CANADIAN ASSOCIATION OF DRILLING ENGINEERS 800, 540 - 5 Avenue SW, Calgary, Alberta T2P 0M2 

2007/2008 EXECUTIVE 

President Ryan Schoenhals 267-0349 

Past President Doug Hollies 604-6645 

Vice President David White 699-5160

Secretary Robin Finley 451-0740 

Treasurer Alice Skoda 234-9999 

Membership Chairman Jason Tiefenbach 543-8012 

Education Chairman Mike Buker 213-3615

Social Chairman Dan Schlosser 531-5284 

CADENews Editor Glenn Mencer 233-3506 

Technical Chairman Henry Schultz 232-5095 

IT Chairman Cris Catrinescu 668-4559 

Executive Member Gord Wagner 232-6066 

Drilling Conf. Liaison Linda D’Angelo 543-8023 

CAODC Liaison Vacant 

MARCH LUNCHEON 

Date: Wednesday, March 12, 2008 

Place: The Westin, Calgary 

Time: 11:30 a.m. Reception 

 12:00 noon Luncheon 

 12:30 p.m. Presentation 

Speaker: Ralph Harris 

 Cleansorb Ltd 

Topic: In-situ acid production for wellbore clean-up, 

deep matrix acidizing and stimulation of natural 

fractures 

In-situ acid production ensures excellent zonal 

coverage and offers advantages over conventional live 

acid systems. This talk will consider applications of insitu acidizing including initial wellbore clean-up filter cake 

treatment deep matrix acidizing and stimulation of 

natural fracture networks. The use of combined in-situ 

acid production and polymer breaking to treat 

water-based mud filter cake in openhole wells will be 

highlighted. The basis of in-situ acidizing systems will 

be explained, illustrated with examples of typical field 

use in both new wells and as remedial treatments 

Ralph Harris studied Applied Biology at the 

University of Bath, UK followed by a Ph.D. in Applied 

Microbiology at the University of Kent, UK, where he 

isolated and studied bacteria capable of breaking down 

cyanide in industrial effluents. Following further 

post-doctoral research in the area of microbial 

metabolism, he joined Archaeus Ltd., a company spun 

out from the University of London, as a project manager, 

developing technologies for Microbial Enhanced Oil 

Recovery (MEOR) and effluent treatment. In 1994, he 

founded Cleansorb Ltd. with Dr. Ian McKay to 

commercialise well treatment methods based on in-situ 

acid production. These processes are now used worldwide, particularly for filter cake clean-up in openhole 

wells. He is an author or named inventor on some 30 

papers and patents. 

MARCH LUNCHEON .....................................................1

LUNCHEON TICKETS...................................................2

REVERSE CEMENTING AS A VIABLE SOLUTION 

FOR CEMENTING UNDER PRESSURE & 

NATURALLY FRACTURED ZONES.............................2

UPCOMING EVENTS.....................................................5

UPCOMING EVENTS.....................................................6

CADENEWS SPONSORSHIP .......................................6

SEARCHING FOR ALBERTA’S OIL — PART III .........7

WELCOME NEW MEMBERS ........................................8

RIG COUNT....................................................................8

 

This issue of CADENews has been sponsored by: 
LUNCHEON TICKETS

Tickets for the Wednesday, March 12, 2008 CADE Luncheon are available on a pre-purchase basis at 

www.cade.ca, by Visa credit card (if ordering through the website, and an e-mail confirmation is not received within two 

business days, telephone Bobbi Murray at 403-264-4311), or from the following ticket sellers until 12:00 noon on Friday, 

March 7, 2008. Accepted methods of payment are Visa, cheque and cash. 

Rosemary Regan 

BJ Services Company Canada

801 - 6 Avenue SW 

531-5151 

Barbara Hewko 

ConocoPhillips Canada Ltd. 

401 - 9 Avenue SW 

260-3794 

Mildred Lenyk 

ExxonMobil Canada 

Room 35097, 237 – 4 Avenue SW 

237-3765 

Sue Binsted 

Petro-Canada 

150 - 6 Avenue SW 

296-6793 

Michelle Brossard 

Schlumberger Canada Limited 

525 - 3 Avenue SW 

509-4598 

Tracey Ullrich 

Shell Canada Energy

940B - 4 Avenue SW 

384-5492 

Tammy Bessette 

Smith International Canada, Ltd.

