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Getting more for less: Frequent low-cost Seismic Monitoring Solutions for Offshore Fields

Start Date: April 19, 2017 - 04:15 PM
End Date: April 19, 2017 - 05:15 PM

By Paul Hatchell 
Shell Houston, Texas, USA
Host: Prof. Gerard Schuster
Venue: Lecture Hall 1 (2322), Engineering and Science Hall (Building 9)

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​​Abstract: Time-lapse seismic reservoir surveillance is a proven technology for offshore environments. In the past two decades, we have seen this technology move from novel to necessary and enable us to monitor injection wells, water influx, compaction, undrained fault blocks, and bypassed reserves. Value is generated by influencing the management of our field operations and optimizing wells to reduce cost, accelerate production, and increase ultimate recovery. 

Significant advances in technology are improving the quality of our data. Errors in acquisition repeats are nearly eliminated using permanently installed systems or dedicated ocean- bottom nodes. We now routinely obtain surveys with such a high signal-to-noise ratio that we can observe production-induced changes in the reservoir after months instead of years. This creates a demand for frequent seismic monitoring to better understand the dynamic behavior of our fields. Increasing the frequency of seismic monitoring will have a proportionate cost implication, and a challenge is how to design a monitoring program that maximizes the overall benefit to the field. 

Reducing individual survey costs is important to enable frequent monitoring. Several techniques are considered for lowering these costs such as:  
  • Reducing the number of shots and/or receivers to minimize offshore vessel time. This includes shooting targeted (i4D-style) surveys on a frequent basis in between full-field surveys that are acquired infrequently. 
  • Use of smaller source arrays towed by less-expensive vessels.  
  • Semi-permanent ocean-bottom nodes that can be left on the seafloor for multiple on-demand surveys.
  • Time-lapse VSPs that use permanent distributed acoustic sensors (DAS) in well bores.  
  • High-resolution 4D surveys that monitor shallow reservoirs cost effectively using low-cost vessels towing arrays of short-streamer cables (e.g., P-cable).
​​There is no single solution that works for every field, and we need to understand the pros/cons of the various technologies to select the best option for a specific field. Some results of applying these techniques to offshore fields will be discussed.

Bio: Paul Hatchell joined Shell in 1989 after receiving his PhD in theoretical physics from the University of Wisconsin. He began his career at Shell’s Technology Center in Houston and worked on a variety of research topics including shear-wave logging, quantitative seismic amplitude analysis, and 3D AVO applications. Following a four-year oil and gas exploration assignment in Shell’s New Orleans office, Paul returned to Shell’s technology centers in Rijswijk and Houston where he is currently a member of the Areal Field Monitoring team and Shell’s principal technical expert for 4D reservoir surveillance. His current activities include developing improved 4D seismic acquisition and interpretation techniques, seafloor deformation monitoring, and training the next generation of geoscientists.​
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