Pressure decline curve analysis for acid fracturing in carbonate rock fractured reservoirs

In this paper,the acid fracturing pressure decline curve analysis model is developed based on the radial fractured model,in which the effect of CO2 generated by acid soak carbonate and the interaction of acid-rock,on artificial fracture volume is taken into consideration.For the high pressure phase equilibrium system composed of CO2,H2O,CaCl2,etc.,CO2 is treated as Super Critical Fluid truly,the volume of which is estimated by BWR state equation suitable for super critical fluid.Based on estimating the type of filtration by constructed G and ψ fraction,and determining the fracture closed point,the parameters such as the geometry of fracture,the leak-off coefficient can be calculated,and furthermore it can direct the acid fracturing design and improve the acid fracturing technology.Good results have been achieved in the pressure decline analysis of the acid fracturing well in Tahe Oilfield.