11 techleaders v9n3 final

7/25/2019 11 TechLeaders v9n3 FINAL

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TechnicalLeaders

Question:What is a mature oil field in

your opinion?

TM:An oil field can be classified

as mature when its production

rate is significantly declining and/

or when it is close to reaching its

economic limit. A field might also be

considered mature when it is close to

attaining a recovery factor considered

acceptable for its reservoir mechanisms.

Typical ly, a mature field will have

very old wells and aged equipment and

infrastructure which have a higher risk

of safety and environmental issues.

BT:One that has been in

production for many years and has

depleted its primary and secondary

reserves. Consequently, its

facilities and technology are usually also

very old.

Question:What are the methods and

technologies used to produce mature

oil fields?

TM:There are several methodologies

and technologies available to revitalize

mature fields. However, before

selecting which one will be used, it

is necessary to assess what is the target

prize of your revitalization project.

The first step is to get a solid

characterization of the reservoir to

reduce the technical uncertainty of

the resources associated with your

project. Today there are many new

tools including logs, modeling and

visual ization software, and seismic to

help you to identify bypassed oil in

your reservoir.

Once you have determined the

target prize, you could decide between

using an improved oil recovery (IOR)

technology (e.g., waterflood, gasflood,

horizontal or infill drilling, conformance

control, stimulation), an enhanced

oil recovery (EOR) technology (e.g.,

continuous steamflood, hydrocarbons/

N2/CO2injection, polymers/surfactants/

alkali/low-salinity injection), or a

combination of IOR/EOR processes.

You can even just choose to revamp

your wells and facilities keeping the same

production scheme.

By using some of these integrated

reservoir-management techniques, a

young professional wil l be able to design

a field-rejuvenation plan that maximizes

production and reserves.

BT:Various techniques that can be

used include waterflooding, miscible

and chemical (e.g., polymer, surfactants,

alkali, and ASP) flooding, and

steamflooding (for heavy viscous oils).

Question:How have these methods

changed over time?

TM:Technology and computing

power have evolved significantly,

which streamlines the process and

timeframe to develop a more accurate

characterization of the reservoir. The

new technologies and techniques include

3D and 4D seismic for data processing

and interpretation, 3D visual ization, new

coring and well testing, and advanced

software for modeling and simulation.

These tools allow you to build models

with thousands of wells and finer

gridding with faster run times.

In addition, we need to recognize

recent technology developments that

include advanced drilling and completion

techniques (including directional and

horizontal extended wells); smart wells;

remote, real-time wireless surveillance

and control systems; reduced footprint

rigs; third-generation modular facilit ies;

novel materials and composites which

resist high temperatures, abrasion

and presence of acid gases; high-

temperature-/high-salinity-resistant

chemical additives for IOR/EOR

How to Tackle the Challenge

of Mature Field DevelopmentThais McComb,Chevron; Brian F. Towler,University of Wyoming

Thais McCombcurrently works as a CO2enhanced oil

recovery (EOR) advisor for Chevron in Houston. With 30

years of broad experience in reservoir engineering, she has

worked for 15 years in research and development related to

CO2injection (fluids phase behavior, rock characterization,slim-tube and core experiments, asphaltene precipitation

and d ispersion), water injection (conformance control and

formation damage), chemical EOR, and heavy oil with Elf

Aqu itaine (Fra nce) and PDVSA (Venezuela). McComb has also held numerous

reservoir-management team lead positions in Venezuela (PDVSA a nd Shell) and the

US (Chevron) that involved high-temperature/h igh-pressure hydrocarbons, N2and

CO2injection, chemical EOR, high H2S production, and heavy oil. She holds a BS in

petroleum engineering from the University of Zulia, Venezuela, and an MS and a

PhD in chemical engineering from the Institute Nationale Polytechnique de

Toulouse (INPT) in France.


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1Vol. 9 // No. 3 // 2013

processes; and new techniques for

selective stimulation.

BT:In the past only waterflooding was

used. Now a variety of EOR technologies

are applied. CO2miscible flooding has

become very popular as well. Previously,

some hydrocarbon miscible flooding

was implemented where applicable. But

the hydrocarbon molecule being used

became too valuable to inject into the

ground. CO2does not have as much use

or value, so it became more economical

to use CO2instead of the more valuable

intermediate hydrocarbons (ethane,

propane, butane, and pentane).

