Li Peiming

Tomographic static corrections with vertically parallel irregular grids

Summary Based on conventional tomographic inversion methods, this paper presents a tomographic static correction with vertically parallel irregular grids. Our approach represents significant improvement in theory and application of tomographic inversion compared to conventional methods. Both synthetic and real data examples show excellent improvement in model convergence, which demonstrates the utility of this method.

High‐frequency static corrections using tomographic inversion

In 2002, BGP successfully solved 3D long wavelength statics problems in a large area in Jiuquan Basin and several blocks in the Tarim Basin and Tuha Basin using tomographic inversion (TI). Recent years also saw the TI improvement in effectively solving 3D short wavelength statics problems. This paper discusses the processing sequence from first arrival (FA) picking to the model test, the methods behind the inversion and the relationship among them.

The Q-correlation Technique for Vibrator Acquisition Data

Summary In conventional vibrator data acquisition, correlation data is obtained by correlating the vibrating signal with the reference signal. This correlating method has difficulty with the propagation characteristics if sweep signal is not considered during the process of correlation. Because the filter effect of earth, sweep signal changes with propagation distance. Therefore a changing sweep signal instead of a vibrator reference signal is needed to perform the correlation with vibrator data. Earth absorption a 2D problem, so the absorption needs to compensate for two variables, time and frequency. The Q-correlation method proposed in this paper is for computing the amount of attenuation and generating a time-varying sweep signal according to the quality factor, Q, and then determines the vibrator correlation with the ability to compensate for absorption. When compared with conventional correlation, the Q-correlation arithmetic has obvious merits. Because the attenuation of earth is compensated for in the Qcorrelation method in the process of correlation and 2D is finished in time domain only, the data resolution is greatly improved, especially for weak signals with high frequency

Challenges and solutions for land seismic exploration

With the continuous development of petroleum exploration, seismic prospecting on land is mainly operated in the more and more complicated mountain, desert, Gobi, loess plateau and swamp areas. The difficulties for seismic exploration include the very complicated near surface and subsurface structures, the difficult data acquisition, too much coherent and random noise, and the seismic data with poor S/N ratio and resolution. However the exploratory development in these areas has a high requirement on the precise of seismic data. Under these challenges, the geophysicists of China have undertaken large amount of technical research on optimization of acquisition geometry design, selection of shooting parameters, static correction, noise suppression and pre-stack depth migration etc. in the recent years. All these have further improved the imaging precision of seismic data in complex areas and greatly increased our exploration capability in complex areas on land.

STEP CALCULATION OF STATIC CORRECTION AND ITS APPLICATION IN COMPLEX AREAS

Facing structural characters of surface in complex mountain areas and effect of difference in travel path between first break and reflected wave on static corrections, the paper presents a method for step calculation of statics which breaks convention that the statics must be calculated to final datum only by one step. The paper also illustrats implementing meaning and steps of the method and its QC tools . The method has important meaning for solving the problem of static corrections in complex regions.

Applying 3D seismic in a complex mountainous area of Tarim Basin

Complex surface and subsurface conditions in Chinas northern Tarim Basin make it impossible to record good 3D seismic data with conventional acquisition geometry. In addition, the thickness of the low-velocity layer varies from 3 to 150 m, making 3D static corrections a challenge.