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RESERVOIR ENGINEERING LAB

MANUAL

2015-2016

UNIVERSITY OF PETROLEUM & ENERGY STUDIES

DEHRADUN

DEPARTMENT OF PETROLEUM ENGINEERING & EARTH SCIENCES

COLLEGE OF ENGINEERING

UPES Campus Tel: +91-135-2776092-94 Energy Acres Fax: +91 135- 27760904 P.O. Bidholi, Via Prem Nagar Web: www.upes.ac.in

Dehradun -248 007 (U K)

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Reservoir Rock Properties Analysis

COURSE OVERVIEW

INTRODUCTION

LIST OF EXPERIMENTS

EXPERIMENT NO. 1:- To Plug a Core Sample from a Rock Block using Plugging machine and measure diameter of the core sample plugged.

EXPERIMENT NO. 2:- To Trim the Core sample (obtained from plugging machine) using

Trim Saw machine and measure its length.

EXPERIMENT NO. 3: - To Clean the core sample in Soxhletion Extraction Unit

EXPERIMENT NO. 4:- To find the Porosity of the core sample using Helium Porosimeter.

EXPERIMENT NO. 5:- To find the Permeability of the core sample using Liquid Permeameter.

EXPERIMENT NO. 6:- To find the Permeability of the core sample using Gas Permeameter.

EXPERIMENT NO. 7:- To find the Resistivity, formation factor and cementation exponent

of the core sample using EPSA Resistivity Meter. EXPERIMENT NO. 8:- Experiments will be carried out with the given - Graphs so as

to solve particular Numerical Problems in various petroleum engineering disciplines

EXPERIMENT NO. 9:- To find the capillary pressure curve using centrifuge (instrument needs to be checked)

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Course Overview

This course provides an introduction to reservoir rock properties as determined by core

analysis. Part of this course introduces the laboratory equipments as well as the procedures

used for the core analysis. The theoretical aspects of the parameters used in the core analysis

are also briefly described.

The aim of this lab exercise is to get familiar with of the main rock parameters, how they are

measured and the possible sources of errors in the results obtained from the laboratory

measurements. At the end of this course, one will have hands on experience on core plugging,

trimming, cleaning and measuring the porosity, permeability, resistivity and possibly

capillary pressures. These values are needed in reservoir engineering. One would also learn

about errors in measurements.

Introduction

Knowledge of the physical properties of the rock and interaction between hydrocarbons and

the formation rock is crucial in understanding and evaluating the performance of a given

reservoir. This information is usually obtained from two main sources: core analysis and

well logging. In this manual we describe the core analysis. A core is a solid cylinder of rock

about 1, 1.5 or 3 inches in diameter and usually 30 feet in length. It is obtained by replacing

the drill bit by a core bit which is capable of grinding the periphery of the rock keeping

intact the inner core which is retrieved as a heavy cylindrical rock. Once the core is retrieved

it is crucial to properly handle (to avoid breaking and any other kind of damage) the core. It is

preserved 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

by obtaining porosity, permeability, fluid saturations, grain density, resistivity and

mineralogy. 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 fluid contacts

and volume in place, definition of completion intervals and fluid production rates. 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

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to high cost and more time need, 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), residual oil saturation and multiphase flow characteristics (function

of capillary pressure and relative permeability). Measurements of electrical and acoustic

properties, which are mainly used in the interpretation of well logs, are occasionally included

in special core analysis.

The outline of this handout is organized as follows: We first describe the main pre-processing

steps that are considered on the core samples preparation (experiments 1 and 2). In

experiment 3 we describe the core cleaning method, which is required before core analysis

tests, as well as the saturation determination methods. In experiment 4, the porosity

measurement technique is described and the instrument available in the laboratory for the

determination of the core porosity is described. In experiments 5 and 6, we describe the

techniques to measure liquid and gas permeabilities respectively. In experiment 7, we

describe the core sample resistivity measurements. Experiments 8 and 9 are under

construction. The instruments available in the reservoir laboratory and their capabilities are

presented below:

Existing Laboratory Equipments

No. Name of Equipment Application

1

Plugging Machine

To plug a core sample from core specimens of different diameters or from blocks of a similar

size.

2

Trim saw

This machine is a bench model designed to produce fast, high quality sliced samples from

all materials without disturbing the structure of the sample.

3

Helium Porosimeter

To find porosity of core sample using Helium

Porosimeter

4 Liquid Permeameter To find the permeability of given core sample using Liquid Permeameter

5

Gas Permeameter

To find the permeability of given core sample using Gas Permeameter

6

Centrifuge

Determination of capillary pressure at various fluid saturations.

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Electrical Properties system Atmospheric

To find resistivity, formation factor and cementation exponent of core sample.

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EXPERIMENT NO. 1

Aim / Objective:- To Plug a Core Sample from a Rock Block using Plugging machine

and measuring the diameter of the core sample plugged.

Apparatus Used:- Plugging Machine.

Description of Machine

The machine can accommodate cores measuring from 1 (1 inch) to 1.5. A swivel joint with

a tap allow internal irrigation of the core drill and a hose fitted with a tap allows external irrigation of the core drill.

The speed can be adjusted by repositioning the belt (1800 rpm 2500 rpm 3500 rpm) like core slabbing machine.

