Distributed Optical Fibre Sensing 2015

1. Distributed Optical Fibre Sensing 2015

2. Contents • Optical fibres and packaging for the downhole environment • Optical fibre cable – downhole deployment options • Distributed sensing – how it works (summary) • Silixa’s distributed sensing technology and specifications • Introduction to Silixa and summary of upstream technology deployment • In-well applications overview • Seismic • Production Monitoring • Well Integrity • Fracture Monitoring • Silixa’s oriented perforation solution • Surface flow metering • Company contacts Confidential

3. Optical Fibres – for Downhole Fibre Types Buffer coating i.e. Acrylate • Optical fibres are flexible glass waveguides. • They consist of a core, which is used to transmit light, surrounded by a transparent cladding of lower refractive index. • The fibre is usually coated with a buffer material to protect the fibre from moisture and physical damage. • Fibres are either single-mode (SMF), which consists of a smaller core and allows only one mode of light transmission, or multi-mode (MMF) which has a larger core and allows multiple modes of light to travel through the fibre simultaneously. • So that fibres can safely be conveyed downhole they are typically placed inside a steel walled cable, shown below. Transparent cladding Fibre Core Single-mode fibre (9µm core) Multi-mode fibre (50µm core) The optical fibres are contained within a smaller metal tube and are often suspended in a partial fill of hydrogen scavenging gel. This construction is known as FIMT (fibre in metal tube). When exposed to hydrogen for extended periods optical fibres can suffer “darkening” which limits their ability to transmit light. High quality fibres are far less susceptible to hydrogen darkening. The fibre optic cable (FOC) can be encapsulated in a polymer coating such as polypropylene for added protection. This is typically 11x11mm square or 11mm OD round and is optional. Colour coded coated fibres: Each FIMT can contain multiple fibres, SMF, MMF or both. The fibres are “overstuffed” into the tube so that they do not break under minor elongation of the cable. This overstuffing can create approximately 0.3% excess fibre length such that a 10kft cable may contain 10,030ft of fibre. The outer steel wall is typically 0.25 inch diameter, is made from stainless steel or Incoloy and resembles a standard control line. A belting or jacketing material between steel layers is optional An encapsulated FOC and control line clamped to tubing Downhole Cable: encapsulated tube-in-tube construction Confidential

4. Optical Fibre Cable Deployment Intervention Permanent Installation The optical fibre cable can be clamped to the production casing and cemented into the well. Typical of mono-bore installations; note that perforations need to be oriented away from the cable to avoid damage. The cable can also be clamped, using standard cross-coupling protectors, to the outside of production tubing or screens and can straddle production packers where necessary. Optical fibres can be incorporated into a number of different cable constructions. The picture, left, shows a stiff 3/8” OD tube-in-tube cable being injected into a highly deviated offshore well for a production monitoring survey using standard coiled tubing conveyance equipment. FIMT can also be incorporated into braided electric line, the second picture shows a coiled tubing string with hybrid fibre-wireline being conveyed into a horizontal well for well integrity and production profiling. The third picture shows a hybrid fibre-wireline being conveyed normally into a vertical well to conduct a borehole seismic survey. Tube in tube cables can be constructed to a variety of sizes including conventional slickline dimensions such as 1/8” OD allowing for real-time downhole surveillance without the need for grease injection pressure control. Where the optical fibre cable penetrates the wellhead it is necessary to install a pressure control device which maintains the integrity of the wellhead barrier envelope but also give you access to the optical fibres so that measurements can be made. Silixa’s API-6A Wellhead Outlet, right, is rated to 10,000psi and connects to a ported wellhead with a 1” autoclave fitting. It provides a double pressure barrier for four optical fibres and allows for block and bleed functions. • Fibre optic cable installations on dry tree, single stage wells are a routine practice • Subsea penetrators exist on the market and facilitate fibre installation on subsea wells • Third party downhole optical fibre wet-connect systems have been developed to enable fibre installation on multi-stage completions; however there is limited amount of test data and/or track record available. Confidential

