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This report mainly discusses applications of the Moving Reference Point (MRP) technique that Pirayesh et al. (2013) have developed as an improvement from Nolte and Smith (1981) who identified the ongoing fracture propagation behavior using pressure-time analysis. Both works are based on the original power-law fracture propagation theory that was developed by Perkins and Kern (1961) and refined by Nordgren (1972). Making a corrective decision on the pumping schedule, as the job is in progress, is one of the advantages of this kind of analysis. Understanding the pressure-time trend as a diagnostic tool will significantly improve the efficiency of the future hydraulic fracture treatments, and hence enhanced the field development optimization. The Nolte-Smith method developed the pressure response idea of a formation in order to identify the fracture mode during injection. Although, that technique showed reliability in pressure-time interpretation, the nature of the used log-log (net pressure, Pnet vs. time) plot has a disadvantage, which is a slow recognition of the mode change due to data compression with time. Limited budget operators consider a previous knowledge of the closure pressure to calculate the Pnet another short coming. The MRP uses a Cartesian (e)-time plot, which can detect the fracture behavior change faster than the Nolte-Smith log-log plot. It requires only the job pressure-time records; using downhole pressure measurement is advised in order to eliminate the pipe friction effect. Five hydraulic fracture treatments from Cotton Valley and Travis Peak formations (East Texas - USA) were included in this project. Difficulties, to relate the fracture physical description to the formation geology, were faced due to unavailability of the wells’ completion and Petrophysical (openhole logs) information. However, the results showed how complex the formations, and observations and recommendations were made to enhance the future hydraulic fracture treatments and hence the field development. Additionally, an empirical method (Pnet derivative) was developed and plotted against the MRP; they are comparable practically in cases where a significant fracture behavior change occurred. Although the Pnet derivative still needs the closure pressure to calculate the Pnet, the short-coming of using a log-log scale plot is eliminated and instead a Cartesian chart is utilized. |
