地质科技通报 (Nov 2021)

Prediction and discrimination of the Middle Carboniferous inner platform shoal distribution at the eastern margin of Pre-Caspian Basin: Taking the North Truwa slope area as an example

  • Chenhao Xu,
  • Zhiguo Liang,
  • Junsheng Cheng

DOI
https://doi.org/10.19509/j.cnki.dzkq.2021.0604
Journal volume & issue
Vol. 40, no. 6
pp. 216 – 225

Abstract

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The Middle Carboniferous KT-Ⅱoil formation in the eastern margin of the Pre-Caspian Basin is widely developed with open platform facies intra platform beach.The sedimentary environment is open and stable, and the terrain is flat.The intra platform beach often floats in isolated micro geomorphic Highlands in the platform, so its distribution is often difficult to predict.Drilling practice shows that the beach facies in the platform is the basis of constructive diagenesis in the later stage, and it is also the main controlling factor for the formation of high-quality reservoir, so it is very important to predict its distribution.In order to improve the accuracy of beach prediction, based on the analysis of regional sedimentary evolution, and gradually carry out three-dimensional seismic attribute analysis and high-resolution inversion, fully combined with the predictability of seismic data and the regularity of geological knowledge, through summing up the geological law of facies belt, the seismic reservoir prediction is supplemented and screened, so as to achieve the unity of geological and geophysical knowledge.The results show that the statistical inversion under the control of seismic attribute trend can accurately describe the spatial distribution characteristics of thin beach body at the level of small layer.According to the sedimentary law, the predicted beach bodies are screened and classified.Among them, there are 7 first-class beach bodies, 4 second-class beach bodies and 3 third-class beach bodies.The first- and second- class beach bodies have been confirmed by drilling, which are consistent with the sedimentary law.The third-class beach bodies are contrary to the geological understanding and should be screened out.The research results have established a complete technical system for the prediction of concealed beach bodies in this area, and have seen actual results.At present, the success rate of drilling for a class of beach bodies is as high as 100%.

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