Geophysical Lunch & Learn seminar

The first Geophysical lunchtime seminar is planned for 3rd March. The presentation will be followed by lunch. The presentation will be by Charlotte Botter from University of Stavanger who has been doing her PhD on fault imaging.

 

The seminar will be held in NPD offices in Stavanger

  • Date 03.03.2016
  • Time 11:00
  • Duration 1.5 hours
  • Participants 49
  • Register by 29.02.2016
Geophysical Lunch & Learn seminar_main_img
Geophysical Lunch & Learn seminar

”Seismic Imaging of Fault Zones: A synthetic workflow to study the impact of faults on seismic images”,
by Charlotte Botter (University of Stavanger), Nestor Cardozo (University of Stavanger), Isabelle Lecomte (NORSAR), Stuart Hardy (University of Barcelona), Gaynor Paton (ffA Geosciences), Atle Rotevatn (University of Bergen), Alejandro Escalona (University of Stavanger)

Abstract:

Although typically interpreted as 2D surfaces, faults are 3D narrow zones of highly and heterogeneously strained rocks, with petrophysical properties differing from the host rock. We present a forward modelling workflow to evaluate the potential of seismic data for imaging fault structure and properties, divided in three parts.

(1) The methodology consists of a discrete element model (DEM) of faulting, empirical relations to modify initial acoustic properties based on volumetric strain, a ray-based algorithm simulating prestack depth migration (PSDM) results, and interpretation and correlation of the seismic and input properties. We illustrate this workflow in 2D to normal faulting in a sandstone-shale sequence at reservoir depth, for two DEM particle size resolutions. Seismic images and resolution of these models are highly influenced by illumination direction and wave frequency. At high wave frequencies, there is a direct correlation between seismic amplitude variations and the input acoustic properties after faulting.

(2) We apply then the same methods in 3D for a large displacement normal fault in a sandstone-shale sequence for two cases, one with constant fault displacement and another with linearly variable displacement along strike. High frequencies on seismic images show the impact of the fault on the offset and distortion of the reflectors. In the variable fault slip model, the fault has less impact as the displacement decreases, and the fault tipline can be interpreted. We extract fault geobodies using an adapted attributes-based workflow. The geobody for the constant fault displacement model corresponds to an inner high deformation area within the fault zone, while in the variable fault slip model the geobody captures better the entire fault zone.

(3) We finally illustrate the workflow using an outcrop-based fluid flow simulated model from the Delicate Arch Relay Ramp (Utah) to study the impact of relay ramps and their fluid composition on seismic data. Changes in porosity in the fault damage zones are visible in the oil-saturated model at the beginning of the simulation, whereas the water-oil contacts have stronger impact on seismic at later stages. We are able to extract volumes corresponding to the two faults and the relay ramp from the three seismic cubes with an adapted tuning of the attributes-based workflow. By varying parameters, we also show reservoir and acquisition conditions that can affect positively or negatively the resolution of the relay ramp seismic imaging.

 

FORCE seminars have previously been fully booked with waiting lists so you are encouraged to sign up as soon as you know you will attend.

Participant fees
 
FORCE member
Free
Non-member
NOK 1000,-
University/student
Free

Please find registration box at the top right of the page. 

Important information:
You can register as a FORCE member and pay "FORCE member" price if you are an employee of a member company.
All FORCE member companies are listed here.

Payment is made online by credit card. Please note that no refunds will be given after you have signed up. If you for any reason can not attend the workshop, you are welcome to send a representative, just inform Janne Puntervold as soon as there are changes.

Photo: Øyvind Hagen - Statoil