Aug 2008 The Geomodeling Network Newsletter

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This newsletter will be sent out to all members of the Geomodeling Network every second month.

This newsletter will be sent out to all members of the Geomodeling Network every second month.

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  • 1. August 2008 The Geomodeling Network Newsletter A very happy summer to all of our Geomodeling Network members. I hope you all enjoyed the first newsletter and are ready to digest the second instalment. Our group has grown quite a bit since June; indeed we are now cruising towards the 300 mark with new members joining each day. For those of you that may be interested you may like to know that the employment category breakdown of our membership is as follows: E&P company staff 48% E&P consultants 12% SW vendors 26% Other 14% Hopefully you’ll agree that it’s a healthy mix of people, dominated (rightly so) by those that carry out Geomodeling tasks and those that supply the Geomodeling technology – this was the demographic I was hoping to achieve. The ‘Other’ category is a mix of academics, recruitment specialists and other interested but “non-G&G” people. Whilst I did receive some feedback regarding the 1st newsletter it would be of great benefit to the group if more people contributed. Not necessarily in the provision of articles but by providing comments or opinions. I appreciate we are all busy but please take a few minutes to do this if you can. The people who write the articles have invested some time and effort in them and are keen to receive as many comments as possible. As before, on the next page you will find a listing of all the articles in this newsletter, hopefully you will find something of interest. As ever, if you would like the format to be changed for subsequent newsletters please let me know – all constructive comments (good & bad) are welcome. Welcome again, Mitch Sutherland (group administrator) mitch.sutherland@blueback-reservoir.com Page 1 The Geomodeling Network – Sponsored by Blueback Reservoir www.blueback-reservoir.com
  • 2. August 2008 The Geomodeling Network Newsletter Table of Contents 1. Member Articles, Reviews & Questions 1.1 Modeling N:G and Associated Properties- workflows and Pitfalls Page 3 By Jose Varghese – Shell An article that looks at some of the ways N:G can be defined and modeled and the inherent pitfalls that await the unwary geologist. 1.2 To model N:G or not to model N:G Page 11 By Juan Cottier – Blueback-Reservoir Should we even be considering modeling N:G in 3D? This article is sure to raise a reaction! 1.3 Questions relating to Probabilistic Vs Deterministic methods of calculating GIIP or STOIIP Page 15 By Jose Varghese – Shell Multiple questions on calculating volumes (methodologies, varying contacts, monte-carlo simulation workflows etc) 2. New Geomodeling Technology 2.1 Roxar’s August webinar’s Page 20 2.2 JOA – Handling of complex fault geometries using Jewel Suite Page 21 2.3 EMGS and Blueback Reservoir launch ‘BRIDGE’, an EM integration tool for Petrel Page 27 2.4 Petrophysical Analysis Workflows using OpenSpirit Page 29 3. Career Networking Page 29 4. Requests for newsletter No3 Page 32 Page 2 The Geomodeling Network – Sponsored by Blueback Reservoir www.blueback-reservoir.com
  • 3. August 2008 The Geomodeling Network Newsletter 1. Member Articles, Reviews & Questions 1.1 Modeling NTG and Associated Properties- workflows and Pitfalls Jose Varghese (Jose.varghese@shell.com) Defining Net to Gross (NTG) at the well level and modeling it in the static reservoir model play an important role in the hydrocarbon volume calculation. Though it may sound simple, there are chances for erroneous calculations in NTG, during reservoir modeling. This document aims to highlight some of the issues, recommended workflows and also invite comments and suggestions from the readers. WORKFLOW PRACTICES When it comes to defining and modeling of NTG, people have been following many workflows, such as: Use Gamma ray or Vshale or Porosity or a combination of all these to define Net and Non Net interval at the well log scale. Use the facies log (created using the log cut-off or manually interpreted) and create a NTG log (e.g. NTG= if(facies=0, 0,1) ; i.e. If the facies code is non reservoir, keep NTG zero, else keep it as 1) Once the facies 3D model is created, generate a binary NTG model from the facies model itself (e.g., NTG_model= if(faciesmodel=1,1, 0); this creates an exact copy of facies model. Upscale binary NTG log into the Geocellular model and interpolate independently. Upscale binary NTG log into the Geocellular model and interpolate it conditioning to facies model, but keeping NTG=0 in non reservoir facies. Upscale Binary NTG log into the Geocellular model and interpolate it Watson: Holmes! What conditioning to facies model, and model it in all facies (including non reservoir kind of rock is this! facies). Keep the property values as zero in the Non reservoir interval, upscale and model conditioned to facies. Holmes: Sedimentary, my Upscale cut property logs (Porosity, permeability etc) and model it conditioned dear Watson. to facies, assign zero values in Non reservoir facies. ......I’ll get my coat! Upscale cut property logs (Porosity, permeability etc) and model it conditioned to facies, (model it in all facies). It can be seen that, there are issues with some of the workflows. These issues become significant, when the cell thickness or layering scheme in the model is very coarse and the heterogeneity seen in the logs are not captured by the Page 3 The Geomodeling Network – Sponsored by Blueback Reservoir www.blueback-reservoir.com
  • 4. August 2008 The Geomodeling Network Newsletter layering scheme. We can see some of these issues in detail in the following sections. DEFINITION As mentioned earlier, NTG is defined either by using a log cut-off or by using a reservoir – Non reservoir discriminator log (a facies log). One of the QC method used in checking the Upscaled/modelled result is to compare the Equivalent Pore Column(EPC), between the well level properties (as shown below) and the corresponding model derived properties. They would (should) match when the the layering scheme has properly captured the heterogeneity seen in the wells. Page 4 The Geomodeling Network – Sponsored by Blueback Reservoir www.blueback-reservoir.com
