effect of carbon dioxide gas kick in oil base mud. project (2)

8/16/2019 Effect of Carbon Dioxide Gas Kick in Oil Base Mud. Project (2)

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Efect O Carbon dioxide Gas Kick in Oil Base Mud.

INTRODUCTION.

Formation kick: A Kick is an entry of water, gas, oil, or other formation fluid into the wellbore

during drilling. It occurs because the pressure exerted by the column of drilling fluid is not greatenough to overcome the pressure exerted by the fluids in the formation drilled. The downhole

fluid pressures are controlled in modern wells through the balancing of the hydrostatic

pressure provided by the mud used. Should the balance of the drilling mud pressure be incorrect

then formation fluids oil, natural gas and!or water" begin to flow into the wellbore and up the

annulus the space between the outside of the drill string and the walls of the open hole or the

inside of the last casing string set", and!or inside the drill pipe. This is commonly called a kick . If

the well is not shut in common term for the closing of the blow#out preventer valves", a kick can

$uickly escalate into a blowout when the formation fluids reach the surface, especially when the

influx contains gas that expands rapidly as it flows up the wellbore, further decreasing the

effective weight of the fluid.

Additional mechanical barriers such as blowout preventers %&'s" can be closed to isolate the

well while the hydrostatic balance is regained through circulation of fluids in the well.

A kick can be the result of improper mud density control, an unexpected overpressured gas

pocket, or may be a result of the loss of drilling fluids to a formation called a thief zone. If the

well is a development well, these thief (ones should already be known to the driller and the

proper loss control materials would have been used. )owever, unexpected fluid losses can occur

if a formation is fractured somewhere in the open#hole section, causing rapid loss of hydrostatic

pressure and possibly allowing flow of formation fluids into the wellbore. Shallow overpressured

gas pockets are generally unpredictable and usually cause the more violent kicks because of

rapid gas expansion almost immediately. *arly warning signs of a well kick are+

• Sudden change in drilling rate

• -hange in surface fluid rate

• -hange in pump pressure

http://oilgasglossary.com/formation-fluid.htmlhttp://oilgasglossary.com/formation-fluid.htmlhttp://oilgasglossary.com/drilling-fluid.htmlhttp://oilgasglossary.com/formation.htmlhttp://oilgasglossary.com/formation.htmlhttp://oilgasglossary.com/drilling-fluid.htmlhttp://oilgasglossary.com/formation.htmlhttp://oilgasglossary.com/formation-fluid.html


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• eduction in drillpipe weight

The primary means of detecting a kick is a relative change in the circulation rate back up to the

surface into the mud pits. The drilling crew or mud engineer keeps track of the level in the mud

pits and!or closely monitors the rate of mud returns versus the rate that is being pumped down

the drill pipe. /pon encountering a (one of higher pressure than is being exerted by the

hydrostatic head of the drilling mud at the bit, an increase in mud returns would be noticed as the

formation fluid influx pushes the drilling mud toward the surface at a higher rate. -onversely, if

the rate of returns is slower than expected, it means that a certain amount of the mud is being lost

to a thief (one somewhere below the last casing shoe. This does not necessarily result in a kick

and may never become one" however, a drop in the mud level might allow influx of formation

fluids from other (ones if the hydrostatic head at depth is reduced to less than that of a fullcolumn of mud.

The material of which a petroleum reservoir rock may be composed can range from very loose

and unconsolidated sand to a very hard and dense sandstone, limestone, or dolomite. The grains

may be bonded together with a number of materials, the most common of which are silica,

calcite, or clay. Knowledge of the physical properties of the rock and the existing interaction

between the hydrocarbon system and the formation is essential in understanding and evaluating

the performance of a given reservoir. ock properties are determined by performing laboratory

analyses on cores from the reservoir to be evaluated. The cores are removed from the reservoir

environment, with subse$uent changes in the core bulk volume, pore volume, reservoir fluid

saturations, and, sometimes, formation wettability. The effect of these changes on rock properties

may range from negligible to substantial, depending on characteristics of the formation and

property of interest, and should be evaluated in the testing program.

Since the inception of rotary drilling operations, the occurrence of abnormal formation pressure

that can lead to a kick and subse$uent blowout has plagued the oil!gas well drilling industry.

Functions of a Drilling Fluid.

