Scale Flow Assurance Workflows in Multiphase Flow Simulation

Transcription

1 Scale Flow Assurance Workflows in Multiphase Flow Simulation Mack Shippen - Schlumberger PIPESIM Product Champion OLI Simulation Conference November 17, 2010

2 Abstract Multiphase flow simulation is critical to the understanding of impact of flow assurance issues on oilfield production system design and operation. While the modeling of organic solids such as hydrates, waxes and asphaltenes has in recent years become commonly available in multiphase flow simulators, detailed modeling of inorganic scales has been regarded as a more specialist discipline due to the inherent complexities of water chemistry. Consequently, scale prediction methods currently available in upstream multiphase flow simulators are quite simplified. As scaling behavior for a given fluid is governed by the prevailing pressures and temperatures, accurate prediction of the occurrence, location and severity of scaling depends on accurate modeling of the pressure and temperature profiles along the complete production system. This work aims to combine state-of-the-art scale prediction models with state-of-theart multiphase flow and heat transfer simulation technology to better understand scaling behavior and quantify risks in performing flow assurance studies. A workflow is presented which describes the coupling of the scale model with multiphase flow simulation and presents an example case study to illustrate the benefits of this approach.

3 Overview Background Multiphase Flow Simulation Mechanism of ScaleChem PIPESIM Workflow Case Study Summary and Future Work

4 Overview Background Multiphase Flow Simulation Mechanism of ScaleChem PIPESIM Workflow Case Study Summary and Future Work

5 Total Production System Separator Compressor Choke Flowline Riser Pump gas Safety Valve oil Export lines Tubing Reservoir Completion

6 Pressure Loss in System ΔP 8 = P sep P CD ΔP 7 = P RB P sep ΔP 9 = P sep P PD ΔP 6 = P DSC P RB ΔP 3 = P USV P DSV ΔP 4 = P wf P tf Flow in porous media Multiphase Flow in pipes Chokes/restrictions Pumps/Compressors ΔP 10 = P CD P GD ΔP 11 = P PD P LD ΔP 1 = P R P wfs

7 Temperature Changes in System ΔT 5 = T tf T DSC ΔT 7 = T RB T sep ΔT 6 = T DSC T RB ΔT 4 = T wf T tf Convection (free, forced) Conduction Elevation Radiation JT Cooling/Heating Frictional Heating ΔΤ 10 = T CD T GD ΔΤ 11 = T PD T LD ΔT 1 = T R T wfs

8 Segmentation

9 Nodal Analysis P sep Node taken at Bottom Hole model reservoir to separator Inflow = P R P wf Outflow = P wf P sep P wf P R

10 Nodal Analysis P sep P R P wf Inflow Outflow P wf P R P sep Flowrate

11 Overview Background Multiphase Flow Simulation Mechanism of ScaleChem PIPESIM Workflow Case Study Summary and Future Work

12 PVT File Structure Vapor/Liquid Phases Gas Hydrocarbon liquid Aqueous liquid V/L Phase Properties Mass Fraction against total composition Density Viscosity Heat Capacity Enthalpy Entropy Thermal Conductivity Compressibility factor Surface tension against gas phase Interfacial tension against other liquid phase Molecular Weight Solid Phases (Optional) Liquid 3 Water ice Hydrate type 1 Hydrate type 2 Wax Asphaltene Scale total Scale species 1 Scale species 2 Scale species Solid Phase Properties Mass Fraction Density Thermal Conductivity Phase appearance curves Etc.

13 Fluid Property File Generation ScaleChem PIPESIM

14 PVT Tables

15 PVT Calculations Loose vs. Tight Loose Advantages Fast Simple to Implement Tight Advantages More accurate Can mix fluids Can sensitize on fluid properties (eg. watercut)

16 Overview Background Multiphase Flow Simulation Mechanism of ScaleChem PIPESIM Workflow Case Study Summary and Future Work

17 Case Study

18 Fluid Composition Stock Tank Properties Hydrocarbon Water Watercut 50 % Gas Oil Ratio 640scf/STB Component Mol % Carbon Dioxide 2.7 Methane 34.6 Ethane 7.0 Propane 6.5 Isobutane 1.5 Butane 4.1 Isopentane 1.9 Pentane 2.6 Hexane 3.6 C C7+ BP 344ºF C7+ MW 283 Species mg/l Cations Na+ 20,400 K+ 402 Ca++ 20 Mg Ba++ 1 NH Anions Cl 37,000 SO4 20 HCO3 715

19 Phase Envelope

20 Nodal Analysis Tubing ID = 3 1/2 Tubing ID = 2.41 Skin = 10 Skin = 0.7

21 Phase Envelope

22 Phase Envelope 2

23 Pressure-Temperature Profile

24 Nodal Analysis Possible Scale Impact Tubing ID = 1.4 Tubing ID = 2.9 Skin = 10 Skin = 0.7

25 Results Available Phase Envelope Scale Appearance Lines (Total & by species) Profile Plots Total Scale Mass Fraction (eg. ppm, mg/l) Scale Species Mass Fraction Scale Species Pre- and Post- Scale Index System Plots Max. Scale Mass Fraction/branch Max. Pre-Post Scale Index/branch

26 Overview Background Multiphase Flow Simulation Mechanism of ScaleChem PIPESIM Workflow Case Study Summary and Future Work

27 Summary ScaleChem-PIPESIM workflow leverages complex water chemistry analysis and rigorous multiphase flow simulation Can be used to predict occurrence, location and severity of scale precipitation for entire production system Availability: ScaleChem? PIPESIM 2011 Summer 2011

28 Future work Tight coupling at engine level Input for pipe corrosion calculations Black Oil scale analysis?

29 Questions?