EFFECTIVENESS OF FLUOBORIC ACID ON TREATING FINES MIGRATION IN SANDSTONE FORMATION

There are many technologies have been introduced to find efficient and cost effective ways to prevent fines migration in the sandstone formation. Fines that able to migrate are usually the main contribution to the reduction of well’s permeability by clogging the pore throat of the rock. Further fines migration also can cause screen erosion and failure. It is important to control fines migration in the producing well as it contributes to a lot of problem. Huge interest on fluoboric acid in oil and gas industry has raised the question how fluoboric acid can stabilize formation clays while improving the permeability properties.
This work focusses on how effective the fluoboric acid stabilize the clay in the sandstone formation. An experiment was set up to show the effectiveness of fluoboric acid in treating fines migration in the sandstone formation. The sand pack was saturated with different concentration of hydrofluoric acid and a high concentration (2500 ppm) of mixed formation fines was flown through the sand pack to simulate migrating fines and finally, the effluent was collected and analysed. From the study, as concentration of hydrofluoric acid is increased, the collected effluent are becoming clearer. This is due the high amount of HF molecules leads to higher concentration of hydrofluoric acid causing stabilized undissolved fines to be obtained. Another experiment was conducted to measure the amount of effluent collected and turbidity reading for 5% and 7% concentrations to identify the optimum concentration to dissolve the fines as the volume of the formation fines solution increases. It turns out that 7% concentration of hydrofluoric acid gives low reading of turbidity as the volumes increases up to 200 ml.
This project can be considered as one of the well stimulation techniques to improve the productivity of the producing well. It is very much related to the current conditions of the wells that are reducing in formation permeability because of the fines migration and deposition results in high positive skin near the wellbore.