  • 5. August 2008 The Geomodeling Network Newsletter Many of the issues come up during the modeling stage only, not at the well log scale of interpretation. For mappable shale layers (deterministic shales), as shown in the figure below, NTG can be assigned to “ZERO”. The accuracy of defining the layer boundary is user controlled. Net pore volume in this case is Zero. No need for even making layers in this unit. But for those shale intervals interpreted in wells, which are not correlatable (present in the reservoir units, which need to be distributed stochastically in a model), the definition and modeling of NTG bring some issues in the workflows practiced. MODELING ISSUES quot;Can ye make a model of Consider a perfect case of layering as shown below. Here both the original facies it? and upscaled cells match exactly. In other words, each cell represents 100% of If ye can, ye understands the same facies at the well log level. But this remains an ideal case, as the user it, and if ye canna, ye does not have a control on the exact match of facies boundaries and layer dinna!quot; boundaries. This can be approximated by taking a fine layering. Sometimes, the model dimensions and the modeling strategy would require going for a coarser layering. Lord Kelvin (supposedly) Page 5 The Geomodeling Network – Sponsored by Blueback Reservoir www.blueback-reservoir.com
  • 6. August 2008 The Geomodeling Network Newsletter Now consider the following situation, where the layering is bit coarser. When the facies logs are upscaled, the resulting cell facies DO NOT represent 100% of the same facies at well log level. Consider the Reservoir and Non Reservoir facies cells inside the red circles. The reservoir cell is not 100% reservoir and similarly Non reservoir cell is not 100% non reservoir. In such cases, the different upscaling and modeling practices have different impact on the GIIP or STOIIP calculated. Page 6 The Geomodeling Network – Sponsored by Blueback Reservoir www.blueback-reservoir.com
  • 7. August 2008 The Geomodeling Network Newsletter Consider the flowing case If NTG is created by using the facies in the model as a criteria (ie NTG_model= if(faciesmodel=1,1, 0); this creates an exact copy of facies model.), as seen in the red rectangle, it can be seen that, we overestimate reservoir facies in some cases (green rectangle) and in some case we underestimate the reservoir facies ( Pink rectangle). So it is clear that the “Binary NTG in the model” is not a representation of the facies at the well log level. So the correct procedure would be to upscale the binary NTG log (raw log), so that it becomes a non binary log (all values between 0 and 1 possible). This will account for the Reservoir and Non reservoir fractions lost during upscaling. Consider the upscaled non binary NTG in the above figure (blue rectangle). See the cell with a yellow boundary. It is a Non reservoir cell in the model. But it has actually about 5% of reservoir facies as well. A binary NTg with “0 “ value will not account for this. But the upscaled NTG with a value of 0.05 accounts for the 5% reservoir facies. When there are many wells and similar discrepancies due to coarser layering occurs, the sum total of all such discrepancies would result in incorrect GIIP/STOIIP. Page 7 The Geomodeling Network – Sponsored by Blueback Reservoir www.blueback-reservoir.com
  • 8. August 2008 The Geomodeling Network Newsletter Summary Always use a facies interpretation (reservoir, non reservoir discrimination). Always use a binary NTG at log level and upscale it to the model. Make sure that the R/NR log used in defining NTG is consistent with the current facies log /model used. Do not use a binary NTG directly in the model (created from facies). MODELING PROPERTIES quot;The primary role of the geologist is to recognise the existence Once the NTG is upscaled, how to proceed with modeling NTG as a full 3D of phenomena before model? The practices seen for creating 3D NTG property are, trying to explain themquot; Create NTG Model directly from facies model (discussed and mentioned as the B.M. Keilhau, 1828 wrong method in earlier section). Model NTG using the upscaled NTG log, independently of facies. Model NTG using the upscaleld NTG log, facies conditioning done, but assign zero facies in Non reservoir facies . Model NTG using the upscaled NTG log, facies conditioning done, model all facies. If NTG is modeled independently of facies, it MAY result in scenarios where the interpolated NTG model shows a low value, in a place where the facies model would show a good reservoir facies. This will result in inconsistency. But if the modeling is done conditioning to the facies (model NTG is each facies separately), the resulting NTG model will be consistent with the facies model. While conditioning to facies, if NTG is assigned as “0” in the non reservoir facies, the same mistake of making a binary NTG in the model would be repeated. In other words, the NTG value in the Non reservoir cell is not necessarily zero always. That cell may have a representation (though low) from a reservoir facies as well. Hence it will have a low but non zero NTG. If we assign this to zero, we are practically loosing that much reservoir volume. Summation of all such “small” errors in a case with many wells, would result in volumetric discrepancies. Page 8 The Geomodeling Network – Sponsored by Blueback Reservoir www.blueback-reservoir.com
  • 9. August 2008 The Geomodeling Network Newsletter Summary Model NTG by conditioning to facies model. Model NTG in all facies including Non reservoir. UPSCALING/MODELING OF OTHER PROPERTIES Similar issues can be seen with the upscaling/Modeling of other properties like Porosity, Permeability etc. Usually when the petrophysicist gives the processed porosity log, it will have a zero value in the non reservoir intervals. These zero values would influence the upscaling process and can cause double dipping in the net pore volume and hence in the GIIP/STOIIP results. Zero is also considered as a value and used for averaging during the upscaling process. Consider the example as shown in the following figure. The cell with a red rectangle on it, has a reservoir facies. But it is not 100% reservoir facies. As shown by the upscaled NTG, that cell is 60% reservoir and 40% non reservoir. But for the 60% reservoir facies, the corresponding porosity is a low value of 0.12, which is not representative of the reservoir facies. In other words Page 9 The Geomodeling Network – Sponsored by Blueback Reservoir www.blueback-reservoir.com
