PinnPoint TM Deformation Monitoring with InSAR and GPS

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1 PinnPoint TM Deformation Monitoring with InSAR and GPS High resolution satellite based wide-area surface monitoring Fully integrated InSAR with high precision GPS and tiltmeter data Detect surface change in remote regions using PSI technique Real-time motion detection with Pinnacle s suite of GPS monitoring tools Pinnacle is the world leader in hydraulic fracture mapping and reservoir monitoring. We provide operators with analytical tools for reservoir management worldwide. Pinnacle combines our fracture and reservoir engineering expertise with the industry s most comprehensive suite of measurement and diagnostic technologies to provide our clients with an uncompromising set of monitoring options. Our ability to offer a spectrum of solutions gives Pinnacle the latitude to assess each client s unique situation and recommend a technological mix based upon the merits of each technique. No one diagnostic tool is ideally suited to all applications. Each has specific advantages and shortcomings. Combining numerous sources of information requires an intimate knowledge of their characteristics and intended deployment so that the integration combines the strengths of each, and not their weaknesses. For over a decade now, Pinnacle s exclusive tilt-based deformation measurement and analytical capabilities have allowed us to accurately characterize reservoir processes such as fracture growth and volumetric changes based upon the micro and macroscopic deformations they generate. is publication highlights two of our advanced PinnPoint monitoring technologies, satellite-based InSAR and automated high-resolution GPS. Figure 1. InSAR provides a means of measuring surface deformation over vast areas, from orbit, with little or no ground instrumentation. Pinnacle s InSAR capability is unique in that it may also be integrated with our full suite of in-house measurement technologies. HAL35993

2 Space Borne Interferometric Synthetic Aperture Radar (InSAR) Pinnacle offers a full suite of InSAR (interferometric synthetic aperture radar) tools which can be fully integrated with our existing tilt and GPS PinnPoint diagnostics. InSAR is a relatively new monitoring technique that can be used to obtain high spatial resolution surface deformation maps. InSAR measurements are obtained by active space-borne microwave sensors that are capable of operating in all weather and lighting conditions (Figure 1 on previous page). While the ultimate mapping resolution of an InSAR product is impressive (10 meter pixel size), the true power of this technique resides in its tremendous spatial coverage. e processing of single synthetic aperture radar images can cover up to a 100 km by 100 km area! To date, no other geodetic technique rivals InSAR s ability to measure deformation over vast areas of the Earth s surface. e ability to measure surface deformation over even larger areas may be accomplished by splicing together a mosaic of many individual radar scenes. An added benefit of increasing the number of acquired radar scenes over a region of interest is a reduction in monitoring interval from 24-days to less than a week. InSAR: How it Works Earth orbiting synthetic aperture radar (SAR) satellites project a beam of microwave energy at the Earth s surface and receive the portion of this beam that reflects from solid features, such as rock or soil. is reflected energy is o en used to make an image, or picture, of the surface based upon how much of the beam is reflected. Hard, rough surfaces typically reflect more of the beam and thus appear brighter in the image. Intensity, however, is only half of the information actually contained in the energy reflected back to the SAR satellite. Of crucial importance is the phase of the reflected microwave (Figure 2). In its simplest analogy, the phase of a microwave is akin to the markings on a ruler. e regular oscillations of a microwave traveling through space provide a reference with which distances may be measured, and the wavelength of a microwave is like the size of a standard ruler. Each microwave frequency has its own unique wavelength, and the receiver on the satellite is capable of measuring the phase, or exact position on the reflected microwave, at the moment it is received by the satellite antenna. Figure 2. Simplified explanation of phase shi, the physical phenomena upon which InSAR is based. Ground motion shi s the phase of the reflected radio signal by a measurable amount proportional to the magnitude of the ground motion. If the distance between a satellite and a specific point on the Earth s surface never changes then the phase of the reflected microwave should always be the same. Should this distance change however, either through the motions of the satellite or the deformation of the Earth s surface, the phase of the reflected waves will change in proportion to the distance change. If one has sufficient knowledge of the precise position of the satellite in its orbit, then the amount a point on the Earth s surface moves in a given period of time may be calculated by measuring the shi in the phase of microwave reflected from that point (Figure 2). Based on this principle, measurements of phase change taken for thousands of points on the Earth s surface are used to produce an InSAR image, or interferogram, that illustrates movement over very large areas. Integration With PinnPoint GPS and Tiltmeter Observations While the fundamental principles upon which InSAR operates are rather simple, the implementation of these principles in a successful measurement campaign is anything but easy. Sophisticated analytical tools and expertise at Pinnacle are necessary to deal with the numerous sources of interference, varying field conditions, etc. that can affect the production of meaningful results. Each interferogram is limited to one-dimensional motion in which all vertical and lateral deformation at each pixel is projected onto the line of sight of the SAR. HAL35994

