Scale Analysis and Inhibitor Evaluation for an Offshore Asset - - PowerPoint PPT Presentation

Public Suyun Wang Oil & Mining Services 21.10.2014

Scale Analysis and Inhibitor Evaluation for an Offshore Asset

Suyun Wang, Oil & Mining Services, 21.10.2014

Table of Contents

Public 2

– Introduction – Data Gathering – Scale Modeling – DSL Experiment – Conclusion and Recommendation

Public Suyun Wang Oil & Mining Services 21.10.2014

Introduction

Suyun Wang, Oil & Mining Services, 21.10.2014

Objectives

Public 4

– Scale review of the offshore asset from the production wells to departing pipelines, then to CPP facilities. – Scale modeling to estimate the scaling severity. – DSL experiment to evaluate the scale inhibitor performance. – Recommendation on the suitable scale inhibitors and initial dose rates.

Public Suyun Wang Oil & Mining Services 21.10.2014

Data Gathering

Suyun Wang, Oil & Mining Services, 21.10.2014

Simplified Diagram of the Offshore Asset

Public 6

Production wells Departing pipelines CPP facilities

WA1 WA2 WA3 WB1 WC1 HP Separator HGOR Separator Oil Trim Exchanger IP Separator

• Prod. Water

Hydrocyclone Oil Heater LP Separator Electrostatic Heater Treater Flotation Cell To Skim Pile

Suyun Wang, Oil & Mining Services, 21.10.2014

Operation Conditions – Production Wells

Public 7

Well THT (°F) THP (psig) Production Rate (BWPD) Departing Pipeline WA1 144 704 122 HP WA2 142 661 208 HP WA3 137 649 103 HP WB1 140 1199 131 HGOR WC1 140 547 825 HP

Suyun Wang, Oil & Mining Services, 21.10.2014

Operation Conditions – CPP Facilities

Public 8

CPP Facility T (°F) P (psig) HGOR Separator 129 1089 HP Separator 126 464 Oil Trim Exchanger 120

a464

IP Separator 111 160 Oil Heater 132

b160

LP Separator 128 10 Electrostatic Heater Treater 131 10

• Prod. Water Hydrocyclone

120 168 Flotation Cell 128 30

–

aPressure of Oil Trim Exchanger was assumed to be the same as that of HP Separator.

–

bPressure of Oil Heater was assumed to be the same as that of IP Separator.

Suyun Wang, Oil & Mining Services, 21.10.2014

Brine Compositions

Public 9

Ion/Neutral Species Composition (mg/L) WA1 WA2 WA3 WB1 WC1

Na+ 5,701 5,819 6,625 8,136 8,782 Ca2+ 2.59 6.72 5.12 17.45 18.67 Mg2+ 3 5 5 24 22 Ba2+ 0.5 3.1 1.5 4.7 4.3 Sr2+ 2.22 4.93 3.78 10.52 9.33 Fe2+ 0.2 Cl- 7,500 7,000 8,500 12,500 13,500 SO42- 230.4 211.2 25.6 44.8 12.8 HCO3- 2,184 3,416 3,233 646.6 707.6 Dissolved CO2 0.65 0.649 0.646 0.64 0.637 Physical Property Data pH 8.1 7.9 8.3 8.1 7.9

Public Suyun Wang Oil & Mining Services 21.10.2014

Scale Modeling

Suyun Wang, Oil & Mining Services, 21.10.2014

Modeling Method

– Software: OLI ScaleChem – Scale modeling performed for

• Production wells
• Departing pipelines: HP and HGOR lines
• CPP facilities

– Scale modeling results reported as

• Scale index
• Precipitation potential in mg/L

Public 11

Suyun Wang, Oil & Mining Services, 21.10.2014

Modeling Results – Production Wells

Public 12

Well THT (°F) THP (psig) Barite (BaSO4) Calcite (CaCO3) Strontianite (SrCO3) SI PP (mg/L) SI PP (mg/L) SI PP (mg/L) WA1 144 704 0.04 0.0 0.06 0.5 0.43 2.2 WA2 142 661 0.76 4.2 0.61 12.0 0.97 7.2 WA3 137 649

• 0.46

0.0 0.42 7.3 0.79 5.1 WB1 140 1199 0.28 3.3 0.24 7.2 0.39 7.2 WC1 140 547

• 0.31

0.0 0.32 12.4 0.40 5.9

– WA1: mild strontianite scale. – WA2 and WB1: mild barite, calcite, and strontianite scales. – WA3 and WC1: mild calcite and strontianite scales.

Suyun Wang, Oil & Mining Services, 21.10.2014

Modeling Results – Departing Pipelines

Public 13

Departing Pipeline T (°F) P (psig) Barite (BaSO4) Calcite (CaCO3) Strontianite (SrCO3) SI PP (mg/L) SI PP (mg/L) SI PP (mg/L) WA HP 144 464 0.48 2.2 0.47 8.0 0.83 5.4 126 464 0.57 2.4 0.35 6.7 0.74 5.2 WB HGOR 140 1089 0.28 3.4 0.24 7.5 0.40 7.3 129 1089 0.31 3.9 0.15 4.1 0.34 7.3 WC HP 147 464

• 0.34

0.0 0.37 14.8 0.43 6.0 126 464

• 0.26

0.0 0.21 8.1 0.33 5.8

– WA HP and WB HGOR: mild barite, calcite, and strontianite scales. – WC HP: mild calcite and strontianite scales.