  • 10. August 2008 The Geomodeling Network Newsletter Net Pore Volume= Gross Volume * NTG * Porosity of the reservoir facies =Gross volume *0.6 *0.12 = 0.072*Gross Volume --- double dipping But it should have been =Gross Volume *0.6 * 0.2 = 0.12 * Gross Volume This issue can be solved by making the porosity (other properties as well) values in the non reservoir interval as “Undefined”. Consider the following illustration The impact of undefining the property values and then upscaling can be seen in the property values in the upscaled cells. Consider the cell with reservoir facies (red rectangle outline). It has 30% non reservoir in it. But the porosity assigned in that cell is representative of the reservoir facies only. Now consider the cell with non reservoir facies (orange rectangle outline). Though it is a non reservoir cell, it is not 100% non reservoir. It has 20% of reservoir facies (with a 20% porosity as well).That brings up another question. Page The Geomodeling Network – Sponsored by Blueback Reservoir www.blueback-reservoir.com 10
  • 11. August 2008 The Geomodeling Network Newsletter If Porosity is modeled, by conditioning to facies AND assigning zero value to non reservoir facies, what will happen to those non reservoir cells which has a reservoir facies fraction in it? It can be seen that, if a zero porosity value is assigned to all non reservoir facies, the cumulative effect of many such non reservoir facies cells (with some fraction of reservoir facies in it), would result in volumetric discrepancies. Even if this would create porosity values in non reservoir, it is co existing with very low NTG values and hence the net pre volume will be correct. Summary Make the properties to Undefined in the Non reservoir sections. Model the properties conditioning to facies and in all facies. ------------------------------ 1.2 To model Net to Gross or not to model Net to Gross! Juan Cottier – Blueback Reservoir (juan.cottier@blueback-reservoir.com) quot;The purpose of war In my view there are two overwhelmingly important and connected issues to consider here: is not battle but victory.quot; Firstly: net to gross is an artificial construction, it does not exist and it should or: not be modeled in 3D. The purpose of analysis is not Secondly: any attempt to model N:G will fail because of simple issues regarding modelling but scale and selection. understanding. Sun Tsu, The Art of War, ca 500 BC So, why does net:gross not exist? The concept of “net rock” has been about since Schlumberger ran the first log in 1927 and probably before that. The idea of “pay” or “producing intervals” or “kh” from a well test is standard oil field practice for reservoir engineers but is very different from a geoscientists idea of n:g. Page The Geomodeling Network – Sponsored by Blueback Reservoir www.blueback-reservoir.com 11
  • 12. August 2008 The Geomodeling Network Newsletter Net to gross is an artificial construction to allow 1 dimensional data namely a well log to be used to explain a 3 dimensional asset. If the well results are not considered in three dimensions then a “good rock / bad rock” discriminator can be applied and everyone can be happy with their “understanding” of their lovely new well and pat themselves on the back. As geologists, we should know that a 4 metre thick channel with a 2cm shale drape on the top can extend for kilometres in one direction and can pinch out to provide a 4m shale sequence within a few metres in another direction. Texans drilling wells in the 1930s and 1940s used net to gross because they had no choice. Those net to gross values were contoured up to create reservoir “You can have it good, quality maps. When mapping software came in to play in the 80s the good, old fast, or cheap: pick any school geologists would complain about the mapping algorithms, and for very two.” good reason, because they were not thinking geologically: ………….. fluvial The Project Manager's Maxim channels, stacked dunes, delta front beach sands or offshore sand-bars. In 3D we should model what we think is representing the subsurface, we can use facies modeling, we can attempt to describe a 3D volume with the detail and heterogeneity and the complexity. We don’t need to start the process by defining “good rock / bad rock”. Nor should we do. All rock is equal, comrades, even if some rock is ultimately more equal than others. So, why is it impossible to model correctly? Well there is a scale thing to start with. See the attached jpg photo. There is no doubting here that there is excellent sand (orange) and non porous shale (grey). There is also little doubt that it would be possible to sum the relative proportions of sand and shale and come up with a n:g. But look at the lens cap(*). We are looking at beds considerably smaller than 6 inches which is the standard sampling interval for logs, the resolution of tools may well be greater than that ….. so how could you possibly get a correct result from log data. For example a gamma log would be smeared with “average values”. It is possible to use curve inflections, or the curve tendency towards a value rather than an absolute value to identify thin beds. But still. It is also worth noting that these are not what would be described a “thin beds” in a “thinly bedded” or “tiger stripes” reservoir. I have worked on a field in West Africa where the sand shale couplets were providing sand beds of 2-5mm. Page The Geomodeling Network – Sponsored by Blueback Reservoir www.blueback-reservoir.com 12
