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Collaborating Authors
Chen, Haolin
A marine field trial for iterative deblending of simultaneous sources
Zu, Shaohuan (China University of PetroleumโBeijing) | Zhou, Hui (China University of PetroleumโBeijing) | Chen, Yangkang (University of TexasโAustin) | Chen, Haolin (Dagang Department, BGP Inc., CNPC) | Cao, Mingqiang (Dagang Department, BGP Inc., CNPC) | Xie, Chunlin (E&D Research Institute, Daqing Oilfield Company)
ABSTRACT Simultaneous sources acquisition (continuous recording, significant overlap in time) has many advantages over the traditional seismic acquisition (discontinuous recording, zero overlap in time). When focusing on data quality, blended acquisition (simultaneous sources acquisition) allows significantly denser spatial sources sampling and much wider range of azimuths. This can improve the quality of subsurface illumination. When focusing on economic aspect, the blended acquisition can greatly shorten the survey time. However, many challenges such as the continuous recording equipment, the availability of boats units and the implementation of speed cable vessels are emerging when using simultaneous sources acquisition. Dagang Geophysical Prospecting Branch of BGP, CNPC has made two field trials to explore the advantages of simultaneous sources and obtained some experience. The goal of this paper is to give an overview of the latest field trial and display the very successful deblending results, which may give an inspiration to the depressing oil price. Presentation Date: Wednesday, October 19, 2016 Start Time: 11:10:00 AM Location: 163/165 Presentation Type: ORAL
- Asia > China (0.90)
- North America > United States > Illinois > Madison County (0.51)
- Asia > China > Heilongjiang > Songliao Basin > Daqing Field > Yian Formation (0.99)
- Asia > China > Heilongjiang > Songliao Basin > Daqing Field > Mingshui Formation (0.99)
A periodically varying code for improving deblending of simultaneous sources in marine acquisition
Zu, Shaohuan (China University of Petroleum) | Zhou, Hui (China University of Petroleum) | Chen, Yangkang (The University of Texas at Austin) | Qu, Shan (Delft University of Technology) | Zou, Xiaofeng (China University of Petroleum) | Chen, Haolin (BGP Inc.) | Liu, Renwu (BGP Inc.)
ABSTRACT We have designed a periodically varying code that can avoid the problem of the local coherency and make the interference distribute uniformly in a given range; hence, it was better at suppressing incoherent interference (blending noise) and preserving coherent useful signals compared with a random dithering code. We have also devised a new form of the iterative method to remove interference generated from the simultaneous source acquisition. In each iteration, we have estimated the interference using the blending operator following the proposed formula and then subtracted the interference from the pseudodeblended data. To further eliminate the incoherent interference and constrain the inversion, the data were then transformed to an auxiliary sparse domain for applying a thresholding operator. During the iterations, the threshold was decreased from the largest value to zero following an exponential function. The exponentially decreasing threshold aimed to gradually pass the deblended data to a more acceptable model subspace. Two numerically blended synthetic data sets and one numerically blended practical field data set from an ocean bottom cable were used to demonstrate the usefulness of our proposed method and the better performance of the periodically varying code over the traditional random dithering code.
- Asia > China (0.68)
- North America > United States > Texas (0.28)
Summary The explosive is the conventional source for seismic exploration in muddy conditions with 0-1m water. However, it will bring certain safety risks and environmental damage. In some regions, due to the environmental regulations, explosive source has been banned. To meet the demand of seismic exploration, it is bound to find a new stimulation method to replace the explosive source in muddy conditions. In this paper, we mainly discuss the possibility of air-guns applied in muddy conditions. Based on the principles of air-gun, we made an experiment, in which the air-guns were fired in a hole filled with water. Then, we analyze the effects with different shooting parameters. Meanwhile, based on the optimized parameters, we compare the effects of air-gun and explosive shooting, which give a further verification in the feasibility of using air-gun source to replace explosive in muddy conditions. Introduction Explosive is the main source in muddy zones with 0-1m water, where the seismic acquisition is very difficult. High safety risk and low efficiency are major problems (Fan et al. 2009). Due to the increasing requirements of environmental protection, shooting by explosive is restricted in some transition zones. Especially in muddy zones with 0-1m water, explosive has been banned, which definitely results in being unable to acquire data in some oil and gas exploration areas. Therefore, the development of special source is imminent for seismic exploration in muddy conditions. With the advantage of environmental protection, air-gun source has been used in the offshore seismic acquisition for many years. Whether the conventional air-gun can be applied in muddy conditions is considerable. We have done some exploratory experiments of air-gun shooting, for example, shooting in sandy and muddy conditions. The results show that most of the energy generated by air-gun is absorbed by the media, so the effective reflection underground decreases. Thus, the demand of seismic acquisition in sandy and muddy conditions can't be met.
- Research Report > New Finding (0.70)
- Research Report > Experimental Study (0.70)
Summary Dual sensors are used for data acquisition in offshore OBC exploration in shallow waters. The coupling between the geophone and the seabed plays a key role in geophone data quality. Better couplings often yield records with higher fidelity, higher resolution, and higher signal to noise ratios (SNR). Field experiments have shown that coupling is negatively affected by tidal currents. This paper focuses on improving the coupling of geophones for OBC dual-sensor prospecting. First, we discuss the methodology of coupling. Then, we list several methods that aim to improve geophone coupling. We also propose principles that should be considered when designing geophone coupling. We tested several different couplers and results show that rectangular compressed alloy couplers are the best with respect to anti-interference and data quality. The improvement of geophone coupling in dual-sensor receivers will advance OBC acquisition technologies.