0rilling fluid or mud is a vital component in the rotary drilling process. 1ost of the problems

encountered during the drilling of a well can be directly or indirectly attributed to the mud. 0ue

to the complexities to treating, monitoring and conditioning the mud, an operating company will


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usually hire a service company to provide a drilling fluid specialist mud engineer" on the rig.

The cost of the mud and the chemical additives may fairly high around 234 of the total well

cost". Although this may seem expensive, the conse$uences of not maintaining good mud

properties may prove much more expensive in terms of drilling problems. 0rilling fluid functions

describe tasks which the drilling fluid is capable of performing, although some may not be essential on

every well. emoving cuttings from the well and controlling formation pressures are of primary

importance on every well. Though the order of importance is determined by well conditions and current

operations, the most common drilling fluid functions are+

22. Remove cuttings from the well+ As drilled cuttings are generated by the bit, they must be

removed from the well. To do so, drilling fluid is circulated down the drill string and through the

bit, entraining the cuttings and carrying them up the annulus to the surface. -uttings removal

hole cleaning" is a function of cuttings si(e, shape and density combined with ate of'enetration &'" drill string rotation, and the viscosity, density and annular velocity of the

drilling fluid. The viscosit and rheological properties of drilling fluids have a significant effect

on hole cleaning. -uttings settle rapidly in low#viscosity fluids water, for example" and are

difficult to circulate out of the well. 5enerally, higher# viscosity fluids improve cuttings

transport. )igh#densit fluids aid hole cleaning by increasing the buoyancy forces acting on the

cuttings, helping to remove them from the well. -ompared to fluids of lower density, high#

density fluids may clean the hole ade$uately even with lower annular velocities and

lower rheological properties. )owever, mud weight in excess of what is needed to balance

formation pressures has a negative impact on the drilling operation therefore, it should never be

increased for hole#cleaning purposes.

26. Control formation !ressures: As mentioned earlier, a basic drilling fluid function is to

control formation pressures to ensure a safe drilling operation. Typically, as formation pressures

increase, drilling fluid density is increased with barite to balance pressures and maintain wellbore

stability. This keeps formation fluids from flowing into the wellbore and prevents pressured

formation fluids from causing a blowout. The pressure exerted by the drilling fluid column while

static not circulating" is called the hydrostatic pressure and is a function of the density mud

weight" and True 7ertical 0epth T70" of the well. If the hydrostatic pressure of the drilling

fluid column is e$ual to or greater than the formation pressure, formation fluids will not flow

into the wellbore.


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"#. $us!end and release cuttings: 0rilling muds must suspend drill cuttings, weight materials

and additives under a wide range of conditions, yet allow the cuttings to be removed by the

solids#control e$uipment. 0rill cuttings that settle during static conditions can cause bridges and

fill, which in turn can cause stuck pipe or lost circulation. 8eight material which settles is

referred to as sag and causes a wide variation in the density of the well fluid. Sag occurs most

often under dynamic conditions in high#angle wells, where the fluid is being circulated at low

annular velocities.

"%. $eal !ermea&le formations: 'ermeability refers to the ability of fluids to flow through porous

formations formations must be permeable for hydrocarbons to be produced. 8hen the mud column

pressure is greater than formation pressure, mud filtrate will invade the formation, and a filter cake of

mud solids will be deposited on the wall of the wellbore. 0rilling fluid systems should be designed to

deposit a thin, low#permeability filter cake on the formation to limit the invasion of mud filtrate.This improves wellbore stability and prevents a number of drilling and production problems. 'otential

problems related to thick filter cake and excessive filtration include 9tight: hole conditions, poor log

$uality, increased tor$ue and drag, stuck pipe, lost circulation, and formation damage.

"'. (aintain well&ore sta&ilit: 8ellbore stability is a complex balance of mechanical

pressure and stress" and chemical factors. The chemical composition and mud properties must

combine to provide a stable wellbore until casing can be run and cemented. egardless of the

chemical composition of the fluid and other factors, the weight of the mud must be within the

necessary range to balance the mechanical forces acting on the wellbore formation pressure,wellbore stresses related to orientation and tectonics". 8ellbore instability is most often

identified by a sloughing formation, which causes tight hole conditions, bridges and fill on trips.

This often makes it necessary to ream back to the original depth. Keep in mind these same

symptoms also indicate hole cleaning problems in high#angle and difficult#to#clean wells."

