Hydraulic, acid, and proppant-carrying acid fracturing stimulation of volcanic reservoirs in Sichuan Basin, China: an experimental study

Nowadays, volcanic reservoirs show great development potential. However, the stimulation mechanism of volcanic reservoir is yet unclear. In this article, hydraulic fracturing, acid fracturing, and proppant-carrying acid fracturing of volcanic rock were analyzed by the laboratory tests. The average acid etching and proppant-embedded depths were assessed. The effect of different proppant sizes and acid types on fracture conductivity was studied. The results indicate that acid fracturing is failed to produce high-conductivity fractures. Large-sized proppants had larger embedded depths. For the hydraulic fracturing, the average depth of the 30/50 mesh proppant (5 kg/m(2), 60 MPa) embedded in the volcanic rock is 33 mu m, and the conductivity is 45.27 D center dot cm, which is 1.5 times that of the 40/70 mesh proppant. Embedded depth of proppant in the proppant-carrying acid fracturing (347 mu m) was ten times larger than that in hydraulic fracturing (33 mu m), but in terms of conductivity, hydraulic fracturing is only 20% better than proppant-carrying acid fracturing. This study is helpful to elucidate the mechanism of different stimulation methods and provide scientific means for the efficient development of volcanic reservoirs.