The Mythical Second Fracture and Its Optimal Placement for Maximizing Production

摘要

Placing a fracture in a formation is obviously well understood in our industry and has been practiced successfully for quite some time. Recently this capability was refined to enable initiation of a fracture into a specific direction through the introduction of super-high-energy jetting. Despite the developments and experience in fracturing technology and know-how, it has still not been possible to know where a farfield fracture goes-we know it will go to the local minimum stress direction-but we do not know what direction that will be. It is most probable that the far-field fracture will go to a less-than-desired area in the formation and result in only an “acceptable” improvement in production. Recently, it has been shown that refracturing actually creates new fractures in the formation, rather than simply reopening old fractures, as was commonly thought. Even reopened fractures are now known to result in new areas being reached by the fractures. It is the opinion of this paper that these new fractured areas are not substantially different from the areas reached by the first fracture because local depletion enhances the effects of the original stress regime. This paper discusses the generation of multiple, consecutive fractures created in a way that enables them to reach formations in a manner not reached before using conventional means. In this scheme, the first fracture achieves “acceptable” production goals. If the process stopped at that point, the expense for this “mediocre” production increase would be high. However, in the new process, a second fracture is quickly initiated to take advantage of the stress modification created from the first fracture, allowing the second fracture to reach more productive rock not accessible to the first fracture. This paper will present field data that supports the feasibility of this concept. Various situations where this approach could reap substantial benefits are also presented.