The machine comprises of:

clamping stand

column

Spindle-Motor unit

adjustable tilting table

protective housing

clamping unit

recycling tank

Table of machine has a rotating capability up to 45. This capability causes that user can make plugs from any part of slab even deviated sides.

Specifications

Features Value

Drilling Capacity (mm) 23

Tapping Capacity (mm) 14

Spindle nose CM2

Quick stoke (mm) 110

Spindle Speeds Variable

Speeds (rd/min) 250-4000

Spindle Motor KW .66/1.1

Column diameter (mm) 100

Distance spindle to Column (mm) 235

Distance spindle to table maxi (mm) 823

Distance spindle to table mini (mm) 110

Distance spindle to ground table (mm) 1225

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Table surface 300300

Figure 1: Core plugging machine

Maintenance of Machine:-

1. Core plug unit

keep the unit and the protective housings clean

remove debris and core particles

remove sludge

clean all moving parts

2. Recycling Tank

change the cooling fluid as soon as it is dirty

make sure that the machine is disconnected

remove the pump and the waste pipe from the recycling tank

empty the tanks

clean the tanks and the separators

fill the tank with cooling fluid

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refit the pump and the waste pipe to the recycling tank

3. Changing the Belt

Make sure that the machine is disconnected

Open the pulley cover

Loosen the 2 clamping screws and the belt tensioning lever

Pinch together the 2 sides of the spindle belt

Change the belts

Tighten the belts with the lever and lock the 2 screws

Close the cover

4. Disassembly of quill spindle

Remove the lowering shaft

Loosen the collar 1

Undo both screws and remove guide pin 3. Hold the quill during this operation

Remove the quill-spindle from its bore

Unscrew and remove the cap 4

Remove nut 5, washer 6 and drive out spindle 8 downwards using a wooden mallet

If necessary, pull out ball bearings 7

T slots (number- dimension- distance) 2/14-200

Height (mm) 1800

Surface on ground 410820

Weight (Kg) 210

Noise level Under 70db (A)

Experiment operation

First Use:-

Check the tension on the pulleys Check the direction of the spindle

Fill the recycling tank Screw down the core drill and lock it in place Mount a core sample and lock it firmly in the clamping unit

Adjust the lower stop on the core drill. 1-2 mm before the end of slab is sufficient for Prevention of plugging the sample in plug driller. Touching of the driller with table

causes severe damage to the driller. Close the core drill protective housing Press the Start button

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Open the irrigation taps Check the flows

Cut the core sample Press the Stop button

Unclamp the core sample

Speed Selection:-

Speed of rotation can be adjusted by changing pulleys. The procedure for this operation is as:

open the pulley cover

loosen the 2 locking screws and pulley tension lever pinch together the two sides of the spindle belt

change the position of the belt tighten the belts with the lever and lock the two screws in place close the cover

If the tension of pulleys is not sufficient then the belt should be changed. The procedure for

changing the belt is as follow:

make sure that the machine is disconnected

open the pulley cover loosen the two clamping screws and the belt tensioning lever pinch together the two sides of the spindle belt

change the belts tighten the belts with the lever and lock the two screws

close the cover

Figure-2:- Plugged Core Sample

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EXPERIMENT NO. 2

Aim / Objective: - To Trim a Core sample (obtained from plugging machine) using Trim Saw machine and measure its length.

Apparatus Used: - Trim Saw Machine

Introduction

After preparing plugs from core drill machine, all of them should be cut into desired size.

This can be done by trimming machine. Trimming machine is a bench model designed to

produce fast, high quality thin sliced samples from all materials without disturbing the

structure of the sample (Fig. 3).

Figure 3: Trimming core plug machine

However, note the following safety notices:

Touching any resinous cutting wheel can be dangerous.

The machine is fitted with safety devices which prevent the wheel from turning when

the hood is open

This machine must only be used by a qualified person who has received the proper

training

required to achieve the quality of cut and the high standard of safety envisaged by the

manufacturer.

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Machine Description:-

The basic model can work either in manual feed or with an optional hydraulic automatic feed

which is driven by the domestic water supply (Minimum pressure 1.5 bars). In the automatic

mode, user can determine the speed of rotation of saws. The machine consists of two radial

saw that can work together and cut both end of pugs simultaneously. Each cuts needs nearly

0.2 litter cooling water. This machine is designed to work with all types of cutting whee l

(resinous - diamond - boron carbide) and various accessories and adaptations enable samples

or core sections to be cut lengthways. These include cradles or devices for holding the

samples configurations using two wheels which allow parallel-sided sections of continuous

length to be cut in a single operation. The machine is fitted with a safety cut-out switch which

can be reset, or rewound should there be no power, as well as a gradual starting device. When

the cover is open this safety switch open the electric current and the machine dont work. The

use of passivated water is strongly recommended to avoid corrosion.

Experiment operation:-

The machine can work in both manual and automatic mode. By setting two lever taps on the

body of machine, three situations are achieved. The lever taps allow the wheel (saw) to

advance or return.

Quick back mode: in this mode the saws go back quickly and positioned at the start

point. This mode can be achieved by setting both taps down.

Stop manual: in this mode user should handle the position of saws for trimming the

plug manually and can be achieved by setting top tap to up and bottom tap to dawn

Automatic feed: in this situation samples are trimmed automatically by the machine.

The rotational speed of the saws can be adjusted by the Movement regulator beside

the lever taps.