5. Distributed Optical Fibre Sensing Distributed optical fibre sensing refers most commonly to Distributed Temperature Sensing (DTS) and Distributed Acoustic Sensing (DAS) DOFS pairs an opto-electronic interrogator box to an optical fibre, as shown in the picture (right). The interrogator injects a pulse of laser light into the fibre which, as it propagates along the fibre, creates tiny reflections, some of which return to the interrogator and are detected. In the case of DTS backscattered light is affected by Raman scattering, a component of which is sensitive to the temperature local to the reflection event. This allows the returning light detected at the interrogator to be converted to a temperature value and assigned to a particular fibre position based on the highly accurate travel time of the light pulse. DAS works in a similar way however in this instance we are interested in backscatter light which is affected by dynamic strain within the optical fibre; in the absence of other influences these tiny strain events are caused by sound waves interacting with the optical fibre.Once the pulse of laser light has reached the end of the fibre and reflected back to the interrogator the fibre can be considered as “dark” at which point the next short laser pulse can be injected. This process is repeated roughly 10,000 times per second on a 10km fibre, the result is an acoustic signal sampled at 10kHz. Higher frequency sampling can be achieved on shorter optical fibres. The acoustic samples are mapped to the fibre distance based on the optical travel time. For downhole applications Silixa’s iDAS and DTS are analogous to having a thermometer and microphone at every metre along the entire length of the well. This information is useful in a number of ways, which will be explained further in the following slides. Confidential

6. Silixa Technology • Silixa’s iDAS is a true acoustic sensor meaning that it records phase-coherent acoustic information. This is a critical for the advanced processing of acoustic data for specific applications.Not all DAS systems are capable of phase coherent measurement. • The iDAS can make acoustic measurements on either single-mode or multi-mode optical fibres. • Dimensions: h-177mm, w-465mm, d-467mm. Weight 16.9kg (19” rack mountable) • Temperature operating range: 5°C to 40°C • Dynamic Range: 120dB • Frequency Range: <1mHz to >100kHz (fibre length dependant) • System samples at 25cm intervals and outputs acoustic data channels at every 1 metre. • Acoustic data is saved to a proprietary format and can be written either to an internal hard disk RAID array or to a high volume external hard disk RAID up to 72TB in capacity (currently).As an example an iDAS sampling at every metre on a 5,000m fibre at a rate of 10kHz for 24 hours would result in 8.2TB of stored data. iDASTM ULTIMATM • Silixa’s ULTIMA DTS range is the worlds highest performing family of Distributed Temperature Sensors offering temperature and spatial resolutions from 0.01˚C and 35cm. • The key to the superior performance of the ULTIMA is in maintaining fine temperature and spatial resolution while allowing short measurement times. • The ULTIMA allows for measurement on up to 8 separate optical fibres and on ranges of 2, 5, 10, 20 and 35km. • The ULTIMA range have similar 19” rack mountable dimensions to the iDAS (above) • The variant on pictured (left) is the ruggedized XT-DTSTM which offers 4 individual channels over a range of 5 or 10km and can operate indefinitely from a low power supply, such as solar panels, and in extreme conditions from -40°C to +65°C. Shown: XT-DTSTM Confidential

7. Silixa Overview Track Record – Inwell measurements to March 2015 Silixa was founded in 2007 to develop the next generation in distributed sensing technologies. We are based near London in the UK and have a regional office in Houston as well as customer support in the Middle East and North Sea. Besides a significant R&D organisation Silixa have an operations team made up of fibre optic installation expertise and oilfield services and data acquisition experience. The company is focused on developing high value applications for the upstream Oil & Gas industry using our key technologies but also supports and develops applications in other industry sectors such as pipeline surveillance, third party intrusion detection, power network monitoring and environmental monitoring applications. Besides the core technologies of iDAS and DTS Silixa hold a number of patents for unique data processing methods and enabling technologies. Since 2009 we have supported data acquisition projects across the globe and in over 50 wells. An overview of in-well data acquisition is shown on the right. London experts in distributed sensing • Established in 2007 • iDAS / ULTIMA DTS • ISO 9001 QMS • 60 Employees Houston Investors Confidential