  • 13. August 2008 The Geomodeling Network Newsletter Rockefeller once explained the secret of success. 'Get up early, work late - and strike oil.' Joey Adams It is also worth considering what is used as a cut off. Vshale? From a gamma log? How is the radioactivity of a rock any indication of if its ability to flow oil? Well, it’s probably because you get a gamma log with any tool run and it’s the one bit of log analysis any geoscientist can do. What about porosity? A porosity cut off at 10% porosity? 5%? Why? Absolutely no reason. Probably because, like many decisions in the oil world, it “feels about right”. But surely porosity can be a direct link to permeability? And permeability is about flow and flow is the discrimination between “good rock / bad rock”. Excellent! That means we should use permeability as a cut off. Isn’t it? Rule of thumb in the oil patch is 1 milliDarcey for oil and 0.1 milliDarcey for gas. Well for start off there is no way to directly measure permeability in the subsurface other than perhaps the NMR tools. Most perm logs come from a transform from a porosity log and that transform often comes from a relationship identified in core plugs. These plugs are samples of rock that have been sitting around for millions of years doing nothing and then within a matter of weeks are taken from some pressure of 1000s of PSI, to atmospheric, shipped across the world, washed and cooked and then tested. No wonder a core plug perm is always 20 times less than that identified by a well test. Which brings us Page The Geomodeling Network – Sponsored by Blueback Reservoir www.blueback-reservoir.com 13
  • 14. August 2008 The Geomodeling Network Newsletter back to scale. So do we apply our n2g cut off to the core perm or the well test perm? Air perm or in situ perm? “The product of an arithmetical computation is the answer to an Consider the following: equation; it is not the solution to a problem.” We use a permeability cut off for defining net:gross. We now have non net rock By Ashley Perry (bad) which doesn’t flow and net rock (good) which does flow. But of course it’s not the perm that flows oil it’s the relative perm …. The relative permeability is dependent on the saturation of the oil versus the saturation of the water. Which is the continuous phase? Oil or water? So should our n:g cut off be relative permeability? As we produce oil and inject water then our oil and water saturations will change, and so will our relative perms, and so will our continuous and non continuous fluids. And this is two phases, shall we add gas and make it three phases? Do we need to constantly update our n:g? Time-lapse net to gross modeling? For those of you still reading, here is Darcy’s Law straight from Wikipedia. Wikipedia: “The total discharge, Q (units of volume per time, e.g., m³/s) is equal to the product of the permeability (κ units of area, e.g. m²) of the medium, the cross-sectional area (A) to flow, and the pressure drop (Pb − Pa), all divided by the dynamic viscosity μ (in SI units e.g. kg/(m·s) or Pa·s), and the length L the pressure drop is taking place over.” “Say you were standing with one foot in the oven That means if permeability is calculated from Darcy’s Law then it is proportional and one foot in an ice to viscosity and indirectly proportional to the pressure drop ……………… so if gas bucket. According to evolves from the oil, then the perm will change and the rel perm will change and statistics, you should be our net to gross will change? Really? No … of course not, because net to gross perfectly comfortable” does not exist. Bobby Bragan, 1963 Then again try telling a senior geoscience manager who has had a long a successful career using n:g that it doesn’t exist. Page The Geomodeling Network – Sponsored by Blueback Reservoir www.blueback-reservoir.com 14
  • 15. August 2008 The Geomodeling Network Newsletter Much of this could well be rubbish …. But it’s worth a thought for a moment or two. ---------------------------- 1.3 Probabilistic Vs Deterministic Results when computing GIIP or STOIIP Jose Varghese – Shell (jose.varghese@shell.com) Question 1: When we compute GIIP or STOIIP using probabilistic methods and deterministic methods(low case, mid or most likely case and high case), is it ALWAYS true that the P50 case of Probabilistic method should be near to the Deterministic mid case(or most likely case)…..and same for Low & P90 and High & P10 cases?? Page The Geomodeling Network – Sponsored by Blueback Reservoir www.blueback-reservoir.com 15
  • 16. August 2008 The Geomodeling Network Newsletter Question 2: Can there be a situation where, the deterministic cases like low case and high case are not at all captured in the Probabilistic ranges? (Logically thinking it should be captured in the Probabilistic range) If the answer to this question is NO (ie deterministic cases should be always within the Probabilistic range), then my real problems comes (next figure) Example Case: varying three contacts in a probabilistic workflow Page The Geomodeling Network – Sponsored by Blueback Reservoir www.blueback-reservoir.com 16
  • 17. August 2008 The Geomodeling Network Newsletter While running the monte-carlo workflow, let’s say each of the contact is put as a variable with a Normal distribution. In every run, a random value is chosen for the contact. But that random selection of all three contacts NEED NOT BE like shown with Blue colour (all lows in one run or all Highs in one run). If only this is achieved, we would be able to include the deterministic low – high cases within the probabilistic ranges. If the situation is like shown with red colour, the probabilistic range will not include the deterministic low- high values. Deterministic Low case is calculated by taking ALL low case contacts (and probably but not necessarily all low cases of other parameters like NTG, Porosity etc). Ie in case of contacts, in all the three zones shown above, the deterministic low case will take the lowermost value only Similarly is the Base/Mid case and high case Page The Geomodeling Network – Sponsored by Blueback Reservoir www.blueback-reservoir.com 17
