Dr. Mohammed M. Amro Dr. Mohammed M. Amro Petroleum Engineering Dept.Petroleum Engineering Dept.

King Saud UniversityKing Saud University

Effect of Scale and Corrosion Effect of Scale and Corrosion Inhibitors on Well Productivity in Inhibitors on Well Productivity in

Reservoirs Containing Asphaltenes Reservoirs Containing Asphaltenes

16.05.2005

OutlineOutline

Statement of Problem Statement of Problem

General AspectsGeneral Aspects

Effect and Preventation of Effect and Preventation of Asphaltenes PrecipitationAsphaltenes Precipitation

Experimental WorkExperimental Work

Material UsedMaterial Used

Results and DiscussionResults and Discussion

SummerySummery

Statement of ProblemStatement of Problem During oil production from several wells in During oil production from several wells in

Arabian Gulf area, significant productivity Arabian Gulf area, significant productivity decline was noticed. decline was noticed.

One of the reasons behind this might be One of the reasons behind this might be asphaltene precipitation. Production data of asphaltene precipitation. Production data of the particular wells were collected and the particular wells were collected and analyzed. analyzed.

Many of these wells were injected with scale Many of these wells were injected with scale and corrosion inhibitors in downhole and and corrosion inhibitors in downhole and surface equipment. surface equipment.

It was decided to investigate the potential of It was decided to investigate the potential of formation damage due to asphaltene in formation damage due to asphaltene in presence of scale and corrosion inhibitors as presence of scale and corrosion inhibitors as field chemicals. field chemicals.

General AspectsGeneral Aspects

Controlling asphaltenes problems Controlling asphaltenes problems requires one to understand the requires one to understand the conditions lead to deposition.conditions lead to deposition.

Reviewing production decline and well Reviewing production decline and well history can identify damaged wells. history can identify damaged wells. Focus on treatment history (acid, other Focus on treatment history (acid, other solvents, …) and subsequent response.solvents, …) and subsequent response.

Laboratory testing helps design Laboratory testing helps design effective chemical treatmenteffective chemical treatment

Effect and Preventation of Asphaltenes Effect and Preventation of Asphaltenes PrecipitationPrecipitation

Asphaltenes Problems in the reservoirs can occur during primary depletion in highly undersaturated Reservoirs, IOR-CO2 or chemical treatment and cause

Permeability reduction Wettability alteration (Oil wetting) Reduce oil production

PreventionPrevention

Predictive method Predictive method PVT, Compatibility tests between PVT, Compatibility tests between

different fluidsdifferent fluids Reservoir pressure above PbReservoir pressure above Pb Mechanical (scrapping)Mechanical (scrapping) Chemical treatmentChemical treatment

Solvents (Aromatics)Solvents (Aromatics) Dispersant and/or surfactant Dispersant and/or surfactant Light oilLight oil

Asphaltene deposition is the consequence of instability of oil

Experimental PartExperimental PartMaterial Used Material Used

Crude oil (11 cp, API 31.2°, 15% resin)Crude oil (11 cp, API 31.2°, 15% resin)

Asphaltene sample as solid paritcles Asphaltene sample as solid paritcles

Scale and Corrosion Inhibitors Scale and Corrosion Inhibitors (5 scale & 2 Corrosion inhibitors)(5 scale & 2 Corrosion inhibitors)

Core Samples (Berea Sandstone) and Core Samples (Berea Sandstone) and

Flooding Apparatus Flooding Apparatus

Experimental PartExperimental PartMethodologyMethodology

The asphaltenic oil was prepared by mixing a The asphaltenic oil was prepared by mixing a certain weight of solid asphaltene at different certain weight of solid asphaltene at different concentrations.concentrations.

The max. concentration was determined by The max. concentration was determined by observing flocculation and precipitation of observing flocculation and precipitation of asphaltenes for a period of 5 days. It was asphaltenes for a period of 5 days. It was found that the used crude oil could stabilize found that the used crude oil could stabilize an asphaltene concentration up to 3%.an asphaltene concentration up to 3%.

Surface and interfacial tensions and contact Surface and interfacial tensions and contact angle of the oil samples were measured in angle of the oil samples were measured in presence of brine as well as brine containing presence of brine as well as brine containing scale and corrosion inhibitors. scale and corrosion inhibitors.

Experimental Part- FloodingExperimental Part- Flooding11stst Using crude oil displaced by 5% brine Using crude oil displaced by 5% brine

(reference experiment).(reference experiment).

22ndnd Using crude oil displaced by 5% brine Using crude oil displaced by 5% brine containing scale or corrosion inhibitors containing scale or corrosion inhibitors (Effect of inhibitors on the floodin in (Effect of inhibitors on the floodin in presence of crude oil without asphaltenes).presence of crude oil without asphaltenes).

33rdrd Using asphaltenic oil at 1% asphaltenes Using asphaltenic oil at 1% asphaltenes displaced by 5% brine. (represent the displaced by 5% brine. (represent the flooding with asphaltenic oil as a reference).flooding with asphaltenic oil as a reference).

44thth Using asphaltenic oil at 1% asphaltenes Using asphaltenic oil at 1% asphaltenes displaced by 5% brine containing 200 ppm displaced by 5% brine containing 200 ppm scale or corrosion inhibitors. scale or corrosion inhibitors.

Experimental Part - FloodingExperimental Part - Flooding

Relative permeability curves were Relative permeability curves were determined using determined using unsteady state unsteady state methodmethod, to evaluate the influence of the , to evaluate the influence of the inhibitors on the multiphase flow inhibitors on the multiphase flow through the porous media. through the porous media.