3 By applying an understanding of the geomechnanical motions of a project with our proprietary GPS and tilt integration capabilities, we are able to present a richer, more accurate depiction of ground deformation (Figure 3). Our experienced petroleum and geotechnical engineers are then able to utilize this integrated dataset to more aptly determine what is causing the deformation and how to best alleviate it. STACKED INTERFEROGRAMS JANUARY 01 - AUGUST Figure 4 (above). PSI measures phase differences of corresponding point targets in a stack of several images acquired over time. HAL Figure 3. When InSAR is integrated with other PinnPoint technologies, the result is a richer, more accurate depiction of ground deformation. HAL35995 PSI: Using point targets to enhance InSAR monitoring capabilities While traditional InSAR is suitable for many regions on the Earth s surface, there are just as many regions that are not. Success with interferometry relies on the ability to observe coherent phase measurements from scene to scene. Many long-term monitoring campaigns occur in regions that are plagued with excessive vegetation, snow cover, flooding, or man-induced earth movement. All of these phenomena can degrade interferometric coherence. e solution to this dilemma is PSI. is technique uses the same technology as traditional InSAR, yet takes greater advantage of point targets (Figure 4) which produce a stable SAR signal return (permanent scatter) over time. PSI is ideal in areas that have a high density of existing point targets such as buildings, towers, dams, levees, and pipelines. Certain natural features, such as exposed rock, may also be used. When previously existing point scatters are not available, cost-efficient corner reflectors may be installed in strategically positioned locations. When co-located with GPS or other diagnostic monitoring equipment, a fully integrated field of deformation can be obtained in regions once thought to be inaccessible to recurring monitoring campaigns! Figure 5 (above). Corner reflectors can be deployed in critical areas where surface measurements are essential. Reconnaissance One of the benefits of offering a full suite of measurement technologies is Pinnacle s ability to apply each in a way that makes the most sense for our clients. When considering InSAR s place in deformation monitoring applications, its tremendous spatial coverage really stands out and makes it an ideal reconnaissance tool. Our ability to identify and apply broad monitoring to troubled regions permits clients to make decisions prior to catastrophic events. is o en includes the deployment of higher sensitivity PinnPoint GPS and tiltmeters into more localized regions to allow detailed source characterization. HAL35998

4 Global Positioning System (GPS) Initially developed by the United States Department of Defense, the Global Positioning System (GPS) is a satellite based system that allows for a precise determination of location anywhere on or above the Earth s surface. ere are currently 30 NAVSTAR satellites operating as part of the GPS constellation, enough to ensure that at least eight are in view at any given time from an unobstructed location (Figure 6). e ability of civilian users of GPS to process and make use of the system has come a long way since its inception and the launch of the first satellite in e original accuracy was crude by today s standards, and was used for lower accuracy navigation and location purposes. GPS receivers were large, power-hungry devices that could only provide high accuracy by collecting and averaging thousands of measurements. In the past 15 years, however, GPS has enjoyed an explosion in development effort, accuracy, and applications. GPS Applications GPS has become a primary tool for studying a wide range of geophysical phenomena including, but not limited to, subsidence, volcanic heave, tectonic strain accumulation and release, mass wasting, glacial flow, and other phenomena requiring stable and precise measurements of small motions. Pinnacle s GPS system provides a robust and economical stand-alone system capable of long-term operation of days to years, but its true power comes when it is fully integrated with our other measurement technologies such as InSAR, tilt, and microseismic. Reliable cost-effective monitoring As part of the PinnPoint deformation monitoring system, Pinnacle s GPS capability provides millimeter level sensitivity with continuous, automated operation in remote, unattended locations. Unlike other GPS monitors on the market, Pinnacle s system combines the low noise and stability of a double-differencing processing engine with Pinnacle s own proprietary filtering technique to provide results that are truly optimized to measure surface deformation originating from sub-surface processes. For applications that require real-time geotechnical, infrastructure or hazard monitoring motion detection we now offer our proprietary 3D-Tracker GPS technology. is GPS offering from Pinnacle combines high sensitivity real-time measurements with long-term stability by implementing a custom tuned Kalman filter with double-difference carrier phase measurements calculated over time (known as triple differencing). Only Pinnacle offers such a full suite of GPS monitoring capabilities that can be tailored specifically for the needs of your project. Ground Truth e long-term stability of GPS, and the fact that it constitutes a direct measurement of position (not an indirect one based on deformation shape) makes it an ideal source of 3-Dimensional ground truth for constraining the unknowns or potential sources of instability inherent in other measurement techniques. In this way Pinnacle s GPS is an ideal adjunct to our suite of technologies, augmenting their capabilities and mitigating shortcomings to produce a composite system with truly remarkable characteristics (Table 1). Additionally, the PinnPoint GPS system uses permanently (Figure 7) installed stations, thus eliminating the potential for error that plagues traditional survey techniques that require periodic visits and on-site equipment assembly. Figure 6. A constellation of 30 NAVSTAR satellites ensures that Pinnacle s GPS monitoring system always sees the optimal number of satellites for sub-centimeter accuracy. Figure 7. Pinnacle GPS operating continuously in the hostile environment of Northern Canada. HAL35999 HAL36001

5 Table 1 Description Synthetic Aperture Radar Interferometry (InSAR) Compares the phase change between reflected radar pulses recorded at two different time from spaceborne satellites Global Positioning System (GPS) Directly measures surface deformation using a network of surface receivers and a constellation of satellites Tiltmeters Measures the gradient (tilt) of deformation using an array of tiltmeter instruments Sensitivity Sub-centimeter displacement 1 ½ mm (0.06 ) of displacement cm (2/10,000 ) of vertical Key Strengths Broad spatial coverage No ground instrumentation required Operates continuously Operable in most weather conditions displacement Operates continuously Uses very little power Monthly monitoring capabilities 3-D displacement monitoring Measurements not influenced by weather Comparative sensitivities and characteristics of three monitoring technologies. Pinnacle combines each to accentuate strengths and compensate for weaknesses, a unique capability. For more information on PinnPoint TM Deformation Monitoring, contact your local Halliburton representative or resmonitor@halliburton.com Halliburton. All rights reserved. Sales of Halliburton products and services will be in accord solely with the terms and conditions contained in the contract between Halliburton and the customer that is applicable to the sale. H /12