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Third EAGE Workshop on Permanent Reservoir Monitoring 2015
- Conference date: March 16-19, 2015
- Location: Oslo, Norway
- Published: 16 March 2015
1 - 20 of 28 results
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Keynote Speech - Ekofisk Permanent Seismic Monitoring - Results After first 4 years
Authors P.G. Folstad, P. Morgan, A. Bertrand, M. Rossing and B. LyngnesSummaryIn 2010, a full-field permanent seismic monitoring (PRM) system based on optical sensing technology was installed over the Ekofisk field.
Since installation, seven seismic surveys have been acquired with a plan to continue acquiring two new surveys each year.
Permanent sensor positioning combined with a high focus on quality during acquisition and processing have enabled achievement of NRMS values on the order of 4% resulting in detectable 4D seismic timeshifts less than 200s and amplitude changes of the order 2–3%.
The 4D seismic data from the system are routinely used for many different purposes including optimization of new well locations and trajectories, suggestion and prioritisation of well interventions, diagnoses of well mechanical issues and updating the reservoir model. In addition to reservoir applications, the data are used extensively for monitoring and surveillance of the impact of injection, production, compaction and subsidence on the overburden section.
In this paper, we will show a selection of cases where 4D seismic data from the Ekofisk PRM system have been used to impact business decisions related to injection and production from the Ekofisk reservoir.
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A Permanent Downhole Electrode Array as Valuable Tool for CO2 Monitoring at the Ketzin Pilot Site
Authors C. Schmidt-Hattenberger, P. Bergmann, T. Labitzke and F. WagnerSummaryAt the Ketzin pilot site (Germany), a multi-disciplinary monitoring concept was established in order to image CO2 injected into a saline aquifer. Within this surveillance program a behind-casing borehole electrode array was deployed as permanent reservoir monitoring (PRM) tool. During the period from 2008 until 2014, weekly geo-electrical cross-hole data were recorded. This comprehensive archive of time-lapse resistivity data forms a respectable base for CO2 saturation estimation. Moreover, the long-term evaluation of the borehole electrode array provided the evidence for its endurance under subsurface conditions, reliability and usefulness for integrative geophysical data analysis.
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Using Ambient Noise for Real-time (Hourly) Overburden Monitoring
By S. BussatSummaryFor monitoring of an injection well we use 172 permanent 4 component nodes on the seafloor close to the Oseberg C platform. By using the platform noise as a permanent seismic source we obtain virtual shot gather for each hour. As an example, these hourly vintages are analysed for 10 days, providing 240 vintages. Time lapse changes for the acoustic guided waves (mulitiples) have been observed with time shifts up to 10 ms related to tidal variations. Time-lapse analysis of Scholte waves reveals time shifts of up to 100 ms within only 4 hours. Observed shear wave velocity decreases correlate well with atmospheric weather variations and changes in wave heights.
The high sensitivity to natural variations caused by tides and weather indicates that early detection of a leak from the injection well is possible with the installed system at the Oseberg C platform.
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Permanent Seismic Reservoir Monitoring for Real-time Surveillance of Thermal EOR at Peace River
Authors J.L. Lopez, P.B. Wills, J.R. La Follett, J.C. Hornman, J.H.H.M. Potters, M. van Lokven, C. Perkins and C. TrefanenkoSummaryPermanent seismic reservoir monitoring (PSRM) solutions, if of high enough sensitivity and low enough cost, can be used to tackle the many known problems faced by seismic monitoring onshore and thereby increase the profitability of such developments. Here we focus on thermal EOR monitoring using continuous seismic, as provided by SeisMovie®, a registered trademark of CGG. We review the PSRM staircase that Shell has climbed since 2009, introduce the most areally extensive deployment at Peace River in Alberta, Canada, and discuss some of the initial findings and plans ahead. We show progress with PSRM to generate better onshore data that will lead to higher recovery, higher production, and safer and cleaner operations. Significant steps were made towards on-demand, lower footprint PSRM, and next steps are set towards cheaper, non-intrusive automated systems that are required for broad application.