Manual mode:-

Steps for operating in manual mode are as follows:

Press the start bottom

Set the taps to " Quick back " position, at the end of the race, the lever is

independent of jack,

Set the taps to the "Manual stop" position.

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Adjust the direction of water line on 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

Close the protective housing of machine

By moving the saws to front start trimming of the sample

Press the Start button

Press the Stop button

Unclamp the core sample

Automatic feed (optional):-

Steps for operating in automatic feed mode are as follows:

Press the start bottom

Set the taps to the " Automatic feed " position

Adjust the direction of water line on 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

Close the protective housing of machine

Gradually open the movement regulator until the required feed rate is obtained.

At the end of the cut, turn the taps to the "Rapid return position.

Press the Stop button

Unclamp the core sample

Maintenance:-

Apart from keeping the machine properly clean, no specific maintenance is required. Make

sure that any sediment or waste matter is removed from the tank before starting. Change the

fluid according to the frequency of use and its deterioration over time (shelf life).

Tools:-

2 Pin wrench (50 mm)

1 Allen key set

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Figure-4:- Trimmed Core plug Sample

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EXPERIMENT NO. 3

Aim/ Objective:- To Cleaning of core sample in Soxhletion Extraction Unit.

Apparatus Used:- Heater, Soxhletion Unit & Rubber pipes

Chemical Used:- Methanol Liquid

Cleaning of core sample

After preparing the core plugs samples, the core samples must be cleaned of residual fluids

and thoroughly dried.

Method of Soxhlet Extraction:-

A Soxhlet extraction apparatus is the most common method for cleaning sample, and is

routinely used by most laboratories. As shown in Fig. 3, Methanol is brought into a slow boil

in a Pyrex flask, its vapors move upwards and the core becomes engulfed in the methanol

vapors (at approximately 65 C). Eventually the amount of water within the core sample in

the thimble will be vaporized. The methanol and water vapors enter the inner chamber of the

condenser; the cold water circulating around the inner chamber condenses both vapors to

immiscible liquids. Recondensed methanol together with liquid water falls from the base of

the condenser onto the core sample in the thimble; the methanol soaks the core sample and

dissolves any oil with which it conic into contact. When the liquid level within the Soxhlet

tube reaches the top of the siphon tube arrangement, the liquids within the Soxhlet tube are

automatically emptied by a siphon effect and flow into the boiling flask. The methanol is then

ready to start another cycle. A complete extraction may take several days to several weeks in

the case of low API gravity crude or presence of heavy residual hydrocarbon deposit within

the core. Low permeability rock may also require a long extraction time

Parts of Soxhlet Unit:-

1: Stirrer bar/anti-bumping granules

2: Still pot (extraction pot) - still pot should not be overfilled and the volume of solvent in the

still pot should be 3 to 4 times the volume of the soxhlet chamber.

3: Distillation path

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4: Soxhlet Thimble

5: Extraction solid (residue solid)

6: Syphon arm inlet

7: Syphon arm outlet

8: Reduction adapter

9: Condenser

10: Cooling water in

11: Cooling water out

Figure- 5:- Parts of Soxhlet Extraction Unit.

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Figure- 6:- The sample is placed in the thimble.

Results

Weight of core sample before experiment= x gms

Weight of core sample after experiment= y gms

Net Weight change_(x-y) gms or ----%

Fluid Saturation = ----%

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EXPERIMENT NO. 4

Aim / Objective:- To find the Porosity of given core sample using Helium Porosimeter.

Apparatus Used:- Porosity meter, Steel Billets, Helium Gas Cylinder & Software loaded computer.

Theory:- From the viewpoint of petroleum engineers one of the most important property of a reservoir

rock is porosity. Porosity is a measure of storage capacity of a reservoir. It is defined as the

ratio of the pore volume to bulk volume, and it may be expressed as either a percent or a

fraction,

= Pore Volume / Bulk Volume= Bulk Volume- Grain Volume/ Bulk Volume

Two types of porosity are total or absolute porosity and effective porosity. Total porosity is

the ratio of all the pore spaces in a rock to the bulk volume of the rock while the effective

porosity e is the ratio of interconnected void spaces to the bulk volume. Thus, only the

effective porosity contains fluids that can be produced from wells. For granular materials

such as sandstone, the effective porosity may approach the total porosity, however, for shale

and for highly cemented or vugular rocks such as some limestone, large variations may exist

between effective and total porosity. Porosity may be classified according to its origin as

either primary or secondary. Primary or original porosity developed during deposition of

the sediment. Secondary porosity is caused by some geologic process subsequent to

formation of the deposit. These changes in the original pore spaces may be created by ground

stresses, water movement, or various types of geological activities after the original

sediments were deposited. Fracturing or formation of solution cavities often will increase the

original porosity of the rock.

Figure- 7:- Cubic packing (a), rhombohedral (b), cubic packing with two grain sizes (c),

and Typical sand with irregular grain shape (d).

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Porosity measurement on core plugs:-

The porosity of reservoir rock may be determined by using core analysis, well logging

technique or well testing. The question of which source of porosity data is more reliable can

not be answered without reference to a specific interpretation problem. These techniques can

all give correct porosity values under favorable conditions. The porosity determined from

core analysis has the advantage that no assumption needs to be made as to mineral

composition, borehole effects, etc. However, since the volume of the core is less than the

rock volume which is investigated by a logging device, porosity values derived from logs are

frequently more accurate in the case of heterogeneous reservoirs.

