Advantages of the Moving Reference Point (MRP) Technique over the Net Pressure (Pnet) Derivative Method: Comparison using Case Studies
An empirical method, based on derivative of net pressure (Pnet ), was developed as a pressure-time diagnostic tool. It inherited the assumptions of the original power-law fracture propagation theory developed by Perkins and Kern (1961) and refined by Nordgren (1972), except that the fracture propagates continuously during pumping. Nolte and Smith (1981) accepted the hypothesis of the continuous confined-fracture extension. However, the Pnet Derivative agreed with the MRP method that the fracture may experience alternating cycles of propagation, dilation, and height growth during pumping. The MRP technique uses the treating pressure while, similarly to the Nolte-Smith method, the Pnet Derivative application needed the closure pressure (Pc ), which is a disadvantage for the limited budget operators. The shortcoming of using a log-log type plot was eliminated and instead a Cartesian chart was utilized mimicking the MRP method style of result display. The present study shows that the results of the MRP and the Pnet Derivative methods are practically comparable when a considerable treating pressure change occurred.
Because of the innovative moving reference point process embedded in the MRP's workflow, the technique revealed its ability to handle fluctuating pressure and to recognize fracture behavior change, even if the treating pressure change is not significant, better than the Pnet Derivative method. This study also identified the disadvantage of presenting highpoint moving average line (to smooth the fracture mode) as it pushes forward the curve in time. The minimum point average line provides more details, but keeps the general fracture mode is recommended to be presented.
Document Type: Research Article
Publication date: 01 December 2016
This article was made available online on 26 December 2016 as a Fast Track article with title: "Advantages of the Moving Reference Point (MRP) Technique over the Net Pressure (P<sub>net</sub>) Derivative Method: Comparison using Case Studies".
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