Simulation of volumetric acid fracturing fracture in low permeability carbonate rock

Abstract

The types of underground paleocarbonate reservoirs in Ordos Basin, China are complex and show a high filling degree as a whole. In the process of acid fracturing, there are many problems, such as unclear understanding of the fracture propagation and extension law of volume acid fracturing, no relevant experimental data on the conductivity of acid corrosion fracture formed after large displacement and large liquid injection, and lack of theoretical basis for volume acid fracturing design. In order to improve the accuracy and effectiveness of acid fracturing design of such reservoirs, taking MW-X well in Ordos Basin as an example, this paper analyzes the influence law of different factors on the formation of complex fracture network by establishing fracture extension model and judgment model of the encounter between hydraulic fractures and natural fractures. Finally, by establishing the acid flow reaction model and productivity prediction model in the fracture, the influence of different factors on the acid fracturing effect is analyzed, and then the volumetric acid fracturing process parameters are optimized.

Keywords:

• Acid fracturing
• acid rock reaction
• fracture propagation
• low permeability carbonate rock
• numerical simulation

Acknowledgment

The authors acknowledge the free and professional help from anonymous reviewers.

Declaration of competing interest

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

The work in this paper is supported by the grant from Science and Technology Cooperation Project of the CNPC-SWPU Innovation Alliance (No. 2020CX010501).