Monitoring of Matrix Acidizing by Using Resistivity Measurements

Abstract

This paper is focused around testing a novel concept based on resistivity measurements to monitor acid stimulation operations. A feasibility study was carried out to show the potential success of the proposed concept. A series of coreflooding experiments were conducted at elevated pressure (3,000 psi) and high temperature (65°C) while recording the resistivity and pressure data from taps placed along a rubber sleeve housing the core samples. Results show the ability of the resistivity measurements to track the acid penetration and provide insight on the wormhole morphology. A numerical model was also derived to determine the electrical resistivity while injecting acid and dissolving the rock sample. A comparative study with the experimental results shows that the model predicts the change in the electrical resistivity during acid injection with good accuracy. It is believed that the proposed concept for monitoring the wormholing process can be adopted in the field with the deployment of the induction tools. A yard test was performed to verify the response of a real induction tool to simulated wormholing features. The results demonstrate the capability of the resistivity measurements to delineate the wormholing zones. The outcome of this novel monitoring concept is expected to provide an unprecedented level of understanding of the depth, the number, and the type of wormholes being created downhole. The interpretation of the wormhole formation and propagation will provide guidance to enhance the operational efficiency and maximize productivity gains along the entire wellbore.