From the definition of porosity, it is evident that the porosity of a sample of porous material

can be determined by measuring any two of the three quantities: bulk volume, pore volume

or grain volume from core plugs (Fig. 6).

Figure 8:- Representation of the different volumes in a plug

i) Bulk volume:-

Although the bulk volume may be computed from measurements of the dimensions of a

uniformly shaped sample, the usual procedure utilizes the observation of the volume of fluid

displaced by the sample. The fluid displaced by a sample can be observed either

volumetrically or gravimetrically. In either procedure it is necessary to prevent the fluid

penetration into the pore space of the rock. This can be accomplished by:

(1) Coating the sample with paraffin or a similar substance,

(2) Saturating the core with the fluid into which it is to be immersed, or

(3) Using mercury.

Gravimetric determinations of bulk volume can be accomplished by observing the loss in the

weight of the sample when immersed in a fluid or by change in weight of a pycnometer with

and without the core sample.

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ii) Pore volume:-

All the methods measuring pore volume yield effective porosity. The methods are based on

either the extraction of a fluid from the rock or the introduction of a fluid into the pore spaces

of the rock. One of the commonly used methods is the helium technique, which employs

Boyle's law. The helium gas in the reference cell isothermally expands into a sample cell.

After expansion, the resultant equilibrium pressure is measured. The Helium Porosimeter

apparatus is shown schematically in (Fig.- 7).

Figure-9:- Helium Porosimeter apparatus is shown schematically

Helium has the following advantages over other gases:

(1) Its small molecules rapidly penetrate into small pores.

(2) It is an inert gas and does not adsorb on rock surfaces (air may do),

(3) It can be an ideal gas (i.e., z = 1.0) for pressures and temperatures usually used in the test,

(4) It has a high diffusivity so affords a useful mean for determining porosity of low

permeability rocks.

Specifications:-

Working Pressure 90- 110 psi

Working temperature Ambient 25 - 40C

Gas Helium

Connections 1/8" Swagelok type

Transducers Range 16 bar (230 psi)

Power supply 1 Phase 220 VAC +/- VAC. Frequency 50 Hz.

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Installation:-

Connect the Console to:-

Suitable Helium facility, rating up to 100 psi approximately

To the matrix cup.

With Optional PC interface:-

Plug the communication cable to the Pc and the consol

Plug the console to the power supply

Switch on the console and the PC

Start the PC and run application

Check the there is no communication error between the PC and the Console

Calculation

The ratio of Pore volume to the bulk volume is Porosity

Porosity = (Pore Volume) / (Bulk Volume.1

For Sharp cylinders, the bulk volume can be determined from geometrical measurement. The

matrix cup can accommodate irregular core sample. In this case the bulk volume must be

determined from mercury immersion for instance.

Pore volume and grain volume can be determined as follows

Core Samples- any shape. Unconsolidated acceptable

Pore volume- from relation 2

Grain volume- directly

Porosity- from the relation 3

Pore volume = Bulk volume Grain volume.2

Porosity = (Bulk volume Grain volume) / Bulk volume3

Boyle- Mariottes law is used to determine grain and Pore volume from the expansion of a

known mass of helium into a matrix cup.

(Pref*Vref)/Tref = (Pexp*Vexp)/Texp Boyle- Mariottes law

Where:-

Pref = Reference Pressure (initial pressure)

Vref = Reference volume (initial volume)

Tref = Reference absolute temperature (initial temperature)

Pexp = Expended Pressure (final pressure)

Vexp = Expended Volume (final volume)

Texp = Expended Absolute temperature (final temperature)

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The reference cell is pressured to 100 psi.

Vref = Volume of the reference cell and associated piping volume.

At a given moment, the valve H-V02 is opened Expand and then the gas expends into the

matrix cup containing the sample to analyze.

We assume that the temperature remains constant during a series of measurements:

Texp = Tref to simplify the boyle- mariottes law.

The gas expends in the volume Vref and the volume of the matrix cup, reduced by the

volume of the solid (Vgrain):-

Vexp = Vref + (Vmatrix Vgrain)..a

It comes-

PrefVref = Pexp*(Vref + Vmatrix Vgrain).b

In the matrix cup, the gas volume gathers the volume surrounding the core (also named Vdead)

and the Pore volume:

Pref*Vref = Pexp*(Vdead+Vpore) ..c

From relation c we get

Vpore = (Pref/Pexp)*(Vref - Bdead).d

Relation a can be written as

Vgrain = Vref + Vmatrix - Vexp .e

Replacing Vexp from Boyle mariotte's law, it comes

Vgrain = (Vmatrix + Vref). (Pref/Pexp)*Vref .f

Pref and Pexp measured with the Porosimeter. Vref, and

Vmatrix and Vdead are determined using the calibration method provide with the

machine.

