Newsletter ECE5 Rev1

WHAT’S NEW IN ECE® 5 ? An introduction to the technical features of Electronic Corrosion Engineer ® Version 5.0 INTRODUCTION ............................................................................................................................ 2 NEW FUNCTIONALITY .................................................................................................................. 2 New Graphing Capability............................................................................................................. 2 Flowline Temperature Profiles ..................................................................................................... 3 Tapered Tubing Strings ............................................................................................................... 4 Corrosion Inhibition ..................................................................................................................... 5 TECHNICAL CHANGES IN THE ECE5 UPGRADE ........................................................................ 5 Iron carbonate saturation ............................................................................................................ 5 Corrosion due to H2S.................................................................................................................. 6 Flow Regime Indicator and HoldUp ............................................................................................. 6 Sour to ISO15156? ..................................................................................................................... 6 Material Selection Rules for CRA Evaluation............................................................................... 7 Temperature and Pressure Profile in Tubing ............................................................................... 7 OPERATIONAL CHANGES IN THE ECE5 UPGRADE ................................................................... 7 Changes to Input Options............................................................................................................ 7 Changes to Input Ranges............................................................................................................ 7 Changed Input for Tubing Water Production rate ........................................................................ 8 Printing and Report Handling ...................................................................................................... 8 Import, Export and Saving Data .................................................................................................. 8 Software Compatibility ................................................................................................................ 9 Licence Transfer ......................................................................................................................... 9 Life Cycle Costing Tools.............................................................................................................. 9 General Updates and Improvements ........................................................................................... 9 PRODUCT ROADMAP ................................................................................................................... 9

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INTRODUCTION ECE5 offers many significant improvement to users over ECE4. These range from technical modelling developments, new functionality, updated information on materials, wider choice of graphs and improved reporting and printing capabilities. The software is in a new-look format which is compatible with latest operating systems. Licencees of ECE5 software will also receive regular updates to keep in line with planned functionality improvements and new materials data as well as receiving the benefit of expert technical support on the use of the program, so ECE5 is a fully supported software.

NEW FUNCTIONALITY New Graphing Capability In addition to the usual selection of graphs for the corrosion rate and risk analysis there is now a drop down selection of graphs on the “All Graphs” tab on the right hand side of the screen: - pH - Water flow rate (m3/d) - Watercut (%) - Liquid Hold-up (%cross-section) - Liquid Velocity (m/s) - Gas velocity (m/s - Pressure (bar) - Temperature (degC)

Dragging the cursor across any area of the graph makes the graph zoom to that area, giving a close-up view of areas of interest, particularly allowing graphs with a low value close to zero to be expanded. Right clicking on any graph brings up a menu:

What’s New in ECE-5 ?


Clicking on the option “Set scale to default” returns the graph to the normal scale settings. Other options allow the graph to be copied or saved. Clicking “Page set-up” allows controls to be set for the page size before clicking on “Print”. The choice of “Show point values” gives a tooltip of all the co-ordinates of the graph as the cursor is passed over the graph. If you click on the drop-down tab for graph selection you can scroll through all the graph selection using the down arrow button on your keyboard. All these new graphs and graph controls allow better explanation of the corrosion rate results and greatly improved capability to extract graphs for inclusion in reports. Flowline Temperature Profiles Flowline Corrosion Predictor has a choice of temperature profile models available; the old straight line between defined inlet and outlet temperature or the option to apply a “cooling curve” temperature profile. In the example shown, the flowline has an inlet temperature of 62.4 degC but the ambient temperature is 4degC (such as seawater). By adjusting the slider controlling the insulation of the coating the temperature profile can be altered to indicate a faster or slower cooling down to ambient conditions at the outlet. Heat transfer values (W/m2/degC) are indicative of a range of insulation options from good to poor.



It is also now possible to model cases where the outlet of the line is warmer than the inlet, whereas in ECE4 the outlet temperature was required to be below the inlet. Whilst this rarely arises, it allows the modelling of (for example) flowlines with heat tracing. Tapered Tubing Strings The Tubing Corrosion Predictor allows the input of upper and lower tubing strings with different dimensions; the risk graph also distinguishes between upper and lower tubing based upon the maximum corrosion rate estimated in either section. Under the input tab “Steel” the data can be entered for a smaller diameter tubing at the bottom of the well by clicking on the “tapered tubing” box. The depth value entered is the depth of the bottom of each tubing section.



Corrosion Inhibition In ECE4 the efficiency of inhibition was assumed to be 99% and the user could only input an availability figure to alter the overall inhibitor effectiveness. In ECE5, both the Efficiency and the Availability of continuous corrosion inhibition can be varied (Advanced Tab) reflecting accepted industry practice and allowing the ECE5 model to more closely reflect results of actual inhibition testing.

