waterflooding ()

In the name of God

WATERFLOODING

Presentation Summary•Type of production•History of waterflooding•Why does (and doesn’t) waterflooding

work in various reservoir situations•What are the optimum conditions for

waterflooding•What are some common problems

associated with waterflooding•Waterflooding in Iran and Saudi

Arabia

Calculating Original Oil in Place (OOIP)• OOIP = 7,758*A*h* *(1-Sw)/Bo• Where:• OOIP = original oil in place, STB• 7,758 = factor converting acre-feet to barrels• A = reservoir area, acres• h = average reservoir thickness, feet• = average reservoir porosity, fraction bulk

volume• Sw = average water saturation, fraction pore

volume• Bo = oil formation volume factor, RB/STB

Primary Oil Production Methods•Oil Compression Drive (0.1-2% OOIP)

•Compaction Drive (0.1 – 2% OOIP)

•Solution gas drive (1-10% OOIP)

•Gascap drive (1-20% OOIP)

History of waterflooding•Accidental water injection in

1865(pennsylvania)• ’’Circle Flooding’’(Center injector,work

outward)•First 5 spot pattern,Bradford field in 1924•1930’s waterflood in Texas and Oklahama•Genral applicability in 1950’s

How does a waterflood work?•Certain oil wells are converted to water in

jection wells•Other oil wells remain as producers•The injected water displaces, or “pushes”

oil to the producing wells•Waterflooding performs two perimary

tasks:•To maintain the reservoir pressure•To drive the oil toward the wells

Waterflood Recovery(cold method)•Depends strongly on a number of factors

to be discussed•Can be as high as 60% of the OOIP in

place in some favorable situations•May be much lower in other cases•There are generally optimum reservoir

types, conditions and implementation strategies for waterflooding to maximize potential oil recovery

TYPES OF WATERFLOOD OPERATIONS

Natural Waterflooding

Infinite Aquifer Type Waterflood

1 m3Out

1 m3In

Limited Aquifer Type Waterflood

1 m3Out

0.5 m3In

Passive Aquifer Type Waterflood

1 m3Out

0 m3In

Modes of Natural Waterfloods•Vertical drive (most effective)

•Edge or horizontal drive (less effective)

Vertical Flood (Common in Reef Structures)

Edge Flood

‘Induced’ Waterfloods

Common Induced Waterflood Types•Edge drive (updip)•Bottom drive (gravity stabilized)•Line Drive•Advancing line drive•Staggered line drive•Pattern•Reservoir dictated

Updip Edge Drive

Vertically Stable Bottom Drive

Line Drive

Staggered Line Drive

Pattern Flooding – 5 Spot

Waterflood Requirements

#1 Suitable Reservoir

#2 Water!!!

Typical Water Sources•Produced water(s) (Native and non native

to formation)•Surface water (Rivers, lakes, etc)•Shallow ground water•Waste water streams•Often a mixture of some of the above

Surface Water

Shallow Aquifer

ProducingFormation

Deep Aquifer

Surface Water - Direct Intake

Surface Water

Shallow Aquifer

ProducingFormation

Deep Aquifer

Surface Water - Infiltration Gallery

Surface Water

Shallow Aquifer

ProducingFormation

Deep Aquifer

Shallow Aquifer

Surface Water

Shallow Aquifer

ProducingFormation

Deep Aquifer

Formation Water

Surface Water

Shallow Aquifer

ProducingFormation

Deep Aquifer

Deep Aquifer

Injection Water Quality Issues•Sufficient volume for future

requirements?•Reliable year round source?•Total suspended solids content (TSS)•Oil and Grease Content (OGC)•Total dissolved solids content (TDS)•Scaling indexes•Specific ionic composition•salinity

Waterflood Progression

Factors Impacting the Displacement Effectiveness of a Waterflood

MACROSCALE EFFECTS•Heterogeneity•Permeability contrasts•Reservoir continuity•Faults and fractures