  • 18. August 2008 The Geomodeling Network Newsletter Do the simplest thing that could possibly work. By Kent Beck One solution is to run the simulation for large number of runs… Expecting that in some runs, it will capture all low ranges and in some cases all high ranges, thereby simulating GIIP/STOOIP values near to the Deterministic Low and High cases. ..But again..this NEED NOT be true always... When deterministic Low or High is calculated, we introduce a DEPENDENCY -..ie for one parameter if a low value is selected, other parameters are also selected from the low value This kind of dependency is difficult to introduce in a Monte-Carlo workflow….or may be large number of runs are needed. (Please correct me if I am wrong In Petrel..it is difficult…what about other 3D modeling software? ) If the parameters can be related in some way, then the dependency can be achieved… eg Contact 3= Contact 1- XX meters Now vary contact 1 in a normal distribution. For every run, and every value of Conatct1, Contact 3 also would get a value with a similar trend (ie high or low ). Page The Geomodeling Network – Sponsored by Blueback Reservoir www.blueback-reservoir.com 18
  • 19. August 2008 The Geomodeling Network Newsletter BUT this is possible only if the two parameters are having same standard deviation (please correct me if I am wrong) The same question goes for dependency between properties like Porosity, permeability, saturation etc. ------------------------------ Page The Geomodeling Network – Sponsored by Blueback Reservoir www.blueback-reservoir.com 19
  • 20. August 2008 The Geomodeling Network Newsletter 2. Technology Updates 2.1 Roxar Webinars For those of you that read the first Geomodeling Network newsletter you will have read about Roxar’s new structural modeling software, so this is a chance to see what all the fuss is about! On the 28th August 2008, Roxar will be hosting a series of solution webcasts on the following: - RMS Structural at 10am - Tempest for Simulation at 11am - EnABLE for history matching at 12pm - VVA a high end attribute package which includes seismic interpretation at 2pm Each webcast is designed to give you a brief insight to the functionality that the software can provide. It should not last more than 20 minutes and will give you the opportunity to request a full demonstration thereafter, at a time and location convenient with you. Please do join us for this informative event and feel free to pass this onto other colleagues within your organization that may find this of interest. To confirm you attendance at any of the above webinars please respond to neelesh.ambedkar@roxar.com who will manage the logistics for the event and will send out the appropriate web address and pass code. ----------------------------- “Software is the only engineering discipline The next ppt presentation from Christian Höcker is certainly one of the first Jewel in which the equivalent of Suite presentations I have read and I found it interesting for a number of changing the wing on an reasons. Firstly because they have successfully focused their technology on a airplane problem that exists and cannot be solved using some of the existing products on constitutes maintenance.quot; the market and secondly it’s nice to see new software from outside of the “big 2”. by Jim Highsmith Mitch Page The Geomodeling Network – Sponsored by Blueback Reservoir www.blueback-reservoir.com 20
  • 21. August 2008 The Geomodeling Network Newsletter 2.2 JOA – Handling of complex fault geometries using Jewel Suite “There are only 2 Christian Höcker – Director of G&G Technology at JOA Oil & Gas BV industries that refer to (hocker@joa.nl) Faulted faults are frequent in geological regions with multi-phase tectonics, their clients as however, they can also be encountered in delta settings. Faulted faults are one „Users‟: illegal drugs of the more challenging geometries when it comes to proper representation of ‘real geology’ in reservoir models. This article in slide format shows an example and computer of faulted faults in a Niger delta field using seismic data, and how it was software” represented in framework models and geocellular grids using Jewel Suite functionality. Edward Tufte It is also argued here that fault relation tables are an insufficient approach when building framework models of so-called ‘fault-flip zones’, a frequent phenomenon in crestal collapse structures. Fault-to-fault relationships must be defined per intersection segment rather than for entire faults. JOA® Jewel Suite™ Handling of complex fault geometries in reservoir models built with Jewel Suite • Faulted Faults • Topology handling in fault flip zones Christian Höcker JOA Oil & Gas INTE(R)MODEL – Integrated Reservoir Modelling Services Page The Geomodeling Network – Sponsored by Blueback Reservoir www.blueback-reservoir.com 21
  • 22. August 2008 The Geomodeling Network Newsletter Introduction quot;640K ought to be enough for • Faulted faults are frequent in regions with multi-phase anybody.quot; tectonics but can also be encountered in delta settings. • Fault-flip zones are common in crestal collapse features. Bill Gates of Microsoft, 1981 • Both geometries are difficult / impossible to represent in common modelling packages – or cannot be translated from static models into simulations models. • The following slides show examples of these geometries in seismic interpretation, as structural framework model and in 3Dgrid representation, using Jewel Suite. Copyright JOA 2005-2008 © Faulted Fault in Jewel Suite™ Surface (Trimesh) Representation Modelling Workflow: • Synthetic fault of older set is dissected set of 4 north-hading faults by 4 antithetic faults • Synthetic fault has been interpreted on seismic using fault sticks assigned to a single fault plane • After automated triangulation limited user edits were applied to consolidate the faulted base geometry • The accurate intersection geometry was established using semi-automated retraction and extension functionality in Jewel Suite™ slivers faulted fault S-hading Copyright JOA 2005-2008 © Page The Geomodeling Network – Sponsored by Blueback Reservoir www.blueback-reservoir.com 22