Suyun Wang, Oil & Mining Services, 21.10.2014

Modeling Results – Departing Pipelines

Public 14

WB HGOR line to CPP WC HP line to CPP

Mild barite, calcite, and strontianite scales Mild calcite and

strontianite scales

Suyun Wang, Oil & Mining Services, 21.10.2014

Modeling Results – CPP Facilities

Public 15

CPP Facility T (°F) P (psig) Barite (BaSO4) Calcite (CaCO3) Strontianite (SrCO3) SI PP (mg/L) SI PP (mg/L) SI PP (mg/L) HGOR Separator 129 1089 0.33 3.9 0.17 4.1 0.37 7.30 HP Separator 126 464 0.40 3.4 0.46 18.2 0.65 8.5 Oil Trim Exchanger 120 464 0.42 3.7 0.39 16.5 0.59 8.5 IP Separator 111 160 0.50 4.1 0.38 15.0 0.62 8.6 Oil Heater 132 160 0.36 3.4 0.48 19.7 0.64 8.9 LP Separator 128 10 0.39 3.5 0.47 19.1 0.64 8.9 Electrostatic Heater Treater 131 10 0.37 3.4 0.48 19.8 0.65 9.0 Hydrocyclone 120 168 0.43 3.8 0.41 17.1 0.61 8.7 Flotation Cell 128 30 0.38 3.5 0.46 19.1 0.64 8.9

– All facilities: mild barite, calcite, and strontianite scales.

Public Suyun Wang Oil & Mining Services 21.10.2014

DSL Experiment

Suyun Wang, Oil & Mining Services, 21.10.2014

DSL Equipment

Public 17

– Three-pump system to enable testing of multiple dosages of a scale inhibitor. – Monitor differential pressure change across the coil for indication of scale formation.

Suyun Wang, Oil & Mining Services, 21.10.2014

DSL Schematics

Public 18

Suyun Wang, Oil & Mining Services, 21.10.2014

Test Method

– Test conditions

• Brine: adjusted synthetic WA2 produced brine (100 mg/L Ca2+)
• Temperature: WA2 tubing head temperature of 142°F
• Scale inhibitors: SCALETREAT A and SCALETREAT B (phosphonate types)
• Inhibitor dosages: 70 ~ 0 ppm
• Test duration: 75 minutes for each inhibitor dosage

– Test procedure

• Prepared the cation, anion, and inhibitor dosed anion brines according to water

compositions.

• Pumped the cation and total anion brines in a 1:1 ratio, with a combined flow rate
• f 3 mL/min.
• Introduced the inhibitor stepwise from high concentration to low concentration.

Pressure increase during dosing indicated that the inhibitor was not effective at the dosed concentration.

Public 19

Suyun Wang, Oil & Mining Services, 21.10.2014

Blank Test Results

– DSL blank tests with various adjusted calcium contents to make sure scale forms in reasonable time at 142 °F.

Public 20

Suyun Wang, Oil & Mining Services, 21.10.2014

Inhibitor Test Results

– DSL inhibitor tests with 100 mg/L calcium in brine at 142 °F. – MIC = 60 ppm for SCALETREAT A, 40 PPM for SCALETREAT B.

Public 21

Public Suyun Wang Oil & Mining Services 21.10.2014

Conclusion and Recommendation

Suyun Wang, Oil & Mining Services, 21.10.2014

Conclusions

Public 23

– Scale modeling results suggested

• Production wells: mild strontianite scale for WA1 well; mild barite, calcite, and

strontianite scales for WA2 and WB1 wells; mild calcite and strontianite scales for WA3 and WC1 wells.

• Departing pipelines: mild barite, calcite, and strontianite scales for WA HP and

WB HGOR lines; mild calcite and strontianite scales for WC HP line.

• CPP facilities: mild barite, calcite, and strontianite scales for all facilities.

– DSL experimental data showed

• Both SCALETREAT A and SCALETREAT B were able to inhibit scale formation

at 142°F in the adjusted synthetic WA2 produced brine (100 mg/L Calcium).

• MIC were determined to be 60 ppm for SCALETREAT A and 40 ppm for

SCALETREAT B.

• SCALETREAT B exhibited better performance than SCALETREAT A.

Suyun Wang, Oil & Mining Services, 21.10.2014

Recommendation

Public 24

– Two treatment plans

• Continuously inject SCALETREAT A with an initial dosage of 60 ppm upstream of

the departing pipelines.

• Continuously inject SCALETREAT B with an initial dosage of 40 ppm upstream of

the departing pipelines. – The actual dosage can be optimized in field trials. – Final selection on SCALETREAT A or SCALETREAT B for field trial are based on their compatibility with produced fluids and other production chemicals, product price, raw material availability, etc.

Public Suyun Wang Oil & Mining Services 21.10.2014

Questions?

Public Suyun Wang Oil & Mining Services 21.10.2014

Thank You!