A Numerical Well Test Model in Multi-media Carbonate Reservoirs and Its Application

Abstract

Due to the existence of the multi-scale caves and fractures, the carbonate oil reservoirs are highly heterogeneous. The fluid flow in the pore space is extremely complex, so the conventional multi-media theories cannot be applied to this type of reservoirs. Based on the analysis of characteristics of fractured-vuggy reservoirs, the seismic and geological data, a numerical well test model was proposed considering a reservoir feed flow by multi-caves in the paper. The model equations were solved by the finite-element method. The analysis on the affecting factors of dynamic pressure at bottom hole shows that, with the existence of caves in the formation, the pressure derivative curve will drop down and concave back several times forming multiple “valleys.” The valleys are caused by the physical property differences between inside and outside of the caves. The scale of caves affects the amplitude of the pressure derivative valley dips. The distance between caves affects the time duration of pressure derivative drops. The interpretations of onsite well testing cases are in agreement with the actual geological data, which proves the correctness of the mathematical model.

Copyright 2018, Shaanxi Petroleum Society.

This paper was prepared for presentation at the 2018 International Field Exploration &Development Conference in Xi’an, China, 18–20 September 2018.

This paper was selected for presentation by the IFEDC&IPPTC Committee following review of information contained in an abstract submitted by the author(s). Contents of the paper, as presented, have not been reviewed by the IFEDC&IPPTC Committee and are subject to correction by the author(s). The material does not necessarily reflect any position of the IFEDC&IPPTC Committee, its members. Papers presented at the Conference are subject to publication review by Professional Committee of Petroleum Engineering of Shaanxi Petroleum Society. Electronic reproduction, distribution, or storage of any part of this paper for commercial purposes without the written consent of Shaanxi Petroleum Society is prohibited. Permission to reproduce in print is restricted to an abstract of not more than 300 words; illustrations may not be copied. The abstract must contain conspicuous acknowledgment of IFEDC&IPPTC. Contact email: paper@ifedc.org.