A Research On Cross-well Seismic And Joint Reservoir Prediction In Jiangqiao Areas In North Songliao Basin

Since 1980s, many seismic explorations have been performed by Daqing Oilfield in Jiangqiao and its surrounding areas. The areas are controlled by basement forms, the structures of T1 and T2 overlying structural layers are simple, the faults are not developed, the whole shows an east-slanting monocline; and the structural line shows a nearly north-south parallel distribution, and a gentle east-north nose-like structure has developed in Tangchi area, which is favorable to the hydrocarbon accumulations. According to a preliminary assessment, the heavy-oil producing reserves in western slope area will be about 1505.0×104t, which causes a new cognition and evaluation to the heavy-oil resources in the area. Focusing on the actual demand of the explorations in Jiangqiao areas, this paper solves some problems to the target area, such as layout design of cross-well seismic acquisitions, velocity tomography and reflection imaging method, cross-well reservoir prediction and so on. As for the inversion method, this paper presents a structural-risk-minimum inversion method and chooses Jiangqiao areas, whose data are complete relatively, to perform a research on the borehole and surface seismic joint reservoir prediction. The following conclusions have been obtained:1. Through the numerical modeling, a rule is concluded, i.e., centering on the geologic target, the cross-well seismic layout design can be completed by using forward modeling, considering some integreted factors, such as equipment capability; and a reasonable layout is designed for Jiang Wellblock 37, and the original data with the primary frequency of 300 Hz have been obtained.2. Through the research on cross-well seismic processing technique, a special processing method and flow is developed. In the velocity tomography imaging, more accurate velocity data have been obtained by using 3D anisotropic velocity inversion methods; in the reflection wave imaging, the unreasonable amplitude of large-angle incidence is controlled out of the effective stack-range by using angle trace gathers to choose the stack, and good processing results have been obtained.3. The inversion results of cross-well seismic data show the distribution law of cross-well sandbodies and the reservoir connectivity clearly, and solve the problem of cross-well thin-reservoir description effectively. The reservoir physical parameters obtained from the interpretation are in accordance with the two wells'data highly.4. Based on the Structural Risk Minimization Theory, this paper presents a structural-risk-minimum inversion method, i.e., the whole inversion is directed by the Structural Risk Minimization Theory, and the accuracy degree of the inversion has been also improved.5. Regarding a certain trace or many traces of the high-resolution results of the cross-well seismic data inversion as the pseudo-well data of the surface seismic inversion to increase the well number involved in the inversion, the output geologic model will be more fine than the original surface seismic inversion. Then a real cross-well seismic and surface seismic joint inversion and reservoir prediction comes ture.The research achievements above are originative, innovative and practicable. The achievements provide theoretical basis for finding subtle traps in the further reservoir predictions of Daqing Oilfield, and offer important practical significance to increasing potential production in Jiangqiao areas.