Pressure transient analysis for a fractured well in a stress-sensitive tight multi-medium oil reservoir

Abstract

Tight multi-medium oil reservoirs are the main source of hydrocarbon resources around the world. Acid fracturing is the most effective technology to improve productivity in such reservoirs. As carbonates are primarily composed of dolomite and calcite, which are easily dissolved by hydrochloric acid, high-permeability region will be formed near the well along with the main artificial fracture when acid fracturing is implemented in tight multi-medium oil reservoirs. In this study, a comprehensive composite linear flow model was developed to simulate the transient pressure behavior of an acid fracturing vertical well in a naturally fractured vuggy carbonate reservoir. By utilizing Pedrosa’s substitution, perturbation, Laplace transformation and Stehfest numerical inversion technology, the pressure behavior results were obtained in real time domain. Furthermore, the result of this model was validated by comparing with those of previous literature. Additionally, the influences of some prevailing parameters on the type curves were analyzed. Moreover, the proposed model was applied to an acid fracturing well to evaluate the effectiveness of acid fracturing measures, to demonstrate the practicability of the proposed model.

Graphical abstract

Keywords

tight multi-medium oil reservoir / acid fracturing / stress-sensitive permeability / composite linear flow

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Acknowledgement

This work was supported by the National Major Research Program for Science and Technology of China (Grant No. 2017ZX05030-002).

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