1600, 335 - 8 Avenue SW 

206-0336 

Lynne Graval 

Talisman Energy Inc. 

3400, 888 - 3 Street SW 

237-1906 

REVERSE CEMENTING AS A VIABLE SOLUTION FOR 

CEMENTING UNDER PRESSURE & NATURALLY FRACTURED 

ZONES 

Steve Chase, Business Development Senior Account Representative, Cementing Product Service Line 

Abstract 

 

New products and technologies are needed, as 

the increased demand on the industry to prevent 

damage to the surface aquifers and the increased 

demand of the oil producers to cut cost and increase the 

life of wells and reduce remedial cementing cost. Zonal 

Isolation is imperative to reduce the damage and the 

extra cost of remediation. 

What are the Options 

Light Weight Slurries for Low Pressure Zones and 

Vugular Formations 

• Conventional light weight slurry additives have 

allowed competent cement slurries to be mixed at 

1200kg/m3 or lower using volumetric mixing 

process. 

• Conventional light weight slurries with the addition 

of reactive spacers and bridging packages can 

fight moderate loss circulation. 

• Conventional light weight slurries can be more 

economical than other solutions in moderate loss 

situations in most cases. 

The Limitations of Conventional Light Weight 

Slurries 

• Longer thickening times especially in low 

temperature designs. 

• The crushing of spheres in deep wells due to 

higher hydrostatic pressures applied to the 

spheres which changes the density and properties 

of the cement slurry. Slurry should be designed 

for downhole required density. 

• Typically low compressive and tensile strength of 

the slurry. 

• The higher cost of quality ceramic, glass bubbles 

or spheres to meet the demand of high pressure 

high temperature (HPHT) wells. 

• Light weight slurries still can only be lowered to a 

certain density and meet the minimum allowable 

compressive strengths over time. The slow 

thickening times and gel strength growth can also 

increase the potential for gas to enter the slurry 

during the setting process and allow for 

channeling and micro annulus. 

Foam Cement is a Very Good Option for Light 

Weight Slurries. 

• Foam cement can reach densities as low as 

500 kg/m3

. 

• Foam cement uses base slurries that do not 

require high water requirements per tonne of 

cement; this allows better compressive strength 

and faster thickening times. 
• Foam cement has natural gas control and natural 

diversion properties for fighting loss circulation, 

vugular formations and low pressure wells. The 

foam bubbles created by the nitrogen (N2) 

continue to apply pressure to the formations right 

up to the point of setting, minimizing the 

opportunity for the gas to enter the well bore. The 

foam cement being a two phased slurry acts as a 

natural diverter, the foamed slurry will bridge in the 

fractures and look for an easier path. 

• Foam cement is tuned to the well parameters and 

is designed by entering the actual caliper log into a 

computer program and generating a program that 

will keep the hydrostatic pressure and Equivalent 

Circulating Density (ECD) in a window between 

fracture pressure and pore pressure for ideal well 

control. 

Limitations of Foam Cement 

• Foam cement requires specialized equipment on 

location which can add to the cost of the job. The 

cost of foam cement vs. light weight conventional 

slurry is higher until you reach a certain volume of 

product. (Typically 2000m wells are the rule of 

thumb when the cost of the extra equipment for 

foaming becomes cheaper then the cost of the 

expensive light weighted additive cement slurries.) 

For shallow wells, a simplified system is used that 

utilizes nitrogen gas instead of liquid nitrogen. 

This allows for elimination of nitrogen pumper on 

location. 

• Logistics and time of setting up foam cement jobs 

vs. conventional jobs. More equipment, more 

personnel, return tanks for energized fluids. 

• Halliburton Energy Services is the only service 

provider actively providing foam cement as a 

solution to the under pressured, highly vugular 

well bores. 

• Halliburton Energy Services has dedicated foam 

cementing equipment and specially trained 

cementing crews and design engineers to meet 

the needs of the industry. 

 Foam systems, in general, create higher 

dynamic viscosity systems that are ideal for wellbore 

cleaning; however, this could be a disadvantage when 

smaller annulus sizes are to be cemented. A computer 

modeling design will provide the needed values to 

ensure the proper selection of treatment. 

Mechanical Solution to Solve Low Pressure 

Formations and Vugular Formation and Loss 

Circulation 

• Multi Stage cementers can be put into a casing 

string to minimize the hydrostatic pressure applied 

to weak zones by splitting the job into stages. 

• Multi Stage cementers can use different blends for 

each stage. 