8. In-well Applications Distributed sensing uses an optical fibre as the sensing array which means there are no moving parts, electronics or power supplies placed downhole making the technique inherently reliable. The systems operate on standard optical fibres and so can be retrofitted to almost any existing downhole fibre installation. Silixa’s iDAS and DTS technologies uniquely operate on either single-mode or multi-mode fibres making older MMF-DTS installations viable candidates for distributed acoustic acquisition. A single optical fibre cable installation can enable multiple measurement opportunities. A permanently installed cable offers life of well monitoring capability. Confidential

9. Borehole Seismic • The Seismic version of the iDAS is designed to measure, in a moving window, the relative strain between two points on the fibre 10 metres apart (gauge length). • The system response is linearly proportional to the average fibre elongation along the gauge length. • Each sample in time is a measure of the change in strain with respect to the previous temporal sample. • The phase fidelity of the iDAS measurement allows data to be handled similarly to a geophone response, for example stacking and velocity filtering. • The result is a system capable of acquiring densely sampled seismic data where the optical fibre can be considered as a huge array of single-component sensors aligned with the well-path. • Seismic data can be gathered from a number of different optical fibre cable deployment methods from intervention, to cables cemented outside casing or clamped to production tubing. In all cases each seismic source activation yields a wave-field covering the entire instrumented well path with 2 metre channel spacing. • Where the downhole optical fibre is permanently installed seismic acquisition can be performed on demand without the need for intervention and without stopping production. • The iDAS field software can be triggered or can provide a trigger to seismic source controllers; alternatively it can passively record using GPS timestamps resulting in data that is sample perfect and free of time drift over any length of acquisition. This capability makes the system ideal for integration with streamer or ocean bottom surveys where source navigation and timing data can be used to extract seismic records post-survey. The result is an accurate depth to time conversion and improved imaging capabilities around the wellbores. • The iDAS can provide high quality seismic images which benefit naturally from the migration of such densely sampled data. Images courtesy of Aquistore, Canada • The above (left) image shows the wave-field sampled on a 3000m multi-mode fibre from a single dynamite shot, (right) a pair of intersecting migrated images from a 3D pattern of dynamite shots over the same vertical well. • Intervention-free borehole seismic acquisition in flowing wells • Synchronised multi-well survey capability through use of GPS timing • Ideal permanent 4D survey tool with consistent channel depths • Field SEGY with 2m channel spacing and 1kHz sample rate • Low cost approach to high-volume seismic acquisition. Confidential

10. Production Monitoring Stand-alone temperature measurements offer important information about the dynamic conditions of a flowing well however when viewed in isolation can be difficult to translate into confident decision making. Temperature information complimented with the unique attributes of true acoustic data can offer more conclusive answers to typical well performance questions. Silixaoffer proprietary, and best-in-class, distributed temperature and distributed acoustic sensors and a suite of software to integrate and process DTS and DAS data. Gas break-through in heavy oil zones Data Visualisation DTS data is sampled over a user defined time averaging window, with a longer window offering higher temperature resolution. Data can therefore be displayed as a single depth based curve for each time window, or as a series of aggregated curves or image. The example right shows a series of 10-minute average curves. TIME TEMPERATURE DEPTH iDAS data is highly sampled in both time and space and so a common method of visualising data is the time domain “waterfall” plot (left) where the x-axis is the fibre depth and the y-axis is time (1 second shown). The colour scale indicates the acoustic energy levels with red being highest/loudest. Diagonal lines in both directions indicate sound propagating within the wellbore in both up-hole and down-hole directions. Louder regions often indicate inflow/outflow zones such as perforations. A standard Silixa method to integrate DTS and iDAS data for basic production and well performance monitoring is shown above. Each (1 minute) block of data is processed into a single image showing current, and differential, temperature and acoustic RMS values across the frequency spectrum. Static depth based data, such as deviation and gamma-ray, can be plotted alongside and time based data such as downhole gauge outputs plotted underneath to support the interpretation of data over time. Since each 1 minute block is represented by a separate frame they can be viewed in succession, or animated, to create a quick view of dynamic well conditions. TIME DEPTH Confidential

