Study on acid-refracturing feasibility in carbonate reservoirs of Tahe oilfield

Acid fracturing is a core technology to explore and develop fracture-cavity type carbonate reservoir of Tahe oilfield, but nearly half wells after acid fracturing didn’t obtain commercial hydrocarbon flow or only achieved low productivity. In addition, production rate decreased rapidly in some wells not long after being put into production due to fracture conductivity failure. By analyzing and re-understanding the reservoir characteristics, operation design, on-site operation and liquid drainage of 27 wells after acid-refracturing in the fracture-cavity type carbonate reservoir of Tahe oilfield, this paper concludes the main factors affecting the acid- refracturing effect. The paper continuous to study the feasibility of acid- re fracturing in carbonate reservoir; develop the principle of wells and layers selection; optimize the high temperature working fluid and matching technology. Thus acid-refracturing treatment technology in the carbonate reservoir is formed. 3 well-times application with acid-refracturing achieved good stimulation effects.