Depicting method for constraining small-scale sedimentary microfacies by using large-scale seismic data

Abstract

The invention relates to a depicting method for constraining a small-scale drilling sedimentary microfacies by using large-scale seismic data. The depicting method comprises the following steps: 1, establishing a construction model of a work area; 2, resampling seismic data into a structural model, and establishing a grid model of the seismic data; 3, acquiring seismic data of each small layer according to a network model; 4, establishing a fitting function model according to the seismic data of each small layer; 5, thinning the seismic attribute points; and 6, according to the step 4 and thestep 5, carrying out fine depiction of the sedimentary microfacies. According to the method, the large-scale seismic data is small-scale and is enabled to be in one-to-one correspondence with small-scale drilling wells in the longitudinal direction, the distribution of the sedimentary microfacies is truly described by using the seismic data, and the description precision of the sedimentary microfacies is greatly improved. By application of the method, mutual combination of well earthquakes under the same scale is realized, and earthquake quantitative constraint geology is truly realized.

Description

technical field [0001] The invention belongs to the technical field of petroleum development, and in particular relates to a method for describing microfacies distribution of small-scale drilling sediments constrained by large-scale seismic data. Background technique [0002] Sedimentary microfacies refers to the smallest unit with unique rock structure, structure, thickness, rhythm and other sedimentary characteristics on the profile and certain plane configuration rules within the scope of the subfacies zone. [0003] Using seismic data to study sedimentary microfacies, the identifiable large-scale (greater than λ / 4, where λ is the wavelength) and qualitative seismic sedimentary microfacies analysis traditionally carried out by waveform classification method and seismic structure attribute mapping method cannot satisfy thin Requirements for oil and gas reservoirs dominated by strata (less than λ / 4). [0004] How to match large-scale seismic data with small-scale sedimenta...

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Problems solved by technology

[0008] However, the above existing technologies all mention the use of various methods to improve the accuracy of sedimentary microfacies, but most of them are qualitative and macroscopically guided and controlled, and the fine characterization accuracy for small-scale sedimentary microfacies is still not enough

However, a large number of literatures show that the resolution and accuracy of seismic data often cannot reach the accuracy of sedimentary microfacies identified on well logs, and generally the longitudinal resolution of seismic data is limited (for example, when the main frequency of seismic data is 30HZ and the velocity is 3500m / s , the vertical recognition accuracy is only 40-60 meters), while the logging resolution is relatively high (8 points per meter, the accuracy reaches 0.25 meters)

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