Fracture analysis and in situ stress estimation of a gas condensate field in Persian Gulf using FMI and DSI image logs

Abstract

A giant gas field (called Field X in this study) in the Persian Gulf is located in the northern part of Qatar's North field was considered in this study. Since the reservoir subjected to a strong tectonic compression, an accurate estimation of in situ stresses is important for reservoir-related issues and stress-related geo-hazards, such as wellbore stability, well completion, drilling a horizontal well, and fracture conductivity in Kangan and Upper Dalan formations. The formation microimager (FMI) and dipole sonic imager (DSI), as effective borehole image techniques, were used for stress determination and borehole breakouts (BOs) and drilling-induced fractures (DIFs) detection in field X. Based on 10 DIFs and 65 BOs derived from FMI logs and measured velocities of P-wave and S-wave from DSI logs in 3 gas wells, in situ stresses were determined in different tectonic units. The orientations of the maximum and minimum horizontal stresses in well B and well C were identified to be NE-SW and NW-SE, respectively. Additionally, the value of minimum horizontal stress was varied from 6210 to 9664 psi, the maximum horizontal stress was ranged between 7124 and 9968 psi, and the vertical stress was gradually increased with the depth from 10,000 to 12,000 psi. Hence, according to the relationships between the in situ stresses (v > Hmax > hmin), the tectonic stress regime of the studied area is normal.

Evaluation and engineering applications of the in situ stress state of deep tight sandstone reservoirs in the Xujiahe Formation of the Yingshan-Longgang in the central Sichuan Basin

“…Until the mud column pressure is less than a certain threshold, this stress is negative, indicating that it is a tensile stress. Once this tensile stress exceeds the rock tensile strength, a tensile-induced fracture appears in the well wall along the maximum horizontal principal stress (Jonaghani et al, 2019). When drilling the core, stress is released in the borehole, but it remains around the borehole.…”