TECHNICAL CHANGES IN THE ECE5 UPGRADE Iron carbonate saturation The ECE5 model assumes as a default that there was always a supersaturation of the environment with iron bicarbonate. This corrosion product builds up in producing systems because, at low temperatures, it is slow to precipitate as iron carbonate. The effect is that the pH is raised and the corrosion rate reduced. This is realistically what occurs in the majority of producing situations. By comparison, some other corrosion models assume there is no iron ion saturation in solution, which is typical of the situation in a laboratory test within the first period of exposure of steel to a fresh corrosive environment of fixed volume. In such cases the pH is lower and initial corrosion rate is higher, until the solution becomes contaminated with the corrosion products. Depending on the temperatures concerned, this approach of ignoring the build-up of dissolved iron concentration will tend to give over-conservative results, but may be useful for specific circumstances, such as freshly condensed water in process streams. In the ECE5 there is the option to choose, on the Input tab called “Advanced”, whether the user wishes to select a starting situation with zero iron ions in solution, or the default condition of iron supersaturation in the environment. The choice of “iron saturation” available in ECE4 has been removed as it is consistently shown that environments rapidly become super-saturated. When the default setting is changed to “no iron”, the ECE5 model calculates the gradual build up of iron ions in solution as corrosion progresses along the pipe. This makes it possible to see the change in pH as a function of distance. This situation may be relevant for the inlet sections of wet gas lines where a condensed water phase may be very “pure” and therefore corrosive. The What’s New in ECE-5 ?


occurrence of such a type of "inlet corrosion" is not generally observed, probably because in practice there are almost always some sources of dissolved iron, and furthermore, other corrosion mitigating factors, such as the low mass transfer in thin water films etc, all help to reduce the actual corrosion rate. In ECE5 the build-up of iron ions is more gradual than in ECE4, using the results of work published by Ohio State University in studies over the last 5 years (Sun, W, “Kinetics of iron carbonate and iron sulphide scale formation in CO2/H2S Corrosion”, dissertation Nov 2006). This results in a less abrupt change in pH and a longer distance over which corrosion rates may be higher when the choice of “none” is made for iron saturation; it does not change the overall values obtained. In many cases, the difference in maximum estimated corrosion rate as a result of this change is not significant. The changes in the dissolved iron concentration as a function of distance is modelled by means of a finite element approach, dividing the pipe/tube length into 100 sections, for each of which the net change in dissolved iron concentration from corrosion, precipitation and in- and out-flow, is zero. Corrosion due to H2S Continued studies by Intetech in sour fields have been used to improve the H2S model used in the ECE. In ECE5 the new model shows increased protectiveness of the iron sulphide film in conditions with very low CO2:H2S ratio. This change has also allowed the range of H2S in the input to be increased to 50%. The effect of this new H2S model may be to reduce the corrosion rate when compared to the values obtained by ECE4. The ECE5 model still distinguishes the corrosion rate found in sour systems underneath a sulphide film, and the potentially high pitting corrosion rate which can arise if the filmed surface fails. The rate of pitting curve is visible when H2S is added to the system, as well as the curve indicating the iron sulphide filmed corrosion rate. Flow Regime Indicator and HoldUp The flow regime indicated on the details tab of ECE5 is only intended to give an approximate indication of the flow regime at the inlet as tubing is considered to be perfectly vertical and flowlines are considered to be perfectly horizontal. In reality, small variations in inclination can dramatically impact the flow regime. The purpose of indicating the flow regime is actually only to clarify if the flow regime is symmetrical or not. The unsymmetrical flow regime of stratified flow in pipelines is the only case where the phenomenon of “top-of-the-line” corrosion will be indicated by ECE5. The change in ECE5 relative to ECE4 principally concerns (for flowlines) the shift from stratified to intermittent/bubble flow at superficial liquid velocity conditions above 0.7m/s. In multiphase flow the calculation of hold-up (the percentage of the cross-section occupied by liquid) is important in determining the flow rate of the liquid and gaseous phases. The flow models assume that the pipeline is in steady state and all the flow parameters are independent of time. In the case of annular flow, all the gas is assumed to flow in the core. Sour to ISO15156? The Details tab now includes an assessment of the partial pressure of H2S and pH of the environment to decide if the conditions are non-sour or sour – Region 1, 2 or 3 according to ISO15156. The decision is based upon the maximum partial pressure at any location in the flowline or tubing string.