Procedure

Initial pressure setting

To set 100 psi accurately:-

Proceed to the following instructions only after a successful tightness test

Switch on the console

Dont connect the matrix cup

Wait for half an hour to get transducer stability

Reset the control valve on the console

Connect the console to the helium facility

Set at 120-150 psi at the facility

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Check that HV01 is open and HV02 is switched to Exaust

Adjust the control valve until getting 100 psi sharp on the application display

In case pressure is too high

a. Close HV01

b. Switch HV02 to expand for 1 second

c. Turn the control valve anticlockwise

d. Open HV01

e. Adjust the control valve to get 100 psi sharp

Watch 2-3 minutes to check that the pressure is OK

Operation

A measurement campaign must follow a calibration sequence. The calibration procedure

exploits the relation f in the reverse way. We have:-

a = - Pref*Vref

x = 1/ Pexp

b = Vmatrix + Vref

We get a linear relation: Vgrain = ax + b where a and b are unknown and x is determined

from the expended pressure measured with the apparatus.

We can generate calibrated grain volumes with reference billits introduced sequentially in the

matrix cup. By running (a minimum of) 2 measures with calibrated billets (Vgrain), we can

determine a and b; c yceeitcep efc epyc i t efc i ec ecye ph efc ei c pdeii ct dp yepeei e

se ii tc g 1/P. for better accuracy it is recommended to run at least 4 experiments.

Shut of Procedure

Bleed off the pressure of Helium at the gas supply

Close HV01

Switch HV02 to exhaust

Set back the billets in the solid case

Result

The Porosity of given core Sample isX %.

Maintenance

Leak Test

1. Switch on the console for 1 hour minimum to get stability

2. Close all the electro valves via APPLILAB interface

3. Set an upstream helium pressure of 120 psi from the facility

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4. Open the manual valve at the console

5. Open the electro valves EV1

6. Adjust the pressure control valve to get exactly 100 psi at the pressure display

7. Close the electro valve EV1

8. Run history to log the pressure and the temperature

9. Wait for half an hour. The pressure reading should be higher than 99 psi for a constant

temperature.

If the Pressure has dropped

10. Switch off the console

11. Unplug the Console from the power supply

12. Proceed to leak detection with an helium detector

13. Fix the leaks

14. Proceed to an new leak test (step 1 to 9) until getting satisfaction.

Figure- 10:- Setup of Porosimeter.

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EXPERIMENT NO. 5

Aim/Objective: - To find the Liquid Permeability of the given core sample using Liquid

Permeameter.

Apparatus Used: - Liquid Permeameter, Brine Saturated Core Plug and 2-Nitrogen

Cylinder.

Theory:-

Permeability is a property of a porous medium which shows the ability of porous media to

transmit fluids. The reciprocal of permeability represents the viscous resistivity. The effective

Permeability of a porous medium is a measure of the rock conductivity to a particular phase

of a multiphase fluid system residing within the porous medium, where the saturation of each

phase is specified. Relative permeability is the ratio of the effective permeability of a

particular fluid phase to some arbitrary reference permeability (i.e. absolute permeability).

Permeability has the unit of m2 in SI system or Darcy in field unit with a conversion factor of

1D 0.98692310-12 m2. Note that a rock sample has a permeability of one meter squared

when it permits 1 m3 /s of fluid of 1 Pa.s viscosity through an area of 1 m2 under a pressure

gradient of 1 Pa/m. Permeability' can be calculated by Darcy's Law, which for liquids under

steady state conditions of viscous or laminar flow may be expressed as:-

K = . .

Where,

K = liquid permeability (Darcies or md)

= viscosity of saturating liquid (Cp)

Q = liquid flow rate (ml/s)

L = length of right cylinder porous medium (cm)

A = cross sectional area of cylinder (cm2)

P = pressure differential across cylinder (Atm)

Calculation

Core dimension: length (cm) is written at column C and D for each sample.

Area (cm2) is obtained from diameter written at column D for each sample.

Viscosity default value for test brine is set to 1. Read the temperature and adjust

QL

AP

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Viscosity by reading Handbook of Chemistry.

Flow rate: Q (ml/s) is calculated time (minutes and seconds) at column F and G to fill

the flask volume (column E).

Differential pressure P (psi) is obtained from direct reading at the console of

upstream pressure P1 because outlet pressure is atmospheric :

P = P1- P2 (atm) = P1 (atm)

The unit conversion (psi to Atm) is automatically made in XLS report.

Figure- 11:- Injection System

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Procedure:-

1. Connect to main supply and Power up the instrument at main switch on the rear panel.

The pressure transducers require an warm up period of about one hour before use.

2. Switch the Source value ON / OFF to OFF position.

3. Ensure that regulators are fully turned anticlockwise initially.

4. Connect two regulated nitrogen supply at the appropriate ports on the rear of the

instrument, i.e. confining pressure supply at valve PRESSURE / VENT (1/8" OD) and

core nitrogen supply at valve on/off (1/8" OD).

5. Initialize the system by filling the dead volume with brine by proceeding without core

in place at first step (confining pressure should NOT be applied)

6. Load the core holder. Different core holders are available for sample diameter of 1",

1.5", 30 mm etc.

7. Regulate confining pressure supply to desired value with out exceeding 400 psi.

Regulate core nitrogen supply without exceeding 100 psi.

8. Turn confining valve PRESSURE / VENT to PRESSURE. Gas at desired pressure is

now applied to the core holder sleeve. This pressure is now displayed on confining

pressure gauge.

