Fracture prediction and application in carbonate reservoirs based on the rescaled range analysis- finite difference numerical analysis methods

Abstract

For carbonate reservoirs, the study of fractures is crucial. In this paper, the identification and prediction of fractures in carbonate reservoirs are carried out by applying R/S-FD numerical analysis method by using core, thin section and imaging logging data. The analysis concludes that the AC, CAL, DEN, and GR curves are very sensitive to the response of fracture development segments as calculated by the rescaled range analysis (R/S) analysis method, but some fractures are still misidentified. After finite difference (FD) calculation on the basis of R/S calculation, high-angle structural fractures can be accurately identified, and the R/S-FD fracture identification results of different curves can be verified with the results of core and imaging logging, and the fracture identification accuracy can reach 71.69%. The number of fracture development segments is positively correlated with the cumulative oil production, the number of producing layers and the cumulative thickness of producing layers, and the wells with more fracture development segments have higher cumulative oil production, more producing layers and larger cumulative thickness of producing layers. This method improves the accuracy of fracture identification in carbonate reservoirs, which is of great significance for oil and gas exploration.

Keywords:

• Fracture prediction
• Ordovician carbonate reservoirs
• R/S-FD method
• structural fracture
• Tahe oilfield

Acknowledgments

The authors would like to thank the staff of all of the laboratories that cooperated in performing the tests and analyses. We are also grateful to the anonymous reviewers, whose comments improved the quality of this manuscript.

Disclosure statement

The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper.

Additional information

Funding

This research was supported by the National Natural Science Foundation of China (Grant No. 42072173) and the Collaborative Project of Research Institute of Petroleum Exploration and Development, Northwest Oilfield Company, Sinopec (No. KY2021-s-093).