A Reinterpretation of Historic Aquifer Tests of Two Hydraulically Fractured Wells by Application of Inverse Analysis, Derivative Analysis, and Diagnostic Plots

Abstract

Aquifer test methods have greatly improved in recent years with the advent of inverse analysis, derivative analysis, and diagnostic plots. Updated analyses of past aquifer tests allow for improved interpretations of the data to enhance the knowledge and the predictive capabilities of the flow system. This work thoroughly reanalyzes a series of pre-and post-hydraulic fracturing, single-well aquifer tests conducted in two crystalline rock wells in New Hampshire as part of an early 1970's study. Previous analyses of the data had relied on older manual type-curve methods for predicting the possible effects of hydraulic fracturing. This work applies inverse analysis, derivative analysis, and diagnostic plots to reanalyze the 1970's aquifer test data. Our results demonstrate that the aquifer tests were affected by changes in flow regimes, dewatering of the aquifer and discrete fractures, and changes due to well development. Increases in transmissivities are related to well development prior to hydraulic fracturing, propagation of a single, vertical fracture hydraulically connecting the two wells after stimulation and expansion of troughs of depression. After hydraulic fracturing, the estimated total yield of the individual wells increased by 2.5 times due to the hydraulic fracturing. However, the wells may be receiving water from the same source, and well interference may affect any significant increase in their combined yield. Our analyses demonstrate the value in applying inverse analysis, derivative analysis, and diagnostic plots over the conventional method of manual type-curve analysis. In addition, our improvement in the aquifer test interpretation of the 1970's test data has implications for more reliable estimates of sustained well yields.

Hydraulic characteristics of a fractured crystalline basement aquifer in Nzhelele area, Limpopo Province, South Africa

“…According to Lasher (2011), when the pressure in the fracture is released, it causes a change in rate of water level, shown by a drop in the derivative; the fracture contribution then reaches equilibrium with the surrounding matrix, showing unconfined aquifer behaviour causing the derivative to increase again. Hammond and Field (2014) also noted that the derivative formed a sharp peak, probably due to a rapid decline related to dewatering of the first fracture followed by recovery due to leakage in a leaky aquifer in New Hampshire. The results of this study show that the aquifer in the study area is characterised by fracture dewatering as they had rising and falling derivative curves in the log-log plots (Figure 3(a-e)).…”

Improving hydrogeological understanding through well-test interpretation by diagnostic plot and modelling: a case study in an alluvial aquifer in France

“…4c), even though the no-flow boundary does reproduce at medium time an increase in the derivative which can be erroneously attributed to a linear flow regime. -Bemani et al (2003) and Hammond and Field (2014) applied numerous analytical solutions to drawdown and log-derivative data solely at the pumping well. In the present study, the results obtained from the pumping-well data only are not sufficient to discriminate between the tested models, whether from their fits or their evaluated parameters, which appeared realistic whatever the model used.…”

“…It provides additional insight into the structure of the aquifer, which the basic Theis approach cannot achieve. Diagnostic plot analyses have been successfully applied in various heterogeneous aquifers such as karst (Maréchal et al 2008(Maréchal et al , 2014Jazayeri Noushabadi et al 2011;Spitzberg and Ufrecht 2013;Nassimi and Mohammadi 2017;Giese et al 2018), alluvial aquifers (Samani et al 2006;Mijinyawa and Gringarten 2008;Corbett et al 2012) or fractured aquifers (Illman and Neuman 2000;Beauheim et al 2004;Maréchal et al 2004;Hammond and Field 2014;Dewandel et al 2018). Usually presented in a log-log graph, the decomposition of the log-derivative signal into separate straight lines makes it possible to identify each hydraulic behaviour and eventually computes hydrodynamic properties (T, S) for each hydraulic behaviour.…”

Potential of Groundwater Reserves in Jeneponto Regency of South Sulawesi Province

“…This analysis aimed to assess the optimum rate of groundwater pumping in the site.Nowadays, the presence of various analysis and diagnostic plots generates fantastic improvements on the aquifer test method. Renewing analysis of the previous test enables to increase the improvement of interpretation of data to gain more knowledge capabilities of prediction of water flow in the system [7]. In managing groundwater resource and for the purpose of planning, many people prefer to conduct parameters model analysis due to more commonly and more accurate results that can be obtained from the analysis [8].Mathematical for groundwater has been generally used to simulate all situations either in local or regional settings [9].Analysing groundwater system can be a solution for many questions.…”