For shallow heavy-oil reservoirs,

steamflooding has become popular.

In certain l imited locations, chemical

flooding has been gaining ground.

Question:What factors play important

roles in determining the appropriate

techniques for specific fields?

TM:If a field has considerable remaining

saturation, in part, the reservoir and

fluid properties will control which IOR

or EOR process(es) are most suitable.

There are many industry tools that can

be used for preliminary screening of

these processes. However, the integrity

of the infrastructure and wells, the

field location, and the availability of

the injectants or additives significantly

influence the economic feasibility of any

of these processes.

An example is a mature offshore

field, with properties that make it an EOR

candidate, and that stil l has high movable

oil saturation. In practice, the feasibility of

applying an EOR process in this case is

low due to the status and capacity of the

infrastructure and the capital investmentrequired to upgrade the facil ities to

accommodate an EOR infrastructure.

Operational expenses associated with

the transportation or manufacture of

injectants or additives might also be

cost-prohibitive. This could also be the

case with remote onshore fields, where

the cost of transportation of additives/

injectants, equipment, supplies, and

spare parts would outweigh the benefit of

extending their productive life.

BT:Initial ly some simple screening

techniques are applied but, in my

opinion, these have limited applicability.

Nearby analogies can be useful because,

if a similar nearby field has been

successfully flooded, it increases the

chance of success in your mature field.

Reservoir simulation can give a good

indication of the recoveries and rates

to be expected from an enhanced oil

recovery project. Core floods and other

lab tests are important tests to be done

which can give an indication of the results

to be expected from a particular flooding

technique. Such lab tests also provide

important data for input to reservoir

simulation models.

Question:What type of mature fields do

you foresee as attractive candidates for

trying enhanced oil recovery methods?

TM:An ideal EOR candidate field should

have remaining oil saturations greater

than 35%, reservoir properties that are

conducive to EOR, access to an injectant

source (e.g., water, CO2), accessible

location, and acceptable infrastructure

and well integrity.

BT:In general, fields with high

permeabilities and high oil saturations,

and fields that have already undergone

successful IOR methods, such as

waterfloods, make the best candidates.

Reservoir continuity is also important and

desirable. Large reserves of remaining

oil in place and thick formations can also

be important. But less ideal reservoirs

should not be ruled out. If money can

be made, EOR techniques should

be applied.

Question:How does a mature oil

fields cost of production compare to a

regular field?

TM:In most cases, production

costs of mature oil fields are low

when compared to regular fields.

Undoubtedly, the cost of extending

the fields productive life will require

extensive capital investment. To do a fair

comparison, one needs to analyze and

prioritize each project under the current

oil industry economic scenario, whereby

sustained high oil prices have been

driving production cost increases due to

the scarcity of rigs and skilled manpower.

It is worth mentioning that the majority

of new conventional oil production is

coming from deepwater basins where

production costs are very high. Secondly,

the current discovery rate of new

fields is low and the costs associated

with the development of this new oil is in

some cases four to five times the cost

of producing oil from onshore, shallow

offshore, and mature fields.

BT:Generally the cost of production is

higher because water/oil ratios and gas/

Brian F. Towler is the CEAS (College of Engineering &

Applied Science) fellow for hydrocarbon energy resources

and professor of chemical and petroleum engineering at the

University of Wyoming. He began his career as a senior

reservoir engineer at Arco in Plano, Texas. He returned to

Austral ia to work as the principal reservoir engineer forOilmin and Moonie Oil. Towler served as chairman of the

SPE Queensland Sect ion. Subsequently, he joined the

University of Wyoming as an assistant professor in petroleum engineering, where

he has conducted research in reservoir simulat ion, wax mitigation, wellbore

stability, coal gasification, and bentonite plugging. In 2004, he was promoted to

professor and appointed head of the Department of Chemical and Petroleum

Engineering. In 2008, he was appointed CEAS fellow. Towler received his PhD in

chemical engineering f rom the University of Queensland (Austral ia). He has two

published books: Fundamental Principles of Reservoir Engineering(SPE) and Coal

Gasification and Its Applications(E lsevier). He has been a registered professional

engineer in the state of Wyoming since 1998.


