Pore volumes to breakthrough estimation in carbonate acidizing with hydrochloric acid by using an analytical derivation method

Abstract

Acidizing treatment is considered as a significant process in the oil well stimulations to form wormholes in carbonate formation in order to enhance the reservoir fluid production. Obtaining the number of pore volumes to breakthrough is an important objective in matrix acidizing, for it contributes to determining the wormhole characteristics such as type, shape, and size. Finding this number in experimental works requires a considerable amount of time, energy and cost. Therefore, this study aimed to establish an analytical method in which a reasonable result is achieved for the number of pore volumes to breakthrough. This purpose is accomplished by solely implementing acid and formation properties without performing any experimental works. The process of wormhole creation is done through developing a numerical model by utilizing the conservation of mass law method in which the carbonate core is considered as a closed system and the overall mass in the system as constant during the acid injection process. Furthermore, a constant number is added to the mathematical part of the model in order to eliminate the dimensionless Damköhler number which is supposed to be calculated experimentally. The results of the numerical procedure of the model are further compared to four other experimental works, which led to calculating the average accuracy of this model that is shown to be 95.98%. This study puts forward a comprehensive numerical model to estimate the number of pore volumes to breakthrough with an acceptable accuracy rate merely through implementing known acid and core properties.

Keywords

Analytical method / Carbonate acidizing / Pore volume to breakthrough / Hydrochloric acid

Acknowledgments

The authors would like to thank the Department of Petroleum Engineering, School of Chemical and Energy Engineering, Univesiti Teknologi Malaysia (UTM) for providing support.

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