AN EXPERIMENTAL-STUDY OF WELL COMMUNICATION BY HYDRAULIC FRACTURING

The possibility of well communication by hydraulic fracturing has been studied through the use of laboratory experiments. The experiments were conducted on 610 x 584 x 305 mm gypstone blocks. True triaxial stresses were applied to the specimens. A fracture fluid was injected simultaneously into two injection wells at a high injection rate. The angle (beta) between the well line and the direction Of sigma(hmax) (the orientation of fracture propagation for single well hydraulic fracturing) was chosen as the controlling variable. The experimental results showed that for a low stress difference (sigma1/sigma3 around 1.5), well communication was obtained for beta up to 60-degrees, but the orientation of fracture initiation was unpredictable by the state of stress in the wall of the wells. Fractures rotated during fracture propagation. For a higher stress difference (sigma1/sigma3 around 2), well communication was obtained for beta up to 30-degrees. Fracture initiation was capable of being predicted by the state of stress in the wall of the wells.