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Simultaneous Acquisition of Distributed Acoustic Seismic Surveys with Single-mode and Multi-mode Fiber Optic Cables at Aquistore CO2 Storage Site and a Comparison with 3C Geophones
Authors M. Longton, A. Strudley, D. White, T.M. Daley and D.E. MillerSummaryThere is a growing interest in the application of Distributed Acoustic Sensor (DAS) for permanent reservoir monitoring. The optical fiber cables installed along the borehole allow for continuous recoding of 3D seismic surveys. We report on a simultaneous acquisition of distributed acoustic seismic surveys with pre-installed single-mode and multi-mode optical fiber cables at Aquistore and compare the results with 3C geophones. The advantages of precise time lapse measurements using the DAS system for the long term evolution of CO2 distribution will be also discussed. Furthermore, the use of multi-mode optical fiber cables marks a significant potential of the DAS system used in this project which opens up the possibility of using existing multimode optical fibers used with the Distributed Temperature Sensor (DTS) for seismic data acquisition.
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The Installers Perspective - Permanent Reservoir Monitoring (PRM) System Installation
Authors E.A. Wilson, O. Foster, I. Griffiths, N. Broom and S. HibberdSummaryGlobal Marine Systems Limited (Global Marine) has a vast wealth of knowledge in designing, installing and maintaining fibre optic cable systems, including lightweight cable in water depths ranging from the very shallow (<10m) to the very deep (>6000m). This paper shares Global Marine’s main considerations when designing and delivering long lasting Permanent Reservoir Monitoring (PRM) installation solutions that reap rewards for those oil majors carefully assessing the opportunity cost of same.
By its very nature the capital investment in PRM is significant thus making it critical to consider all aspects of system planning, installation and maintenance; this includes all aspects of cable engineering from desk top study through to installation and associated burial options. Experience with the handling and deployment of the small-diameter cable types that are used in PRM is crucial to the successful delivery of these systems, which places Global Marine with a cable installation legacy that spans over 160 years, at the core of the installation solution.
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Jubarte PRM System Manufacturing and Installation Lessons Learned
Authors S.J. Maas, J.B. Bunn, D.R. Metzbower, A.B. Smith and D. SticklerSummaryUpon successful installation and acquisition of 4D data from the Jubarte pilot PRM system, we would like to share some of the lessons learned from the Jubarte experience. Discussion includes the technical challenges and supply chain difficulties that needed to be overcome. We successfully dealt with manufacturing and installation challenges, leading to the delivery of the system in 2012. After the third active acquisition of seismic on the field, the system continues to operate providing excellent data to Petrobras. As a result of the data from the Jubarte PRM system, decisions have been made by Petrobras to relocate various well placements. During the process we have taken the issues and incorporated them into a new revision of the system which shall also be explained, comparing the current “Next Generation” OptoSeis design to that which was installed on the Jubarte field. While the design changes are subtle they will lead to a more cost effective and reliable system in the future.
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North Sea Buzzard Field – Baseline OBN Survey Parameterisation
By R. GordonSummaryA Life of Field study for the UK North Sea Buzzard Field focused the strategy on reserves maximisation. 4D seismic technology was recognised as a key potential contributor to achieving this goal, supporting the long term monitoring effort of field depletion and future drilling decisions. A review of possible options was undertaken and a retrievable seabed acquisition approach was adopted. From a technical perspective, a significant concept determining factor was the initial uncertainties in geometry optimisation. The business case itself will be discussed elsewhere.
The same uncertainties about geometry optimisation apply equally to retrievable seabed surveys as they do to permanent installations. The geophysical features influencing the decisions on source effort and receiver effort are considered. The final design chosen for the Buzzard acquisition is compared to published acquisition geometries and target classifications to provide confidence in the ability of the baseline survey to provide the desired results. The survey was successfully acquired in the summer of 2014.
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PRM - Do it with Nodes!
Authors P. Hatchell, C.D.T. Walker and J. ThompsonSummarySince full azimuth nodal acquisition has become the technique of choice for imaging below complex salt overburdens in the deep-water Gulf of Mexico, with more than 25 surveys acquired in the last 10 years, new high speed underwater communications technology is allowing the development of a “semipermanent” reservoir surveillance/Life of Field (LoF) capability using Ocean Bottom Nodes (OBN.)
Christened ZLoF this semi-permanent solution is a development of the Z3000 system that has delivered 98%+ reliability since its commercial introduction in 2005. ZLoF is designed to provide a highly cost effective alternative to cable based Permanent Reservoir Monitor (PRM) systems. Since the ROV deployed nodes are autonomous there are no cables to deploy/trench and there is no requirement to tie into a field’s production facilities all of which simplifies installation and significantly reduces costs.
With a 300 day active recording life and a 5 year on the seabed lifetime ZLoF allows, for example, 12 25 day surveys to be shot – Baseline + 11 Monitors – before node recovery. Node-on-node 4D has been shown to be extremely robust and it is expected that this semi-permanent system will enable frequent monitoring of reservoir integrity, injection rate optimization, improving water flood effectiveness and pressure maintenance.
