Improving seismic data quality with high-density data acquisition

1985 ◽  
Author(s):  
T. W. May
1977 ◽  
Author(s):  
Charles F. Spitzer ◽  
Theodore A. Jensen ◽  
John M. Utschig

2016 ◽  
Vol 56 (2) ◽  
pp. 601
Author(s):  
Nabeel Yassi

The desire to conduct onshore seismic surveys without cables has been an elusive dream since the dawn of seismic exploration. Since the late 1970s, seismic surveys were conducted with cabled multi-channels acquisition systems. As the number of channels steadily grew, a fundamental restriction appeared with hundreds of kilometres of line cables dragged on the ground. Seismic surveys within rugged terrain—across rivers, steep cliffs, urban areas, and culturally and environmentally sensitive zones—were both challenging and expansive exercises. Modern technology has made different cable-free solutions practical. High-resolution analogue to digital converters are now affordable, as are GPS radios for timing and location. Microprocessors and memory are readily available for autonomous recording systems, along with a battery the size and weight of a field nodal now promising to power an acquisition unit for as long as required for normal seismic crew operations. Many successful 2D and 3D seismic data acquisition using cable-free autonomous nodal systems were attempted in the past few years; however, there remain a number of concerns with these systems. The first concern queries whether the units are working according to manufacturer specifications during the data acquisition window. The second is the limited or no real-time data quality control that inspires sceptics to use the term blind acquisition to nodal operations. The third is the traditional question of geophone array versus point receiver acquisition. Although a string of the geophone can be connected to autonomous nodes, the preference is to deploy a single or internal geophone with the nodes to maintain the proposed flexibility of cable-free recording systems. This case study elaborates on the benefits of the cable-free seismic surveys, with specific examples of 2D and 3D exploration programs conducted in Australia in the past few years. Optimisation of field crew size, field crew resources, cost implications, and footprint to the environment, wildlife and domestic livestock will be discussed. In addition, the study focuses on the data quality/data assurance and the processes implanted during data acquisition to maintain equivalent industry standards to cable recording. Emphases will also include data analysis and test results of the geophone array versus the cable-free point receiver recording.


2017 ◽  
Vol 5 (2) ◽  
pp. SF177-SF188 ◽  
Author(s):  
Wei Wang ◽  
Xiangzeng Wang ◽  
Hongliu Zeng ◽  
Quansheng Liang

In the study area, southeast of Ordos Basin in China, thick lacustrine shale/mudstone strata have been developed in the Triassic Yanchang Formation. Aiming to study these source/reservoir rocks, a 3D full-azimuth, high-density seismic survey was acquired. However, the surface in this region is covered by a thick loess layer, leading to seismic challenges such as complicated interferences and serious absorption of high frequencies. Despite a specially targeted seismic processing workflow, the prestack Kirchhoff time-migrated seismic data were still contaminated by severe noise, hindering seismic inversion and geologic interpretation. By taking account of the particular data quality and noise characteristics, we have developed a cascade workflow including three major methods to condition the poststack 3D seismic data. First, we removed the sticky coherent noise by a local pseudo [Formula: see text]-[Formula: see text]-[Formula: see text] Cadzow filtering. Then, we diminished the random noise by a structure-oriented filtering. Finally, we extended the frequency bandwidth with a spectral-balancing method based on the continuous wavelet transform. The data quality was improved after each of these steps through the proposed workflow. Compared with the original data, the conditioned final data show improved interpretability of the shale targets through geometric attribute analysis and depositional interpretation.


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