Deng Zhiwen

Converted Wave Seismic Exploration & Static Correction

More and more attentions have been paid to the applications of converted wave exploration in assessing oil and gas reservoirs. Experimental study has also been fulfilled in China for over 10 years. Due to the difficulties in acquisition, statics, data processing and interpretation, the technology has been in a slow progress. In the past few years, a series of studies have been fulfilled aiming to the technologies of converted wave acquisition, static correction and processing in Sulige Gas Field, Erdos Basin. The converted wave section processed is in a high quality; and the interpretation result correlates with the drilling result wonderfully

Quantitative interpretation and joint inversion of multicomponent seismic data: application to the Sulige Gas Field, China

Summary In this paper, we focus on the interpretation and joint inversion of multicomponent (MC) seismic data in the Sulige gas field in China for the purpose of improving lithology and fluid prediction. Based on a detailed rock model analysis, we select the sensitive elastic properties for reservoir characterization. We investigate issues on marking the PS wave and matching the PP and PS data. The PS AVO curves are thoroughly analyzed based on 12 wells that have different production types such as high gas production, low gas production, and water-producing and overall the features are similar. Another 8 wells with different sand body thicknesses are also analyzed for the purpose of finding the relationship between the AVO characteristics and the sand thickness. The PS AVO responses are shown to be related to the sand layer thickness. A joint inversion of PP and PS data based on Aki & Richards approximation equation is presented and the joint inversion results are supported by the real well production data.

3C/3D Seismic Exploration Technology And Application Results

Multicomponent seismic survey can provide a variety of information for development of reservoirs, reduce the multiresolution of predicting reservoirs and increase the successful drilling rate. In the past two years, BGP has imported digital seismograph and geophones to research the techniques in 3C/3D seismic data acquisition, processing and interpretation, design & demonstration of 3D converted-wave geometry, multiwave uphole survey and surface survey & 3D converted wave static corrections, rotation of horizontal component data & wave field separation, computing 3D common converted bins of converted wave, 3D converted wave residual static correctoins, CCP & iterative velocity analysis, converted wave prestack time migration by Kirchhoff integration, horizon labeling of converted wave & P-SV wave and Pwave joint interpretation, using converted wave to analyze physical property of reservoir and predict the lithology & oil/gas reservoir etc., forming a complete set of 3C/3D seismic technology that has seen a visible effect in application to Sulig Gas Field. Using the 3-componet data to predict gas-bearing character of reservoir made the 4 exploration drillings presented total success. The matching ration of the survey grid with the drilling completion is over 80%.

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.

The multivariate statistic residual static correction method and examples of its application

Static corrections in complex areas always pose challenging problems, due to the low accuracy of nearsurface models, resulting in difficulty in fully satisfying the requirements of seismic data imaging. In this paper, we propose a residual static corrections method based on the statistics of refraction waves to improve the accuracy of datum static corrections. This method first applies datum static corrections to the picked first break times, then fits data for the same refraction layer on CSP gathers (common shot point gather) and CRP gathers (common receiver point gather) to calculate the fit time difference for shot points and receiver points. The final step is to perform statistics based on fit error of all points to get the average statistical errors and use them as the final residual static corrections. The actual processed data on conventional 2-D survey lines and crooked seismic lines shows that this method has a relatively good effect suggesting that it can be used to improve the accuracy of datum static corrections in complex areas.

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.