MICROSCALE EFFECTS•Pore size distribution and geometry

•Capillary pressure•Wettability•Relative permeability character•Advance rate•Injection fluid induced damage

Factors Affecting Waterflood Success• Timing of flood – earlier is betterHigher primary depletion (lower pressure) increases

gas saturation High gas saturation decreases oil recovery• Well spacing Tighter well spacing is better Increases Ea and Ev accelerates waterflood recovery• Pattern selectionBalanced patterns improve Ea and WOR performance

MACROSCALE ISSUES

Reservoir Heterogeneity

Permeability Contrasts

Reservoir Continuity

Natural Fractures Parallel to the Line of Flow

Microscale IssuesPrimarily Dominated by Wettability Effects

What is Wettability?•Preferential Attraction of a fluid to a solid

surface in the presence of one or more other immiscible fluids

Wettability Types•Water Wet•Oil Wet•Neutral Wet•Mixed Wet•Spotted Wet

Mixed Wettability•A fairly common wettability type in which

tight microporosity is water saturated and water wet, while oil saturated macropores are oil wet

Impact of Wettability on Relative Permeability to Water and Oil

Relative Permeability

Water Saturation - Fraction

Rel

ativ

e P

erm

eabi

lity

- Fra

ctio

n

Swi 10%Crossover 22% SwKrw = 0.88

Swi approx 25%Crossover approx 68% Krw = 0.08

General Impact of Wettability on Rel Perm

Factor WaterWet

Oil Wet Neutral Wet

Mixed Wet

Swi >15% <15% 10-20% >15%

CrossoverPoint

> 50% Sw < 50% Sw Approx 50% Sw

< 50% Sw

Krw at Sor <0.2 >0.5 0.2-0.5 >0.5

Specific Impact of Wettability on Waterflood Performance

Favorable vs. Unfavorable Mobility Ratio

Factors Improving Mobility

M = x Krw

w x K ro

Low Oil Visc Low Krw / Krg

High Displacing Phase Visc

High Kro

Example – Waterflood in a Favorable Mobility System (M=0.5)

Example – Waterflood in a Unfavorable Mobility System (M=20)

Given this – What are the Optimum Reservoir Wetting Conditions for a Waterflood?

For Maximum Ease of Water Injection

OilWet!

For Maximum Oil Recovery and Lowest Residual Oil Saturation

Neutral/MixedWet

For Most Rapid Oil Recovery and Minimum Water Production

WaterWet!

Optimum Conditions?•In most cases, optimum economic recovery efficiency is achieved when the wetting condition is a strongly water wet as possible

Does This Mean if my Reservoir is NOT Water Wet Waterflooding Will NOT be Economic?

To Flood?

To Not to Flood?

???

Many Successful Waterfloods have been Conducted in Oil Wet and Mixed Wet Reservoirs

•Overall economic benefit may be less than if the reservoir had been strongly water wet, but may still represent substantial improvement over straight primary depletion

Waterflood Screening and Evaluation Process

General ProcessMacroscaleScreening

MicroscaleScreening

Water SourceAnd QualityEvaluation

Simulation,Implementation

Conclusions•Waterflooding can result in significant

additional incremental oil recovery in many reservoir situations

•Not all reservoirs are prime waterflood candidates

•Macroscale features may control the effectiveness of a waterflood

•Mobility dominates microscale sweep efficiency

•A detailed protocol for evaluation has been presented

Part 2:Waterflooding in Iran and Saudi Arabia

waterflooding in iranمیانگیIن تزریIق آIب بIه میدانهای دورود، سIلمان، بالل، سIیوند، دنIا و اسفند در •

هزار بشکIه در روز بوده که از ایIن میزان بیشتریIن حجم ٢٩۶ حدود 93سIال تزریق آب به ترتیب به میدانهای دورود، اسفند و سلمان بوده است.

