A powerful reservoir management solution for our times

I OIL AND GAS I TECHNOLOGY I The 3D model is becoming the default platform for analysis and decision making A powerful reservoir management solution for our times What do you know about your reservoirs? The rise of 3D modelling From seismic surveys to production history, today s hydrocarbon industry generates huge amounts of data from its oil & gas reservoirs. IBM Business Consulting Services recently estimated that a single oil or gas field can generate on average up to one terabyte of data per day 1. The organisation of this data and its transformation into valuable decision-making information is one of the industry s greatest challenges. Get your interpretation of the data wrong and bid valuations, new field development plans, and By : Elizabeth Thompson, Emerson Process Management, Roxar This article will take you through the different stages of the 3D modelling process and will also look at the crucial role IT and a strong workflow play throughout. 1 IBM Business Consulting Services Meeting the Challenges of Today s Oil & Gas Exploration and Production Industry. production estimates will all suffer. The North Sea is a case in point. Here, reserves have increased or decreased by more than 50% in more than 40% of the fields 2, leading to the requirement to drill 60 to 80% more wells than originally anticipated. One means of making better use of your data is through the creation of 3D models. 3D models are a focus for scenario generation, a tool to explore possibilities, and a place to store and analyse information. The 3D model is becoming the default platform for examining and understanding subsurface geology. It improves communication between colleagues. It allows different ideas to be evaluated. It provides the reservoir engineer with better quantification of the uncertainty within the reservoir. Areas of the reservoir which require more detailed analysis can be determined. More accurate assessments and predictions of reservoir performance can be generated. The result will be reduced levels of financial risk. In order to provide the most reliable plans for the future, however, it is essential that your 3D model is as accurate as possible, as continuously as possible. This accuracy is vital, since the geometry and properties of the model determine 2 The Norwegian Petroleum Directorate, May 2003. 3 Tackling the Oil and Gas Industry Skills Gap, Booz Allen Hamilton, January 2008 DEW JOURNAL November 2009 21

The Roxar industry leading reservoir modelling solution - RMST contains state of the art tools to conduct 3D uncertainty assessments where and how big the hydrocarbon accumulation may be. This article will take you through the different stages of the 3D modelling process and will also look at the crucial role IT and a strong workflow play throughout. Developing the production plan Once you have found a good prospect and proved it with a couple of wells, the next stage is to develop a detailed production plan. You need to know how much actual reservoir there is, where it is, how good the porosity is and where the best well locations are for maximum recovery. You also need to have an accurate idea as to what will happen in the reservoir when you initiate production. 3D models can provide this information. Emerson Process Management s Roxar provides an industry leading reservoir modelling solution, RMS, containing state of the art tools to conduct, for example, 3D uncertainty assessments. What if the depth conversion is a little inaccurate? What happens if Simulation with the parallelised Tempest can handle multi-million cell models with thousands of wells the water saturation is a little different? What happens if the net to gross is more variable than expected? These are all questions which can only be reliably addressed using 3D models. While there will always be a certain degree of uncertainty in operator decisions, today s 3D reservoir modelling techniques can better quantify these uncertainties, whether they lie in depth conversion, structural modelling, geological property modelling, or dynamic reservoir simulation. Take RMS s property modelling tools - techniques which combine seismic and well data with geological understanding to generate the most accurate and best constrained model for describing which rocks are where. From simple indicator modelling extrapolating well information, to more complex multi-point statistics which can produce sophisticated geological scenarios, 3D modelling can ensure that the full impact of often independent uncertainties is captured. Another common challenge is finding that reservoir performance is significantly affected by fractures. Fractures play an important role, both positive and negative, in the fluid flow behaviour of many fields. They can greatly enhance the permeability of rocks and will change the distribution of flow in the reservoir through altered connectivity patterns. Their influence can be particularly profound in carbonate fields and basement reservoirs, where they can critically affect reservoir performance and be potentially fatal to individual wells. In this context, 22 DEW JOURNAL November 2009

