A method for the division and comparison of granite strata

Abstract

The invention provides a granite stratum division comparison method. The method comprises the following steps: 1, preparing logging curve data; 2, analyzing logging curve maximum entropy spectrum; 3, obtaining a data difference curve; 4, converting the data difference curve into a frequency spectrum curve; 5, performing filtering processing on a reconstructed frequency spectrum curve; 6, determining abnormal points; 7, numbering the abnormal points; and 8, performing stratum division and comparison: connecting key similar difference points of each well on a backbone profile according to a sequence, i.e., finishing granite stratum division comparison. According to the invention, the abnormal points in each well are analyzed and compared, compared to a conventional similar stratum comparison method, for a granite stratum which is small in lithologic difference, small in vertical change and not obvious in cyclicity, the operability is higher, and compared to a conventional stratum comparison method, the practicality is higher. Since a maximum entropy spectrum analysis method is employed, the stratum comparison quantitative degree is enhanced, the operability is higher, and the stratum comparison efficiency is greatly enhanced.

Description

technical field [0001] The invention relates to a method for dividing and comparing granite strata, which belongs to the field of oil field exploration. Background technique [0002] Stratigraphic division and correlation is an essential link in oilfield exploration and development. Subsequent geological modeling, development layer division and well pattern deployment are all carried out on the basis of accurate stratigraphic division and comparison. At present, based on conventional clastic rock and carbonate strata, various stratigraphic division and correlation methods such as seismic stratigraphy, sequence stratigraphy, and chronostratigraphy have been explored, and corresponding theoretical systems and technical means have been formed. However, the division of granite strata is rarely involved. There are two main reasons for this. On the one hand, because the existing theoretical system is based on the time category, it emphasizes the concept of isochronism, which is cl...

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Problems solved by technology

However, the division of granite strata is rarely involved. There are two main reasons for this. On the one hand, because the existing theoretical system is based on the time category, it emphasizes the concept of isochronism, which is closely related to the concept of sedimentary cycle, while granite strata have no sedimentation. The cycle concept and lithology are mostly single, the seismic reflection characteristics inside the formation are usually unclear, and the vertical electrical characteristics of a single well are mostly uniform, so it is not suitable for reservoirs formed by magma intrusion and subsequent structure and weathering; on the other hand The granite type oilfields are rarely discovered, so the corresponding research techniques are relatively scarce, and the traditional isochronous stratigraphic division and correlation approach is not suitable for this type of reservoir stratigraphic division and correlation work

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