On the cutting edge of 3D seismic imaging, Total has been focusing in recent years on breakthrough technologies to continuously improve the quality of subsurface images. To solve major problems related to geophysical imaging in areas of complex topography, the company has embarked an integrated geophysics and logistics R&D project called METIS, Multiphysics Exploration Technology Integrated System. METIS aims to improve the quality and speed of data acquisition through real-time quality control and processing, while at the same time slashing both the cost and HSE risks of operations. The ultimate purpose is to be able to build ever more predictive 3D models for our interpreters.
Geophysical imaging of the subsurface in hard-to-access topography is a major challenge for oil and gas exploration. Conventional acquisition and imaging techniques can be expensive and too hazardous in terms of HSE risk — in other words, impossible to use — in some hard-to-access areas. The result is significant uncertainty in any subsurface mapping; seismic imaging is often very poor quality. Hence the need to overhaul our thinking.
To address this, in summer 2014 we introduced the Multiphysics Exploration Technology Integrated System, or METIS, project. The goal is to develop within 10 years an integrated geophysical and logistics system to acquire, process and obtain in real time quality structural and quantitative data. This innovative approach should eventually multiply the value of information (VoI) of the data acquired in complex topography, enabling us to optimize field development, secure new exploration licenses or rejuvenate the interest of acreage relinquished in the past because of an inability to understand it.
A Novel, Holistic Wireless Acquisition System for Onshore Exploration
Complex topography is demanding in terms of geophysical data quality, turnaround times and costs. That’s why METIS takes a holistic approach, combining the innovative use of Downfall Air Receiver Technology (DART) with intensive use of airships and drones. The new acquisition method, known as carpet recording, “carpets” the ground in the exploration area with DART wireless geophysical sensors — which are, as their name suggests, dart-shaped. The drone fleet can safely drop up to 400 receivers per square kilometer. All the seismic traces recorded are then sent in real time to the processing center. This density will deliver high-resolution images.
METIS can be adapted to accommodate all geological data, no matter how complex, in the field. It also minimizes logistics, which are every bit as vital for efficient, safe deployment. This fully simulates the acquisition-processing-imaging chain and allows for fit-for-purpose sensor density and measurement types. Adjustments required by freshly discovered ground conditions can be made directly as needed in the field.
Real-Time Processing and Shorter Turnaround Times
Various imaging techniques recorded at different scales are added to the conventional seismic acquisition. These include satellite or airborne data analysis (optical, radar, LiDAR and hyperspectral), electromagnetic and gravity techniques for the surface and near-surface, and magnetotelluric techniques for deep formations. METIS is being developed in partnership with two U.S. companies, Geokinetics, an integrated services company, and Wireless Seismic, an equipment manufacturer.
METIS puts interpreters in the driver’s seat, since they’ll be able to assess the quality of the data acquired and the illumination of the geological formation directly and locally, allowing them to adjust and optimize the acquisition plan in real time based on results. This will significantly shorten the time between completing data acquisition and finalizing the geoscientific processing, offering benefits when evaluating prospects and making the final decision. Finally, METIS will give more time to interpret and mature our prospects. As the saying goes, “Tempus Omnia Revelat” (time reveals all things).
Sharply Enhanced Imaging of Complex Topography
Satellite data are used to precisely model the surface beforehand.
Other airborne methods are then deployed to model the near-surface, including seismic wave propagation, LiDAR and electromagnetic and gravity techniques.
METIS’s acquisition design uses 3D elastic modeling in particular.
The first-generation DART prototype weighs 700 grams and is 50 centimeters long. It is wireless and made of biodegradable polylactic acid (PLA), a type of plastic. It will eventually be entirely biodegradable (electronics, battery, etc.).
4,000 DART sensors can be deployed in a day, with results already comparable to conventional sensors.
Green Seismics: An Application in Papua New Guinea Onshore Exploration
METIS will also address environmental issues by lessening the impact of seismic surveys in complex areas. Chief among them are fold and thrust belts in foothills.
So that will be one of the challenges of the small-scale pilot that will be conducted this year in Papua New Guinea, where onshore acquisition is impeded by nearly impenetrable virgin rainforest. To compensate, the apertures for seismic acquisition in such areas have traditionally used bridging. Despite the environmental impact, the resulting subsurface imaging often isn’t precise enough. We expect METIS to reduce apertures by a factor of 1 in 15 compared to conventional methods. That will be followed by an industrial test covering 100 square kilometers on PRL15 (Elk Antelope) in 2021.
Airborne Logistics, a Key Component of the METIS System
Seismic surveys require ferrying heavy equipment to the exploration areas. To develop a more eco-friendly approach, Total researchers teamed up with the French start-up “Flying Whales” to create the HA2t (Hybrid Airship 2 tons), a multipurpose inflatable that helps helicopters with logistics support. Also used for non-seismic acquisition, this new kind of airship will additionally serve as a shuttle between the exploration area and the base camp.
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