Paleo-water-depth quantitative calculation method aiming at lake facies deposition

Abstract

The invention provides a paleo-water-depth quantitative calculation method aiming at lake facies deposition. The method comprises: a step 1, screening out lakes similar to a researched region; a step 2, aiming at the lakes screened out, establishing a quantitative relation between a lakebed deposit and a water body depth; a step 3, aiming at the researched region, carrying out a mudstone TOC test, and carrying out statistics on the formation thickness of target layers; a step 4, establishing a quantitative relation between paleo-water-depth data and the formation thickness; and a step 5, drawing a paleo-water-depth planar distribution graph. By adopting the paleo-water-depth quantitative calculation method aiming at the lacustrine deposition, the paleo-water-depth recovery means is further improved, and a new research idea and technical means are provided for the paleo-lake deposition evolution process research and the prediction of multi-type lake facies sand bodies.

Description

technical field [0001] The invention relates to the fields of theoretical research on sedimentary basins, technical application and geological exploration of oil and gas fields, in particular to a quantitative calculation method of paleowater depth for lacustrine deposition. Background technique [0002] Paleo-depth restoration is an important research work in oil and gas geological exploration, and it has important guiding significance for the study of basin sedimentary evolution process, sand body genetic type and distribution law. At present, the commonly used paleo-depth restoration methods mainly include qualitative and quantitative methods. In the early stage, qualitative paleogeomorphic restoration was the main method. Commonly used methods include residual stratigraphic method, sequence stratigraphic method, sedimentological method and gamma energy spectrum logging method, etc. Through the application of the above methods, it is possible to qualitatively restore th...

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Problems solved by technology

Another example is the superposition method of micro-paleontological categories. Since the distribution of paleontological fossils in the stratum is very uneven, in practice, there will often be no fossil points. The water depth data of such points can only be estimated based on data from adjacent points or other methods. The method is determined, resulting in unreliable paleo-depth restoration results

The shoreline trajectory method is mainly a seismic sedimentology method proposed for large-scale delta sedimentary areas. The calculation process of this method involves many factors such as decompaction, provenance supply rate, and late differential structural settlement. The calculation process is very complicated, and the theoretical Although rigorous in theory, the operability is poor, and the complexity of the delta deposition process itself has caused a lot of uncertainty to the actual restoration results.

[0004] For lacustrine deposits, the most commonly used method in oilfield exploration and production is still the stratum thickness method, that is, the current stratum thickness is used to approximate the ancient water depth in the geological history period, and the greater the thickness, the deeper the water body. Qualitatively reflect the shape of the lake basin

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