## What does a well log tell you?

Well logs present a concise, detailed plot of formation parameters versus depth. Logging tools record the magnitude of a specific formation property, such as resistivity, measured as the tool traverses an interval defined by depth; a well log is a chart that shows the value of that measurement plotted versus depth.

## How do you find the porosity of a well log?

The most common method of determining porosity is with Well Logs….

1. ϕsl is the porosity from the sonic log (log measurement) , fraction.
2. Δtsl is value of the acoustic transit time measured by the sonic log, μsec/ft.
3. Δtma is value of the acoustic transit time of the rock matrix measured in the laboratory, μsec/ft.

What is RT in well logging?

Rw= Resistivity of formation water. Rmf= Resistivity of mud filtrate. Rt= Resistivity of uninvaded zone.

### What is logging in oil and gas?

Well logging, as it applies to the petroleum industry, is used to identify oil and gas intervals, and quantify properties of reservoir rock by placing various types of sensors in the borehole. The signatures are then analyzed to evaluate the formation properties that are of interest for producing oil and gas.

### How do I get a well log?

Depending on your location, your state or county health department, Department of Natural Resources, or some other similar agency may house well logs that you can access or request a log from. If you know who drilled your well, it might be a good first step to contact them and ask for your log.

How do you determine porosity?

Porosity = ( ( Total Volume – Volume of the Solid ) / Total Volume ) x 100%. A larger percentage means that the rock has the ability to hold more water.

#### What is PEF log?

1. n. [Formation Evaluation] A log of photoelectric absorption properties. The log measures the photoelectric absorption factor, Pe, which is defined as (Z/10) 3.6 where Z is the average atomic number of the formation.

#### What is FMI log?

A downhole micro electrical resistivity technique first used for oil and gas wells in the late 1980’s.

What are the two main types of logging?

Logging is generally categorized into two categories: selective and clear-cutting.

## How many types of well logging are there?

Four types will be described here: acoustic velocity, acoustic waveform, cement bond, and acoustic televiewer. Spontaneous potential (SP) is one of the oldest logging techniques.

## What to look for in a well log?

Plot Density-Neutron together on the same track. The values should be decreasing as we go from the left to the right. To look for a reservoir, you need a Gamma Ray log. Normally, your reservoir will give low Gamma Ray reading. High Gamma Ray reading most probably indicates shale zones or non reservoir rocks.

But the results are magical.This is a technique I called ‘The Ko Ko Rules’ . To make it work, you need to have Gamma Ray Log, Resistivity Logs, Density and Neutron logs plotted on the same log plot respectively.

### How to easily read a well log using GR-res?

By combinating the patterns of each curve deflections, we can tell the difference between reservoir and non reservoir and/or the fluid types (oil vs gas vs water). 1. Look at the directions of the curve deflections (whether to the right or to the left) in these following sequence: GR-Res-Density-Neutron.

### How are SP logs used in oil and gas wells?

Thus, SP logs are often used to tell sandstones from shales. Resistivity logsdetermine what types of fluids are present in the reservoir rocks by measuring how effective these rocks are at conducting electricity.