Conventional coring involves using a hollow steel tube to extract a cylindrical rock sample from the formation. Side wall coring extracts smaller samples from the walls of the borehole using hollow bullets. Conventional coring provides larger, more representative samples but requires removing the entire drill string, while side wall coring obtains smaller samples without removing the drill string by shooting bullets into the borehole wall.

1. TOPIC :
CORING AND ITS TYPES

2.  ADNAN ZADA (03)
 USMAN ALI (48)
 WAQAS NADEEM (52)
 WAQAR ALI (51)
 ISRAR AHMAD (17)
 YOUSAF KHAN (33)

3.  CORING
 PURPOSE OF CORING
 TYPES OF CORING
 1 CONVENTIONAL CORING
 2 SIDE WALL CORING
 DIFFERENCE BETWEEN CONVENTIONAL
AND SIDE WALL CORING

4.  Cores which extract from the formation /reservoir
using special coring tools. once the cores is cut
,they are captured and retrieved to the surface for
analysis of different physical parameters
 A core sample is a cylindrical section of (usually) a
naturally occurring substance. Most core samples
are obtained by drilling with special drills into the
substance, for example sediment or rock, with a
hollow steel tube called core drill. The hole made
for the core sample is called the "core bowling". A
variety of core samplers exist to sample different
media under different conditions. More continue
to be invented on a regular basis.

5. In the coring process, the sample is pushed more
or less intact into the tube. Removed from the
tube in the laboratory, it is inspected and
analyzed by different techniques and
equipment depending on the type of data
desired

6.  The purpose of getting cores is to obtained rock
samples of sufficient size for :
`1 making reservoir analysis test to determined
porosity, permeability ,residual oil and water
saturation(primery purpose of coring)..
2 To establish the physical character of
formation boundry..
3 To furnish paleontological data for age and
facies correlation
4 To determined the structural attitude of the
beds

7.  There are two types of coring which are
 1 conventional coring
 2 side wall coring

8.  Conventional coring is a methed of drilling and
acquiring rock samples to retrieve the core
samples ..the complete rod string and core
barrel has to be removed from the hole
 When the bit is about to enter a formation of
special interest .a service company may be
brought in to take barrel cores. The coring tools
consist of an annular diameter bit to cut the
core and a hollow barrel to catch it

9.  Core samples may be of any length .but cores of
over 90 feet are hard to handle. A 60 feet core is
average cores ,which can be handle easily..
 A core diameter range from 11/8 to 5 inches with 4
inches being the most popular size for core
analysis
 Since it is costly and time consuming ,also
removing the cores is some time dangrous .since it
is possible to swab the well and cause a blowout.
 So sidewall coring is most commonly used than
conventional coring

10.  Side wall coring is a methed used in zones
where core recovery by conventional methed
was less than expected or wheres cores were
not obtained as drilling progressed
 Side wall coring is useful in paleontological
work ,for it is possible to get shale samples
micropaleo analysis at definite depth
 A side wall coring device is lowered into the
hole on a wire line cable and a sample of the
formation is taken at the desire depth .

11.  This done by shooting a hollow bullet into the
bore hole wall, then pulling it out of the well
and bring up to the surface..
 There are as many as thirty bullets per guns
and since two guns can be used .. Up to sixty
cores can be obtained during one run. If
electric logs have been run prevously , a
spontanous potential or gamma ray curve is
used to determined gun position by direct log
correlation

12. Conventional coring:
1 Conventional coring provides large samples
2 It is more better and more consistent
representation of formation..
3 It is better for heterogenous rocks or for more
complex lithologies…
SIDE WALL CORE :
1 Side wall coring provides smaller samples
2 It is less representative of heterogenous
formation..

13. 3 within 1 to 2 percent of whole cores for medium
to high porosity formation