  • 23. August 2008 The Geomodeling Network Newsletter Faulted Fault: Detail Detail: • Detail of intersection geometry between faulted synthetic and outermost antithetic fault of younger crestal collapse set outermost antithetic fault map view of faulted fault of younger collapse set (interpretation is not necessarily complete) quot;Contrary to popular belief, UNIX is very user friendly. It's just very selective about Copyright JOA 2005-2008 © who it's friends are.quot; Anon. Faulted Fault in JOA® 3Dgrid Geocellular Gridding: • The faulted fault surfaces have been used as input to 3Dgridding (100 x 100 m, 2000 - 8000 ft) • The grid orientation was defined at an arbitrary angle to the fault direction. This means that JOA® 3Dgrids are insensitive to structural orientation and can chosen freely to optimally address subsequent work steps, i.e. full-field or sector reservoir simulation. • Faults in the 3D grid seem to continue too far if compared to displayed fault surfaces. This is not a real issue but relates to the fact how faults are drawn on the 3Dgrid slice, i.e. faulted cells are Copyright JOA 2005-2008 © Page The Geomodeling Network – Sponsored by Blueback Reservoir www.blueback-reservoir.com 23
  • 24. August 2008 The Geomodeling Network Newsletter Faulted Fault in J-slice of JOA® 3Dgrid Geocellular Gridding: • Slice through 3Dgrid model in J-direction (along faulted edge of synthetic fault) Copyright JOA 2005-2008 © Topology Handling with ‘Fault Flip Zones’ Issue: • Crestal collapse structures commonly show fault flip zones in N-hading antithetic which fault hierarchy changes. • For fault framework building this means that a unique abutting rule between faults (as in fault relation tables) cannot be defined. blue fault is dominant at these • In Jewel Suite™ fault-to-fault intersection segments relations are defined for single intersection segments between faults, meaning that laterally varying topology relationships in fault flip zones can be handled properly. “Don't take a map drawn at a smaller 3 S-hading synthetic faults scale and enlarge it for work at a larger scale” synthetic faults are dominant at these intersection segments geologist & Copyright JOA 2005-2008 © cartographer proverb Page The Geomodeling Network – Sponsored by Blueback Reservoir www.blueback-reservoir.com 24
  • 25. August 2008 The Geomodeling Network Newsletter experiment is ”An Full-Field 3Dgrid model considered successful if no more than half of the data must be discarded to obtain agreement with your theory” The Compensation Corollary • The previous slides are from small features in a much bigger full-field model with the specs: 100 x 100 m, ijk dimensions of 200 x 100 x 50 cells. A final 50 x 50 m model is in preparation. • The model geometry and properties extend to surface (not shown here) to support integrated velocity modelling and geomechnical simulation. • This means a new definition of ‘full-field’ to include overburden at appropriate resolution for Copyright JOA 2005-2008 © integration loops outside the conventional static-dynamic reservoir modelling. Do X-faults exist? Issue: • In radial extension geometries the abutting relationship between conjugate fault sets is not always easy to determine from seismic evidence. • In fault flip zones one can encounter seismic sections with an apparent X-geometry – the example here is a quite convincing case. • Obviously the X-geometry does not extend far laterally; the grey fault terminates some 100 m behind this section while the green one stops 50 m in front of it. However, the geometry is real and relevant for HC containment – fluid contacts in the reservoir above 1600 ms differ to either side of the X-fault geometry. Ignoring either one of the two faults in modelling or increasing the gap between them would mean a significant flaw in reservoir definition. Copyright JOA 2005-2008 © Page The Geomodeling Network – Sponsored by Blueback Reservoir www.blueback-reservoir.com 25
  • 26. August 2008 The Geomodeling Network Newsletter Summary • Proper representation of fault geometries in framework models and 3D (simulation) grids is a prerequisite for effective subsurface workflows. • In Jewel Suite it is also easy to implement: – The 3D gridder takes fault and horizon geometries as interpreted and turns them into high-fidelity grid models. – The resulting 3Dgrids can be transmitted to simulators without geometry degradation. – Non-Neighbour Connections or fault transmissibilities are properly handled by the software  no tedious edits in the simulator environment. Copyright JOA 2005-2008 © Jewel Suite is a ‘young’ integrated workflow application for subsurface modelling, simulation and decision making. It has been developed and is marketed by JOA Oil & Gas, a Dutch software company with long-standing experience in subsurface modelling, now with global support coverage. Jewel Suite 2008 contains modules covering seismic interpretation, well log correlation, structural framework modelling, property modelling, upscaling and reservoir simulation, all integrated in one platform. The heart of this ‘new kid on the block’ is the revolutionary and patented 3Dgridder that supports building of geological and simulation models without the constraints known from the big players in this field. Not only can complex geometries like with faulted faults be represented in the geological models without simplification, the geometries can also be communicated without degradation to a number of linked reservoir simulators, among which Eclipse. A more extensive discussion of 3Dgrid types used in geomodelling and simulation environments is in preparation for the next edition of the Geomodelling Network News. ------------------------------ Page The Geomodeling Network – Sponsored by Blueback Reservoir www.blueback-reservoir.com 26