"). (inimi*e reservoir damage: 'rotecting the reservoir from damage that could impair

production is a big concern. Any reduction in a producing formation;s natural porosity or

permeability is considered to be formation damage. This can happen as a result of plugging by

mud or drill solids or through chemical mud" and mechanical drilling assembly" interactions

with the formation.


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usually allows efficient production, even if near#wellbore damage exists. -onversely, when a

hori(ontal well is completed with one of the 9open hole: methods, a 9reservoir drill#in: fluid =

specially designed to minimi(e damage = is re$uired. 8hile the effect of drilling fluid damage

is rarely so extensive that oil and!or gas cannot be produced, consideration should be given to

potential formation damage when selecting a fluid for drilling potential reservoir intervals.

"+. Cool, lu&ricate, and su!!ort the &it and drilling assem&l: -onsiderable frictional heat is

generated by mechanical and hydraulic forces at the bit and where the rotating drill string rubs

against the casing and wellbore. -irculation of the drilling fluid cools the bit and drilling

assembly, transferring this heat away from the source, distributing it throughout the well. 0rilling

fluid circulation cools the drill string to temperatures lower than the bottom#hole temperature. In

addition to cooling, drilling fluid lubricates the drill string, further reducing frictional heat. %its,

mud motors and drill string components would fail more rapidly if it were not for the cooling andlubricating effects of drilling fluid. The lubricity of a particular fluid is measured by its

-oefficient of


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conditions after drilling also influence formation evaluation. 0uring drilling, the circulation of

mud and cuttings is monitored for signs of oil and gas by technicians called mud loggers.

"1. Facilitate cementing and com!letion: The drilling fluid must produce a wellbore into

which casing can be run and cemented effectively and which does not impede completion

operations. -ementing is critical to effective (one isolation and successful well completion.

0uring casing runs, the mud must remain fluid and minimi(e pressure surges so that fracture#

induced lost circulation does not occur. unning casing is much easier in a smooth, in gauge

wellbore with no cuttings, cavings or bridges. The mud should have a thin, slick filter cake. To

cement casing properly, the mud must be completely displaced by the spacers, flushes and

cement.

In summary recommending a drilling fluid system should be based on the ability of the fluid to

achieve the essential functions and to minimi(e anticipated well problems. Although thefunctions discussed in this chapter may provide guidelines for mud selection, they should not be

the sole basis for selecting a drilling fluid for a well. The selection process must be founded on a

wide experience base, local knowledge and consideration of the best technology available.

Com!osition of Drilling Fluid.

a" 8ater#based muds+ consist of a mixture of a solids, li$uids, and chemicals. some solids clay"

react with the water and chemicals in the mud and are called 9active solids:. The activity of

these solids must be controlled in order to allow the mud to function properly. The solids, which

do not react within the mud, are called 9inactive: or inert solids e.g. %arite". fresh water is used

as the base for most of these muds, but in offshore drilling, salt water is more readily available.


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b" &il# based muds+ are similar in composition to water#based with the exception that thecontinuos phase is oil. In an invert emulsion mud, water may make#up a large percentage of the

volume, but oil is still the continuos phase. The water is dispersed throughout the system as

deoplets"


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below.

a3 (ud Densit

This is an important parameter, which determines the hydrostatic pressure exerted by the

mud column. a sample of mud is weighed in a mud balance usted until the arm is level. The

density can be read directly off the graduated scale at the left#hand side of the rider. 1ud

densities are usually reported to the nearest 3.2 ppg lbs per gallon". &ther units in common use

are lbs!ft, psi!2333ft, kg!2 and specific gravity S.5."

&3 4iscosit

In general terms viscosity is a measure of the li$uid;s resistance to flow. Two common methods

are used on the rig site to measure viscosity namely.i) Marsh funnel + This is a very $uick test, which only gives an indication of viscosity and not an

absolute result. the funnel is a standard dimension 26: long, C: diameter at the top. 6: long tube

at the bottom, !2C: diameter". A mud sample is poured into the funnel and the time taken for

one $uart DBC ml" to flow out into a measuring cup is recorded.


