Optimized Approach to Conduct Hydraulic Fracturing Test on True Tri-Axial Stress Condition

Feng, Runhua (Curtin University) | Wang, Hongyu (The University of Western Australia) | Abdolghafurian, Mohsen (Curtin University) | Tarom, Nathan (Curtin University) | Hossein, Salemi (Curtin University) | Ezdini, Ayman (Curtin University) | Rezagholilou, Ali (Curtin University)

OnePetro 

ABSTRACT: Hydraulic fracturing has been widely applied to enhance hydrocarbon recovery in oil and gas field, especially for unconventional reservoir in which the permeability is usually nano-Darcy. In the field implementation, numerical modelling is initially performed, then the field testing (i.e. minifrac test) are conducted to infer the geological parameters. However, it is vital to perform laboratory tests (i.e. rock mechanical and hydraulic fracturing tests.) to obtain the rock mechanical parameters and important observations, which helps to mitigate uncertainties and risks encountered in both simulation modelling and field testing. Thus, a series of rock mechanical tests (i.e. unconfined/confined compressive, Brazilian tensile, and semi-circular bending) were conducted. Scaling analysis and true triaxial stress cell were applied to ensure the fracture propagated at the analogues field condition. Next, the logistic experimental procedure was explained and hydraulic fracturing tests were conducted on the 10cm cubic samples under true triaxial stresses. The unpredictable results were discussed and the optimized approaches were proposed. We concluded that system leakage and unbalanced stress loading can be detected and fixed at the earlier stage to avoid the sample was damaged.

1. INTRODUCTION

Hydraulic fracturing(HF) has been applied to assist the hydrocarbon flow by creating artificial permeability in unconventional reservoirs (i.e. shale, coal, and tight sandstone). This technique has been widely implemented in North American shale gas basin for more than three decades, which has been approved as an effective approach to significantly enhance the hydrocarbon recovery (Rezaee, 2015). The blooming of shale gas production in North America motivated the industrial engineers and researchers to investigate the potential reserves in unconventional basins in the world. However, the strong logistic and high expense are required to ensure the successful HF implementation in the field. Laboratory rock mechanical and HF experiments are usually conducted to obtain key parameters of the selected candidates which are applied for numerical modelling in the field. The preliminary bench-scale HF tests are recommended to obtain the required underground information before implementing the expensive field scale HF tests (Sarmadivaleh and Rasouli, 2015). However, there are some challenges that the engineer or researchers may encounter during conducting an effective hydraulic fracturing test (i.e. scarcity of core samples, apparatus, and logistic issues, etc.).