  • 27. August 2008 The Geomodeling Network Newsletter 2.3 EMGS AND BLUEBACK RESERVOIR LAUNCH BRIDGE, AN EM INTEGRATION TOOL FOR PETREL Trondheim, 11 June 2008 Electromagnetic Geoservices (EMGS) and Blueback Reservoir have collaborated to develop and launch a new decision-support tool for exploration professionals called Bridge. Bridge has been created to help oil & gas companies find and develop hydrocarbons more efficiently. The new software enables the easy integration of electromagnetic (EM) data with other geophysical and geological information, resulting in a clearer and more complete understanding of the subsurface. Terje Eidesmo, EMGS chief executive officer, said: “This is an important milestone for EMGS and the industry. Bridge will enable our customers to capitalise on the benefits of EM by allowing the easy integration EM information with their workflows. By integrating EM data with conventional geophysical, quot;Everything that can be geological and well log information, our customers can improve their invented has been exploration risking process and the assessment of a reservoir’s potential.” invented.quot; Bridge is an EM plug-in for Petrel, one of the industry’s leading geological and geophysical integration platforms. The launch of Bridge brings long-awaited EM Charles H. Duell, functionality to the standard Petrel workflow. Petrel was originally created and Commissioner, U.S. Office of developed by the founders of Blueback Reservoir. Patents, 1899. “We have been working with the team who created Petrel. The heritage, expertise and experience we bring from our respective fields is an endorsement for Bridge and the increasing demand for EM integration by the industry bodes well for the uptake of this product. The launch of Bridge also reaffirms our leadership in the EM sector”, continued Eidesmo. Jan Egil Fivelstad, Blueback Reservoir’s chief executive officer, commented: “EM data adds great value for geoscientists, and Bridge will make this technology more accessible and understandable. There has been a growing recognition throughout the oil and gas industry of the need for extra functionality in interpreting EM data and as a result we expect the demand for this product to continue to grow”. Page The Geomodeling Network – Sponsored by Blueback Reservoir www.blueback-reservoir.com 27
  • 28. August 2008 The Geomodeling Network Newsletter Blueback Reservoir and EMGS will be demonstrating Bridge at the EAGE, SEG and PETEX exhibitions in 2008. Contacts Terje Eidesmo EMGS chief executive officer +47 73 56 88 10 Chris Guldberg EMGS PR manager +47 73 56 88 10 Paul Hovdenak Blueback Reservoir, Manager Software Sales & Development +47 98 23 03 40 About EMGS EMGS is the market leader in deep EM imaging. The company launched the EM imaging industry in 2002 with the commercialisation of seabed logging, a proven exploration method that uses EM energy to find offshore hydrocarbons without drilling wells. This proprietary and patented technology has been developed over the past 10 years, and its ability to indicate hydrocarbons directly is enabling EMGS's customers to dramatically improve their exploration performance in frontier and mature provinces. EMGS employs over 300 people from three main offices in Trondheim, Norway; Houston, USA; and Kuala Lumpur, Malaysia. The company operates the world's largest EM vessel fleet, and has conducted more than 350 surveys for many of the world's leading energy companies. Please visit our website www.emgs.com for the latest news and in-depth information about EMGS and EM imaging technology. For general enquiries please email findinghydrocarbons@emgs.com About Blueback Reservoir Headquartered in Stavanger, Blueback Reservoir AS is an independent E&P service company with offices in Stavanger and Oslo, Norway, and London, UK. The company supplies subsurface consulting services and software solutions to the E&P industry globally and is recognised as a leading provider of subsurface 3D reservoir modelling services and solutions. Blueback Reservoir delivers such services to a whole range of companies, including service companies, small and medium-sized independent E&P companies, super majors and national oil companies. Page The Geomodeling Network – Sponsored by Blueback Reservoir www.blueback-reservoir.com 28
  • 29. August 2008 The Geomodeling Network Newsletter For further information, please visit www.blueback-reservoir.com or email sales@blueback-reservoir.com ------------------------------ 2.4 Petrophysical Analysis Workflows using OpenSpirit Attached is link to a webcast to enable you to learn how to enhance your integrated petrophysical workflows by importing curve data from any OpenSpirit-enabled data store into your petrophysical analysis application. Data can then be exported back to the corporate data store, or any OpenSpirit- enabled interpretation application. A live demonstration of a workflow will be shown during the webcast. Please either click on the link below or cut and paste it into your internet browser. http://www.openspirit.com/movies/Webcasts/2008%20August/Aug2008.htm ------------------------------ 3. Career Networking Another of the reasons for instigating The Geomodeling Network was to advertise career positions that may be of interest to our members. This will never be the major part of our newsletter as the intention is to keep it as technically focused as much as possible. However I intend to carry on with this section until someone convinces me otherwise. Position: Pore Pressure Analyst Location: Houston Contact: Cole Wiseman on wiseman@intellicaprecruiting.com or (US)713-529- 2100 The pore pressure analyst will be responsible for supporting the Gulf of Mexico exploration teams by applying established tools and techniques to constrain subsurface fluid pressure regimes. Required experience includes using either 1) basin modeling techniques, 2) offset well drilling and petrophysical analysis, and/or 3) seismic velocity analysis to determine subsurface fluid pressures. Candidate should have working knowledge of all above-mentioned technologies used in pore pressure applications, and ideally, extensive experience in applying one or more of these technologies in exploration. The candidate should have or quickly develop the ability to incorporate basin modeling, drilling, petrophysical, and/or seismic datasets to develop an Page The Geomodeling Network – Sponsored by Blueback Reservoir www.blueback-reservoir.com 29
