Evaluation of Organic Carbon Logging in the Chang 7 Section of the Yanchang Formation, Huanjiang Area, Ordos Basin

Chenhui Yan; Qiquan Chen; Qunfeng Ding; Zixuan Zhao; Linxi Jia

doi:10.54097/efkqhw55

Authors

Chenhui Yan
Qiquan Chen
Qunfeng Ding
Zixuan Zhao
Linxi Jia

DOI:

https://doi.org/10.54097/efkqhw55

Keywords:

Source rock; Organic carbon; Logging evaluation; Ordos Basin; Chang 7 section.

Abstract

During the early stages of shale oil exploration, challenges such as limited coring of source rocks and the discontinuous distribution of measured samples arise. Logging data can be used to quantitatively evaluate source rocks. Organic-rich source rocks typically exhibit characteristics such as high gamma radiation, low density, high sonic lag, high resistivity, and high neutron porosity on logging curves. This paper systematically introduces two quantitative evaluation methods for source rocks based on logging data: the Δlog R method and the BP neural network model. Corresponding prediction models were developed to forecast the organic carbon content of source rocks in the Chang 7 section of the Yanchang Formation in the Huanjiang area of the Ordos Basin. The predicted TOC (total organic carbon) data were copared with measured TOC data. The results indicate that both the ΔlogR model and the BP neural network model are effective for the study area, with the BP neural network model showing significantly better fitting performance than the ΔlogR model. The study also predicts the plane distribution of TOC content in the source rocks of the study area.

Downloads

Download data is not yet available.

References

[1] Tissot B. P. Petroleum Formation and Occurrence[J]. Journal Of Sedimentary Research, 1978, 55p. 643-644. DOI: https://doi.org/10.1007/978-3-642-96446-6_5

[2] Du J., Zhang X., Zhong G., et al. Analysis on the optimization and application of well logs indentification methods for organic carbon content in source rocks of the tight oil illustrated by the example of the source rocks of Chang 7 member of Yanchang Formation in Ordos Basin[J]. Progress in Geophysics, 2016, 31(06), p. 2526-2533.

[3] Bertrand P., Lallier-Verges E., Boussafir M. Enhancement of accumulation and anoxic degradation of organic matter controlled by cyclic productivity: a model[J]. Organic Geochemistry, 1994, 22(3), p. 511-520. DOI: https://doi.org/10.1016/0146-6380(94)90123-6

[4] Carroll A. R., Bohacs K. M. Lake-type controls on petroleum source rock potential in nonmarine basins[J]. AAPG Bulletin, 2001, 85p. 1033-1053. DOI: https://doi.org/10.1306/8626CA5F-173B-11D7-8645000102C1865D

[5] Derenne S., Largeau C., Brukner-Wein A., et al. Origin of variations in organic matter abundance and composition in a lithologically homogeneous maar-type oil shale deposit (Gérce, Pliocene, Hungary)[J]. Organic Geochemistry, 2000, 31(9), p. 787-798. DOI: https://doi.org/10.1016/S0146-6380(00)00093-0

[6] Sun Z., Peng J., Jiang S., et al. Organic facies and well logging evaluation of source rocks in centeral-south sag of Miaoxi Depression and its surrounding areas，Bohai Sea[J]. Lithologic Reservoirs, 2020, 32(01), p. 102-110.

[7] Lu P., Mao X., Zhang F., et al. Prediction of organic carbon content in Lunpola Basin by neural network method[J]. Progress in Geophysics, 2021, 36(01), p. 230-236.

[8] Liu Z., Tang S., Zhang P., et al. Organic Matter Characteristics and Total Organic Carbon Content Prediction of Coal Measure Shale: A Case Study of the South Ningwu Block[J]. Science Technology and Engineering, 2023, 23(27), p. 11593-11604.

[9] Jin Q. Importance and research about effective hydrocarbon source rocks[J]. Petroleum Geology and Recovery Efficiency, 2001, (01), p. 1-5.

[10] Guo G., Wang K., Guo Y., et al. Analysis of the relationship between Chang 7 tight oil and reservoir characteristics in Huanjiang area[J]. Petrochemical Industry Application, 2015, 34(01), p. 92-96.

[11] Wang W., Wang H. Study on accumulation law of Jurassic Yanan Formation reservoir in Huanjiang area[J]. Petrochemical Industry Technology, 2018, 25(10), p. 111.

[12] Luo L., Li J., Yang W., et al. Characteristics and Hydrocarbon Generation Potential of Chang 9 Source Rocks on Yishaan Slope, Ordos Basin[J]. Xinjiang Petroleum Geology, 2022, 43(03), p. 278-284.

[13] Gao P. Characteristics and hydrocarbon generation and expulsion potential of Chang7shale oil source rocks in Wuqi Area,Ordos Basin[J]. Unconventional Oil & Gas, 2024, 11(03), p. 10-18.

[14] Chen S. Logging evaluation of organic carbon in Chang73 subsection of Yanchang Formation in Ordos Basin[J]. Unconventional Oil & Gas, 2024, 11(03), p. 58-66.

[15] Yang T., Fan G., Lv F., et al. The logging features and identification methods of source rock[J]. Natural Gas Geoscience, 2013, 24(02), p. 414-422.

[16] Passey, R Q. A Practical Model for Organic Richness from Porosity and Resistivity Logs[J]. AAPG Bulletin, 1990, 74p. 1777-1794. DOI: https://doi.org/10.1306/0C9B25C9-1710-11D7-8645000102C1865D

[17] Kamali M. R., Allah Mirshady A. Total organic carbon content determined from well logs using ΔLogR and Neuro Fuzzy techniques[J]. Journal of Petroleum Science and Engineering, 2004, 45(3), p. 141-148. DOI: https://doi.org/10.1016/j.petrol.2004.08.005

[18] Feng R., Liu Z., Meng Y., et al. Optimization and Application of Organic Carbon Logging Prediction Models for Source Rocks: A Case Study of Chang９Member of Yanchang Formation in Ansa iArea, Ordos Basin[J]. Journal of Jilin University(Earth Science Edition), 2024, 54(02), p. 688-700.

[19] Hu H., Su R., Liu C., et al. The method and application of using generalized ΔLgR technology to predict the organic carbon content of continental deep source rocks[J]. Natural Gas Geoscience, 2016, 27(01), p. 149-155.

[20] Zhang X., Cheng G., Zhao J., et al. Research on classification and evaluation of Chang 3 reservoir in H area based on BP neural network technology[J]. Progress in Geophysics, 2023, 38(03), p. 1272-1281.

[21] Wei M., Zhou J., Duan Y., et al. Prediction Model of Total Organic Carbon Content in Shale Gas Based on Machine Learning[J]. Science Technology and Engineering, 2023, 23(30), p. 12917-12925.

[22] Yang H., Dou W., Liu X., et al. Analysis on Sedimentary Facies of Member 7 in Yanchang Formation of Triassic in Ordos Basin[J]. Acta Sedimentologica Sinica, 2010, 28(02), p. 254-263.

[23] Zhang W., Yang H., Yang Y., et al. Petrology and element geochemitry and development environment of Yanchang Formation Chang 7 high quality source rocks in Ordos Basin[J]. Geochimica, 2008, (01), p. 59-64.