11. Production Monitoring Quick-look methods Optical fibres across the production interval allow for temperature and acoustic data to be acquired continuously without the need for intervention. A snapshot in time can provide insight into the well performance and continuous distributed monitoring can help to describe the dynamic conditions that conventional production logging cannot. Where data visualisation may allow for binary conclusions such as flow/no-flow, quick-look evaluation based on relationships linking inflow to temperature and acoustic response can provide better understanding of zone-by-zone production allocation. Silixa’s proprietary processing software enables the user to select DTS and iDAS quick-look methods and to analyse results side by side so that decisions can be supported by independent measurements. Standard data outputs include PNG log graphics and LAS2.0 data files although other file formats can be produced. Flow quantification and fluid typing As shown on the previous slide the iDAS can track the propagation of sound within the borehole. Due to the leading spatial resolution and phase coherent measurements of the iDAS, and using proprietary array processing techniques, Silixa are able to extract speed of sound information from the acoustic field. This process involves the conversion of a block of sampled data (eg. 50m by 1 second) into the space-frequency domain by 2D FFT, where coherent sound transmission modes are identified from across the frequency range. A radial scan of the two quadrants of the 2D FFT window (below) picks up amplitude peaks at the dominant speed of sound components. Sound in production fluid UP DN DTS & iDAS DATA VISUALISATION Inflow Allocation vs. Depth Where sound propagation is detected in the production fluid it is possible to identify the fluid type based on known speed-of-sound properties. In two phase flow the mixture speed of sound can be used to estimate fluid fractions. The Doppler shift between up and down-going sound is a direct indicator of fluid velocity and so with the correct pipe dimensions can be converted to flow rate. By sliding the 2D FFT window along the length of the well it is possible to build up a depth log of sound speed and flow speed, above right. QUICKLOOK OUTPUTS Zone by zone contribution; current & cumulative Confidential

12. Well Integrity Well integrity surveillance has traditionally used temperature and noise logs to help locate undesired fluid movement within, or around the wellbore caused by tubing/component leaks, poor cement or the failure of permeability barriers. Conventionally these logs are acquired using point sensors which must be moved across the region of interest in order to build up a depth log. This procedure requires well intervention, is costly and can have limited success as it depends on the ability to place the point sensors at the right depth and at the right time to capture the event. Distributed sensing allows the user to gather continuous temperature and acoustic data along the entire instrumented length of the well, and where the optical cable is permanently installed in the well this can be achieved without the need for intervention and with minimal surface equipment and personnel requirements. Where optical fibres are not present in the well it is possible to deploy them as a cable intervention and then to benefit from reduced operating time by scanning the entire well continuously. The example on the right is of a distributed acoustic survey performed in a shallow abandoned well where gas was escaping to surface between casing strings. The infrequent nature of the gas release events meant that the well had to be surveyed for several hours in order to capture an event which would indicate the depth of the gas leak. The result is an image showing how the gas pressure migrates up-hole before dissipating, the frequency distribution shows content up to 4,000 Hz which is consistent with gas movement. The discrete, and short-lived nature of the event would have made it very difficult to capture with a wireline conveyed noise tool. Similar techniques have been used with permanently installed cables to confirm leaking gas lift mandrels and to record baseline and time-lapse integrity surveys on critical wells including CO2 disposal wells. Time domain waterfall plot Frequency distribution plot Gas Migration Confidential

