What are the types of resistivity logs?
Resistivity Logging. There are three main categories of well Logging: Electrical, Nuclear and Acoustic/Sonic.
What do resistivity logs measure?
Resistivity logging is a method of well logging that works by characterizing the rock or sediment in a borehole by measuring its electrical resistivity. Resistivity is a fundamental material property which represents how strongly a material opposes the flow of electric current.
What is micro resistivity log?
MICRO-RESISTIVITY LOG Micro log is a resistivity log of a bore hole which Is measured by two electrodes that are installed on a pad of a microresisitivity measuring device. 3. PRINCIPLE • All micro-resistivity logs are based on the application of Ohm’s Law.
What is ILD log?
(ILD). The depth of investigation of the deep induction log (ILD) is controlled by the resistivity of the formation, being lower in low resistivities. Figure 1 shows that a gap exists in both resolution and depth of investigation between the FMS and SFL (factors of 100 and 20 approx.
What is meant by resistivity well logging?
What is RT logging?
Rw= Resistivity of formation water. Rmf= Resistivity of mud filtrate. Rt= Resistivity of uninvaded zone.
What is Laterolog resistivity?
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.
What is fluid logging?
Detailed Description. Fluid-resistivity logs record the electric resistivity of water in the borehole. Changes in fluid resistivity reflect differences in dissolved-solids concentration of water. Fluid-resistivity logs are useful for delineating water-bearing zones and identifying vertical flow in the borehole.
What is Rhob log?
The density log usually labelled ‘RHOB’ measures the density of the borehole and the rocks penetrated by the drill bit. The unit for density is gram per cubic centimetre. The logs (sonic and density) measurements are usually made every 6 in. down hole, but must be aligned to be ‘on-depth’ with each other.
What is porosity log?
The “Porosity” logs. There are three types of logging tools that are used to estimate the amount of pore space in a rock: the neutron, density, and acoustic velocity (or sonic) tool.
What is bore log?
A borehole log is a record or graph of the sensor output (e.g., gamma ray count rate) plotted on the horizontal axis versus depth on the vertical axis.
What is mid logging?
Mud logging is the creation of a detailed record (well log) of a borehole by examining the cuttings of rock brought to the surface by the circulating drilling medium (most commonly drilling mud).
What is the resistivity of air?
Table of Resistivity and Conductivity at 20°C
| Material | ρ (Ω•m) at 20 °C Resistivity | σ (S/m) at 20 °C Conductivity |
|---|---|---|
| Hard rubber | 1×1013 | 10−14 |
| Wood (oven dry) | 1×1014 to 16 | 10−16 to 10-14 |
| Sulfur | 1×1015 | 10−16 |
| Air | 1.3×1016 to 3.3×1016 | 3×10−15 to 8×10−15 |
What is high resistivity materials?
A material with high resistivity means it has got high resistance and will resist the flow of electrons. A material with low resistivity means it has low resistance and thus the electrons flow smoothly through the material. For example, Copper and Aluminium have low resistivity. Good conductors have less resistivity.
What are the different types of resistivity logs?
Consequently, various combinations of electric and induction resistivity logs are deployed depending on the borehole diameter, drilling fluid, and salinity of the fluid. Thus, resistivity logs involve fluids to measure the resistance of the rocks surrounding the borehole.
What are the two main types of mid-level clouds?
The two main type of mid-level clouds are altostratus and altocumulus. Altostratus clouds over Kentucky Altocumulus (sunset 23 Nov. 2005) Altostratus clouds are “strato” type clouds (see below) that possess a flat and uniform type texture in the mid levels.
What is the resistivity log of a circuit?
5. The resistivity log is a measurement of a formation’s resistivity, that is its resistance to the passage of an electric current. It is measured by resistivity tools.
What is a spurious peak in resistivity log?
• Two spurious peaks appear, one above and one below the bed; the distance between the two peaks is equal to bed thickness plus the spacing of the normal. 9. 9 Resistivity Logs are used to determine Water saturation, Sw and hydrocarbon zones, porosity and permeability.