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Hield 'oint H'" G θ33 # '7 lb!233 ft6"

'lastic viscosity can be though of as part of the flow resistance caused my mechanical friction

i.e., solids content". Hield point is that component of resistance caused by electrochemical

attraction within the mud while it is flowing.

c3 5el $trength

A third property to describe the attractive forces while the mud is static is called gel strength. It

can be thought of as the stress re$uired to get the mud moving. the gel strength can be measured

using the viscometer. After the mud has remained static for some time 23 secs" the rotor is set as

a low speed rpm" and the deflection noted. This is reported as the 9initial or 23 second gel:.

The same procedure is repeated after the mud remains static for 23 minutes, to determine the 923

minute get:. %oth gels are measured in the same units as Hield 'oint lbs!233ft 6". 5el strength

usually appears on the mud report as two figures e.g. 2F!6F. The first being the initial gel and

the second is the 23 minute gel.

d3 Filtration

The wall#building properties of the mud can be measured by means of a filter press. This test

measures+

i" The rate at which fluid from a mud sample is forced through a filter under

specified temperature and pressure.

ii" The thickness of the solid residue deposited on the filter paper caused by the lossof fluids.

The instrument consists of a mud cell, pressure assembly and filtering device. the

A'I standard test is at room temperature F33 psi, 33


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e3 $and Content

The percentage of sand in the mud is measured by using a 633 mesh sieve and a graduated tube.

The glass measuring tube is filled with mud up to the scribe line. 8ater is then added up to the

next scribe line. the fluids are mixed by shaking and then poured through the sieve. the sand

retained on the sieve should be washed thoroughly to remove the remaining mud. A funnel isfitted to the top of the sieve and the sand is washed into the glass tube by a fine spray of water.

After allowing the sand to settle, the sand content can then be read off directly as a percentage.

f3 6i0uid and $olid Content

A carefully measured sample of mud is heated in a retort until the li$uid components are

vaporised. the vapours are then condensed, and collected in the measuring glass. The volume of

li$uids oil and !or water" is read off directly as a percentage. The volume of solids suspended

and dissolved" is found by subtration from 2334.

g3 !7 Determination

The p) test is a measure of the concentration of hydrogen ions in a$ueous solution. this

can be done either by p)ydrion paper or by a special p) meter. The p) paper will turn to

different colours depending on the concentration of hydrogen ions. a standard colour chart can

be used to read off the p) to the nearest 3.F of a unit on a scale of 3 to 2B". 8ith a p) meter,

the probe is simply placed in the mud sample and the reading taken after the needle stabilises

make sure probe is washed clean before use". The meter gives a more accurate result to 3.2 of a

unit.

h3 8lkalinit

Although p) gives an indication of alkalinity, it has been observed that the characteristics of a

high p) mud can vary considerably despite constant p). A further analysis of the mud is usually

carried out to assess the alkalinity. the procedure involves taking a small sample, adding

phenolphthalein indicator and titrating with acid until the colour changes. The number of ml of

acid re$uired per ml of sample is reported as the alkalinity. 'f G filtrate alkalinity, 'm G mud

alkalinity". Another parameter related to 'f and 'm is lime content. This can be calculated from+

?ime -ontent G 3.6C 'm #


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Car&on dio9ide chemical formula CO" is a chemical compound composed of

two oxygen atoms covalently bonded to a single carbon atom. It is a gas at standard temperature

and pressure and exists in *arthJs atmosphere in this state. -&6 is a trace gas comprising 3.3D4

of the atmosphere.

'hysical 'roperties of -arbon dioxide.

2. -arbon dioxide is colorless, odourless and tasteless gas.6. It is denser than air . ected in the reservoir, it reacts with the formation water to form

carbonated acid, it affects the reservoir property rock. Simulations of the interaction between

formation water, source rocks and reservoir rocks suggest that the carbonate content of the