13. Fracture Monitoring Distributed sensing, when applied to hydraulic fracture monitoring, allows the user to monitor the placement of frack fluid and proppant along the stimulated stage in real time. Optical fibre cables can be installed on the outside of production casing on shale wells such that they traverse the entire production lateral; on a plug-and-perf completion oriented perforation techniques are used to direct perforating charges away from the optical fibre cable. With the sensor array in place it is then possible to use distributed acoustic and temperature data visualisation to watch the fracking process downhole and to quickly recognise undesirable events such as perforation screen-out or leaking plugs. The image (right) shows an example of Silixa’s real-time field software; acoustic and temperature data is streamed in real time from individual interrogators to a common processing platform. Acoustic data is viewed as a waterfall plot as well as a frequency distribution plot with corresponding acoustic RMS curves, while temperature data is plotted as an image and continuously updating curves. This view allows the user to see the activity of each perforation cluster as an indicator of proppant outflow. By applying similar quick-look methods as discussed under production monitoring it is then possible to quantify the relative outflow of proppant slurry at each cluster during pumping, as shown on the chart (right), giving a valuable indication of the effectiveness of stimulation at each stage. The temperature and acoustic response can also quickly indicate when a plug or packer is leaking, and negatively affecting the frack job, so allowing the operator to make rapid operational decisions. Where remedial action is taken, such as to introduce fluid diverters, the iDAS/DTS combination can help to validate the effectiveness of remediation. By monitoring the flow-back and early production using the same methods the operator can further understand the effectiveness of fracking on a zone by zone basis allowing for decisions about future well placement and completion strategy. Confidential

14. Oriented Perforation • The main challenge in introducing an optical fibre cable to a conventional perforated casing completion is avoiding damage to the cable during perforation as this would render the optical fibre sensor array unusable. • Current methods involve running a significant amount of metal mass on the outside of the casing alongside the optical cable then using Wireline conveyed oriented perforating tools to locate the position of the metal mass relative to the high side of the hole so that perforating guns can be deployed directed away from the cable. • The primary drawbacks to this method are the cost and complexity of installation and the added cost of the required Wireline measurements. • Silixa have developed an autonomous perforation beacon which can be deployed alongside the cable, under standard cable clamps placed periodically along the production interval. • These beacons are temperature activated, battery operated devices that, once downhole, will measure the relative bearing of the device/cable position and then generate an audible tone at a frequency determined by the measured angle. • Once the casing is on bottom Silixause the iDAS to interrogate the optical fibre and so detect the precise depth of each audible tone and decode the dominant frequency to a relative bearing value that describes the position of the cable on the outside of the casing. • Silixa can then provide a depth log of cable orientation (example shown right) allowing the perforating provider to set up passively oriented gun strings to avoid damaging the optical fibre cable. The method also provides valuable correlation between the completion tally and the optical fibre depth. • Reduced completion complexity and cost • Eliminate costly wireline measurements to determine cable position • Reduce hardware requirements in the annulus and so improve casing running efficiency and cement quality Sample Cable Orientation Log • Autonomous Perforating Beacon • Non-retrievable • 7/8” OD by 10” long • 150C Maximum temp • 15,000 psi Maximum pressure • 48hr+ battery life Confidential

15. Surface Flow Metering • The Silixa surface flow meter uses optical fibre attached to the exterior of a pipe to enable real-time monitoring of flow within the pipe. The system can be used to measure the velocity of single or two-phase liquid/gas flow. • Silixa’s flowmeter operates on pipe diameters from 1” upwards. It is bi-directional, non-intrusive and passive, with no power requirements at the sensing point. The flow meter can be retrofitted on an existing pipe without any interruption of operations. • Key benefits • Flexible architecture means that up to 10 measurement stations can be linked in series using a single sensing fibre and a single acquisition system • Sensor is entirely optical, and does not require electrical power at the point of flow sensing • Non-intrusive, retrofittable without interrupting operations and easy to install Confidential