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Identificationof Scales

Scales are mineral deposits that can form in oilfield tubing, perforations, and formations. They precipitate due to changes in temperature, pressure, and fluid mixing during production. This procedure provides instructions to identify unknown scale samples using a decision tree. Safety goggles and protective clothing should be worn when handling acids. The test involves examining a scale's solubility in water, hydrochloric acid, and other solutions to determine its mineral composition.

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Amina Mekkakia
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94 views2 pages

Identificationof Scales

Scales are mineral deposits that can form in oilfield tubing, perforations, and formations. They precipitate due to changes in temperature, pressure, and fluid mixing during production. This procedure provides instructions to identify unknown scale samples using a decision tree. Safety goggles and protective clothing should be worn when handling acids. The test involves examining a scale's solubility in water, hydrochloric acid, and other solutions to determine its mineral composition.

Uploaded by

Amina Mekkakia
Copyright
© © All Rights Reserved
We take content rights seriously. If you suspect this is your content, claim it here.
Available Formats
Download as PDF, TXT or read online on Scribd
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STIMULATION LABORATORY

PROCEDURES
Procedure A04: IDENTIFICATION OF OILFIELD SCALES

IDENTIFICATION OF OILFIELD SCALES

INTRODUCTION

Scales are precipitated mineral deposits. They can precipitate in the tubing,
perforations and/or formation. Scale deposition occurs during production
because of the lower temperatures and pressures encountered in or near
the wellbore area. Scales can also form by mixing of incompatible waters,
formation water and either a fluid filtrate or injection water.

SAFETY

Goggles and protective clothing should be worn when working with acid.

EQUIPMENT

•
Hydrochloric acid (~15%)
•
Hot plate / water bath
•
U104 or U42
•
Test tubes / glass beakers
•
Magnet

1.0 PROCEDURE

Follow the decision tree, below, to identify the unknown scale sample

EATC Stimulation Page 1 of 2 Rev A - Nov 1997


STIMULATION LABORATORY
PROCEDURES
Procedure A04: IDENTIFICATION OF OILFIELD SCALES

Scale Diagnosis
D o e s s c a le
flo a t i n w a t e r ?
Yes
No

Soluble in water? Organic


No Yes

Soluble Probably
in HCl? NaCl
Yes
No

Odour of rotten eggs? Soluble in hot HCl?


Yes No Yes No

Possibly CO2 Iron Soluble in hot HCl/HF?


FeS evolved? Oxide
No Yes No
Yes No Yes No

FeCO 3, Fe 2(CO 3) 3 Ca(SO 4) 2 Magnetic? Silica base Soluble


CaCO 3, MgCO 3 Slowly soluble (sand/clay) in U42 or U104?
Also sol. in U42
Yes
SrSO 4 (slow) Yes
Magnetite BaSO4 (very slow)
FeCO 3

EATC Stimulation Page 2 of 2 Rev A - Nov 1997

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