Category: Oil & Gas

22 Jul 2015

Estimating Stimulation-Zone Anisotropy Effects During Microseismic Monitoring

Summary

Hydraulic fracture operations can be optimized using knowledge about the stress regime, flow permeability, and fracture networks in the subsurface. Surface seismic data and nearby well data give a first assessment of the properties present in the hydraulic fracture treatment zone, though on vastly different scales and at different resolutions. When hydraulic stimulation operations are monitored using downhole seismic sensors, microseismic events can be used to derive valuable velocity anisotropy estimates in-situ throughout the entire fracturing operation. These estimates can be both time and space variant. We show a real data example where microseismic events were recorded using a 40 level array of 3-component downhole seismic sensors in an observation well straddling the treatment zone in depth. The observed microseismic event gathers exhibit shear wave splitting even at the onset of treatment operations due to anisotropy which was not readily predicted by either surface seismic or sonic scanner logs. We demonstrate that this apparent contradiction can be explained by proper upscaling of sonic scanner data using equivalent medium theory. Using a group-theoretical approach, we calculate an anisotropic replacement medium that explains the measurements from surface seismic, VSP and microseismic data while also preserving the well-log defined properties. Although the fine-scale log velocities are isotropic, this averaging shows that some layers exhibit anisotropic behavior at larger seismic scales. We extract anisotropy parameters epsilon, delta, and gamma (Thomsen parameters) from the upscaled layers. These anisotropy estimates explain the shear-wave splitting observed in the data. Estimating anisotropy parameters in the fracture zone both before and during the treatment opens up the possibility of time-lapse characterization of the fracture zone anisotropy on a stage-by-stage basis. Reconciliation of microseismic observations, surface and sonic scanner data through upscaling using an equivalent medium approach bridges the resolution gap and allows further detailed frac zone analysis.

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13 Jul 2015

Monitoring Hydraulic Fracturing Operations Using Fiber-Optic Distributed Acoustic Sensing

Abstract

Taking downhole measurements during a hydraulic fracturing operation has many challenges, mainly the instrument survivability inside the hostile, high pressure, abrasive environment inside the casing during injection. Therefore, instrumentation must be attached on the outside of the casing, which has its own challenges in running-in-hole, cementing, pressure, etc. A fiber-optic cable with protective jackets can be permanently installed on the outside of the production casing and used to measure acoustics and temperature across the entire length of the borehole, without well intervention, for all operations from completions to production to abandonment. Fiber-optic distributed acoustic sensing (DAS) systems work by pulsing light into a fiber and measuring the backscattered light along the fiber length. An acoustic pressure wave that contacts the cable will create a small strain in the fiber and change the backscatter profile. The strain can be measured at surface, depth-matched using the speed of light in the fiber, and converted back into an acoustic signal. This paper will describe some of the acoustic events and signatures related to a typical plug-and-perf hydraulic fracturing operation including: wireline gun tracking, perforating, bridge plug setting, ball drops, and injection (axial flow and flow through perforations). Although this paper will only describe a typical signature of the listed activities, it will be evident that such continuous full wellbore measurements can be useful in redesigning and optimizing future operations, troubleshooting well problems, and making real-time operational decisions to avoid or mitigate non-productive time.

 

Click here to download the complete technical paper.

28 Apr 2015

OptaSense and Weatherford partner to deliver integrated well surveillance solutions

Farnborough, 28 April, 2015: OptaSense, a QinetiQ company, and Weatherford International plc have partnered in a strategic alliance to deliver integrated optical sensing solutions designed to optimize well planning, construction and production across the asset lifecycle.

The partnership combines OmniWell™ in-well optical production and reservoir monitoring systems from Weatherford with optical Distributed Acoustic Sensing (DAS) technology from OptaSense, including DAS-VSP™ vertical seismic profiling (VSP), DAS-HFP™ hydraulic fracture monitoring and DAS-Flow™ production flow monitoring.  These capabilities will provide customers with robust and actionable information that improves reservoir management and ultimate recovery.

Weatherford’s sensing technology includes pressure and temperature gauges, distributed temperature sensing, array temperature sensing, flow measurement, and seismic sensors.

Magnus McEwen-King, Managing Director of OptaSense, said “When Weatherford sensing technology is combined with DAS technology from OptaSense, the solution will deliver enhanced data acquisition and monitoring of seismic activity, well construction, completion and fracture operations, and production flow. In addition to acquiring accurate data in real time, OptaSense DAS technology can also reduce data acquisition costs by eliminating the need for well intervention.”

