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-situacid 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 Lu ncheon 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 fr om 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 Repr esentative, Cementing Product Service Line

Abstract

New products and technologies are needed, as
the increased demand on t he 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/m 3

.

• 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 pr essure 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 Servic es is the only service provider actively providing foam cement as a solution to the under pr essured, highly vugular
well bores.

• Halliburton Energy Servic es 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 duri ng the well construction phase when conditions are suitable for this

process.

• Reverse cementing allows the well to be designed utilizing any cement slu rry 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 drille d 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 sl urry. 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 becaus e 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

1200TVD(m) Pore Pressure Gradient Fracture Gradient Minimum Hydrostatic Gradient Maximum ECD

OptiCem v6.2.3 5-Nov-07 08:48 0 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

1200TVD (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 175 e slurry pumped @ 800l/min 0kg/m3 bas 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, produ ction, 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 stru cture and to suggest which
formation warranted ex ploratory 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 info rmation from them was available, the results were usually easier to interpret. Given that so much comparing and contrasting with existing information was invo lved, 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 informati on. It, too, was considered
more of a reconnaissance devic e. 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 me thod 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 Serv ices 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