http://en.wikipedia.org/wiki/Chemical_formulahttp://en.wikipedia.org/wiki/Chemical_compoundhttp://en.wikipedia.org/wiki/Oxygenhttp://en.wikipedia.org/wiki/Atomhttp://en.wikipedia.org/wiki/Atomhttp://en.wikipedia.org/wiki/Covalent_bondhttp://en.wikipedia.org/wiki/Covalent_bondhttp://en.wikipedia.org/wiki/Carbonhttp://en.wikipedia.org/wiki/Carbonhttp://en.wikipedia.org/wiki/Carbonhttp://en.wikipedia.org/wiki/Gashttp://en.wikipedia.org/wiki/Standard_temperature_and_pressurehttp://en.wikipedia.org/wiki/Standard_temperature_and_pressurehttp://en.wikipedia.org/wiki/Standard_temperature_and_pressurehttp://en.wikipedia.org/wiki/Standard_temperature_and_pressurehttp://en.wikipedia.org/wiki/Earth's_atmospherehttp://en.wikipedia.org/wiki/Trace_gashttp://en.wikipedia.org/wiki/Trace_gashttp://en.wikipedia.org/wiki/Chemical_formulahttp://en.wikipedia.org/wiki/Chemical_compoundhttp://en.wikipedia.org/wiki/Oxygenhttp://en.wikipedia.org/wiki/Atomhttp://en.wikipedia.org/wiki/Covalent_bondhttp://en.wikipedia.org/wiki/Carbonhttp://en.wikipedia.org/wiki/Gashttp://en.wikipedia.org/wiki/Standard_temperature_and_pressurehttp://en.wikipedia.org/wiki/Standard_temperature_and_pressurehttp://en.wikipedia.org/wiki/Earth's_atmospherehttp://en.wikipedia.org/wiki/Trace_gas


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source rock not only influences the chemical reactions in the system, but also affects the

overall porosity and permeability of the reservoir rock itself. It also affects the wettability of

the phase of the rock.

6IT/R8TUR/ R/4I/;.

1ost of the drilling operation problems are closely related to improper mud conditioning.


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in poor agreement. This is because of the inade$uate assumption of the gas bubble distribution in

the annulus.

Rader et al+ conducted experiments on the behavior of a single large gas bubble in the annulus.

Their work claimed to have revealed some valuable factors that affect a single bubble rise. Thesefactors include the shape profile of the single bubble in annulus and, the non#linear trend of the

observed rates of casing pressure rise during well shut#in as opposed to constant rate of casing

pressure rise being predicted and used by the existing gas kick models. They found that the

assumption of bullet shape of a single bubble migrating upward in an annulus is incorrect.

Instead, a shape that resembles a 9bent hot dog bun: was observed to exist in the annulus for a

large single bubble. The degree of curvature of such a single large bubble has been observed to

be dependent on the viscosity of the li$uid or mud. -onse$uently, a shape correction factor was

incorporated into the various correlations developed for air#water flow in cylindrical tubes to

describe the flow of air in drilling fluid. In order to >ustify their observations of non#linearity of

the rate of shut#in casing pressure rise, they assumed that the gas kick initially exists as single

bubble at the bottom of the hole. Afterwards, the single bubble starts to break into numerous

slugs of gas as the upward migration continues during well shut#in. This speculation was used as

a line of defense for the poor agreement between their results and field cases.

(athews+ utili(ed a similar approach as Rader et al +, but his study Schematic representation

of the top view of a 9bent: shaped single bubble in the annulus containing viscous fluid

(athews + also resulted in poor agreement between the results from the model and field cases.

-1 performed an analytical study on the transient behavior of li$uid!gas flow

system. The study incorporates some sets of transient mass# and momentum#balance e$uations

that relate gas and mud densities gas void volume" fraction gas and mud velocities and,

pressure and temperature. These e$uations are based on vertical#hole geometry, and one#

dimensional flow analysis. The semi#empirical correlation developed for the gas slip velocity of

the airwater systems, and single# and two#phase frictional relationships were included in the

analysis. )e emphasi(ed the importance of considering the possible influx of considerable

amount of gas after the %&' and choke have been closed. )e also stated that accurate knowledge


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of gas distribution pattern in the annulus helps to ade$uately analy(e gas behavior during well

shut#in and kick control. In light of this, he assumed three cases of different combination of &'

and formation permeability. *ach of these cases was assumed to result in a uniform bubble si(e

distribution of gas in the annulus rather than a single bubble. )owever, no >ustification was

provided that these cases would actually produce discretely distributed gas flow. 0espite all the

inade$uacies, the results showed a better agreement because of the assumed discretely

distributed bubbly gas flow pattern.


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there are glaring variations in the slip velocity of gas bubbles in the two#phase region. That is, as

the gas volume or gas void fraction increases, the bubble slip velocity increases. )owever, when

they plotted the mean gas velocity against the homogeneous velocity for gas void fractions of

higher value than E.F4, a constant gas slip velocity value resulted. This clearly shows

inconsistency in the analysis of the experimental observations.

