Case Study: An Approach for Hydraulic Fracturing Minifrac G-Function Analysis in Relation to Facies Distribution in Multilayered Clastic Reservoirs

Abstract

Summary An industry-accepted standard for minifrac analysis for evaluating and improving design of hydraulic fracturing treatments originated from the original Nolte analysis (Nolte 1979) of pressure decline, followed by the introduction of Castillo G-function in a Cartesian plot (Castillo 1987). The latter provides a graphical method for the identification of fracture closure pressures and stresses with subsequent derivation of other parameters such as fluid efficiency and fracture geometry. With the introduction of a more advanced consideration of the G-function interpretation for various reservoir conditions (Barree et al. 2007), subdividing the interpretation into calculations based on flow regimes and leakoff modes, this approach has become even more sophisticated. Particularly, interesting flow regimes and leakoff modes during fracture closure include the fracture height recession mode. This mode tends to result in rapid screenout and difficulty in placing high proppant concentrations. Regarding interpretation, the G-function derivative curve for this mode can have more than one plateau, an outcome that is possibly indicative of features that have not been widely considered to date or on which little to no data have been published. This paper presents a case study as an example of such height recession mode, along with a subsequent G-function interpretation and analysis and with consideration of the vertical facies distribution along the wellbore. Considerable attention is paid to the G-function derivative plateau analysis. Three distinctive wells, namely X-1,X-2, and X-3, are discussed. Using this technique can lead to an improved fracture calibration, optimized fracture design, and adoption of a successful completion strategy; additionally, the confirmation of 1D facies distribution can provide new insights into the fracture closure period.

Fracture size inversion method based on water hammer signal for shale reservoir

“…The common calculation methods are: G-function analysis, AVO (Amplitude Variation with Offset) inversion, thermal neutron detection technology and field direct logging or microseismic detection. Since the G-function method was proposed in 1987, the research on fracture size calculation methods by G-function had been widely studied (Castillo, 1987;Yuan et al, 2016;Recep et al, 2021;Tu et al, 2022;Jatykov and Bimuratkyzy, 2022). However, the traditional G-function model is difficult to estimate the shape of the multi-fracture network in each fracturing stage.…”

“…Parameters that can represent the impact of fractures on pressure signal are added into the transient flow model. When the fitting pressure value satisfies with the real data of actual stimulation pressure curve, those parameters presenting fracture impacts can be set as the real fracture size (Qiu et al, 2022;Carey et al, 2015;Hwang et al, 2017;Iriarte et al, 2017).…”