This paper aims to present the use of organic acid system for matrix acidization. When multiple minerals are present, they can create more formation damage and pose a challenge for acid treatments. In such cases, the paper proposes how a successful treatment can be designed.

Frequent acidizing operations are carried out in western onshore field of Oil and Natural Gas Commission (ONGC). It was observed that some wells were not responding effectively. To get more effective stimulation activities, a methodology was developed, under whichthe first step was to obtain the data related to well details and lithology, and second step was to obtain quantitative mineralogical data using (XRD).

Based on the above methodology it was found that the formation contained large amount of chlorite and other minerals, and that high concentration of HCl can create irreversible damage to this. To avoid this potential damage by HCl preflush, it was proposed to use organic acid preflush instead. Organic acid was proposed because of slow reaction rate, better result in presence of high iron content, better application in high bottom hole temperature etc compared to HCl. Organic acid, and HF were used as mainflush followed by overflush. This organic acid system was used in water injector well of the same formation.

Well head pressure and pumping rate data was recorded for well A and using that matrix acidization evaluation techniques were applied to the wells to quantitatively analyze the effectiveness of stimulation treatment. The same acid system was used for well B and a positive result was observed. Effectiveness of this result, of well A, was compared with previous operations where organic acid was not used. Same procedure of treatment evaluation was carried out and reduction in skin factor was calculated.

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