Design and Performance Testing of an Integrated, Subsea Compact Separation System for Deep-water Applications

Transcription

1 Design and Performance Testing of an Integrated, Subsea Compact Separation System for Deep-water Applications MCE Deepwater Development April 8 & 9, 2014 Madrid, Spain Ed Grave Fractionation & Separation Advisor Houston, TX USA Upstream Research

2 Millions of oil-equivalent barrels per day Business Incentives Global Liquids Supply By Type 2005 Deepwater ~ 3% 2040 Deepwater Contribution = ~ 14 MBDOE Biofuels Other Liquids NGLs Oil Sands Tight Oil Deepwater 2040 Deepwater ~ 12% ExxonMobil Resource Base Distribution In Percent Oil- Equivalent Barrels About 11% of Resources Please refer to disclaimer note regarding forward projections within the referenced sources below: Source: 2013 The Outlook for Energy: A View to 2040 ( 2 Source: 2013 Financial & Operation Review (

3 ExxonMobil Subsea Compact Separation System ExxonMobil Upstream Research Company (URC) designed and is testing a compact separation system for application in 3000m water depth and internal pressures up to 690 bar EM qualification philosophy is to qualify for a wide range instead of specific field conditions to reduce timeline of application Robust, flexible to inlet fluids, and scalable API Gravity: Oil Rate: 60 kbpd/train Gas Rate: Sm3/day Water Cut: 0 90% Slug Size: 5m3 Currently being qualified at ProlabNL (3) Crudes with API 19, 28 & 38 Scaled to kbpd Methane Gas at 45 bars Gas Rate: Am3/hr Water cuts 10 70% Slug Tests: 0.2 to 0.6m 3 Upstream Research 3

4 ExxonMobil Subsea Compact Separation System Simplified Schematic of ExxonMobil Subsea Compact Separation System being tested at ProLabNL. Cyclonic Inline Gas Polisher Gas Liquid Slug Generator Inlet URC Inlet Gas/Liquid Slug Catcher Aker CEC FMC CDS IEC tested at FMC separately URC Liquid/Liquid Pipe Separator and Level Controls Oil ASCOM Inline De sander Reject Water Fast Acting Mokveld Subsea Control Valve ASCOM Hiper MixedFlow 2 stage de oiling Hydrocyclones and Canty Oil/Water Monitors OiW Monitors 4

5 ExxonMobil Multitube/Subsea Slug-Catcher High-Pressure Testing at Steady-State Conditions 50 Effect of Liquid Level on Liquid Carry-over 15 Level (%) Carry over (m3/h) 0 405M70DMLG 405aM70DMLG Level Carry over (coriolis) Carry over (calculated) 0 Effect of Water Cut, Temperature, and Liquid Velocity on Gas Carry-under 0.5 Effect of Liquid Level on Gas Carry-under 200 GVF (%) GVF (%) Level (mm) Additional CFD analysis performed prior to tests at ProLabNL Liquid velocity (m/s) 20% WC at 50C 70% WC at 50C 20% WC at 70C 70% WC at 70C Tested at high-pressure (45 barg) in ProLabNL s HP flow loop facility with natural gas, crude & water; test parameters included liquid level, fluid properties, crude type and flow variations (flow rate, GLR, slugging) Test Results/Findings: Minimal liquid carry-over in majority of test points; gas outlet quality improved at lower liquid levels Liquid outlet quality improved at higher temperature (i.e., lower viscosity in oil phase) and lower oil flow rates Determined optimum liquid level and control scheme to minimize both liquid carryover and gas carryunder :51 20:54 20:57 21:01 21:04 21:07 21:11 21:14 Time (hh:mm) GVF Slug Catcher Level Slug Catcher 21:17 21:20 21:24 21:27 21: All data generated by or on behalf of ExxonMobil