MEASUREMENT OF CONSOLIDATED CORES SAMPLE

9. Sample Name/No : 10. Length, L : 11. Diameter, d :

12. Liquid Viscosity; :

P (psi)

Duration, t (sec)

Volume of Liquid

collected

(ml)

Flow rate

(cc/sec)

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Calculation Sheet

q/A P/L K

Result:-

The Liquid Permeability of Given Core Sample is .md.

Maintenance:-

1. Leak test:-

Before starting the unit, a leak test must be performed. PCV cannot be tested because

a built- in vent releases the pressure in absence of flow. For this reason, disconnect the

2 Pressure control valve and plug the downstream the PCV.

2. Instrument calibration:-

For optimum accuracy, pressure transmitter must be calibrated on a regular basis.

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EXPERIMENT NO. 6

Aim/ Objective: - To find the Permeability of given core sample using Gas Permeameter.

Apparatus Used: - Nitrogen Gas, Permeameter.

Introduction:- The Gas perm is a research quality instrument but it can be used for routine core analysis

when rapid sample turnaround and throughput is desirable. A mass flow meter of range 0-500

cc/min with a 0-29 psi relative pressure transmitter are used to sense gas flow and pressure

drop across the sample and therefore provides an accurate determination of permeability,

when the transmitters have been correctly calibrated.

General specification

Max. pressure 100 psig (line pressure)

400 psig (confining)

Operating temperature Room temperature 18- 28 C

DP transducer range 0 8 psid

Flow range (low)- 0 20 cc/min

(high) 0 2,000 cc/min

Connection 1/4 and 1/8 SWAGELOK type

Sample size Dia (according to model) 30 mm 1 11/2

Length 1 to 3

Facility required

Power supply 240- VAC 1 phase + ground 50 Hz / 60 Hz 200 W

Nitrogen supply adjustable up to- 100 psig (line pressure) 400 psig (confining)

Miscellaneous accessories required

Gas operated pressure calibrator (0-100 psig) with small increments.

Soap film flow meters (eg.G.C. accessory) or reference flow meter.

To fit 0 20 cc/min and 0 2,000 cc/min ranges

Stop watch

Caliper

Thermometer- optional

Barometer

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Theory, Calculation and interpretation of steady state results

Theory:- Darcy's law is used for the calculation of permeability, which under steady state conditions

for viscous or laminar flow is:

k = QL/ AP ... (1)

Where:

k = liquid permeability (D standing for Darcies)

= viscosity of saturating liquid (Cp)

Q = liquid flow rate (ml/s) L = Length of right cylinder porous medium (cm)

A = cross sectional area of cylinder (cm2)

The expression for determining the permeability of porous medium to gas is of different from

to that of liquid because of the fact that gas is compressible whereas liquid is not. Gas flows

towards the downstream end of core sample, its pressure decrease, the gas expands and so its

velocity will increase.

The Darcy equation for ideal horizontal laminar flow of gas under steady state isothermal

condition is given by:

kgas = [2ZT (Pb) L (Qb)] / [A(Tb) (P12 P22)].(2)

Where as:-

kgas = permeability to gas (mD)

= gas viscosity (Cp)

Z = mean gas compressibility factor

T = mean temperature of flowing gas

Pb = base or atmospheric pressure (absolute Atm)

L = length of sample (cm)

Qb = atmospheric gas flow rate (cm/s) at base pressure Pb

A = cross sectional area of cylinder (cm2)

Tb = base temperature (ambient)

P1, P2 = upstream and downstream absolute pressure respectively.

Now, if the base temperature equals the mean temperature of the flowing gas and Z is taken

as the unity, which is approximately true for nitrogen under typical operating ambient

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conditions, and since core pressure drop p = P1 P2;and core mean pressure Pm=(P1 + P2)/2

then the equation (2) can be reduced to the less unwieldy expression:

kgas = [(Qb) L (Pb)] / [AP (Pm)]..(3)

Where as:

= gas viscosity (Cp)

Qb = atmospheric gas flow rate (cm/s)

Pb = base or atmospheric pressure (absolute Atm)

P = differential pressure (Atm)

Pm = mean core gas pressure (Atm)

L = length of sample (cm)

A = cross sectional area of cylinder (cm2)

This equation is therefore used to calculate core permeability to nitrogen, under laminar flow

conditions.

Calculation:-

Viscosity for nitrogen is calculated automatically from Sutherlands formula in the

XLS report, depending on temperature during the test.

= o * (a/b) * [(T / To) raised to power 3/2]

Flow rate: Q (ml/s) can be obtained from direct reading at the console.

Core dimension: length (cm) and area (cm2) are obtained form measurements made on

core plug and reported on the XLS report tab INFO respectively at column C and D

for each sample.

Ambient pressure: Pb (atm) can be obtained from measurement of the atmospheric

pressure on a barometer (psi) and reported on XLS report tab CONTROL at line 5,

column B.

Differential pressure DP (psid) is the difference between core upstream P1 and

downstream P2 pressure across the core.

P = P1-P2 (atm)

For P less than 8 psid, differential pressure is given directly from the DP transducer suitably

corrected for any zero shifts. Unit conversion (psi Atm) is automatically made in the XLS

report.

If no back pressure is used, then: P1 = P (psid) / 14.695949 + Pb (atm) and

P2 = Pb (atm), this takes advantage that DP reading is more accurate than

P1 = reading (3 decimals instead of 2).

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If back pressure is used, then P1 = [P1(psig)/140695949] + Pb(atm) and

P2 = [P1(psig) P (psid)]/ 14.695949 + Pb(atm).

