KOYA UNIVERSITYFACULTY OF ENGINEERING

SCHOOL OF PETROLEUM AND CHEMICAL

FLUID MECHANIC LAB

NAME OF EXPEREMENT: Core Plugging TestNAME OF STUDENT: Kamal Abdurahman

Group: B

SUPERVISED BY: Mr.Ali Kamal

Aim of Experiment:

In this test we will try to prepare core plugs from 4`` cores.

Different core sizes can be obtain during the drilling operation

process, the main object behind this is to get more information

about some targets in which we may get or find hydrocarbon or

for many other objects.

Introduction

Knowledge of the physical properties of the rock and interaction

between hydrocarbon system and the formation rock is crucial in

understanding and evaluating the performance of a given

reservoir. These data are usually obtained from two main

sources: core analysis and well logging. In this test we describe

the analysis of cores. A core which is a solid cylinder of rock

about 3 inches in diameter and would usually be about 30 feet

long is taken by replacing the drill bit by a “core bit” which is

capable of grinding out and retrieving the heavy cylinder rock.

Once the cores are retrieved it is crucial to properly handle (avoid

damaging) and preserve them by avoiding exposure to air. When

the core arrives in the laboratory plugs are usually drilled 20-30

cm apart throughout the reservoir interval. Then the plugs are

analyzed with respect to porosity, permeability, saturation, grain

density and lithology.

This analysis, which is performed at high sampling frequency and

low cost, is called routine core analysis. The results from routine

core analysis are used in interpretation and evaluation of the

reservoir. Examples are prediction of gas, oil and water

production, definition of fluid contacts and volume in place,

definition of completion intervals. There are other important

measurements with the aim of obtaining the detailed information

about the multiphase flow behavior. This analysis, which is

performed at low sampling frequency due to high cost and more

time due to gathering the data, is called special core analysis.

Special core analysis gives information about the rock wettability,

the distribution of oil, gas, and water in the reservoir (capillary

pressure data).

Theory

A coring program is similar to many engineering projects. It

begins with the idea that an investment will reap a reward. It

progresses through a phase of exploring alternate sources of

information; well tests, logs, previous cores, and cuttings or

sidewall cores.

Planning begins by listing the objectives of the coring program.

This is best done by a team of petro physical, reservoir,

geological, drilling, and production personnel. When discussing

objectives, every expenditure must ultimately lead to producing

more oil or gas at a lower unit cost. Constraints in budget,

location, and timing will be placed on the program.

Hole size, hole angle, temperature, pressure, and rock type will

influence the selection of the coring tools. Planning becomes an

interactive process where consensus is built and a detailed

program formulated.

The keys to a successful coring operation are planning and

communication.

Objective

The objective of every coring operation is to gather information

that leads to more efficient oil or gas production. Some specific

tasks might include the:

a. Geologic objectives:

1. Lithologic information:

(a) Rock type.

(b) Depositional environment.

(c) Pore type.

(d) Mineralogy/geochemistry.

2. Geologic maps.

3. Fracture orientation.

b. Petrophysical and reservoir engineering:

1. Permeability information:

(a) Permeability/porosity correlation. (b) Relative permeability.

2. Capillary pressure data.

3. Data for refining log calculations:

(a) Electrical properties.

(b) Grain density.

(c) Core gamma log.

(d) Mineralogy and cation exchange capacity.

4. Enhanced oil recovery studies.

5. Reserves estimate:

(a) Porosity.

(b) Fluid saturations.

Coring Fluids The selection of a coring fluid should be based

on four points:

a. Safety.

b. The primary objective of the coring program.

c. Environmental concerns.

d. Cost.

Apparatus of experiment

1-Conventional Core Barrel.

2- Heavy-Duty Conventional Core Barrels.

The core cutting machine is designed to cut cores of between 3 to

6 inches, or from blocks of a similar size. The produced plugs are

in two different size of 1 and 1.5 inches.

