Abstract

We introduce the concept of Fracture Treatment Optimization (FTO) to find and analyze the Point of Diminishing Return (PDR) of stimulations. The approach is based upon locating the opening and closing points of fractures as identified through Seismic Moment Tensor Inversion (SMTI) analyses of microseismic data collected during treatments. By using SMTI data, it is postulated that the size of a treatment, the proppant concentrations and amounts, types of fluid pumped and amounts, the rates of treatment, and disposition of the fracture network may be analyzed to determine if they are optimal for the formation and the stress conditions of each individual fracture stage. As described, FTO is performed as a post-treatment approach to characterize the effectiveness of the treatment process. The PDR is identified by analyzing the SMTI data for each event in time and compared to the fracture treatment data. We show, through example, how the SMTI data can be used to establish when the transition between fractures with opening components of failure and those including significant closure components of failure. We suggest that these states are indicative of reaching a PDR thereby allowing for changes to the treatment to be considered. In the examples provided, we identify apparent PDRs due to leakoff dominated pad stages which are too large and when proppant is added too late in the stage. Additional PDRs are identified in the treatment when an energy balance has been reached, where leakoff and fluid injection is at equilibrium. At this point we suggest that introducing a change in energy or proppant concentrations can optimize the treatment. This empirical optimization allows for potentially more economic and efficient stimulations in subsequent hydraulic fracture treatments in the field.

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