Core mean pressure Pm is found from Pm = (P1 + P2) /2 (atm) where P1 and P2 are

calculated as in stage above.

Interpretation of results:-

Klikenberg (1) noted that gas permeability decreased as the mean gas pressure in cores

increased, and found that the gas permeability of a core was always higher than its

permeability to a single saturating inert liquid.

If the gas permeabilities obtained at different mean core pressures are plotted against

reciprocal mean pressure (1/Pm), a straight line should be able to be drawn through the

points. Extrapolation of this line to infinite mean pressure (i.e. zero reciprocal pressure)

intersects the gad permeability axis. The intersections points correspond to the liquid

permeability and may be found from:

KL = Kg/ [1+ (b/ Pm)]

Where-

KL = theoretical liquid permeability

b = Klikenberg correction factor. The slope of the line is given by bKL

The factor b is different for different gases and decreases as the liquid permeability increases.

Sample operation:-

Sample selection

The core sample used in the Gas perm must be right cylinder with end faces perpendicular to

the core axis with a diameter close to 25 (1) or 38 mm (1") according to version in use.

Core with uneven or irregular ends or with diameter significantly less than nominal might

cause the sleeve to rupture when confining pressure is applied.

Core holder selection

Check that the sample is of suitable diameter 1 or 1.5" according to core holder installed. To

change the core holder, release the overburden pressure, then disconnect the confining SS

tubing from the core holder. Disconnect and remove the inlet and outlet flexible tubing.

Installing core holder is reverse procedure.

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Removing a core sample

To remove the core sample, firstly ensure that the flow system and confining system has been

depressurised: switch the valve ON OFF to OFF position, switch the valve DP ON / DP OFF

to OFF. Release the confining pressure by switching PRESSURE / VENT to VENT.

Slacken the adjustment screw slightly turning the screw anti-clockwise about a quarter turn,

and pull back the SS connection tube from the core face.

Pull on the outer knurled ring then rotate a quarter turn until the end platen component is

freed. The quick release end should be able to be easily removed. If the core does not come

on the bottom platen, help by pushing the top platen. Be careful not to use too much force

initially just sufficient to free the core from the sleeve.

Loading a core sample

Place the core in the core holder and push it with the quick release end plug until it

butts against the adjusting platen.

Replace the quick release en platen by lining up the male clover leaf component with

the corresponding female component.

Now, push the inner knurled ring forward and rotate the ring clockwise until it locates

in position

If the length of the sample is longer than the previous sample, you may encounter resistance

when inserting the end platen. Turn the adjusting screw anticlockwise, and pull back on the

SS junction tube until the quick release en platen ca be easily inserted. The adjusting screw

should now be turned clockwise until the other end platen contact the core face. This is all

that is required to ensure a pressure seal. Never attempt to over tighten the adjustment screw.

When properly engaged, the quick release end neither this platen nor the adjustable end

platen will be able to be moved. In case the platen can be moved, dismount the adjusting

platen and insert the bronze spacer provided with the core holder.

Note: the adjusting screw thread should be totally engaged in the body. If is not the case, the

sample is too long and not acceptable for test in the Gas perm.

Do not attempt to finally, switch the valve PRESSURE / VENT to PRESSURE to set the

confining pressure.

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Instrument operation procedures:-

Initial procedure

Connect to main supply and power up the instrument at main switch on the rear panel.

The pressure transducers require a warm up period of about one hour before use.

Switch the source valve ON / OFF to OFF position.

Ensure that regulators are fully turned anticlockwise initially.

Connect two regulated nitrogen supply to the appropriate ports on the rear of the

instrument, i.e. confining pressure supply at valve PRESSURE / VENT (1/8" OD) and

core nitrogen supply at valve ON / OFF (1/4 OD). 100 psig connection for flowing

gas. Fitting " OD.

Set the valve to OFF position before connection.

Load the core holder. Different core holders are available for sample dia. of 1, 1 ,

30 mm etc.

Regulate confining pressure nitrogen supply to desired value registered on supply

cylinder gauge. Regulate core nitrogen supply using cylinder regulator to just above

desired maximum test pressure (without exceeding 220 psi).

Turn confining valve PRESSURE / VENT to PRESSURE. Nitrogen at desired

pressure is now applied to the core holder sleeve. This pressure is now displayed on

confining pressure gauge.

Result

The Gas Permeability of given Core Sample ism Darcy.

Maintenance

Leak test

Before starting the unit, a leak test must be performed. PCV cannot be tested because a built-

in vent releases the pressure in absence of flow. For this reason, disconnect the 2 Pressure

Control Valves and plug the unit downstream the PCV.

When the second stage leak test is OK rotate the switch valves to check all sections. In the

above illustration, we display a satisfactory pressure ramp (the scales are magnified to check

the leak rate.

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EXPERIMENT NO. 7

Aim/ Objective: - To find out Resistivity, formation factor and cementation exponent of

given core sample in (EPSA) Resistivity Meter.

Apparatus Used: - Resistivity Meter, Compressor or Air Cylinder

Introduction Core Resistivity measurements, together with porosity and resistivity of connate water is

used for calculation of water saturation, in porous volume of reservoirs; consequently

hydrocarbon content can be calculated by difference. This information is essential for proper

management of reservoir.

