Today we're going to take a look at the most common types of wireline logging operations.
Wireline logging is often performed in the wells after they were drilled to
find more information about the wellbore and nearby formation. Some examples of the
formation characteristics that can be determined with the help of wireline logs are
rock type, porosity, fluid type, and pay zone size. Usually, a combination of different logs are used
to get a better picture of downhole conditions. Depending on the wireline used and the job objectives
the data can either be sent to surface right away or it can be stored in the
built-in memory on the tool and then retrieved later when the wireline tool gets to the surface.
Wireline logging can be divided into two main branches: the open hole and the cased hole. Open
hole wireline logging is performed on the wells where there is no casing yet and the cased hole
is done on the wells with the casing and in most cases that casing is cemented as well.
Let's take a look at the types of open-hole wireline logging operations. First, we have gamma-ray
logging and it's used to detect natural radiation emitted by the formation this data can be used
to distinguish between different reservoir rocks and determine reservoir thickness it's also used
to correlate other logs. Formations like shale and clay with high potassium and content are
more radioactive than for example sandstone or limestone since gamma-ray can penetrate
the metal casing gamma-ray logging can also be performed on cased wells as well. Sonic logging is
performed to measure how fast the sound travels through the formation and this data can be used
to calculate the porosity and the type of rocks information. Spontaneous potential logging
is performed to find out the electrical potential created along the wellbore to determine the rock
and fluid types. One of the electrodes is placed at the surface and the other one is run in the hole.
Caliper logging is used to measure the size of the hole
and it's usually a downhole tool with some type of spring legs is used for use for that.
The data acquired can be used to determine how much cement is required to secure the casing.
Density logging is performed by emitting the radiation from the tool and measuring how the
formation responds to it and this information can be used to determine the porosity of the formation.
Resistivity logging is performed to determine the resistivity of the formation rock. Salt
water will have much lower resistivity than for example hydrocarbons and that's why
with resistivity logs it's easy to distinguish between the two different types
of fluids in the formation as well. Neutron logging is performed by emitting neutrons from the tool
and then determining how they interact with the formation. The neutrons are affected by
the number of hydrogen atoms in the formation. Liquids like water and oil can be easily detected because
of the high amount of hydrogen atoms in those
liquids and this data can be used to measure the porosity of the formation. Now let's take
a look at the types of cased-hole wireline logging operations. First, we have production logging and
for production logging usually, the special tool is run well to determine which zones are producing and
this tool usually has some type of spinner to measure the fluid velocity this can also be
combined with temperature and pressure sensors to get a better understanding of the production
and injection zones. Another common log performed in the cased hole is cement bond logging or CBL and it's
done to determine the cement integrity between the casing and the formation. Using wireline is not
the only way to get well logs and there are a few other options one is logging while drilling or LWD
and it is performed in real-time while drilling the well. The LWD tool is usually placed above the
drilling bottom hole assembly and the data can be sent to surface in real-time and can be used
to make real-time decisions while drilling do well and another option is to store all
the data in the built-in memory on the tool and retrieve it later when the tool gets to the surface.
The next option for well logging is fiber optic well monitoring which is becoming more popular
for production logging. Fiber optic cable can either be permanently installed in
the well or it can be run inside of a coiled tubing and then this coiled tubing can be run in the well.
Fiber optic is a little more expensive option but it gives a much better understanding of the
wellbore production and injection profiles in comparison to conventional logging tools. So
guys this is the overview of the most common wireline logging operations and if you guys
learned something new please don't forget to subscribe and I will see you guys later. Bye!