Otake et al"1 conducted a comprehensive experimental study using high speed

cinematography to monitor the #0 movements of a single bubble, and an isolated bubble from a

swarm of bubbles.


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most sensitive means of early kick detection because of the slower rates at which other

parameters change.

C782T/R T7R//

(/T7ODO6O5@.

Oil =ased (ud: An oil#based mud is the one where the continuous phase is oil . Since the

2D3s is has been recognised that better productivity is achieved by using oil rather than water as

the drilling fluid. Since the oil is native o the formation it will not damage the pay (one byfiltration to the same extent as would a foreign fluid such as water. -rude oil was first used to

drill through the pay (one, but it suffered from several disadvantages low get strength, limited

viscosity, safety ha(ard due to low flash point". 1odern oil#based muds use refined oils diesel,

kerosene, fuel oils" and a variety of chemical additives to build good mud properties. The oil in

the drilling fluid does have several disadvantages.

i" )igher initial cost

ii" 1ore stringent pollution controlsiii" educed effectiveness of some logging tools resistivity logs"

iv" 0etection of kicks more difficult due to gas solubility in diesel

)owever for some applications oil#based muds are very cost effective. These include

i" To drill and core pay (ones

ii" To drill troublesome formations e.g. shale, salt"


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iii" To add lubricity in directional drilling preventing stuck pipe"

iv" To reduce corrosion

v" As completion fluid during perforating and work over"

There are two types of oil#based muds in common use.

i"


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Fig. 1.1: A 4-Scale Metal Mud Balance with Carrying Case.

Cali&ration

2.


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(aintenance

2.


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2. )old the funnel in an upright position with index finger over the outlet.

6. 'our the test sample through the screen on top of the funnel until mud level >ust reaches the

underside of the screen.

. Immediately remove finger from the outlet tube and measure number of seconds with astopwatch" for a $uart of the sample to run out.

(aintenance

2. -lean and dry thoroughly after each use.

Results

2. eport the funnel viscosity in seconds sec" A'I.

=. Rotar 4iscometer

The otary 7iscometer determines the flow characteristics of oils and drilling fluids in terms ofshear rate and shear stress over various time and temperature ranges at atmospheric pressure.

Speeds are easily changed with a control knob, and shear stress values are displayed on a lighted

magnified dial for ease of reading. The eight precisely regulated test speeds shear rates in '1"

are as follows+ 5el", C, 3, C3, 233, 633, 33, and C33. Speed may be changed with a control

knob selection, without stopping the motor. The gel strength of drilling fluids is a measure of the

minimum shearing stress necessary to produce slip#wise movements. Two readings are generally

taken+ the first, immediately after agitation of the mud in the cup the second, after the mud in the

cup has been $uiescent for a period of ten minutes. The difference in the two readings is


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considered to be a measurement of the thixotropy of the mud system.

Fig. 2.2: Rotational isco!eter.

2rocedure

2. 'lace the splash guard onto the bob shaft with short tube end up towards the bearings. 'ush

up.

6. Screw on the appropriate bob with the tapered end up towards the splash guard.

. 'lace the sleeve onto the rotor over the bob. The threads assure the rotor will attach evenly and

uniformly each and every time.

B. -onnect the instrument to a power source.

F. 'lace the test fluid in a sample cup and immerse the rotor sleeve exactly to the fill line on the

sleeve by raising the platform. Tighten the lock nut on the platform.

C. The power switch is located on the back panel. Turn the unit on.

E. otate the speed selector knob to the stir setting and mix the sample for a few seconds. otate

the knob to the C33 '1 setting, wait for the dial to reach a steady reading, and record the C33

'1 reading.


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N. otate the speed selector knob to the 33 '1 setting, wait for the dial to reach a steady

reading, and record the 33 '1 setting.

D. otate the speed selector knob back to the stir setting and re#stir the sample for a few seconds.

23. otate the speed selector knob to the gel setting and immediately shut off the power.

22. As soon as the sleeve stops rotating, wait 23 seconds and turn the power on while looking at

the dial. ecord the maximum dial deflection before the gel breaks at the 23#second gel strength.

26.


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Fig. ".1: A#$ Filter #ress

2rocedure

2. %e sure each part of the cell is clean and dry, and that the rubber gaskets are not distorted or

worn. The screen should be free of sharp edges, burrs or tears.

