Experimental study on the fracture conductivity in the carbonate reservoirs with low elastic modulus

The carbonate reservoirs in the Middle East and the Central Asia have lower elastic modulus, which is only 1/2-1/3 that in China. After this type of reservoirs is treated with acid fracturing, the effective stimulation period is short and the fracture conductivity can be hardly maintained. In this paper, laboratory experiment was carried out to study the influences of elastic modulus, displacement and acid fracturing technology on the fracture conductivity. The results show that when gelling acid fracturing is applied in the carbonate rocks with low elastic modulus (<20 GPa), the fracture conductivity cannot be maintained after the closure stress exceeds 20 MPa. As for the carbonate rocks with low elastic modulus, the fracture conductivity at high displacement is stronger than that at low displacement. At high closure stress, closed acidizing can improve the fracture conductivity effectively. And in the situation of closed acidizing, the fracture conductivity can be improved better at low-displacement acid injection. After acid fracturing is carried out in the carbonate rocks of S Oilfield of the Middle East, a great number of acid wormholes are generated, but effective fracture conductivity is not formed. And the fracture conductivity gets better after sand fracturing.