OptaSense’s innovative DAS technology offering complements Weatherford’s proven high reliability in-well technology. Together, these technologies provide a more complete, integrated, well surveillance solution. It will include multi-point and distributed VSP acquisition, production flow monitoring and hydraulic fracture monitoring, enhanced with microseismic imaging—which are critical in optimizing well performance.  The solution will also add value to customers with existing optical systems who are interested in DAS acoustic monitoring.

Weatherford and OptaSense have established a leading position in providing optical reservoir monitoring systems around the globe, installing and/or monitoring optical sensing solutions for more than 1,000 wells.

Both companies will continue to offer their respective products and services independently but together they will bring forward an integrated solution that delivers long term value to the customer.

03 Mar 2015

Cloud-Based Solution for Permanent Fiber-Optic DAS Flow Monitoring

In 2014, a first permanent installation of a fibre-optic (FO) distributed acoustic sensing (DAS) system was piloted in a tight gas well in Northern British Columbia. The project had three goals; to permanently monitor flow rates along the entire well bore, to make that information available to collaborative teams worldwide in real-time and to advance the system for future installations.

In oil and gas field development there is often a lack of frequent quality well and reservoir surveillance (WRS) data for quality decision making; leaving significant reservoir or well performance uncertainties potentially leading to suboptimal reservoir development. The need for frequent and good quality surveillance data is highest in complex reservoir developments such as unconventional plays, water-flooded reservoirs, thermal and chemical Enhanced Oil Recovery projects.

Often, well surveillance data is not acquired in practice because of concerns associated with production deferment, costs & logistics, HSE exposure or because it creates operational risks associated with well interventions when using conventional logging methods.

The attractiveness of FO-based surveillance lies with the fact that once the passive FO cable has been installed, no subsequent well interventions are required to collect downhole data; allowing for continuous (long-term) measurements or repeated measurements as and when required while eliminating the concerns associated with conventional logging methods.

The pilot system deployed at the well site is continuously measuring and recording qualitative and quantitative flow information. Using a secure web browser, the asset team can access the real-time and historical data when required or share with collaborative teams worldwide. The pilot has helped identify where improvements can be made in the enabling Distributed Sensing infrastructure such as handling and evaluation of the large data volumes, seamless data transfer, the robustness of the system installation and the overall integration of data into the full workflows. It will take further development of the system to implement all these improvements, but it is clear that FO based applications will play a key role in future well and reservoir surveillance.

This paper presents the system architecture and details the lessons learnt in designing, commissioning and running this system including the extraction of low data rate, actionable, qualitative data from distributed fibre-optic sensors and the IT challenges of creating a reliable, permanently installed system.

Click here to download the complete technical paper.

19 Feb 2015

Fourth generation OptaSense Distributed Acoustic Sensing system provides the highest data quality for borehole imaging

Farnborough, 19 February 2015: OptaSense, a QinetiQ company and global leader in Distributed Acoustic Sensing (DAS), has successfully demonstrated improved sensitivity of its DAS Interrogator Unit (IU).

As part of its ongoing product development, a pre-production version of the 4th generation of the OptaSense DAS IU was used to acquire a Vertical Seismic Profile (VSP) on a Carbon Capture and Sequestration (CCS) well during customer trials this month in North America. In these tests the new 4th generation IU achieved the targeted 6dB increase, a four times increase in sensitivity over the previous 3rd generation system.

The next generation ODH4 Interrogator Unit will also have a wider receive bandwidth, finer spatial resolution and greater programmable flexibility so it can be operated simultaneously in one or more acquisition modes. These features will be implemented in the commercial release of the 4th generation IU due in Summer 2015.

Magnus McEwen-King, Managing Director of OptaSense said, “The development of this 4th generation system once again pushes the boundaries of known performance. Our DAS-VSP™ service is already reducing the cost of data acquisition. Our 5th generation system, which is in development with Shell, is also showing great gains that will see OptaSense DAS capability deliver on an extremely ambitious technical target.”

The 4th generation IU will acquire higher quality DAS-VSP™ measurements, enabling geophysicists to see clearer images of the subsurface with the unique flexibility afforded by acquiring seismic measurement on an optical fibre deployed downhole.

The 4th generation IU is also expected to improve microseismic monitoring with smaller events now detectable, and flow monitoring where the simultaneous use of more than one acquisition mode will extend the ability of DAS to accurately measure inflow and axial flow rates across the length of the well.