6. Assemble the cell as follows+ base cap, rubber gasket, screen, filter paper, rubber gasket, and

cell body.

. 'our a freshly stirred sample of fluid into the cell to within 3.F inch 2 millimeters" to the top

in order to minimi(e contamination of the filtrate. -heck the top cap to insure the rubber gasket

is in place and seated all the way around and complete the assembly. 'lace the cell assembly into

the frame and secure with the T#screw.

B. 'lace a clean dry graduated cylinder under the filtrate exit tube.

F. Turn the regulator T#screw counter#clockwise until the screw is free#turning and the diaphragm

pressure is relieved. The Safety %leeder 7alve on the regulator should be in the closed position.

C. -onnect the air hose to the designated pressure source. &pen the valve on the pressure source

to initiate pressuri(ation into the air hose. This pressure must be regulated to a maximum

pressure of 6F3 psi. 0o not exceed this pressure limit.


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E. Ad>ust the regulator by turning the T#screw clockwise so that a pressure of 233 F psi CD3

F k'a" is applied to the cell in 3 seconds or less. The test period begins at the time of initial

pressuri(ation.

N. At the end of 3 minutes, measure the volume of filtrate collected. Shut off the air flow

through the pressure regulator by turning the T#screw in a counter#clockwise direction. -lose the

valve on the pressure source and open the relief valve carefully.

(aintenance

2. -heck to see that all pressure has been removed from the cell, and then remove the cell from

the frame. 0isassemble the cell, discard any remaining mud and using extreme care save the

filter paper and deposited cake with minimum of disturbance to the cake.

Results

2. eport the volume filtrate collected in cubic centimeters to the nearest 2!23th cm as the A'Ifiltrate.

6. eport the time interval and the mud temperature in &< &-" at the start of the test. Save the

filtrate for running chemical analysis if desired.

. 1easure and report the thickness of the filter cake to the nearest 2!6 inch 3.N millimeter". A

cake#thickness less than 6!6 inch is usually considered acceptable. &bservations as to the

$uality of the cake should be noted. @otations such as hardness, softness, toughness, slickness,

rubberiness, firmness, flexibility and sponginess are appropriate descriptions.

/A2/RI(/NT FOUR: $8ND CONT/NT$

It is desirable to know the sand content of drilling fluids because excessive sand may result in the

deposition of a thick filter cake on the wall of the hole, or may settle in the hole about the tool

when circulation is stopped, thus interfering with successful operation of drilling tools or setting

of casings. )igh sand content may also cause excessive abrasion of pump parts and pipe

connections. The sand content kit determines the volume percent of sand#si(ed particles in the

drilling fluid. A'I defines sand#si(ed particles as any material larger than EB microns 633#mesh"

in si(e. The test can be performed on low solids fluids as well as on weighted fluids.


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Fig. 4.1: Sand Content %its.

2rocedure

2.


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2. /sing the scale on the graduated tube, read the volume percent of sand.

/A2/RI(/NT FI4/: R/$I$TI4IT@ D/T/R(IN8TION.

1easurements of the resistivity of water muds, filtrates and filter cakes are routinely applied in

electrical logging. esistivity measurement provides a rapid means of detecting soluble salts in

barite and in waters, such as makeup or produced waters. The resistivity meter is a portablemeasuring device designed to give a $uick, reliable measurement of the resistivity of a small

sample expressed in ohm#meters. The transistori(ed meter accurately measures the resistivity of

fluids, slurries and semisolids having resistivities of from 3.32 to 23 ohm#meter6!meter. This

ohm#meter reading may be converted into parts per million ppm" Sodium -hloride using the

nomograph provided


27/34

2. /se the suction bulb to pull the sample into the ?ucite cell. *mpty and refill the cell several

times to thoroughly wet the cylinder walls.

6. -onnect the cell assembly to the two terminal posts on the meter. %e sure the sample fills the

area between the two metal posts in the cell. If the sample is not at room temperature, wait for

the temperature of the sample and cell to reach e$uilibrium.

. 0epress and hold the black button to calibrate the meter. Turn the ad>usting control knob to set

the meter needle to the 9A0: position.

B. 0epress both the black and the red button at the same time, and read the resistivity of the

sample directly from the meter in ohm#meters.

