Prediction of Fracture Opening Pressure in a Reservoir Based on Finite Element Numerical Simulation: A Case Study of the Second Member of the Lower Triassic Jialingjiang Formation in Puguang Area, Sichuan Basin, China

Abstract

All stages of oil and gas exploration and development involve the study of in-situ stress. Since the traditional two-dimensional and three-dimensional homogeneous models can no longer fulfil the requirements of research and production, numerical simulation of the stress field has become an effective study method. In this study, we took the Jia 2 member in Puguang area as a case to establish a geological model and a mechanical model based on the tectonic framework and the distribution characteristics of the rock mechanical parameters, respectively, and loaded the model with the present-day in-situ stress state calculated from the logging data as the boundary conditions. The simulation results show that 1) the orientation of the maximum horizontal principal stress in the study area is near E-W, and the in-situ stress orientation is locally deflected due to the influence of faults; and 2) the magnitude of in-situ stress is predominantly affected by the burial depth and lithology, and the minimum horizontal principal stress, maximum horizontal principal stress, and differential stress are mainly concentrated in the ranges of 30–60, 50–80, and 10–40 MPa, respectively. We also analysed the opening sequence of the multiple fracture systems during development, using the present-day stress field model. The analysis revealed that the E-W fractures will open first, and the continuously increasing operating pressure will lead to formation breakdown, producing a fracture network.

Numerical simulation of the palaeotectonic stress field and prediction of the natural fracture distribution in shale gas reservoirs: A case study in the Longmaxi Formation of the Luzhou area, southern Sichuan Basin, China

“…In the numerical calculation process with the finite element model, the measured stress result of a single well is taken as the constraint condition and controls the error value of the calculation result through each constraint point. The error calculation formula and statistical results of the model are as follows (Li, Qin, Li, & Wan, 2022; Li, Zu, Li, et al, 2022; Xie et al, 2019): …”

“…T A B L E 5 Error comparison between measured and predicted maximum principal stress. (Li, Qin, Li, & Wan, 2022;Li, Zu, Li, et al, 2022;Xie et al, 2019):…”

“…On the premise that shale gas is preserved in a reservoir, the more developed the natural fractures are, the larger the gas storage space and the higher the gas content. In hydraulic fracturing development, when hydraulic fractures penetrate natural fractures, it is easier to form network fractures (Li, Zu, Li, et al, 2022; Wang et al, 2021; Xiao et al, 2022; Yu et al, 2022; Zhao & Gray, 2022). Examples of exploration and development in the Sichuan Basin have shown that fractures play an important role in the process of oil and gas production (Guo et al, 2016; He et al, 2016; Song et al, 2021; Wang & Wang, 2021; Zhang et al, 2016; Zou et al, 2017).…”

Characteristics and Controlling Factors of Natural Fractures in Deep Carbonates of the Puguang Area, Sichuan Basin, China

“…The Lower Triassic Feixianguan Formation is an important hydrocarbon-bearing stratum in the Sichuan Basin, China. − In the last few decades, numerous large-scale gas reservoirs have been found in the Feixianguan carbonates from Puguang, Yuanba, and Luojiazhai areas and have obtained appreciable commercial gas flow. The Puguang gas field is a key region for the natural gas exploration and development in the northeastern Sichuan Basin, with total proven geological reserves in the Feixianguan reservoirs exceeding 1000 × 10 8 m 3 .…”