where approximately half of the world s proven reserves of oil and gas are in carbonate or fractured reservoirs, full-field fracture modelling is essential to gain a clear understanding of how the field is likely to behave. As fractured fields also display a greater potential for variation in performance through time, an up-to-date and accurate model is crucial for planning and managing long-term field performance. Roxar provides an integrated, easy to use fracture modelling package which enables geologists and reservoir engineers to create detailed and reliable permeability maps. Using these in flow simulation and history matching of reservoirs to quantify uncertainties allows the team to make sensible risk avoidance plans. The Roxar Fracperm software, which is integrated with the main Roxar modelling and simulation suites, combines data, geological properties, geo-statistics and geohistory in a data-driven approach. It is designed to make maximum use of available data and allow rapid and interactive quality control of the model as it is being built. It can also link with the Roxar history matching solution, EnABLE, to provide a single workflow where uncertainties can be monitored, their impact assessed and technical effort focussed where it will make most difference. Furthermore, Fracperm s non-specialist, practical approach means that the asset team, who know the field best, can build and refine their own models. Using advice and QC from experts makes maximum use of both Extracting information directly from seismic data greatly increases the power and accuracy of facies modelling techniques expert and non-specialist staff and brings fracture modelling into the mainstream. Once you have a good appreciation of the sub-surface geology, the next question is where to drill. RMS s well planning tools allow the geologist to plot and refine well trajectories to maximise extraction, minimise costs and avoid collisions. Proposed wells can even be included in streamline runs to assess their likely performance. Numerous potential locations can therefore be proposed and examined in the virtual world before committing time and money to actually drilling. Hitting the target - realtime adjustments One of the biggest challenges in reservoir modelling today is the delay between the analysis and integration of real-time drilling data and the updating of the geological model. Delays can lead to crucial information not being available to the decision-making process as the drilling takes place. To meet these challenges, Roxar has developed a real-time geosteering methodology where the continuous flow of available data can be smoothly integrated into the model. Measurement while drilling (MWD) and logging while drilling (LWD) data is used to evaluate the position of the well, assess the physical properties of the rocks and fluids drilled, and analyse the behaviour of the drillstring in realtime. The monitoring of the reservoir consists of gathering different FracPerm helps asset teams model their field behaviour without needing external experts to build the model DEW JOURNAL November 2009 23

types of real-time information, such as survey data, LWD data, drilling information and bottom hole assembly information for the different drilling phases. All of this data can be displayed in multiple views in combination with elements of the geological model. Roxar s geosteering functionality can then monitor the proximity between the bit and objects in the model. Alarms can be triggered when approaching or exiting proximity to objects in the model, for example, a fault, the reservoir top or the oil-water contact. The position of the well under monitoring is automatically quantified within the geological model with this being achieved through the continuous real-time updating and adjustment of well paths from current positions (real and modelled) and targets. Locating the position of the LWD tool s sensors within the geological model; monitoring in real-time the proximity between the well and objects in the model; and using a workflow-based approach to update the model while drilling: all these allow the operator to make timely, informed decisions, and reduce the risk in well planning and drilling. And the result for the operator? Improved wellbore stability and hole quality, and optimised well paths, leading ultimately to fewer, cheaper and more productive wells. Managing Mature Fields Managing a mature field brings a number of challenges in its own right. It means dealing with not only the geology, but also the impact of decisions made when the field was young and less well-understood. Here a 3D model is vital for documenting the history of the field, and building a picture of how the way it has been produced will affect the way it can be produced in the future. The model can examine the impact of proposed enhanced oil recovery (EOR) processes, such as gas or water flooding and pressure 24 DEW JOURNAL November 2009 support, individual well stimulation, or expected behaviour from the different patterns of infill drilling. The rise of robust and fast reservoir simulation and computer assisted history matching - the act of adjusting a reservoir model until it closely reproduces the observed field behaviour - has played a crucial role not only in mature fields but across the reservoir lifecycle. History matching, for example, is critical for monitoring displacement processes, predicting future performance and estimating where our knowledge of the reservoir is incomplete. It also plays a key role in developing an integrated approach to reservoir management because it allows the static geological model to be synchronised with production data. In this way, the rise of computer assisted history matching has allowed the engineer to focus on developing an understanding of physical mechanisms active in the reservoir during production and their relative impact on production behaviour. Powerful statistical techniques can be used to determine multiple models of the reservoir that will provide good matches to the production history. An analysis of these models will, in itself, provide information on uncertain areas or properties. The history matched results are then used with the simulator to predict how a field s future performance may look and give measures of the uncertainty about these predictions. In this way, it brings geological modelling and simulation closer together and provides valuable information on the economics of the reservoir. Improving production performance estimates The Roxar history matching solution, EnABLE, is used by operators worldwide to gain a better understanding and measurement of uncertainty in reservoir performance estimates. EnABLE allows the engineer to choose parameters to which model performance may be sensitive. Assisted history matching software can evaluate the impact of individual parameters, thereby assessing which parameters need to be changed and exploring how they could be changed in order to achieve a history match. The ability to distinguish between critical modelling parameters, either static or dynamic, and parameters which will have little impact on decision-making is crucial, allowing resources to be deployed efficiently, and ensuring that people can better target the physical assets. Furthermore, real-time data from the field, such as pressure, temperature and flow rates, and other available data, such as seismic, petrophysical and facies updates, are also used to update the model and quantify structural and reservoir property uncertainties in real-time. The end result is a rapid model updating workflow, running on a continuous basis as new production data is gathered. Roxar s goal is to develop a big loop workflow of reservoir management that carries uncertainties and details in the geologic model through to simulation. This is now being achieved. And the recent introduction to the market of the latest version of EnABLE - EnABLE 2.3, will take this process even further forward. EnABLE 2.3 comes with simplified workflows, new and improved diagnostics, statistical engine advances and better interfaces with reservoir simulators. The result will be the ability for operators to estimate technical and economic uncertainty within their reservoirs even more accurately and comprehensively than previously. Moving towards a digital future This article has taken the reader through the reservoir modelling,