Multi Stage Cementers Limitation 

• Stage tools have been known to fail, either by 

opening when it is not suppose to, or not closing at 

the end of the job. The results of either problem 

can be very expensive. 

• Stage tools do not guarantee returns and the ECD 

may still increase when pumping through a stage 

tool. 

• Stage tools add cost to the casing string and also, 

to increase chances of being successful, the rig 

must wait on the first stage cement to set. The 

cost of the rig time waiting on cement can equal 

the cost of the cement job. 

• Stage tools need to be drilled out after the cement 

job. 

Reverse Cementing as a Viable Solution 

• Reverse cementing system can be designed for 

any string of casing during the well construction 

phase when conditions are suitable for this 

process. 

• Reverse cementing allows the well to be designed 

utilizing any cement slurry both conventional or 

foam and can be tuned to meet each individual 

well issues. 

• Reverse cementing requires little additional 

equipment to perform the cement job. 

(Continued...)
REVERSE CEMENTING AS A VIABLE SOLUTION ...

(Continued) 

• Reverse cementing allows for minimization of the 

amount of slurry used. Thickening times can be 

shortened so the cost of expensive additives 

(retarder) is reduced. Lead slurries are now the 

last cement, pumped and excess cement can be 

returned to the plant and used again. 

• Reverse cementing uses gravity force to its favor 

to place the cement, and the natural tendency is 

for the flow path of the cement is to flow 

downward. 

• ECD is very low as the cement wants to fall faster 

then it is being pumped. 

• More aggressive cement slurries can be pumped 

since the casing is not at risk of being cemented 

on the inside. Right angle cement slurries 

minimize seepage losses into the fractures or 

weak formations. 

• Reverse cementing allows for addition of cement 

volume to the annulus continuously until the 

cement slurry will stay in the annulus. Once the 

annulus stays full, a slight squeeze pressure can 

be applied to the annulus to help ensure zonal 

isolation is established. 

Reverse Cementing Limitations

• Reverse cementing surface casing requires some 

form of diversion. Not all rigs run diverters and 

there are limited numbers of diverters in Canada 

to meet the demand. Halliburton Energy Services 

owns patented tools to isolate the surface casing 

and conductor barrel. 

• Design of a reverse cement job is more difficult to 

calculate the ECD. Drilling engineers need to 

ensure that the service company has developed a 

robust computer model and design methodology, 

which has been calibrated against actual field 

measurements. 

• The selection of float equipment for reverse 

circulation cement jobs is critical, especially in the 

aspect of well control. The drilling engineer should 

insist on purpose built equipment to maximize the 

potential for success while minimizing the risk for 

unplanned events. 

• Reverse cementing has the similar chance of 

bridging while placing the cement slurry in the 

annulus as conventional cementing. In case of a 

bridge off, the upper portion of the well will be 

cemented and the shoe track will not have cement 

around it. 

• The challenge of knowing when cement is inside 

the casing and how much volume is inside is dealt 

with through various methods including logging 

tool. 

• Reverse cementing production and liner casing 

strings will need to be drilled out post cement job. 

What Method is Best for Fighting Loss Circulation 

and Weak Zones? 

 

Each well is unique and must be treated as 

such. Too often the industry does not look at the life of 

wells and the consequences of a poor cement job when 

designing the overall well construction design. Poor 

zonal isolation and remedial repair will far exceed the 

cost of the initial cement job. 

 

When comparing costs of the original casing and 

cementing well design, the overall life of the well must be 

considered. Pay now or pay later. 

Light weight cement slurries are well suited for 

wells with slight-to-moderate loss circulation issues 

and with good area knowledge can be used on most 

wells and be the most economical solution. The 

drawback to light weight slurries is the slow gel strength 

transition time because of the increased water or 

addition of spheres. The number one concern is gas 

infiltration and micro annulus. 

Stage tools can be effective in weak zone 

applications with the addition of light weight slurries. 

The additional cost of equipment and the additional rig 

time makes this process more expensive and is still only 

effective in moderate loss situations. 

Foamed cement slurries have all the qualities 

you look for in cement slurry. The benefits of foam 

cement cannot be matched by any light weight 

conventional slurry. The cost of foamed cement is 

increased with the extra equipment on location, but it 

can reach densities well below the weight of water. 

 Foamed cement would be the recommended 

cement slurry for most moderate-to-severe loss

circulation situations because of its very low densities 

and its natural diversion and expanding properties. 