Machine Description:

Figure 3: Core plugging machine

The speed can be adjusted by repositioning the belt (1800 rpm –

2500 rpm – 3500 rpm)

The machine comprises of:

• clamping stand

• column

• « Spindle-Motor » unit

• adjustable tilting table

• protective housing

• clamping unit

• recycling tank

Procedure

1- Slab bedding; the cores need to be slab bed with the aim of

making the rock structure visible. This can simply be done by

sawing down the middle of the core and cutting it at desired

length. 2- Plugging: one can drill the plugs at every one foot of the

core.

3- Trimming: both end of the plugs and core samples can be

trimmed in order to produce high quality without disturbing the

structure of the sample.

1- Core Slabbing :

Core slabbing is the first step in the preparation of samples for

core laboratory experiments, with the use of saw machine for

cutting rocks into the smaller parts. Figure below shows the core

slabbing machine (Fig. 1).

The machine has a motor which supplies the rotational motion for

sawing. The main machine parts are:

• Radial saw

• Electro motor

• Shaft and pulleys

• Adjustable tilting table

• Cooling system, including pumps, water supply, flexible pipes.

Experiment Operation

The procedure for cutting a given sample is as follows:

• If the rock is big then it should first be cut by another method

• Put the sample on the table

• Check the tension on the pulleys

• Adjust the direction of water line on both saw and sample

• Check water tanks and fill them if they are empty

• Start the water pump and check the direction of water and check

the flow

• Start the saw by pressing the start bottom

• Cut the sample by screwing up and down of the saw and

pushing the sample table of machine

• Press the stop button

• Unclamp the core sample

However, in working with the machine consider the following

safety issues:

(1) Prevent touching of saw with the machine sample table,

because of damaging of saw.

(2) Protect yourself from any splash and water drops by wearing

overall and safety glasses.

2- Plugging using plug drill Press machine :

The core cutting machine is designed to cut cores of between 3 to

6 inches, or from blocks of a similar size. The produced plugs are

in two different size of 1 and 1.5 inches.

Discussion

Q: Why we take the core plugging?

-We take the core plug to determined the physical properties of

the rock like (porosity ,permeability ,saturation ,capillary

pressure ,surface & interfacial tension &…..so on).

Q: What is the target of this experiment?

The target of this experiment is to prepared a core plugging

sample underground in laboratory (rock sample)to know

information of these beds(for ex:

porosity ,permeability ,saturation).

Q: What are the types of core?

Q: What are the objectives of coring?

Result of Experiment

The results from routine core analysis are used in interpretation

and evaluation of the reservoir. Examples are prediction of gas,

oil and water production, definition of fluid contacts and volume in

place, definition of completion intervals. There are other important

measurements with the aim of obtaining the detailed information

about the multiphase flow behavior. This analysis, which is

performed at low sampling frequency due to high cost and more

time due to gathering the data, is called special core analysis.

Special core analysis gives information about the rock wettability,

the distribution of oil, gas, and water in the reservoir (capillary

pressure data).

Reference

1. Andersen, G., 1975, Coring and Core Analysis Handbook:

Tulsa, OK, PennWell Books, 200 p.

2.  Park, A., 1985, Coring, Part 2—core barrel types and uses:

World Oil, v. 200, p. 83–90.

3.  Bradburn, F. R., Cheatham, C. A., 1988, Improved core

recovery in laminated sand shale sequences: Journal of

Petroleum Technology, v. 40, p. 1544–1546., 10.,

2118/18570-PA

4. Toney, J. B., Speiglets, S. L., 1985, Coring, Part 6—sidewall

operations: World Oil, v. 201, p. 29–36.

5. Craft, M., Keelan, D. K., 1985, Coring, Part 7—analytical

aspects of sidewall coring: World Oil, v. 201, p. 77–90.

6. American Petroleum Institute, 1960, RP-40 recommended

practices for core analysis procedures: Dallas, API, 55 p.