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LoFS Processing for 4D Attributes at the BC10 Field – Offshore Brazil
Authors Y. Chen, H.G. Farmer, Z. Liu, M. Lydon and H. WuSummaryThe BC10 LoFS system is providing early benefits from its investment. Fast-track 4D results were obtained within only 7 days after the field data arrived at the processing centre in Houston. These 4D results have been confirmed by the follow-on full-fidelity processing of the down-going wavefield. The 4D results indicate clear hardening at the injector wells and softening at the producing wells. These 4D results correlate accurately with the documented performance of the wells in the field.
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High Resolution Mirror Imaging of 4D OBC Data at Valhall
More LessSummaryThe specifications of the permanent OBC (LoFS) array at Valhall were designed to produce time-lapse images of the reservoir at 2.5km depth. Advances in processing technology have been leveraged to reprocess the data from several legacy LoFS surveys in order to produce high resolution images of the overburden, beyond the original specification of the array. Inclusion of the down-going arrivals into the workflow improves shallow coverage to provide a near-continuous image of the sea bed. Processing of the down-going arrivals in a 4D sense provides high resolution time-lapse images much shallower than was previously achievable. Analysis of LoFS recordings of an ultra-high resolution site survey demonstrate that the array can be reliably used to record frequencies up to 500Hz.
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Using Primaries and Multiples to Extend Reservoir Illumination for Time-lapse Monitoring - Application to Jubarte PRM
Authors D. Lecerf, A. Valenciano, N. Chemingui, S. Lu and E. HodgesSummaryA depth migration method, that uses primaries and all orders of multiples, has been adapted to produce extended 3D and 4D images in the context of seabed acquisition. The technology has been validated using the Petrobras 4D datasets acquired during the deep-water Jubarte PRM pilot. As result of its application, the reservoir illumination has been significantly expanded to more than 100 km2 from an approximate 10 km2 coverage obtained from the conventional imaging of primaries. The resulting 4D signal shows a good match with the well trajectory, validating the use of all orders of multiples for 4D imaging studies.
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Correcting Air Gun Source Signatures for Variation in Sea Water Temperature
Authors K. E. Haavik and M. LandrøSummaryA simple solution for correcting the effect of seawater temperature changes from base to monitor survey is presented. We find that the NRMS difference between the source signatures corresponding to a 10 degree centigrade change in the seawater temperature is approximately 8 % when the whole signature is considered and approximately 30 % in the area of the bubble oscillations.
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Calendar Time Interpolation of Amplitude Maps from 4D Seismic Data
More LessSummaryA calendar time interpolation method for two dimensional amplitude maps is used on real data from the Sleipner CO2 storage project. Interpolation uncertainty increases with the time gap between consecutive seismic surveys and is estimated by leaving a survey out (blind test). Field-life cost of various acquisition systems and repeat frequencies are linked to the time-lapse interpolation errors.
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The Development of a Dual Containerised Source System
Authors T. Hibben and M.J. BurnettSummaryFor Statoil’s Snorre & Grane PRM project, WGP has developed and operates a dual containerised source system (otherwise known as a Dual-Portable Modular Source System, D-PMSS).
The equipment has been utilised to acquire baseline surveys over Grane (2014), and baseline plus repeat surveys over Snorre (2013, 2014). The equipment is installed on the Statoil supplied vessel “Siddis Sailor” for the duration of each survey program only.
This is the fourth generation containerised source system that WGP has developed, with a number of notable improvements:
- Dual Source capability: Towing 2 × 3,250cu.in. sources at 50m separation. Naturally, this provides increased source effort productivity, relative to single source operations. The main challenges that were overcome involved developing a modular handling system for the deployment, towing and recovery of the barovanes to achieve the source separations.
This was a necessity due to the extent of the trenched seabed cable array, combined with the required offset and resultant source area,and requirement to acquire 2 surveys over each field per year.
- Improvement of realtime and post-acquisition QC of the source array. By inclusion of a fully distributed source controller, with: Depth Transducer and Pressure Transducer (with fill)at each element and Near Field Hydrophones at each cluster.