 Foam cement is much more effective then any 

chemical gas migration control additive in today’s 

market. 

 Foamed cement is a more viscous fluid than 

most lightweight slurry and some wells cannot be kept in 

balance as the ECD during placement exceeds the 

maximum allowable pressure even when the cement 

density is equal to the mud density in a static well bore. 

Reverse cementing can use any cement slurry 

that can be pumped conventionally including foam 

cement. The ECD is reduced by significant margins 

during placement, which is the opposite to 

conventionally pumping which always increase ECD. 
OptiCem

Downhole Pressure Profiles Minimum Hydrostatic Pressure and Maximum ECD vs. TVD

400 600 800 1000 1200 1400 1600 1800 2000

ECD (kg/m3)

0

200

400

600

800

1000

1200

TVD (m)

Pore Pressure Gradient Fracture Gradient

Minimum Hydrostatic Gradient Maximum ECD

OptiCem v6.2.3

05-Nov-07 08:48

O

le P

ptiCem Downho ressure Profiles M inim u m H ydro static re and M axim u m E C D vs. TV D Pressu

400 600 800 1000 1200 1400 1600 1800 2000

E C D (kg/m3)

0

200

400

600

800

1000

1200

TVD (m)

P ore P ressure Gra die nt Fracture Gr nt adie

Reverse cementing uses gravity to get past 

major loss circulation zones and can be continuously 

pumped or staged until the annulus stays full. 

M a xim um E C D

Reverse cement can be tuned to minimize 

expensive chemical costs and excess is based on use, 

not on a guess. 

 

Reverse cement slurries can be tuned for very 

fast setting times, as the casing is never at risk of being 

cemented off. O ptiC em v6.2.3

05 - N ov-0 7 09:10

 

Reverse cementing can be used in any well 

situation from moderate-to-severe losses on surface 

hole to extremely tight annulus on liner jobs. 

The two graphs below show how reverse 

cementing affects the ECD. 

Surface Well Issues 

 311mm hole size, 244mm casing, TD 1000m 

with severe losses from 850m to 950m. 

Graph # 1 

Conventional Cementing 1750kg/m3 base slurry pumped @ 800l/min 

equals ECD of 1900 kg/m3 at the loss zone @ 850m 

Graph # 2 

Reverse Cementing 1750kg/m3 base slurry pumped @ 800l/min 

equals ECD of 1050 kg/m3 at the loss zone @ 850m 

 

Halliburton Canada has successfully performed 

10 reverse cementing jobs including abandonment and 

surface, intermediate, production, and liner casing 

strings from the Beaufort Sea to Heavy Oil areas. 

 Every well is unique and every well has a 

cementing solution. Economics to Extreme. 
UPCOMING EVENTS 

CADE Technical Luncheon 

Wednesday April 16, 2008 

The Westin, Calgary 

CADE Technical Luncheon 

Wednesday, May 14, 2008 

The Westin, Calgary 

CADE●CAODC DRILLING CONFERENCE 

Tuesday, June 3, 2008 

The Playhouse at Vertigo Theatre Centre

CADENEWS SPONSORSHIP

Have you considered sponsoring an upcoming 

edition of the CADENews? The newsletter is produced 

with the support of our sponsors and is an excellent 

forum that reaches industry in both print and electronic 

formats. 

If you are interested in promoting your firm and 

its support of our Association, learn more about 

sponsoring an upcoming issue; contact Glenn Mencer by 

telephone at 403-233-3506. 

CADENEWS — 

PAST AND PRESENT SPONSORS
SEARCHING FOR ALBERTA’S OIL — PART III 

Sandy Gow 

Concordia University College, Edmonton 

After the mid-twenties, basic instrumentation 

played an increasingly important role in defining the 

future of geophysics that centered on the use of 

instruments to determine structure and to suggest which 

formation warranted exploratory drilling. 

Gravity methods were designed to detect 

variations in the earth’s gravitational field created by 

density variations and structural configurations, locating 

anomalies several miles below the surface. The torsion 

balance was the first successful gravity-measuring 

instrument, measuring changes in the gravitational field 

rather than its actual intensity. Unfortunately, torsion 

balances were very large, bulky, sensitive instruments 

and only a small number of readings could be obtained 

in a day. Moreover, making corrections for the terrain’s 

effects required lengthy and tedious computation. The 

calculation of torsion balance observations and their 

conversion into geologic deductions was complex; errors 

of observation and calculation were often greater than 

the anomalies on which the conclusions were based. 