simulation and history matching process. At all stages, IT has played a vital role. Let s take a look at some areas. Firstly, the rise in computing power has played an integral role in creating an enhanced reservoir modelling workflow. Distributed computing, improved visualisation, collaborative tools and ever more sophisticated Supervisory Control and Data Acquisition (SCADA) systems have all brought the oilfield closer to the geoscientist. The rise in computing power has also led to increased efficiencies within the asset team. With expert, experienced personnel scarce and teams frequently spread across different countries, the increased connectivity of a generation of internet-native geoscientists allows the sharing of experience as never before. Collaborative work through teleconferencing and shared models is the only way to ensure that both deadlines are met and high standards are maintained. In the long run, this sharing of expertise benefits the entire company. Take reservoir simulation, for example. The rise of desktop parallel processing via the new 64-bit multi core chips, and increasingly affordable clusters, means that multimillion cell reservoir simulation models are now increasingly common. Algorithmic developments, such as single grid dual porosity modelling, and software developments, are all leading to higher resolution, and more accurate, finerscale simulation of oil and gas reservoirs. The growing accessibility and adoption of reservoir modelling and simulation on the more generalist engineer s desktop, has ensured that the entire subsurface community can be involved in creating these models and simulation runs, rather than a few, highly specialist reservoir engineers. A Roxar customer, John Campanella from Norwest Questa Engineering Corp, put it well when he said: Personally, I think reservoir simulation should be brought down to every engineer s desktop. We need to push simulation out of the back room and into the mainstream where people can use it on a daily basis. By adopting workflows and tools that encourage this distributed-effort approach, organisations are discovering that they can exploit as yet untapped potential in their workforce, involving non-specialist disciplines and skill levels. At a time when Booz Allen Hamilton 3 predicts that up to half of the current workforce is likely to retire within the next ten years, such efficiencies and democratisation of the reservoir modelling process are to be welcomed. The importance of workflow Closely aligned to the rise in computing power is the importance of workflow. From seismic acquisition and interpretation through to the building of a structural model, fault and fracture modelling, history matching and simulation, it is an integrated, seamless and collaborative workflow which provides the glue to all activities. Such a workflow is vital as a repository for experience and knowledge, for disseminating best practices across global teams, and helping new staff become proficient and efficient in their various modelling roles. A strong, IT-based workflow simplifies the model building process, ensures a high degree of quality control by coordinating inputs and outputs and ensures transparency and accountability through the generation of job sequences. An easy to use interface is also vital, which is why the latest Roxar reservoir modelling software comes with a new and modernised user interface which resembles familiar, everyday software applications. This includes a task pane which outlines the kind of tasks users are likely to want to use at any given point. Seeing what is relevant, as it is required, enhances the user s sense of control, helps them maintain their own high standards, and expands their range of experience and competence. A rapid model updating workflow Imagine a world where reservoir models are kept evergreen as drilling data arrives, updating in realtime. New production data is equally quickly assimilated through continuous, computer assisted history matching. The end result is a rapid model updating workflow running on a continuous basis as new production data is gathered, ensuring the most correct model is always available for making important decisions about the reservoir. This is what Roxar is achieving today At a time when the industry is looking for fast, easy-to-use powerful reservoir management solutions to optimise production from increasingly marginal assets, and to make better decisions over the allocation of capital and resources, the timing could not have been better. ABOUT THE AUTHOR dewjournal.com Elizabeth Thompson is Technical Information Manager at Roxar, responsible for ensuring that all technical information is gathered and made available to the marketing and product groups. Liz was formally product manager for Roxar s fracture modelling software and technical product manager for Roxar s structural geological tools. DEW JOURNAL November 2009 25