درصIد نفت مخازن فالت قاره ۴٠مطالعات جدیIد نشان مIی دهIد کIه بیIش از •را در حوزه خلیIج فارس مIی توان بIه روش تزریIق آIب (بIا توجIه بIه منابIع آبی

فراوان و دسترسی آسان) برداشت کرد.(حدود • شرکIت ایIن تولیIد از توجهIی قابIل ١بخIش طریق ۵ از درصIد)

فرازآوری گاز در چاهها انجام می شود.هIم اکنون تزریIق گاز و تزریIق آIب، دو روش اصIلی ازدیاد برداشت از مخازن •

نفتIی کشور اسIت؛ اگرچIه در مناطIق خشکIی کشور، تزریIق گاز به عنوان برخی (در گیرد مIی قرار اولویIت در برداشIت ازدیاد روش تریIن اصIلی میدانهای نفتIی مناطIق نفIت خیIز جنوب، تزریIق آIب همچنان ادامIه دارد) اما در فالت قاره ایران بIه دلیIل دسIترسی آسIان بIه آIب، تزریIق آIب در اولویت

قرار می گیرد.

Waterflooding in Saudi Arabia آرامکIو در • اعالم کرد کIهI نرخ افت ۲۰۰۶س�ال سIخنگوی شرکIت

۸توليIد مياديIن نفتIی بالIغ عربسIتان را بدون انجام هيچ اقدام جديدی، کاهش درصد ۲است که فعاليت های آرامکIو اين ميزان را به درصد

خواهد داد. در واقع عربستان سIعی می کنIد تا از دو طريق، تأثيIر افت توليIد بر روی ظرفيIت توليIد خود را کاهIش دهIد؛ نخست به کارگيری دوم و توليدی ميادين در تکنولوژی های موجود جديدتريIن و بهتريIن

توسعه ميادين جديد. جهIت حفIظ فشار ميادين توليدی، ۱۹۵۰ايIن کشور از اواسIط دهIه •

شروع بIه تزريIق گاز همراه نفIت کرد. اوليIن واحIد تزريIق گاز در سال در ميدان عين دار ۱۹۵۹ در ميدان آبقيق و دوميIن واحد در سال ۱۹۵۴

احداث شد. پIس از چندی بIه دليIل اينکIه تزريIق گاز نتوانسIت به طور کامل از افت فشار مخازن جلوگيری کند، به تزريق آب روی آوردند.

Waterflooding in Saudi Arabia در ميدان آبقيIق باز می گردد کIه به ۱۹۵۶اوليIن تجربIه تزريIق آIب بIه سIال •

کار تزريIق به ۱۹۶۰ بودن ايIن عمليات، در اوايIل دهIه موفقيت آميIزدليIل معادل ۱۹۹۸ميدان قوار قبIل از افIت فشار ايIن ميدان آغاز شد. در سIال

ميليون بشکه در روز به دو ميدان قوار و آبقيق آب تزريق مي شد. ۱۲ ۱۲بر اسIاس گزارش های شرکIت سIعودیI آرامکIو،I در حال حاضIر روزانIه •

بIه ميليون بشکIه آبقيIق و بری تزريIق می شود که ۳آIب I،۷ ميدان قوار I،اIدري آIب تصIفيه از آIن بشکIه واحدهای ۳ميليون از بشکه ميليون

ميليون بشکIه نيIز از سIفره های آIب زيرزمينی ۳جداسIازی نفIت و گاز و تأمين می شود.

ميليون ۴ ميليون بشکIه به ميدان قوار و ۸ ميليون بشکIه، ۱۲از مجموع •با وجود آرامکIو آبقيIق تزريIق می شود. شرکIت بIه مياديIن بری و بشکIه

اين ۴گذشIت از هIم هنوز I،یIنفت مخازن بIه آIب تزريIق از شروع دهIه عمليات درس می گيرد.

Thanks for Your Attention!

waterflooding ()

Education

Transcript of waterflooding ()