6 ASCOM Monoline Gas Polisher A compact, in-line cyclonic separation device for liquid removal from gas-dominated streams; rated for 3000 m water depth and high internal pressures Applicable for liquid loading between 0-15 vol% High-Pressure Testing at Steady State Conditions Medium Crude (All Test Runs) 100 Efficiency (%) LVF (%) m3/h m3/h m3/h m3/h Courtesy of Ascom Advanced Separation Company Results/Findings: Better separation efficiency during high-pressure tests at higher liquid loadings (> 1.7 vol%) and gas rates (> 200 m3/hr) Gas carry-under from ASCOM Monoline boot observed during high-pressure tests when liquid residence time was low; degassing in vertical boot is not sufficient 6 All data generated by or on behalf of ExxonMobil

7 ASCOM Monoline Optimization Gas carry-under from ASCOM Monoline boot observed during high-pressure tests increased overall gas carryunder in the oil and increased emulsion height in the downstream pipe separator. Evaluated horizontal boot in low-pressure, model fluid tests; improves degassing at the same liquid residence time; no effect on liquid carry-over Gas Carryunder- High Pressure Testing Design Optimization-Low Pressure 1000 Medium Crude (All Test Runs) Vertical Boot Density (kg/m3) Residence time (sec) Horizontal Boot Courtesy of Ascom Advanced Separation Company Results/Findings: Evaluated horizontal boot in low-pressure, model fluid tests; improves degassing at the same liquid residence time; no effect on liquid carry-over Horizontal boot requires fast response level instrument due to limited span length. The horizontal boot design has not yet been tested in the high pressure loop 7 All data generated by or on behalf of ExxonMobil

8 ExxonMobil Pipe Separator Pipe separator tested at high-pressure (45 barg) in ProLabNL s HP flow loop facility with natural gas and crude; test parameters included liquid level, fluid properties, and flow variations (flow rate, GLR, slugging) High-Pressure Testing at Steady-State Conditions WIO/OIW Along Pipe Separator Length Crude with 40%WC at 35 C WIO/OIW Along Pipe Separator Length Crude with 40%WC at 70 C Mixing w/ U-bend pipe separator studied for the large scale unit Results/Findings: Oil/water qualities highly dependent upon interface level; small changes in interface level lead to significant changes in Oil in Water (OiW), as emulsion layer is pulled into water outlet Oil/water qualities improved at higher temperature (i.e., lower viscosity in oil phase, less stable emulsion layer), low or high water cuts, and lower liquid flow rates 8 All data generated by or on behalf of ExxonMobil

9 Aker CEC & ExxonMobil Pipe Separator Heavy oil separation is challenging in compact separation system Testing has shown that oil and water quality targets are difficult to meet requires reduced flow and/or additional heat or chemicals Incorporating electrostatic coalescence in compact separation system is expected to enhance performance. Aker CEC testing at ProlabNL on going Aker CEC previously tested at Porsgrunn, Norway for the Hebron qualification tests (2009) with a conventional separator Demonstrated increased separation efficiencies by factor of 5, reducing residence times from 60 to 10 minutes Data limited to 10% WC and C Pipe Separator High-Pressure Testing at Steady-State Conditions NO Aker CEC WiO/OiW for 2x velocity in Pipe Separator Lighter Crude with 20%WC at 70 C WiO/OiW for 1x velocity vs Sample Points in Pipe Separator Heavier Crude with 20%WC at 70 C 9 All data generated by or on behalf of ExxonMobil

10 Conclusions The ExxonMobil Subsea Compact Separation System proved to be very robust for a wide range of operating conditions As expected performance decreased significantly with heavy oil Slug Catcher Small variations in liquid level control in slug catcher affects both liquid carryover and gas carryunder. Gas carryunder increased emulsion in Pipe Separator Horizontal boot in ASCOM Monoline enhanced degassing Pipe Separator OiW concentration highly dependent on liquid level control Closed most of the gaps with ExxonMobil Compact Separation System ExxonMobil Multitube Slug Catcher ExxonMobil Pipe Separator ASCOM Monoline Gas Polisher ASCOM Deoiling System ASCOM Inline De sander Tracerco s Profiler Control system dynamic simulation can not be validated in a closed loop system Oil in Water monitors is still an open gap. Working with a number of vendors. 10

11 Thank You! Thank You!! Questions? Questions? Ed Grave Fractionation & Separation Advisor Houston, TX USA Upstream Research

12 ProlabNL Simplified Flow Loop Schematic ExxonMobil URC Subsea Compact Separation System Test Unit 12