Acidizing Technology of Carbonate Reservoir Used for Enhanced Oil Recovery in the Oilfield of Iraq

An acidizing technology was applied to a carbonate reservoir oil field in Iraq. The oilfield is located in the Southeast of Iraq, whose main production reservoirs have two intervals. Interval A mainly consists of dolomite, limestone and a little of sandstone whereas interval M mainly consists of limestone. Both A and M belong to the middle-high porosity and low-middle permeability carbonate reservoir. The oilfield has rich resource and low oil production rate and low productivity. The matrix stimulation is a technology which can effectively improve the production of the oil wells of carbonate formation. The acidizing system, operation and spent acid flowing-back technology are selected to apply for the carbonate reservoir in the oilfield according to the reservoir characteristic and acidizing technology requirement including retarding property on the condition of high temperature, dissolving the matrix, passing by the plug, low damage to the reservoir and deeper perforation distance. 15 wells have been treated from June to December 2012 and the acidizing result is very obvious with the increasing production per day by 5897 m³ in the early after treatment.