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Nodes Provides a Reliable Repeatable and Cost Effective Solution for Reservoir Monitoring
Authors E.W. Berg and C. VuillermozSummarySeabed data acquisition methods offer numerous advantages over towed streamer data. These advantages can lead to improved static and dynamic reservoir characterization. Full vector field data is recorded at the sea floor with improved shallow resolution, signal-to-noise ratio, broad band content and 3D illumination through full azimuth data acquisition. The last ten years the autonomous node technology has demonstrated its capability to improved imaging of complex reservoir structures with both pressure (PP) and in some cases converted shear (PS) data compared to previous OBC survey. The main reasons for these improvements are the stable and consistent measurements achieved by very well coupled nodes to the seabed as well as the full azimuth acquisition with densely sampled shots.
Node cost sensitivity studies analyzing different 4C–4D node scenarios show clearly with respect to field size, water depth and node spacing that the node concept are getting radically more cost effective with increased field size and water depth.
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Telecom Business Model introduced to the PRM Marketplace
Authors E. Bouvart, M. Eriksrud and H. NakstadSummaryThe supplier of the Ekofisk fibre-optic PRM system (Optoplan) has recently been acquired by the global leader for subsea fibre-optic telecommunication systems (Alcatel-Lucent Submarine Networks or ASN). It is expected that this merger will impact the PRM marketplace. The Ekofisk PRM system has clearly demonstrated the benefits that PRM technology can bring to subsurface teams through generating high quality 4D images. Nevertheless, the general acceptance of PRM technology by oil companies is slower than expected by the PRM community due to various financial and organizational barriers. In particular, PRM projects are considered to be costly, complicated and time consuming to implement. The entry of ASN into this market together with Optoplan will reduce or eliminate some of the existing barriers by offering full turnkey solutions for equipment manufacturing and installation and by leveraging a successful telecom culture. The resulting business model introduced to the PRM marketplace is discussed.
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Tailoring the Solution – To What Objective
Authors D.I. Hill, D. Lowden, R. Newman, K. Westeng, M. Paydayesh and S. SonikaSummaryIn order to optimally utilize repeat 4D Time-lapse seismic data for the purpose of seismic reservoir monitoring, it is necessary to first fully understand the acoustic and elastic response to both reservoir and field-wide changes. This is a complex interaction. It incorporates not only the reservoir dynamics component - which encompasses fluid properties, fluid flow characteristics, field performance history and pressure distributions and profiles over time, but also all the changes in stress induced by the pressure changes during production. It is those changes in stress that induce strains/deformations not only within the reservoir but also around it. Understanding the reservoir dynamics is not possible from studying the individual geologic, reservoir simulation and reservoir geomechanical models in isolation – it requires them all to be fully integrated into a full-field coupled Dynamic Integrated Earth Model (DIEM). Only by fully understanding the mechanisms that produce the 4D signal via a DIEM can we hope to design an acquisition configuration in order to measure the 4D response at time intervals necessary, within the survey specific coherent and incoherent noise conditions, to be used for pro-active closed loop seismic reservoir monitoring and management.
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Customized Injection Monitoring Solution Using PRM Technology
Authors J.E. Lindgard, S. Bussat and T. MatveevaSummaryOctio has installed a permanent monitoring system at a waste injection site at the Oseberg field on the Norwegian continental shelf. This system comprises a small ocean-bottom seismic array of 4C stations, designed for both passive monitoring of microseismic events and active seismic surveys (see Lindgård and Matveeva 2013 and Løvheim 2013 ). The system was designed and installed in a Demo 2000 project supported by the Research Council of Norway and Statoil, and has provided real time data since its installation in 2013. The results from the first year of monitoring show that the system is able to characterize different passive energy sources from sub-hertz up to Nyquist frequency. These passive sources include weak regional earthquakes (M < 4.5) and microseisms from ocean wave oscillation (see Bjerrum et. al., 2014 ). During the summer 2014 a 4D baseline active survey was successfully conducted. The Oseberg installation is an example where a system is dedicated to injection monitoring over a limited area. The system will provide early warning for caprock integrity issues using passive and microseismic monitoring.
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A Flexible Sensor Network is Key to PRM Cost Reduction
Authors L. Lovheim and M. OldervollSummaryFor PRM systems, the main cost drivers - apart from the cost of the system itself - are installation, operation/maintenance and survey costs. There are many decisions to be made during the system development and design phases that will heavily impact these follow-on costs. Flexibility is key. Offshore O&G fields differ in water depth, reservoir depth, bottom conditions, currents, water temperature, distance to subsea and/or topside infrastructure and also the level of existing ocean bottom obstructions such as pipelines, cables, moorings etc. It is important that the PRM system is flexible, ie. the basic technology and components that make up the system should allow for tailored solutions to fit the specific site where it is to be installed.
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