Sichuan Basin is one of the richest shale gas basins in China. Exploration and development experiences in recent years proved that geophysical technology could serve as an important tool for shale gas production. The key technologies include: seismic imaging under complex surface and subsurface conditions, rock physics, fracture prediction, sweet spot identification, pressure estimation, horizontal well design, and fracturing monitoring. This paper demonstrates the applicability and effectiveness of these technologies in Jiaoshiba area.
Presentation Date: Monday, October 17, 2016
Start Time: 1:25:00 PM
Presentation Type: ORAL
The inverse scattering series (ISS) free-surface multiple elimination algorithm has certain prerequisites: (1) removing the reference wavefield, (2) estimation of source wavelet and radiation pattern, and (3) source and receiver deghosting. In this abstract, the impact of prerequisites (2) and (3) on the ISS free-surface multiple elimination algorithm (Carvalho, 1992; Weglein et al., 1997) is discussed. To improve the ISS multiple predication, the algorithm is also modified and extended to accommodate the source radiation pattern. That radiation pattern accommodation can provide added value compared to previous methods that assumed an isotropic point source for predicting amplitude and phase of free-surface multiples. All these prerequisites can be provided by Green’s theorem methods without requiring subsurface information. They are consistent with the ISS free-surface multiple elimination algorithm. The new extended ISS algorithm that accommodates the source radiation pattern is tested on a 1D acoustic model, and the results indicate that the new extended ISS free-surface multiple elimination algorithm can predict more accurate results in comparison with methods without that accommodation when the source has a radiation pattern. This increased effectiveness in prediction is essential for removing free-surface multiples that are proximal or interfering with primaries (or other multiples).
Presentation Date: Tuesday, October 18, 2016
Start Time: 4:10:00 PM
Location: Lobby D/C
Presentation Type: POSTER
Zhang, Qingchen (China University of Petroleum) | Zhou, Hui (China University of Petroleum) | Wang, Jie (SINOPEC Geophysical Research Institute) | Zuo, Anxin (China University of Petroleum) | Xia, Muming (China University of Petroleum)
Due to the gradient calculation requiring cross-correlation of the forward wavefields and back-propagated residual wavefields at each time step, the great storage amount becomes an obstacle of practical application of full-waveform inversion, especially in three-dimensional elastic case in time domain. In this paper we extend the efficient boundary storage to the time domain three-dimensional elastic full-waveform inversion on multi-GPU. Based on the efficient boundary storage strategy, the storage amount can be reduced dramatically. As a result, we can save the partial forward wavefields directly on the GPU memory and reconstruct the full forward wavefields synchronized with back-propagated residual wavefields along the reverse time direction. This strategy avoids frequent CPU-to-GPU or GPU-to-CPU memory copy (extremely time-consuming) at the cost of the recomputation (little time-consuming) of the forward wavefields. Our forward simulation tests show that the GPU’s supercomputing effect can be fully exploited with this strategy. In addition, we perform a three-parameter simultaneous inversion of P-, S-wave velocities and density. The favorable inversion results verify that our algorithm is feasible and efficient.
Li, Dong (SINOPEC Geophysical Research Institute) | Wang, Lixin (SINOPEC Geophysical Research Institute) | Xu, Zhaotao (SINOPEC Geophysical Research Institute) | Zheng, Xiaopeng (SINOPEC Geophysical Research Institute) | Mu, Jie (SINOPEC Geophysical Research Institute)
The seismic data acquired in the mountains area are generally irregular or sparely because of the complex surface, which may not fulfill the processing requirements and degrades processing quality, so these data should often be interpolated. A projection onto convex sets (POCS) algorithm using Fourier transforms is a well-known technique to reconstruct the irregular seismic data, helping on the processing of data with different acquisition problems. We proposed the interpolation procedure using POCS method based on OVT domain and applied it to the field data. Numerical examples indicates that the proposed scheme is effective and applicable, as it can reconstruct missing traces of complex data acquisition.
There are abundant oil and gas resources in the mountainous area of South China, which has broad prospects for exploration and development. However, seismic data is usually irregularly or sparsely distributed along the spatial direction in the complex surface area, which may not meet the processing requirements and then degrades processing quality, so it is important and necessary to regulate and interpolate seismic data at the missing spatial locations where measurements are not acquired in the seismic data processing stage.
Wang, Lixin (SINOPEC Geophysical Research Institute)
Primary reflections are generally applied in seismic imaging. The information of primary waves, however, is insufficient for structural imaging in obstacle restricted areas where no shots but only receivers are allowed. Multiples, if developed, can be applied as effective signals. In this paper, the author presented to take multiples as effective information to highlight the obstacle area and supplement the incomplete image obtained by only primaries reflection in obstacle restricted areas, and obtain complete and rich subsurface structure information. Synthetic model and the real data application demonstrate the feasibility and effectiveness of this approach.