2rocedure = B $emi $olid $am!les Filter Cakes, (ud $olids, etc.3

2. 'repare samples of uniform moisture content.

6.


28/34

Fig. '.#: Resistivit Nomogra!h for NaCl $olutions.

/A2/RI(/NT $IA : 7@DRO5/N ION CONC/NTR8TION !73.

The term p) is used to express the concentration of hydrogen ions in a$ueous solution. p) is the

logarithm of the reciprocal of the hydrogen ion concentration in gram moles per litre. In a neutral

solution e.g. pure water", the hydrogen ion L)M and the hydroxyl ion L&)#M concentrations are

e$ual, and each is e$ual to 23#E. A p) of E is neutral. A decrease in p) below E shows an

increase in acidity, while an increase in p) above E shows an increase in alkalinity. The p) can

be determined either using the colorimetric method or the electrometric method.

8. Colorimetric (ethod !7 2a!er3

The p) paper is impregnated with dyes that exhibit different colours when exposed to solutions

of varying p). )igh concentration of salt in the sample may alter the colour developed by the

dyes and cause the estimate of p) to be unreliable.


29/34

Fig. 6.1: pH aper.

2rocedure

2. Tear off and place a short strip of p) paper on the surface of the sample.

6. After the colour of the test paper stabili(es, the colour of the upper side of the paper, which has

not contacted the mud, is match against the standard colour chart on the side of the dispenser.Results

2. eport the value of the p) using the standard colour chart as a guide to the nearest 3.F p)

unit.

Remarks Concerning !7 2a!er Testing

2. 8hen the -hloride concentration is greater than about 23,333 mg!l, p) paper does not give an

accurate measurement.

6. 0o not stick the p) paper or strips into the fluid sample.

. The p) of mud filtrate may be taken and sometimes gives a faster colour change, but the p)

of the filtrate may differ from that of whole mud.

=. /lectrometric (ethod !7 (eter3

The p) meter is an instrument that determines the p) of an a$ueous solution by measuring the

electropotential generated between a special glass electrode and a reference electrode. The

electromotive force *1


30/34

Fig. ".2: p# Meter.

2rocedure

2. 'ush the &@!&


31/34

C. If K-l or e$uivalent storage is not available, use a B.33 p) buffer, E.33 p) buffer or tap water.

Results

2. eport the sample p) to the nearest 3.2 p) unit and the temperature of the sample tested.


32/34

C782T/R FOUR: R/$U6T

The composition of the mud used is outline below+

1ass of bentonite P F3g

7olume of diesel oil P 633cm

7olume of water # F3cm

1ass of @a-l P Fg

Initial experiments

• 0ensityGGN.Eppg• 7iscosity measurement

7iscometer readings

R2( U reading"

C33 26633 22B633 223233 223C3 23E3 23FC 232

Test for mud filtration !ro!erties

7olume of filtrate collected G 2Fcm

7olume of water G 22.Bcm

7olume of oil G .Ccm

Thickness of filter paper mud cake G 3.26

Thickness of the filter paper G 3.32 Therefore, the 1ud cake thickness would be G 3.22cm

(UD Resistivit test

The resistivity of the mud was 3.BEVm

hdrogen ion concentration, 27


33/34

The mud was 22which implies that the mud is basic.

The mud was then separated into two places and were labeled SA1'?* A and SA1'?* %. In

this experiment, SA1'?* A is used basically for density monitoring while SA1'?* % is

ma>orly for viscosity monitoring

$8(26/ 8

0ensity monitoring on sample A

O&servation !eriod " + das3

SA1'?* A mud at room temperature was bubbled with -&6 at about F33psi. The mixture wasleft for the next seven days to allow for all chemical reactions to take place.

Densit : N.Dppg

O&servation !eriod # das3

Sample A was bubbled with -&6 at about N33psi and the mud was observed for another days

Densit : D.2ppg

O&servation !eriod # ' das3

Sample A was observed for another F days without bubbling with -&6

Densit: D.6ppg

$8(26/ =

7iscosity monitoring on $8(26/ %

Initial

R2( U reading"

C33 26633 22B633 223233 223C3 23E3 23FC 232


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8fter seven das of co inEection

R2( U reading"

C33 6233 23

633 32233 6NEC3 663 22FC NF

effect of carbon dioxide gas kick in oil base mud. project (2)

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