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Geophones are key instruments used for seismic data acquisition, and the quality of seismic data acquired for prospecting depends directly on their performance. With the development of geophysical prospecting technologies and high-resolution exploration requirements, especially in tight marl oil exploration, an increased demand on the accuracy and quality of seismic data is presented, which includes broadening the frequency band and increasing the fidelity and signal to noise ratio in an attempt to better identify lithology, pore fluids, and fractured reservoirs. In the Jizhong Depression, the tight marl oil is mainly located in the Shulu Sag, where the background interference is strong and the marl strata are deeply buried with variable occurrence. These factors pose new challenges on the ability of digital geophones to detect oil. In this paper, the operation and performance characteristics of digital geophones are described, and then we focus on the first test conducted for tight marl oil exploration in the Shulu Sag. The test results show that compared with analog geophones, seismic data acquired using digital geophones are characterized by providing less waveform distortion, broader frequency bandwidth, and more abundant information. These improvements lay a foundation for high-resolution processing and identification of fractured reservoirs.

The oil fields in eastern China have already been explored several times with 3D seismic exploration in most areas. With the further exploration of deeper targets and new reservoirs, the existing 3D seismic data can hardly meet the demand for revealing these complex structures. In this paper, we will present some integrating techniques for multi 3D seismic survey. Multi 3D seismic survey means 3D seismic data acquired repeatedly in the same area by a uncertain time interval which is usually about ten years. Here we will integrat the 3D data acquired in the different times and new 3D data into the same data volume. The techniques include geometry design based on prestack image and inversion, spatial-time domain comprehensive static correction and integrated data processing techniques etc. .

Along with the deepening of exploration works, static problem are getting more and more serious so that it has become an important factor that influences the quality of near-surface anisotropy data. Inappropriate low-frequency statics affects the structural features of the section; and inappropriate high-frequency statics affects the imaging quality of the data. In this paper, a tailor-made static method, which can better solve the static problems caused by near-surface anomaly, is advanced.

Summary At present, we always use the rectangular orthogonal mode layout for control point in near-surface structure investigation. Only in areas where the lithology or the near-surface structure is vary significantly, do we increase the density of control points in order to control the variation of the long-wavelength static correction. Because the accuracy requirements for near-surface structure investigations are increasing, it is necessary to study and analyze the control point layout mode. In this paper we study the problem of uniformity of control point layout in near-surface structure investigation by theoretical analysis and demonstration using real seismic data in order to research the influence of control point layout mode on the near-surface structure model and static corrections in nearsurface structure investigations.

Summary The ongoing exploration in the Saihantala Depression has been focused on lithologic reservoirs. It is difficult to reduce ambiguity and to assess uncertainty in seismic lithology discrimination and fluid type identification using conventional compressional wave (P-wave) exploration. A three dimensional, three component (3D-3C) seismic survey with P-wave source and 3C geophones has been performed in the study region, taking advantage of combining P-wave and converted wave (C-wave or PS-wave) exploration. Instead of using vibroseis, a dynamite source is used to improve the signal-to-noise (S/N) ratio and bandwidth of the C-wave data. High quality C-wave imaging has been achieved using four-parameter velocity analysis and anisotropic pre-stack time migration (PSTM). Sedimentary facies have been well discriminated using the obtained Vp/Vs ratios in the target layer. Our study shows that the combined exploration method effectively characterizes the lithologic reservoir.

The uphole time τ is a kind of important parameter containing abundant near-surface information and it has the characteristics that include a large quantity of shots. The τ value directly reflects the depth and the lithology of each shooting well. Studies show that application of the uphole time τ has the advantages, the improvement of the static correction precision, the establishment of the near-surface velocity dataset, and quality control of the shooting well depth.