22 Nov 2014

QINETIQ ACQUIRES SEISMIC PROCESSING AND IMAGING CAPABILITY FROM SR2020

November 21st, 2014

Transaction Helps Accelerate OptaSense Growth In VSP Services

Farnborough, 21 November 2014: QinetiQ has acquired the seismic processing and imaging capability of SR2020 Inc for a purchase price of up to $1.7m. The transaction, completed yesterday, accelerating the development of QinetiQ subsidiary OptaSense by providing it with state of the art VSP and microseismic imaging services to complement its proprietary DAS-VSP™ acquisition capability.

The transaction will allow OptaSense to provide customers with not only the subsurface seismic data but also analysis, advice and interpretation of the seismic data using world class geophysicists to produce a subsurface image, in an end-to-end service.

Magnus McEwen-King, Managing Director of OptaSense, said: “We have worked with SR2020 to use their ProVSP tool to process our unique DAS-VSP™ data for our customers with excellent results. We are pleased to add their patented capability in high definition borehole seismic imaging to our service offerings. ProVSP is ideally suited to imaging long array data like that of OptaSense DAS-VSP™ and this acquisition adds a team of world class borehole geophysicists to OptaSense that will help deliver an enhanced understanding to our customers ”

Borehole seismic surveys, commonly known as Vertical Seismic Profiling (VSP), have been an industry standard technique for several decades but traditionally require well intervention to insert geophone strings into the well bore. OptaSense DAS-VSP™, which was awarded the Special Meritorious Award for Engineering Excellence in the geosciences category at the E&P Awards 2013, provides operators with the opportunity to obtain high definition borehole seismic images without well intervention which reduces the costs and risk associated well intervention.

The products and service capability acquired from SR2020 will enable OptaSense to offer the full range of Seismic services including VSP and Microseismic acquisition, processing, modelling and interpretation.

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29 Oct 2014

Flow Monitoring and Production Profiling using DAS

Abstract

This paper discusses the application of DAS for flow monitoring. While previous publications (Van der Horst et al (2013, 2014)) focused on vertical and horizontal tight gas wells in North America, the focus here is on liquid producers and injectors in Brunei. Specifically, it was found that DAS has potential for zonal production and injection allocation across ICVs, monitoring interzonal inflow from the reservoir, monitoring artificial lift, tracking fluid transport through the well bore, detecting leaks, and monitoring wax build up or other types of deposition in the well.

Introduction

Distributed Acoustic Sensing is an emerging technology in the oil and gas industry, coming from the defence industry, which has the potential to revolutionize the way we secure our transport pipelines, acquire (micro-) seismic data, and monitor and optimize our wells and fields in the future. Following the successful introduction for pipeline integrity monitoring several years ago (Williams (2012)), Shell and OptaSense started a collaboration to develop DAS also for downhole applications (Koelman (2011), Koelman et al (2012, 2012)).  This has led to major developments in the area of in-well monitoring (Boone et al (2014), Johanessen et al (2012), Molenaar et al (2011, 2011), Ugueto et al (2014), Van der Horst et al (2013, 2014)) and geophysical imaging and surveillance (Mateeva et al (2012), Mestayer et al (2012), Webster et al (2013, 2014)). The focus of this paper will be on the application of DAS for in-well flow monitoring.

DAS offers many advantages over traditional surveillance methods such as production logging tools, gauges, or geophones. A standard telecom fiber can be used for time lapse or continuously for both in-well and seismic applications throughout the life of the well and can also be shared with other fiber-optic technologies such as Distributed Temperature Sensing (DTS).  The full length of a well can be interrogated simultaneously providing data at a spatial resolution as low as 1 m and at sample rates as high as 20 kHz. As a result DAS is a robust and potentially a cost-effective and powerful technology for permanent real-time monitoring of well operations. It also does not require well interventions, thereby reducing deferment and HSSE exposure.

The main drivers for pursuing fiber-optic technologies such as DAS and DTS are the increasingly complicated recovery mechanisms that we are going into, such as improved or enhanced oil recovery and unconventional oil or gas, the requirements to reduce the operational costs and HSSE exposure, and the need to increase production and reservoir recovery. In these types of environments there is a need for frequent and high-quality data that conventional logging methods often cannot offer. The reason is that they are either expensive, cause production deferment, increase HSSE risks, or because surveillance cannot be done frequent enough or over all depths of interest.  Especially offshore, subsea, or in horizontal wells the costs and complex logistics of traditional surveillance often cannot be overcome.

 

Click here to download the complete technical paper

02 Oct 2014

OptaSense recognised for improving the safety of hydraulic fracturing

October 2nd, 2014

Selected as finalist for World Oil Award in HSE / sustainable development category

Farnborough, 2 October 2014: OptaSense, a QinetiQ company and global leader in Distributed Acoustic Sensing (DAS), has been recognised for its contribution to improving the safety of hydraulic fracturing. OptaSense’s DAS Hydraulic Fracture Profiling (DAS-HFP) service has been selected as a finalist for the prestigious World Oil Award in the Best Health, Safety & Environment / Sustainable Development Onshore, category.

