Method for exploring development of ancient lakes by using triangulation diagrams of sporopollen and algae

Abstract

The invention provides a method for exploring ancient lake development by using a sporopollen and algae triangular diagram, which comprises the following steps of: determining a research area range, selecting a plurality of exploratory wells with relatively complete ancient biological data in the research area, carrying out sedimentary environment subdivision on each well in combination with electrical property and logging data, and enabling each sample point to correspond to the subdivided sedimentary environment; according to different living environments of sporopollen and algal fossils, determining three-terminal control factors of the triangular diagram; arranging sporopollen and algae fossil data of each selected well; sorting the loading data of the selected triangular diagram plumbing points of each series of each well; a triangular diagram of each selected well is established by utilizing graphics software; analyzing a plumbing result of each selected well; establishing a sporopollen and algae quantitative statistics triangular chart lacustrine facies model in the research area; the invention discloses an application method of a sporopollen and algae quantitative statistics triangular diagram lacustrine facies model. A new means is provided for searching the sedimentary environment of the ancient lake, and the blank in the field of paleontology is filled.

Description

technical field [0001] The invention relates to the technical field of petroleum exploration, in particular to the technical field of environment identification of lake facies, swamp facies and river facies, and more specifically relates to a method for exploring the development of ancient lakes using a pollen and algae triangle diagram. Background technique [0002] Since the end of the Oligocene, the Bohai Bay Basin has transformed from a large-scale faulted basin to a depression basin. After the Paleogene paleo-lake group in Bohai Bay disappeared, the Neogene was once considered to be fluvial sediments and lacked good cap rocks. , Exploration risks are relatively high, and this understanding once restricted the oil and gas exploration of the Neogene in the Bohai Sea area. However, under the guidance of the "late accumulation theory", the Neogene system in the central Bohai Sea area gradually confirmed the existence of ancient lakes, and successively discovered several lar...

AI Technical Summary

Problems solved by technology

The Neogene in the Bohai Bay Basin is mainly composed of fluvial facies deposits, and later studies have suggested that there are shallow water delta deposits. Such a sedimentary background near provenance means that even if there are ancient lakes, the lakes must be small in scale and scattered in distribution. At the same time, the Bohai Bay Basin The density of the well pattern is small, which brings difficulties to the search for ancient lakes

[0004] In particular, from the perspective of paleontological research methods, due to the extensive development of fluvial facies, there are very few preserved animal microfossils, and most algae fossils are freshwater algae, which cannot clearly indicate the existence of ancient lakes

Wang Kaikai once proposed the use of palynological statistical methods to study the modern surface sediments of the Yangtze River Delta, but this method is not applicable to the paleoenvironment

Images