These two factors tended to limit its applicability. 

The torsion balance was soon replaced by the 

gravity meter, an instrument that literally measured the 

gravitational pull determined by a rock’s density. The 

heavier igneous and metamorphic rocks tended to have 

a higher pull rating than the potentially oil-bearing 

sedimentary rocks. The corrected results of the gravity 

meter were plotted on a map and contoured. Various 

factors had to be taken into consideration before the 

map could be interpreted. If wells had already been 

drilled in the area and information from them was 

available, the results were usually easier to interpret. 

Given that so much comparing and contrasting with 

existing information was involved, the gravity method 

was usually considered a form of reconnaissance. By 

the end of the fifties, it had largely disappeared from the 

scene. 

Of course, the magnetic method and the gravity 

method are similar in that they both measure physical 

properties of the subsurface rocks. The gravity method 

measures changes in rock density. The magnetic 

method measures changes in the magnetic character of 

rock with a magnetometer. This magnetic method was 

more successful than the gravity method largely 

because metamorphic and igneous rock exert a pull 

many times greater than those of sedimentary rocks, 

dramatically distorting the data. Nevertheless, the 

magnometer also required correction and, therefore, was 

best used with other information. It, too, was considered 

more of a reconnaissance device. By the late 1950s, it 

was being replaced by seismic. It had been used only 

occasionally in the Turner Valley field, the largest field in 

Alberta before the Leduc discovery of 1947. Both the 

gravity meter and the magnometer saw wider service 

elsewhere in Alberta, as well as in Saskatchewan and 

frontier areas. 

 

By 1946, the airborne magnetometer was in use, 

an outgrowth of the Royal Canadian Navy’s antisubmarine warfare against the Axis powers in the North 

Atlantic, Mediterranean Sea, and elsewhere. War 

surplus Canso flying boats, the Canadian version of the 

American amphibious PBY Catalina, carried the 

instrument aloft. This method was fast, less expensive 

for large surveys than the surface magnetometer, easy 

to use over rough terrain, and more effective when it was 

in the presence of anomalies such as pipe lines, ore 

bodies, and railroads. Gulf Oil had used a flying bird 

somewhere on the Great Plains prior to 1949, the year 

that Aeromagnetic Surveys Limited of Toronto arrived in 

western Canada to carry out surveys for oil companies. 

Despite advantages over the ground version, the 

airborne magnetometer had also been replaced by 

seismic, by the late fifties. 

In 1952, the scintillometer was also being used 

in the Alberta oil patch in conjunction with the airborne 

magnetometer. Originally devised to search for uranium, 

it, too, was meant to be airborne. The scintillometer 

incorporated an ultra-sensitive gamma ray detector and, 

during World War II, those hunting for uranium had 

noticed that a type of radioactive halo appeared around 

the edges of oil fields, revealing that there was less 

radioactivity above the oil fields themselves. 

All of these methods were the precursor to the 

one that would really prove to be much more effective, 

seismic surveys. 
WELCOME NEW MEMBERS 

Name Company Telephone Email 

Kevin Coan Apex Oilfield Services 403-257-5152 kcoan@apexoil.ca 

Len Dirk Q'Max Solutions Inc. 403-269-2269 ldirk@qmaxsolutions.com 

Jeff Gerlitz Petro-Canada 403-269-8000 jgerlitz@petro-canada.ca 

Steve Kalny Hallmark Tubulars Ltd. 403-266-3807 skalny@hallmarksolutions.ca 

Peter Stanton Stanton Drilling Inc. 613-624-5622 stanton-drilling@cyberus.ca 

Bassem Zaki Halliburton Canada Inc. 403-231-9300 bassem.zaki@haliburton.com 

RIG COUNT 

March 11, 2008 March 13, 2007 

Active Down Total Utilization Active Down Total Utilization 

AB 403 283 686 59% 361 332 693 52%

BC 73 30 103 71% 60 26 86 70%

SK 56 24 80 70% 61 26 87 70%

NWT 5 2 7 71% 4 0 4 100%

MB 9 1 10 90% 5 2 7 71%

TOTAL 546 340 886 62% 491 386 877 56%

Canadian Association of Drilling Engineers 

800, 540 – 5 Avenue SW 

Calgary AB T2P 0M2