For many oilfields developed by Orenburgneft JSC, there is a technological problem of decreasing carbonate matrix treatment efficiency with the increase in their multiplicity, caused by a reducing in the depth and selectivity of the stimulation. The situation is considerably aggravated on water-encroached heterogeneous formation. In order to improve efficiency hydrochloric acid treatment a complex of core tests and physicochemical studies aimed at determining optimal acid compositions were carried out. The dependence of the volume of acid composition required to break through the rock sample on the injection rate was revealed, on the basis of which the model of acid treatment was adapted. A semi-empirical mathematical model of acid dissolution based on Damköller and Pecklet numbers and acid capacity was chosen to determine optimal treatment parameters (injection rate, acid volume) and develop recommendations for treatments. Based on the results of mathematical modeling and determination of economic costs of acid composition preparation the optimal formulations for the conditions of priority objects of Orenburgneft JSC have been selected. The influence of various exposure parameters and properties of acid compositions on the value of the required volume of the composition was evaluated. Pilot tests of the selected acid compositions were carried out, during which a higher efficiency of the treatments was noted; the results of the research and the relevance of the approach used were confirmed. The advantages of this approach are the consideration of the economic component, geological and physical characteristics of productive formations and properties of acid compositions, as well as the possibility of its implementation using mathematical models or acid treatment simulators.
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