Growth Behavior of Hydraulically Created Crack and its Size Evaluation Using Well Logging Data -- Crustal Rock Fracture Mechanics Approach

Abstract

In order to analyze the growth behavior of hydraulically created cracks and to evaluate their sizes, crustal rock fracture mechanics approach was utilized in connection with well logging data obtained before, during and after hydraulic fracturing. In the analysis, unsteady state fluid permeation through crack surfaces into a formation was considered for a growing crack. The effects of hydraulic toughness of the consisting rock mass on crack growth behavior were first discussed based on numerical results and then the analysis way applied to evaluate the amount of crack extension during the small scale hydraulic fracturing at East Hachimantai field performed last fall. Furthermore, a new procedure was proposed for determining the instantaneous shut in pressure based on the physical insight into the pressure decay curve after shut in during hydraulic fracturing.