Machine Description:

The system includes:

An atmospheric Electrical Core Holder

An ambient Brine Resistivity cell

A RFL meter (Fluke make)

The apparatus consists of:

1. A plastic cover which contains the electrodes and the sample during

measurement.

2. Two electrodes, one fixed, one movable to enable measurements on cores of

size 2" to 3".

3. A piston and integral valve to facilitate the movement and ensure repeatable

contact pressure on the electrodes.

4. Connectors and cables for connection to the RFL measuring device.

5. A special plug for connection trimming (for 1" and 1" diameter samples)

Figure-12:- Illustration of core sample loading

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Figure 13: Illustration of system under locked pin and tighten the knob

Theory and Calculation

1. Phenomenon involved

In brine, the electrical conduction relies on the transport of ions, predominantly sodium, Na

f- , and chloride, (1- , ions. The core samples saturated or partially saturated with brine are

conductive through the connate brine

In rock with open, well connected pore paths filled with brine, ion flow occurs easily

and resistivity (Rw) is low.

Rocks with sinuous, constricted pore paths hinder ion transport and have higher

resistivity.

2. Resistivity (Ro)

Ro = R. (A/L) = (V /I).(A/L)

Where:-

R is the core resistance (Ohm or n)

A is the core cross section (m2)

L is the core length (m)

V is the potential (Volt) between the 2 electrodes

I is the current (Amp) going through the core.

3. Formation Factor (Fr)

Fr = Ro/Rw

Where:

Ro is the core resistivity (Ohm. m or n. m) at 100% brine

saturation and Rw is the brine resistivity (Ohm. m or n. m)

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4. Cementation Exponent (m)

Fr = a -m

Where:

a is the Archie's coefficient (unit less)

is the core porosity (unit less)

m is the cementation exponent (unit less)

For a tank of water, Ro = Rw. Therefore Fr = 1.

If porosity is zero, Fr is 0 and both a and m can have any value.

However, for real rocks, both a and m vary with grain size, sorting, and rock texture. The

normal range of a is.5 to l.5 and for mis 1.71:0 about 3.2.

Finally, a is commonly taken equal to 1 and ma can be expressed as:

m = -[In(Fr)/Ln()]

5.Determination of Archie constant a

Most of time Archie constant is taken as equal to one. When you have samples of various

porosity from the same field formation, it is possible to determine accurately the value of a.

For each sample, measure Fr = Ro/Rw and then plot the Fr versus porosity obtained from he

same field formation.

Using XLS trend facility (add trend line/Power/ display equation) fit this data with a curve of

type Fr = a ( raised to power -m)

6.Resistivity Index (Ir), Saturation

Ir = Rt/Ro = Sw raised to power -n

Where

Rt is the core resistivity (ohm. m or n. m)

Ro is the core resistivity (ohm. m or n. m) at 100% brine

saturation

Sw is the core saturation (unit less)

n is the saturation exponent (unit less)

And then, Saturation Exponent can be expressed as:

n == - [Ln (lr) / Ln (Sw)]

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Procedure

Sample loading

1. Ensure the piston is fully retracted. Wet 2 pads with test brine.

2. Stick them on the electrode plates respectively.

3. Take a core sample from the brine and roll it once over paper towel to

remove surface brine.

4. Lie and balance the core sample on the seat.

5. Rotate the piston switch to actuate the cylinder; this will cause the core

sample to be firmly held between the 2 pads.

6. Topple the electrode set on the sample and dose the lid over the sample to

prevent evaporation of the liquid from the sample.

7. Close-up for correct loading.

Adjustment for small length sample

1. For small length samples, lift one of the cradles and insert back in order

to reduce the supports distance. 2. If the pins are not on the 'sample because the sample is too short; then we

can use the 2 leads pattern.

Sample unloading

After measurement, retract the cylinder by rotating the valve command in

the appropriate direction. Open the lid and the electrode. In case that the

measure series is completed or in case that the next measurement

concerns different brine, carefully dry the electrode and operate with new

wet pads.

Dip Cell

Description: The dip cell consists of a probe with electrodes embedded.

It must be completed with a thermometer to dip close to the Dip Cell in

a beaker.

Connection: Plug the connector to the RCL meter in respect of the red dot

orientation (on top of the connector).

Calibration and measure

Result

The value of Archie's constant is. .

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Maintenance

As with most systems operated with brines the most important consideration is ensuring

the brine doesn't corrode the metals or crystallize in the apparatus. Therefore all the cells

which have been in contact with brine should be flushed thoroughly with distilled water

and then dried with a cloth after use.

EPSA

If the electrode plate is partially covered with o ld pad deposit then remove

the pad and rub it with new wet pad.

Dip cell-

If the measure is not possible, check the junction cable. For this purpose,

disconnect the cable from the RCL meter. Now, check each of the 4 leads.

Repair or order another cable.

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EXPERIMENT NO. 8 (Under Development)

Aim / Objective:-

These experiments will be carried out with the given - Graphs so as to solve particular

numerical problems related to specific objectives on various topics given below:-

1. Reservoir Modeling & Simulation

2. Basic Reservoir Engineering

3. Production Engineering

4. Drilling Engineering

5. Well Stimulation

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EXPERIMENT NO. 9 (Under Development)

Aim / Objective:-

To calculate the capillary pressure curve using centrifuge.