-mud resistivity is assumed to be 0.18 Ωm, which corresponds to a water-based mud with addition of a strong electrolyte to make it more conductive ( Sherborne and Newton, 1942 ).
What is filtration control?
Filtration control is an important property of a drilling fluid, particularly when drilling through permeable formations in which the hydrostatic pressure exceeds the formation pressure.
What are drilling fluid additives?
Drilling Fluid Additives supplies various grades and blends of lignite and bentonite to the drilling division of the oil and gas industry.
What are the types of drilling mud?
There are three main types of drilling mud: water-based, oil-based and synthetic-based.
What is purpose of drilling mud?
The function of drilling muds conduct cuttings away from the drill face, provide a hydrostatic head that counters the pressure of gas or oil, and provide a physical and chemical means of stabilizing and protecting the rock formation that is being drilled.
Why is bentonite used for drilling mud?
The most common use of bentonite is in drilling fluids. The bentonite in the flush fluid lubricates and cools the cutting tools whilst protecting against corrosion. As the drilling fluid generates hydrostatic pressure in the borehole, it hinders fluid and gas penetration.
What is the difference between drilling fluid and drilling mud?
Both liquid and mud are used to drill boreholes but the composition is different. One term is often used for the other, but strictly speaking gaseous drilling fluid, using an array of gases, is a fluid. But fluids that are water or oil based are called mud.
Why mud is called mud?
late 14c., mudde, “moist, soft earth,” cognate with and probably from Middle Low German mudde, Middle Dutch modde “thick mud,” from Proto-Germanic *mud- from PIE *(s)meu-/*mu- [Buck], found in many words denoting “wet” or “dirty” (source also of Greek mydos “damp, moisture,” Old Irish muad “cloud,” Polish muł “slime,” …
What are the three drilling muds?
What is fluid loss additive?
Fluid loss additives are also called filtrate-reducing agents. Fluid losses may occur when the fluid comes in contact with a porous formation. This is relevant for drilling and completion fluids, fracturing fluids, and cement slurries.
What is the filter cake in drilling?
The filter cake is a very thin layer of solid particles deposited from the drilling fluid onto the surface of the drilled formation. This is essential during the drilling process as it reduces fluid filtrate invasion, contributing for the well’s integrity.
What is mud filter cake?
Mud filter cake is a layer formed by solid particles in drilling mud against porous zones due to differential pressure between hydrostatic pressure and formation pressure. For the drilling operation, it is preferred to have a filter cake that is impermeable and thin.
What is true resistivity?
The true resistivity (Rt) of a formation is its resistivity when not contaminated by drilling fluids. It may contain formation water only (water saturation [Sw] = 100%) or formation water and hydrocarbons (Sw < 100%). Using a valid Rt is fundamental when analyzing well logs for the presence of hydrocarbons.
What is laterolog?
Laterolog resistivity tool injects electric currents into geological formations and records the potential drop across a specific length along the open hole well. Laterolog measurements are related to the electrical resistivity of the formation. Laterolog tools are reliable in boreholes drilled with water-based muds.