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TechnicalLeaders

oil ratios can be high and production

rates are low.

Question:Where are mature oil fields

mostly concentrated in the world?

TM:I have not done an extensive search

on the number of mature oil fields

recently, but I will guess that China,

the US, Middle East, and former Soviet

Union contain the largest number of

fieldsfollowed by some members of the

Organization of the Petroleum Exporting

Countries (OPEC), such as Venezuela.

BT:Mature oil fields are located all over

the world because the oil industry is a

mature industry. But the places where

they are most concentrated are: the USA,

Russia, Middle East, and China.

Question:Are there additional

environmental regulations to be followed

for mature oil fields?

TM:Generally, mature fields have an

infrastructure that is aging and was

likely built before many of the current

environmental regulations were adopted.

It is likely that the highest exposure are

oil spills from aged wells and facilities,

as well as gas venting due to the need for

shutdowns for maintenance and repair.

BT:Not really. Different conditions may

mean different regulations are relevant.

In the USA, for example, the Clean

Air Act and Clean Water Act still must

be followed.

Question:Mature reservoirs are

accompanied by old wells. So what are

the different well-integrity practices

used in these mature oil fields?

TM:Well-integrity practices might

include scheduled Christmas tree or

wellhead maintenance, cement-bond

logs, pressure tests, temperature and

ultrasound logs, or downhole sensors

to detect casing, tubing, and valve

leaks. Repairs or intervention activities

must have very specific and rigorous

plans for addressing barriers to prevent

uncontrollable flow from the wellbore

to the external environment: At least

two independent barriers need to be

in place during all well activities and

operations, including suspended or

abandoned wells.

BT:Wells have to isolate formations so

that oil and salt water cannot contaminate

drinking water supplies. It is also

necessary to keep hydrocarbons from

migrating into other formations and

becoming lost. Wells that lose integrity

generally have to be plugged and

abandoned and/or re-drilled.

Question:Do you think young

professionals should consider working

on a mature reservoir where many

processes and methods have already

been tested or on a new field where he/

she can implement novel technologies?

TM:I believe mature fields give you

the opportunity of reviewing the field

history and learning from past events.

This al lows you time to expand your

knowledge and become more proficient

in reservoir and production engineering.

Additionally, in the current economic

scenario where oil prices seem to stay

above USD 80/bbl, it is reasonable to

expect that oil companies will continue

to develop projects to revitalize

or extend the production of their

mature fields. This focus gives young

professionals the opportunity to use

their creativity and enthusiasm to apply

novel technologies.

BT:It doesnt really matter. Each

situation creates its own challenges

and experience. The oil industry is an

exciting business. It is always interesting.

So take your opportunities when

they arise. TWA

committee understand what sets

your candidate apart by using clear,

concise statements to illustrate why a

nominee is deserving of an award. Be

specific. Its unfortunate, but sometimes

nominations are poorly written. Consider

this fictitious example: Maria served

on our scholarship committee and as YP

liaison. She is now our membership chair.

Nothing here makes Maria stand out.

Instead, the nominator could writeWhile

serving on the scholarship committee,

Maria helped us to engage a larger

student audience than we had previously

been able to reach. Our applicant pool

is now twice as big as it used to be. As a

YP liaison, Maria brought energy to what

had been a struggling program. It is now

alive and well with regular technical and

social activities. Now serving as our section

membership chair, Maria has identified

a number of innovative ways our section

can recruit and retain members. We are

starting to implement her ideas.

Letters of recommendation are

an important part of most award

nominations. When considering whom

to ask for a letter of recommendation,

consider their knowledge of the

candidate and their stature within SPE.

It may be desirable to show the breadth

of an individuals contribution by having

letters submitted by colleagues working

for a different company than your

nominee. Be sure to check www.spe.

org/awards to verify the requirements

regarding recommendation letters for the

specific award you are considering.

Preparing a great nomination isnt

as hard as it may seem. Giving your

candidate the best chance to succeed

does take effort, so bear in mind that

nominations are typically due by 15

February and that they may take several

weeks to prepare. If youre overwhelmed

by the process or have questions, SPE

staff are a lways available to help (contact

[email protected] for international

awards or [email protected] for regional

awards). All nomination materials will be

kept confidential. TWA

SPE101Continued from page 14

11 techleaders v9n3 final

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