Catálogo de publicaciones - revistas

<jats:p> Full-waveform inversion (FWI) has become the centerpiece of velocity model building (VMB) in seismic data processing in recent years. It has proven capable of significantly improving the velocity model and, thus, the migration image for different acquisition types and geologic settings, including complex environments such as salt. With the advent of FWI imaging, the scope of FWI applications has extended further from VMB into the imaging landscape. However, current FWI applications in the industry prevalently employ the acoustic approximation. One common problem of acoustic FWI (A-FWI) is the apparent salt halos at the salt-sediment interface in the resulting FWI velocity and FWI image, the presence of which hinders direct interpretation and imaging focusing around salt bodies. With synthetic and field data examples, we demonstrate that this salt halo is caused mainly by the large mismatch between the elastic recorded data and the acoustic modeled data, particularly at middle to long offsets. To overcome limitations imposed by acoustic assumptions, we developed an elastic FWI (E-FWI) algorithm that combines an elastic modeling engine with the time-lag cost function, which we call elastic time-lag FWI (E-TLFWI). With a more accurate modeling engine, E-TLFWI significantly reduces the salt halo observed in its acoustic counterpart. However, we also observe that the images migrated using the A-FWI and E-FWI velocity models remain similar overall, with some slight improvements around and beneath salt boundaries, particularly near steep salt flanks, as a result of the reduced salt halo. By contrast, FWI images derived from E-TLFWI show considerable benefits over those from acoustic time-lag FWI, such as improved event focusing, better structural continuity, and higher signal-to-noise ratio. The sharpened salt boundaries and enhanced quality of the FWI images reveal the significant value of E-FWI and provide the justification for its greatly increased cost. </jats:p>

<jats:p> Gas hydrates are a recognized drilling geohazard. If not mitigated, they may result in plugged blowout preventors, gas kicks, blowouts, borehole instability, gas leaks outside casings, and inadequate cementing operations. Gas hydrates located within the gas-hydrate stability zone (GHSZ) are difficult to interpret solely from seismic amplitudes. In this paper, we apply a multifaceted approach using the velocity pullup method in combination with 3D visualization of seismic attributes for the interpretation of gas hydrates within the GHSZ. The approach is applied to an area in the eastern part of the Gulf of Mexico in water depths greater than 2400 m. The practical outcome of this study is the choice of safe drilling locations outside of areas where gas hydrates have been interpreted to be present. </jats:p>

<jats:p> Land Seismic Case Studies for Near-Surface Modeling and Subsurface Imaging, by Öz Yilmaz, 2021. </jats:p>

<jats:p> SEG Board of Directors actions in December 2022 </jats:p>

<jats:p> Nominees for Board of Directors </jats:p>

<jats:p> The National Geophysical Research Institute (NGRI) Geophysical Society is an SEG student chapter located in Hyderabad, India. Members of the student chapter have enjoyed giving back to our alma-mater universities and community in a variety of ways. </jats:p>

<jats:p> Applications for Active membership have been received from the candidates listed herein. </jats:p>

<jats:p> Carl H. Sondergeld passed away in Norman, Oklahoma, on 9 November 2022 following a long and courageous struggle with cancer. </jats:p>

<jats:p> Charles Jahren died 3 September 2016. Wilburn Frank Albers died 17 March 2022. Allen Adrian died 21 April 2022. John Pflueger died 10 May 2022. Michael Sroczynski died 2 June 2022. Paul Madeley died 28 June 2022. Henry Bernhard Sawatzky died 12 August 2022. </jats:p>

<jats:p> The Meetings Calendar chronologically lists professional events of interest to SEG members and means by which further information can be obtained. </jats:p>