Method for combining logging velocity and seismic velocity to establish there-dimensional velocity field

Abstract

The invention provides a method for combining the logging velocity and the seismic velocity to establish the three-dimensional velocity field. The method comprises steps that the pseudo well velocitycurve is extracted from the seismic velocity body along the well trajectory; the residual velocity curve is obtained by comparing the pseudo well velocity curve with the logging velocity curve; the residual velocity curve is utilized for interpolation under the geological framework constraints to obtain the residual velocity field; the residual velocity field is utilized to correct the seismic velocity. The method is advantaged in that not only can the method be suitable for areas with relatively low exploration degrees, but also is suitable for areas with relatively high exploration degrees,with increase of the exploration degree and increase of the well number, precision is gradually improved; the transverse seismic velocity resolution and the vertical logging velocity resolution are combined to obtain the more accurate velocity field; problems of complexity of the underground structure and severe stratum velocity transverse variation of research areas can be solved.

Description

technical field [0001] The invention belongs to the field of seismic exploration, and in particular relates to a method for establishing a three-dimensional velocity field by combining logging velocity and seismic velocity, which is mainly used for seismic data processing and interpretation in the field of petroleum exploration. Background technique [0002] Seismic exploration is currently a commonly used method to find oil. It uses artificial excitation to generate seismic waves that propagate underground, and when they encounter different rock layers, they are reflected back and received by surface geophones to form seismic records. The seismic records can be processed and interpreted. Infer the nature and morphology of subsurface rock formations. Since the seismic records are in the time domain, and the drilling wells used to extract oil are in the depth domain, a velocity field is needed to link the two. Speed ​​prediction has always been one of the difficult problems ...

AI Technical Summary

Problems solved by technology

The first type is to use logging information to establish velocity field, including regional time-depth conversion scale, velocity curve interpolation, well-seismic calibration time-depth relationship, etc. Inner Mongolia Petrochemical Industry, 2005, (11): 114-115), the velocity field established by this method is relatively accurate at the well point, but it is difficult to grasp the lateral change between wells, and it is also difficult to use in areas with few wells

The second type is to use the velocity of seismic processing (Li Mingjuan et al., Application of Seismic Velocity Spectrum in Making Fine Depth Map [J]. Petroleum Geophysical Prospecting, 2004, (3): 272-274), the characteristics of this type of method to establish velocity field It is evenly distributed, and the lateral velocity distribution characteristics can be known, but due to some approximations and assumptions when converting from superposition velocity to layer velocity, there is a certain error compared with the true velocity of the formation

The third category is to use the drilling time-depth relationship and geological stratification to constrain the seismic velocity to establish the velocity field (Jia Yirong et al., Construction and Application of Variable-speed 3D Seismic Velocity Field [J], Geophysical and Geochemical Exploration Computing Technology, 2011, (33): 243- 247), this type of method is commonly used at present. Compared with the previous two methods, its accuracy has been improved to a certain extent, but the disadvantage is that on the one hand, the accuracy of geological stratification is The requirements are high. On the other hand, the seismic velocity is only corrected at the well point, and the variation between wells is ignored.

The above three types of methods have their own characteristics and also have certain limitations. There will be certain errors in the time-depth conversion of the velocity field constructed using these methods, which is not conducive to further exploration and development.

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