Material Selection Rules for CRA Evaluation The CRA evaluator considers the suitability for service of typical types of CRAs which are used for flowlines and for tubing. The selection rules used to select these materials are continuously reviewed to ensure they are up to date with latest published data and performance in service experiences. The experience with 13Cr and S13Cr alloys for downhole tubing has been subject to much review and ECE5 reflects the safe operating envelope for these two materials. The upper temperature limits of both 13Cr and S13Cr materials has been increased slightly based on continued strong performance in the field. The 13Cr alloy has also been shown to be able to withstand slightly higher H2S levels in practice than the S13Cr grade reflecting its lower yield strength. Details of the new limits are shown in the help files under Flowlines/Tubing CRA evaluation. The selection of Alloy 316L has been adjusted to reflect its widespread use in sour gas plants where the chloride content is negligible (<50ppm). Under these conditions the material has been shown to withstand high levels of H2S, which is reflected in the new ECE5 limits. This 50ppm chloride limits has also been applied to duplex stainless steels and to CRA materials more highly alloyed than Alloy 316L. Other materials’ limits are largely unchanged relative to ECE4, although all have been reviewed. Temperature and Pressure Profile in Tubing The temperature and pressure profiles from bottom hole to top conditions are assumed linear with true vertical depth. Since the deviation survey is entered based upon measured depth, ECE5 automatically applies the deviation-corrected temperature and pressure profile over the full depth. (Note that ECE4 used a more conservative approach of applying the temperature and pressure profiles over the full tubing measured depth.)

OPERATIONAL CHANGES IN THE ECE5 UPGRADE Changes to Input Options In ECE5 you can type inputs in either units. Changes to Input Ranges In the new format of ECE5, input parameters that have ranges feature a “range selector” to the right hand side of the slider. When clicked the choice of ranges is given and the required one can be easily selected. Whilst the widest range may be useful in some cases, the choice of smaller ranges makes the slider steps smaller, allowing data to be entered with greater accuracy.



Temperature ranges have been extended up to 160 °C. The Pressure range has been extended up to 700 bar for downhole tubing and the allowable ranges of CO2 and H2S pressure are now based on partial pressure not mol %. CO2 – still allowed up to 100% and with constraint of maximum partial pressure of 200 bar. H2S – increased from 10% up to 50% and with constraint of maximum partial pressure of 50 bar. Changed Input for Tubing Water Production rate The water production rate input for the Tubing Corrosion Predictor tool is now based on the water rate at the wellhead.as that is the usual parameter measured from well testing or production data. The ECE5 model calculates the water content in the tubing.from the bottom to the top. The Details Tab now reports the liquid water content flowing at the bottom of the well. In some cases (where all the produced water is coming from condensation from the gas phase) the liquid water content may be zero indicating that the bottom of the well is dry (and hence non-corrosive). At some height in the tubing water starts to condense as a liquid and from that height upwards corrosion will commence. Printing and Report Handling Responding to the requests from several clients, the reporting and printing capabilities of the ECE program have been significantly improved in order that the output information from the ECE can be easily exported into “Excel” and “pdf” file formats from where it can be easily copied into reports. This allows a table to be created in a report of multiple cases where a project may have various conditions or numbers of streams. ECE graphs can also be directly printed, saved as images, or cut & pasted into other documents. Import, Export and Saving Data • Reports (ie results) from the Corrosion Predictor and Life Cycle Costing Tools can be exported to Excel or pdf formats. Click on FILE and select Pipeline/Tubing corrosion predictor report and then choose Export. What’s New in ECE-5 ?


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Graphs can be copied for inclusion in other documents, saved as images or printed. Just right click on the graph to access these menu options. Data from all ECE tools are saved as a single Project in a single data file (ECE 4 had different file types for the Corrosion Predictor and for Life Cycle Costing tools and for tubing and flowlines)

Software Compatibility The ECE 5 software has been written and tested for compatibility with Windows XP, Windows Vista and Windows 7. Licence Transfer Licence Transfer Wizard guides customers through the transfer process with a simple 3 step process and now allows licences to be transferred via any removable media or network shared drive. Life Cycle Costing Tools The layout of the data input pages has been improved. More of the inputs can be entered with sliders as an alternative to typing the values. The LCC tool is now entirely independent of the corrosion predictor tool and no data is linked between them. General Updates and Improvements • All the help files have been reviewed and updated. • The manufacturers database has been updated. • Some features of the program e.g. the button for "water dropout", are greyed out and only active when they are relevant. • The program is now able to handle number formats with either comma or dot for the decimal point, so that it is compatible with both systems used internationally.

PRODUCT ROADMAP ECE 5 has a development Road Map for future enhancements. We are very interested to hear suggestions from users so that these can be included in the Road Map. Planned enhancements in the short-term include, the addition of ISO15156-3 rules as an option to the CRA selector tool and more flexibility in treatment of erosional effects at high fluid velocity.


Newsletter ECE5 Rev1

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