Driving fluid at constant flow rate Driving fluid at constant flow rate displaces the in-situ fluid.displaces the in-situ fluid.

Johnson-Bossler-Naumann (JBN) was Johnson-Bossler-Naumann (JBN) was used to calculate the Kr.used to calculate the Kr.

Results of Flooding ExperimentsResults of Flooding Experiments

The presence of scale inhibitors does not The presence of scale inhibitors does not affect the fluid flow behavior in porous affect the fluid flow behavior in porous media (confirmed by contact angle and media (confirmed by contact angle and IFT).IFT).

The presence of corrosion inhibitors The presence of corrosion inhibitors showed significant change in Krshowed significant change in Kr

The experiments conducted in series 1 The experiments conducted in series 1 and 2 were analyzed and compared and 2 were analyzed and compared

Series 1: Crude oil displaced by brine

Series 2: crude oil displaced by brine containing corrosion inhibitor

Results of Flooding ExperimentsResults of Flooding Experiments

00.10.20.30.40.50.60.70.80.9

1

0 0.2 0.4 0.6 0.8 1

Sw, Water Saturation, % PV

Rel

ativ

e P

erm

eab

ility

, Kr Kro (core #1)

Krw (core #1)

Kro (core #3)

Krw (core #3)

The experiments conducted in series 1 and 3 were compared. The experiments conducted in series 1 and 3 were compared. It shows a reduction in oil relative permeability in presence It shows a reduction in oil relative permeability in presence

of asphaltenes. This is probably due to higher viscosity (14 of asphaltenes. This is probably due to higher viscosity (14 cp)cp)

Results of Flooding ExperimentsResults of Flooding Experiments

00.10.20.30.40.50.60.70.80.9

1

0 0.2 0.4 0.6 0.8 1

Sw, Water Saturation, % PV

Re

lati

ve

Pe

rme

ab

ilit

y,

Kr

Kro (core #2)

Krw (core #2)

Kro (core #4)

Krw (core #4)

Results of Flooding ExperimentsResults of Flooding Experiments

0

0.2

0.4

0.6

0.8

1

0 0.2 0.4 0.6 0.8 1Sw, Water Saturation, % PV

Rel

ativ

e P

erm

eab

ility

, Kr Kro (core #3)

Krw (core #3)

Kro (core #4)

Krw (core #4)

Photograph of core#3 & 4

Core #3Core #3 Core #4Core #4

SummarySummary There is no significant change in wettability There is no significant change in wettability

in presence of scale inhibitorsin presence of scale inhibitors

The presence of corrosion inhibitor solution The presence of corrosion inhibitor solution resulted in alteration of wettability to resulted in alteration of wettability to strongly oil wet.strongly oil wet.

A mixture of corrosion and scale inhibitors A mixture of corrosion and scale inhibitors will not affect the water wettability of quartz will not affect the water wettability of quartz plateplate

It was found that the combination of It was found that the combination of asphaltenic oil and corrosion inhibitor leads asphaltenic oil and corrosion inhibitor leads to asphaltenes deposition (formation to asphaltenes deposition (formation damage)damage)

SummarySummary

A successful chemical treatment in the field A successful chemical treatment in the field is based on laboratory investigations to is based on laboratory investigations to verify the compatibility of any field chemicals verify the compatibility of any field chemicals with the well productivity prior applicationwith the well productivity prior application

The overall results are important for oil The overall results are important for oil reservoir containing asphaltenesreservoir containing asphaltenes

Thank youThank you

DiagnosisDiagnosis

Information Analysis

Plugged Wells Non Plugged Wells

Deposit

Inorganic DepositOrganic Deposit

Paraffins

Asphaltenes

Scale

Sand

Prediction:• PVT•Asphaltenes Solubility•Characterization

% Asphaltene(Each 2 Months)

% AsphalteneReduction

Fine ParticlesFine Particles

Contact AngleContact AnglePre-ScreeningPre-Screening

Time [hr]

Brine S-10 S-27 S-45 S-78 S-81

0 50° 0° 45° 45° 40° 90°

24 60° 0° 52° 48° 42° 90°

48 60° 0° 60° 52° 48° 90°

72 60° 0° 60° 52° 55° 90°

Contact angle measurements in presence of crude oil

(Water wet)

Time

[hr] Brine S-10 S-27 S-45 S-78 S-81

0 50° 12° 53° 25° 20° 90°

24 65° 15° 55° 35° 36° 90°

48 65° 15° 65° 55° 68° 90°

72 65° 20° 65° 55° 68° 90°

Contact angle measurements in presence of asphaltenic crude oil

Surface tension of asphaltenic oil

Interfacial tensions between asphaltenic oil and brine containing scale inhibitor

Surface and Interfacial TensionSurface and Interfacial TensionCorrosion InhibitorsCorrosion Inhibitors

Contact Angle of asphaltenic oil in presence of corrosion inhibitor 180° (Strongly oil wet)

C-68C-68 C-62EC-62E

Surface TensionSurface Tension 3737 3737

Interfacial tension with Interfacial tension with Arabian lightArabian light 6.86.8 1.21.2

Interfacial tension with Interfacial tension with Arabian lightArabian light 1.81.8 0.20.2

Relative PermeabilityRelative Permeability

0

0.2

0.4

0.6

0.8

1

0 0.2 0.4 0.6 0.8 1Sw, Water Saturation, % PV

Re

lati

ve

Pe

rme

ab

ility

, Kr

Kro (core #1)

Krw (core #1)

Kro (core #2)

Krw (core #2)