  • 30. August 2008 The Geomodeling Network Newsletter integrated approach to pore pressure prediction. Work will be required at multiple scales, from regional to prospect scale, including active drill-well operations. Support regional team by developing an understanding of regional controls on fluid pressure regimes. Support portfolio teams by performing “A good rule of thumb is prospect evaluations of top-seal integrity and effective stress. Provide predictions on hydrocarbon column capacity given a prediction of effective if you've made it to stress and a spectrum of possible fluid densities. Support active drill-well thirty-five and your job operations from pre-drill well planning through real time modeling adjustments still requires you to wear as drilling parameters and new petrophysical data are collected. a name tag, you've made Roles/Responsibilities: a serious vocational error.” Technical focus in or practical knowledge of pore-pressure prediction from the standpoint of basin modeling techniques Dennis Miller Technical focus in or practical knowledge of pore-pressure prediction from the standpoint of seismic velocity data and geophysical attributes Technical focus in or practical knowledge of pore-pressure prediction from the standpoint of offset wells (drilling parameters & petrophysical data) Perform evaluations of top-seal integrity and effective stress; provide predictions on hydrocarbon column capacity given a spectrum of possible fluid densities Work with Exploration & Production Technology group to devise new approaches and innovative solutions to complex problems confronting the business unit Work with both Regional and Portfolio teams in the Gulf of Mexico and provide subsurface pore-pressure analysis at multiple scales, from regional down to prospect level Work with drilling and well-operations groups to support well planning and real-time operations decisions regarding fluid pressures and borehole stability Effectively communicate technical workflows and results to audiences with varying exposure to the technology, from inexperienced staff to senior-level management Skills/Competencies: “It‟s just a job. Grass Apply two or more relevant workflows in pore-pressure prediction Learn and apply technical workflows for seal-capacity analysis grows, birds fly, waves Have ability to adapt to solve technical problems within this technical pound the sand. I beat specialty Work with Exploration & Production Technology to seek out people up.” innovative approaches Muhammad Ali Have an appreciation for technical uncertainties and be able to incorporate their impact on modeling results Ability to work at multiple scales Page The Geomodeling Network – Sponsored by Blueback Reservoir www.blueback-reservoir.com 30
  • 31. August 2008 The Geomodeling Network Newsletter Contribute to a team-oriented work environment Required Experience: Minimum of (5) years of related experience in the upstream oil and gas industry Required Education: Bachelors Degree in Geological Sciences, Masters or PhD a plus ------------------------------ Position: Product Champion – Geophysics & Electromagnetics Location: Stavanger Contact: Paul Hovdenak, Manager of Software Development & Sales (paul.hovdenak@blueback-reservoir.com) Blueback Reservoir is currently in a growth phase and we are now looking to expand our software team and strengthen our support and technical sales. Our new software product for integration of electromagnetic data (CSEM) with Petrel has generated strong interest in the market place, and combined with our further software development plans, we are now hiring a product champion to meet our goal of bringing electromagnetic data and CSEM technology to the masses! The product champion position involves: Planning our development strategies Working with our developers to ensure our products are delivered according to plan Working with our sales people to ensure commercial success Working with our clients to help them get started and utilize our solutions successfully Successful candidates will have: Relevant education at MSc or similar level Experience with Petrel or other G&G applications Relevant industry experience within geophysics and electromagnetic domains Self motivated and able to act independently with minimum supervision Willingness and ability to travel domestically and internationally In return Blueback Reservoir can provide an interesting and challenging position, whilst at the same time offering a highly attractive base salary and company bonus scheme. Page The Geomodeling Network – Sponsored by Blueback Reservoir www.blueback-reservoir.com 31
  • 32. August 2008 The Geomodeling Network Newsletter ------------------------------ 4. Requests for the newsletter No3 After receiving 2 Geomodeling Network newsletters you should by now realize the kind of newsletter we are trying to achieve. If you would like to add any article for the 3rd newsletter (scheduled for December 2008), then simply email me the proposed article and I will do my best to include it. That goes for SW vendors too. If you have some new functionality coming out at the end of the year or you have a case study you think our readers would be interested in then forward the details to me and I will add it to the technology section in the next newsletter. You may have also read a previous email from me detailing a Schlumberger training course/field trip. I do not mind advertising these type of events, but it doesn’t mean I’ll be listing the ‘Introduction to Petrel/RMS training courses occurring over the next few months! if there are some unique events or field trips coming up in your region that are open to general participation then send me the info to include in the next newsletter or as an extra email shot. Apology As a member of the Geomodeling Network you will have received an email from me earlier on this month promoting the Schlumberger fracture modeling training course/field trip. Unfortunately I issued the email without checking where I had placed the members email details. This meant that your email details were then made available to the other network members. Once I realized my mistake I tried to recall the message but this only worked for a small handful of the entire list and was therefore largely ineffective. Based on my error a few members were contacted directly by recruitment consultants (who are also network members), so my sincere apologies for any discomfort and inconvenience that I may have caused and will try to do better next time. Regards, Mitch mitch.sutherland@blueback-reservoir.com Fin Page The Geomodeling Network – Sponsored by Blueback Reservoir www.blueback-reservoir.com 32