A Method of Identifying Lithologic Traps Using Seismic Data

Abstract

The invention relates to a method for identifying a lithologic trap via earthquake data, and belongs to the field of petroleum natural gas exploration and exploitation. A sedimentary facies map of a work area is utilized, the distribution area of identifiable sand bodies is analyzed, and the range of a research target area is reduced; and well density or sound wave time difference data is used to make well synthesis records, one to one correspondence between the drilling well profile rock stratum and earthquake phase of the target area is established, a symbolic earthquake phase of stable target layer in the research target area is determined, earthquake phase corresponding to low-density high porosity and permeability sand body existing locally in a continental facies environment is analyzed and screened, the special distribution form of the lithologic trap of the target sand is analyzed, interference of restricted error is eliminated, influence on complex geological environment is reduced, the prediction precision of the lithologic trap is improved, and the cost of exploration and exploitation is reduced.

Description

technical field [0001] The invention relates to a method for identifying lithological traps by using seismic data, belonging to the field of oil and gas exploration and development. Background technique [0002] The exploration and development of oilfields in central and eastern China has entered the middle and late stages, and a breakthrough in the exploration of lithologic reservoirs is imminent. At present, common lithological trap prediction technologies include seismic attribute extraction technology and logging-constrained inversion technology. These two technologies rely on the powerful computing power of the computer to capture the differences between the seismic data of the work area and the corresponding seismic signals of sand and mudstone, so as to predict the distribution of sandstone and analyze and evaluate lithological traps. The prediction accuracy of these two techniques is affected by the seismic phase tracking accuracy and the size of the inversion time ...

AI Technical Summary

Problems solved by technology

All in all, using seismic attribute extraction technology and logging constraint inversion technology to predict lithologic traps, in the Dongpu area with complex geological conditions, there are two deficiencies that affect the prediction results: 1. Difficulty in tracking seismic phases in complex areas Firstly, faults are developed in complex areas, and fault cutting affects the identification and tracking of strata; secondly, contemporaneous faults affect strata deposition, and strata in the same segment will change in thickness, lithology, and physical properties on different sides of the fault, and the corresponding The seismic phase shape will also change accordingly, which will easily lead to misidentification and cross-layer phenomena in the identification and tracking of seismic phases, and eventually lead to errors in reservoir prediction results; 2. The value of the seismic inversion time window depends on personal experience. The value of the performance time window can neither be too large nor too small, which has regional characteristics; if the value of the inversion time window is too large, the data collection of the target layer will cause the signal information of the adjacent layer to be mixed in. Affect the seismic inversion results of the target layer; too small value of the inversion time window will cause incomplete data collection of the target layer, or omit the main peak data, which also affects the accuracy of seismic inversion; the seismic inversion time window The limitation of value selection is also reflected in the fact that the appropriate seismic time window within a certain range of the same work area often needs to be re-determined in other areas of the same work area, especially in areas dominated by continental sediments. Due to the complexity and diversity of sedimentary environments, The spatial development of each sand body has its own characteristics, the thickness of each sand body is different, and the position of each sand body on the profile is variable, which affects the value of the seismic inversion time window

In addition, there are wedge-shaped sand bodies, lenticular sand bodies, and irregular-shaped sand bodies underground that are not parallel to the formation, which will make it difficult to obtain a seismic time window. Under the constraints of a seismic inversion time window, the signal information is acquired more, less or missed, which will eventually reduce the accuracy of the seismic inversion results

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