Tang Chuanzhang

Analysis of the influence of vibrators on the first break in refraction statics

Summary Along with the increased degree of exploration for and development of oil-rich depressions, exploration aimed at complex fault-blocks, lithologic traps, low amplitude structures and thin reservoirs has become an area of great interest. Consequently, precision requirements of static corrections are critical. Until the present, vibroseis surveys in China have all been performed with multiple–vibrator arrays. This method has an influence on the precision of exploration that is theoretically the result of the time difference caused by the array, such that the precision of the first break refraction statics are affected. In this paper, the affect on first arrival and first break refraction statics on vibrator arrays is analyzed and quantified.

Control Point Uniformity Analysis In Near-surface Structure Investigation

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.

Application of 3D-3C Seismic Exploration In Saihantala Lithologic Reservoirs

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 application of uphole time t in high‐precision seismic prospecting

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.