The DAS-HFP service is used within hydraulic fracture operations where OptaSense technology is not only used to improve the operational efficiency of hydraulic fracture stimulation but also provides a real-time monitoring capability to verify well integrity.

OptaSense helps operators manage unplanned events such as flow behind casing, casing leaks and ruptures, casing collapse and isolation failures between stimulation stages. This not only has economic value for optimising a hydraulic fracturing program but also delivers significant value for environmental monitoring of fracture fluid break-through into other subsurface formations and freshwater aquifers due to wellbore barrier failure.

Currently the American Petroleum Institute (API) regulatory guidelines state that the internal conduit of the well must be isolated from the surface and subsurface environments. However, conventional technologies are typically limited to pressure measurements at the wellhead and are inadequate for real-time detection and characterisation of most failures other than catastrophic ones.

By contrast, the OptaSense DAS system provides a means to directly measure and monitor the performance of these barriers from wellhead to toe continuously and in real-time. The system is used to detect, localise and characterise barrier failure. It also detects fluid communication behind casing, casing collapse, and leaks through or between casing strings, many of which are unnoticed by conventional monitoring methods.

The World Oil Award nomination recognises that the real-time data OptaSense delivers provides invaluable information to operators, greatly minimising the environmental cost of a leak, due to early detection.

Magnus McEwen-King, OptaSense Managing Director, said: “It is an honour to be recognised alongside the major service companies in one of the industry’s most prestigious awards. Our DAS-HFP service is just one of several services provided over fibre-optics that improve the efficiency and safety of hydraulic fracture operations. Distributed fibre-optic sensing has the potential to provide monitoring throughout the life of the well. The ability to monitor the whole wellbore continuously enables operators to confirm wellbore integrity and better understand, diagnose and correct sources of failure to improve operational effectiveness.”

In this year alone, OptaSense has won two prestigious Queen’s Awards for Innovation and Export and was a finalist for the Royal Academy of Engineering MacRobert award, the UK’s longest running national prize for engineering.

The winners of the World Oil Awards will be announced at the ceremony held at the Houstonian Hotel in Houston, Texas, on Thursday 16 October.

For further information please contact:

About OptaSense

  • OptaSense is a wholly-owned subsidiary of the QinetiQ Group.
  • OptaSense is a platform technology which has applications in a number of markets, including infrastructure security where the technology is already in use to monitor 13,000kms of assets, principally providing leak detection and third party intrusion detection for oil and gas pipelines.
  • OptaSense is the World leader in Distributed Acoustic Sensing and operating in 40 countries globally with operations across multiple industries including Oil & Gas, Defence & Security, Transport and Utilities.
  • Website: www.optasense.com
05 Sep 2014

OptaSense and Shell install world’s first permanent DAS production flow monitoring system

September 5th, 2014

DAS-Flow system provides real time flow measurements on-demand

Farnborough, 5, September 2014: OptaSense, part of the QinetiQ Group, is pleased to announce that its on-going relationship with Shell International Exploration & Production B.V. has resulted in delivery of the world’s first permanent fibre-optic Distributed Acoustic Sensing (DAS) in-well production flow monitoring system, in North America

The production flow monitoring system continuously monitors a well through on-demand measurements of flow along the entire well bore.  The DAS-Flow™ project marks the latest milestone in a product development agreement signed between the companies in 2009.

The DAS-Flow™ system has now been in service for three months after being developed by the OptaSense and Shell teams. Flow reports are sent through a secure network system allowing the asset team to gain a better understanding of well flow performance with no requirement for potentially costly well intervention activity.

Magnus McEwen-King, managing director of OptaSense, commented: “We have enjoyed a successful working relationship with Shell over several years; the creation and now installation of the world’s first permanent fibre-optic DAS production flow monitoring system is a significant step forward for the industry. The DAS-Flow™ system provides our customers with on demand well bore flow measurements which provide operators a real time view that can be used to optimise oil & gas production. There is a high potential optimization value to be realized within the industry with the advent of more detailed flow information across individual well production and injection zones.

“OptaSense is the global leader in DAS technology including hardware performance, software and data interpretation. With commercial services available in hydraulic fracture profiling, production flow monitoring and vertical seismic profiling (VSP), OptaSense is transforming the ability to understand in real-time what is happening along the well bore.”

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